Tag Archives: health

5 ‘superfood’ myths

While many foods may be packed with certain nutrients and molecules that play a role in health, the food industry and health nuts have taken a massive leap of logic and applied the term ‘super’ to foods which are actually fairly ordinary.

The main message here: Some foods are better for you than others but there is no such thing as a super food.

I’ve come across articles titled ’52 of the best super foods’. So pretty much all food then. It contained everything from eggs to apples. It’s all nonsense. Maintain a balanced diet and get in some good exercise. That’s it.

Here are the top 5 super foods and the real truth behind them…

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#1 : Goji Berries

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Eat me and live for 170 years guy! healthline.com
Eat me and live for 170 years guy!
healthline.com

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.These bad boys have been a major component of Chinese traditional medicine for hundreds of years.  An ancient Chinese herbalist, Li Ching-Yuen, who loved these berries, was said to have lived for over 170 years because he ate so many. Obviously that’s mental.

There is no evidence of any kind that eating the berries or drinking the juice is any better or worse than drinking juice from other fruits.

The ‘studies’ that attribute miraculous health benefits to these berries are hugely biased, poorly planned, performed, reported  and very few in number (1,2)

These berries are fairly expensive, probably because they have been labelled a super food. If you enjoy eating them then by all means carry on but don’t expect any particular health benefits for your buck.

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#2 : Kale

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'basically cabbage' lifehack.com
‘basically cabbage’
lifehack.com

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Kale, to me, seems rather exotic. It’s all the rage at the moment at organic cafes and other ‘alternative’ hangouts. Like other ‘super foods’, many magical properties have been attributed to kale – it helps you ‘make red blood cells’ and ‘mops up free radicals’ thereby reducing your risk of cancer.

While kale contains high levels of calcium and vitamins like B6, this isn’t really any different to other, similar green vegetables like cabbage. There is also no evidence supporting claims that diets high in kale can reduce cancer or really help with anything else either in humans. The limited evidence there is is all in vitro (cell based work in a lab) data which has been misinterpreted (probably on purpose) to promote kale as a super food. There is no doubt that a balanced diet with lots of vegetables is better for you than one full of processed foods (lowered risk of various cancers for one thing) but attributing the health benefits to kale alone is wrong.

Kale does contain a decent level of anti-oxidants but so do many other fruits and vegetables and other foods.

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Anti-oxidants play myriad vital roles in the body but massively increasing your intake will not improve your overall health and may even damage it (3).

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All these health food blogs keep banging on about anti-oxidants without understanding the basics tenants of biology that I keep droning on about. There is a saturation point for all nutrients and molecules past which your body just gets rid of them or maybe even starts suffering negative consequences (4). Taking more of something when you aren’t deficient in the first place very rarely produces a positive benefit. I read a good analogy online:

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”It’s like putting more petrol in your car to make it go faster”.

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Neither cars nor your body work like that.

Kale is not super. It’s no more special than your average sad piece of cabbage.

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#3 : Pomegranates

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pomegranates.org
pomegranates.org

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Pomegranates are delicious. Those little juicy nuggets of pure flavour are always welcome in my home. However things turn sour when I hear that pomegranates are not just a simple fruit – they can fight against heart disease, inflammation, high blood pressure and some cancers (the list always seems to be the same). In other words they are super. Or are they?

Now surprisingly there is some potential for further work looking at pomegranate consumption and health benefits. Although the data are currently inconclusive regarding human health – there does appear to be a positive effect in some small trials.

Pomegranate consumption has been linked to increased bone strength in mice (5).

A small study (perhaps too small) involving 45 human patients  with coronary heart disease concluded that daily pomegranate juice increased blood flow to the heart and a reduced risk of heart attack (6). The trail was small so the result could be down to chance – this is worth repeating with a larger cohort.

A study undertaken a year previously using patients with carotid artery stenosis (narrowed arteries) found that a small daily glass of pomegranate juice (50ml) over three years reduced cholesterol buildup and cholesterol-damage in the artery by almost a half. A clear reduction (7). Over ten years later and the mechanics of this are still not understood. The study also fails to demonstrate how this will positively effect stroke and heart attack rates or outcomes.

It seems, out of all of these ‘super foods’ that pomegranates have the most real evidence behind them. However, these are all small studies so the chance of a positive result occurring by chance are much higher.

One pomegranate based company has been warned by the FDA for using published data, as shown above, to make illegal claims of unproven anti-disease benefits: this is very common in the health food industry and is extremely unfair and misleading for the consumer.

In order to make specific health claims,  far larger cohort studies followed by detailed mechanistic studies would have to be performed before we label pomegranates as having any real health benefits. 

As it stands, pomegranates may have some protective effects on heart and cardiovascular health – but we need more solid data to firmly conclude this.

 

 


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#4 : Avocado

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avocado-sliced-in-half
I’m all stone baby avocado.org.au

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First off. I love avocados. I’m not here to insult them or their families – just to question there position as a ‘super food’. An avocado is a fruit, even though I think of it as a vegetable. Getting even more technical, an avocado is apparently a large berry. What?

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Avocados are packed with all sorts of deliciousness – Vitamin A, C, K and E as well as potassium and carotenoids. On top of that an avocado is basically just a big fat berry. Literally. It’s full to the brim with a wide variety of fats, with most calories from avocado being in the form of monounsaturated fat. Due to this they are a great way to gain weight if strength training or bodybuilding – just go easy on them due to the fat content!

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Now, are they super foods? Do they cure cancer or diabetes or arthritis. As you may have guessed the answer is probably no. Although the literature is very sparse regarding avocado consumption and health specifically, we can look more closely at the effects of a high intake of monounsaturated fats on our health. Eating a good amount of these fats is protective against cardio-vascular disease (8). A review of available studies looking at avocado consumption and cardiovascular disease also suggests a protective effect but be wary as the review was paid for by Hass Avocado Board (9).

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Again, any advocate of super foods will list a number of benefits and then reason them like this with little to no sources. This is an actual argument I came across:

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  1. Luetin is a carotenoid found in the human eye and plays a role in vision
  2. Avocados contain luetin
  3. Avocados improve eyesight (this is a massive leap in logic and not confirmed by any investigation)

And another to hammer the point home..

  1. Vitamin B6 plays a role in the regulation of hormones like testosterone
  2. Avocados contain B6
  3. Avocados increase fertility and sexual health (nope – for the same reasons)

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Avocados are delicious but they wont help you with sexual function, fertility, diabetes or cancer. These things may be reduced or combated by changes to your entire lifestyle – not just eating one particular giant berry.

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#5 : Broccoli

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wikipedia.org
Can’t get enough of those baby trees – Wikipedia

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When I was a young boy/girl, broccoli was the worst. It was sort of universally hated by children. I think it still is. But for adults, and the health food market, broccoli has made a solid comeback in recent years and frequents ‘super food’ lists all over the web. What does the science say about the health benefits of this baby tree vegetable?

Well unlike avocados, more research has been undertaken in this area but unfortunately most of it is very small scale, too small to be conclusive on it’s own.

First, eating more non-starchy vegetables such as broccoli (but not necessarily broccoli only) is associated with a reduced risk of some cancers, namely throat, mouth and stomach cancer. It is therefore possible that something in the broccoli is responsible but this would need to be tested directly in further trials.

There is no evidence that broccoli helps reduce blood pressure despite some claims that it does. A cohort of individuals with high blood pressure consumed daily broccoli for 4 weeks – no change was observed in their blood pressure nor was the risk of atherosclerosis reduced (10). However in a similar but positive vein, diabetic patients consuming broccoli powder daily, saw reduced levels of circulating cholesterol and triglycerides – both of which are risk factors for cardiovascular disease (11).

”Broccoli sprout powder could have favourable effects on  lipid profiles”

What about treating diabetes itself? Well, in an odd study, researchers applied the antioxidant sulforaphane (found in broccoli) to human blood vessels incubated in sugar. They were trying to mimic the conditions of chronic diabetes and elevated blood sugar levels. They found that the anti-oxidant appeared to prevent vascular damage to small blood vessels caused by high blood sugar as seen in many diabetic patients (12). As this is pure lab work using isolated tissue it remains to be seen if sulforaphane would be protective  in diabetics.

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What are your thoughts?

-ScienceGuy

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References

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1) Zi et al (1994) ”Observation of the effects of LAK/IL-2 therapy combining with Lycium barbarum polysaccharides in the treatment of 75 cancer patients’‘ Chinese Journal of Cancer Research. 16(6):428-31.

2) Amagase, H; Nance, D, H. (May 2008) ”A randomized, double-blind, placebo controlled clinical study of the general effects of standardised Lycium barbarum Juice” 14(4):403-12.

3)) Bjelakovic et al (2012) ”Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases” Cochrane Database of Systematic Reviews

4) Ristow et al (2009) ”Antioxidants prevent health promoting effects of physical exercise in humans” PNAS 106(21) 8665-86705

5) Spilmont et al (2013) ‘‘Pomegranate and its derivatives can improve bone health through decreased inflammation and oxidation stress in an animal model of postmenopausal osteoporosis” European Journal of Nutrition 53(5) 1155–1164

6) Sumner et al (2005) ”Effects of pomegranate juice consumption on myocardial perfusion in patients with coronary heart disease”  96(6):810-4.

7) Aviram et al (2008) ”Pomegranate juice consumption for 3 years by patients with carotid artery stenosis reduces common carotid intima-media thickness, blood pressure and LDL oxidation” Clinical Nutrition 23(3):423-33.

8) Sacks and Katan (2002) ”Randomised clinical trial on the effects of dietary fat and carbohydrate on plasma lipoproteins and cardiovascular disease” The American Journal of Medicine 113(9), Supplement 2. p. 13-24

9) Dreher and Davenport (2013) ”Hass avocado composition and potential health effects”  Critical Reviews in Food Science and Nutrition 53(7): 738–750.

10) Christiansen et al (2010) ”Ingestion of broccoli sprouts does not improve endothelial function in humans with hypertension” PLos One 5(8)

11) Bahadoran et al (2012) ”Broccoli sprout powder could improve serum triglyceride and oxidised LDL/LDL-cholesterol ratio in type 2 diabetic patients: a randomised double-blind placebo-controlled clinical trial’Diabetes Research and Clinical Practice  96(3):348-54

12) Mingzhan Xue et al (2008) ”Activation of NF-E2-related factor-2 reverses biochemical dysfunction of endothelial cells induced by hyperglycemia linked to vascular disease’Diabetes 

5 common food myths

Myths about common foods that we eat are all over the internet, fitness and health shops and of course the gym. Once these ideas and ‘facts’ take hold they are exceptionally hard to shift.

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Here are the top 5 myths about  the foods we eat.

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#1 : Eggs are full of cholesterol and will lead to a heart attack

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eggs-1I plan on addressing this more fully in a later post because it definitely deserves further attention (I bloody love eggs). Eggs received a bad reputation a number of years ago and unfortunately this has stuck around. Many people mistakenly believe that eating eggs, especially the yolk, has a terrible effect on your cholesterol which increases risk of cardiac/circulatory issues.

It is true that elevated levels of LDL cholesterol is definitely bad for your health but eggs aren’t a significant contributory factor (1,2)

Eggs are a cheap and plentiful source of proteins, fats and an assortment of minerals. If you want to sneak some protein in quickly without spending a lot, eggs are perfect for you.

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#2 : Margarine is healthier than butter

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.I myself am a marge to butter convert. I used to eat margarine, not for any health reason, but because I simply always had. I switched to butter a few years ago after being insulted for eating margarine. ‘what is this bullshit’ people would say when searching for butter in the morning and finding a massive tub of Utterly Butterly or as ALDI calls it, Wonderfly Butterfly ( I love ‘almost’ copyright infringement)

There’s not much difference in calorie content between marge and butter but margarine often contains much higher levels of trans-fats. Eating lots of trans fats is linked to numerous health problems. (3)

Magarine was created as a cheaper and healthier alternative to butter but can actually end up way worse for you in the long run (4). On top of that butter tastes far better!

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#3 : Eat an orange to prevent colds

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I have written  extensively about the role vitamins play in our day to day health and how vitamin supplements, for the average person, are a massive waste of money.

There is a commonly held belief hat vitamin C, found in large amounts in oranges, can prevent or cure common colds.

Neither is true (5).

Vitamin C only seems to play a role in limiting cold duration in specific scenarios involving intensive exercise in cold environments (6)

For a more in depth read about the multivitamin scam take a look here.

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#4 : Go with fat-free alternatives to lose weight

 

fage

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The issue that food manufactures have, especially with more processed foods, is that fat = flavour. If you remove fat from a product in an attempt to create a healthier product then the flavour has to come from somewhere. The answer? Sugar.

This has proved to be a short sighted and potentially health-damaging decision.

Fat has been demonised for decades (mainly due to the power of global corporations that produce sugar-filled products) and the public, and even the government (based on their eating guidelines) believe eating fat is to blame for the obesity epidemic. This has been more heavily scrutinised in recent months following the publishing of a damning report on the topic.

The truth is much more complicated and companies adding sugar to everything in place of fat is nothing but detrimental. In most cases, you would be better off eating the full fat version as the quantity of sugar found in fat-free versions of processed products is preposterous.

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#5 Canned food is less nutritious and ‘healthy’ than fresh

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This all depends on timing. If vegetables and fruit are picked in front of you and you eat them  right there, the fresh stuff will be more nutritious.

However, if we are comparing products in a supermarket the story is reversed. Canning or freezing food essentially fixes it as it was just as it was sealed away – hopefully full of nutrients. In comparison, although visibly fresh, fruit and veg lying around in supermarkets is on a constant downwards nutritional slope from the moment it is picked, all through transport  to the moment you buy and then finally eat it (7).

There is nothing wrong with canned or frozen fruit and veg – in fact, sometimes it might beat the ‘fresh’ version. Taste is another matter!

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Well there you go. Enjoy your canned eggs with butter.

 

-Science Guy

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References

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1) Rong, Ying; Chen, Li; Tingting, Zhu; Yadong, Song; Yu, Miao; Shan, Zhilei; Sands, Amanda; Hu, Frank B; et al. (2013). “Egg consumption and risk of coronary heart disease and stroke: dose-response meta-analysis of prospective cohort studies”. British Medical Journal. 346

2) Hu FB, Stampfer MJ, Rimm EB, et al. (1999). “A prospective study of egg consumption and risk of cardiovascular disease in men and women”. JAMA. 281 (15): 1387–94.

3) K. Hayakawa, Y.Y. Linko, P. Linko, “The role of trans fatty acids in human nutrition,” Journal of Lipid Science and Technology102, 419–425 (2000)

4) Zaloga GP, Harvey KA, Stillwell W, Siddiqui R (2006). “Trans Fatty Acids and Coronary Heart Disease”. Nutrition in Clinical Practice. 21 (5): 505–512.

5) Hemilä H, Chalker E (January 2013). “Vitamin C for preventing and treating the common cold”. Cochrane Database of Systematic Reviews.

6) Douglas RM, Hemilä H (June 2005). “Vitamin C for Preventing and Treating the Common Cold”. PLoS Medicine. 2(6)

7) S.D. Holdsworth (1985) ”Optimisation of thermal processing – A review” Campden Food Preservation Research Association.

The Multivitamin Hoax

I was flicking through good old Facebook, the book of face, the other day when I came across an advert for yet another multivitamin product under the name of VITL. Presumably a play on the word vital…as in, you vitally need this supplement to be healthy. Or do you?

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Multivitamin supplements and other products that fall into that sort of category such as anti-oxidant pills are consumed in huge quantities in the UK and US. Many people swear by them and start their day swallowing down a random amount of varied vitamins. Vitamins are good right? They are important in loads of physiological processes so surely more of them is better?

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Looks enticing but 35.99 a month is a bit steep....
Looks enticing but 35.99 a month is a bit steep….

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In reality the science suggests two things rather clearly if you are an average person:

  • All your vitamin needs are met by your diet if its fairly balanced
  • Taking too much of a particular vitamin can have serious repercussions to your health

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I don’t wish to target VITL directly as many companies are peddling their vitamin wares. It’s not the product itself I have an issue with but the target market. It makes medical sense to supplement a vitamin that you are clinically deficient in but trying to sell expensive vitamins to people who don’t need them is a complete waste of the customers money and in some cases potentially harmful to their health.

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What is a ‘vitamin’ 

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 A vitamin can be defined as such :

‘A vitamin is an organic compound and a vital nutrient that an organism requires in limited amounts’ (the key phrase here is ‘in limited amounts’)

Technically speaking, ‘vitamin’ refers to a chemical compound that an organism requires but cannot synthesise by itself in sufficient quantities. The vitamin must therefore largely be obtained from dietary sources.

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Vitamins are classed based on their biological and chemical activity, not on their structure. Therefore a number of vitamin-like compounds (vitamers) may be grouped together under one umbrella vitamin name. For example ‘Vitamin B’ includes a large number of ‘vitamers’ each with their own B number and additional name. Vitamin B9 for example is Folic Acid. Not all vitamers are in the biologically active state but can be converted into this form in the body.

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Thirteen vitamins are currently recognised: Vitamins A, B (8 vitamers), C, D, E and K

 


Physiological Roles

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Vitamins play a varied and diverse role in the body and have widely different functions.

I’ve made a table to summarise this section in brief as it’s fairly in depth!

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vitamin-table-1

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The large group of vitamin B type-compounds  act as co-enzymes (and precursors) in metabolic processes. Co-enzymes are non protein compounds that are required by the protein enzyme to catalyse specific reactions in a cell (1). They therefore perform an extremely important role in the minute by minute function of cells. Acting as co-enzymes is their most recognised functional role but there are many others (2). Large amounts of research effort has been put into uncovering the therapeutic potential of the B vitamin family of compounds. Many do have true therapeutic value but only in the treatment of serve disorders. B9 for example, also known as folic acid, has been shown to reduce the rate of neural tube defects (NTDs) in infants and as a result can be found fortified into many different foods in a hope to reduce the incidence of NTDs in the population (3). There is also some evidence that folic acid supplementation may confer a small reduction in the risk of stroke and cardiovascular disease if taken over a long period of time (4)

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Vitamin D possesses hormone-like functions and act as regulators of mineral metabolism and plays a part in the control of tissue growth and differentiation (5). A chronic lack of vitamin D famously leads to ‘rickets’, a disorder of bone growth and structure. Sunlight (certain wavelengths) modify Vitamin D into its active form which is why at least some exposure to the sun is important. Foods are often fortified with vitamin D in countries that receive lower levels of sunlight (less hours and or/less intensity) but can be found naturally in oily fish and eggs (6).

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Vitamin C acts as both an enzymatic co-factor and also  functions as  an anti-oxidants to protect agasint oxidative stress. The vitamin is a co-factor in a number of important enzymatic reactions, a few of which are related to the synthesis of collagen,  a key structural protein. A lack of vitamin C can impact collagen production leading to scurvy. 

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Yaaaaargh. Eat an orange.
Yaaaaargh. Eat an orange.

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Vitamin C is a well studied vitamin and makes common appearances in health food shops and websites as a sort of ‘cure-all’ especially targeting things like the common cold and other respiratory pathologies (that website link claims you can cure pretty much any disease). However vitamin C supplementation studies have shown conflicting results. A number of studies suggest that vitamin C supplementation may reduce the duration of common colds (7) but it doesn’t seem to prevent colds in the first place (8). The potential protective effects of vitamin C supplements regarding cardiovascular health and lung cancer has also been explored in depth but overall studies suggest no detectable protective effect (9,10,11). Two of these references are systematic reviews and analyse the data from multiple studies. One of which is a Cochrane review who are known to be very thorough in their approach.

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Vitamin E has a number of roles including acting as a fat-soluble anti-oxidant. The vitamin essentially mops up free radicals preventing oxidation stress and tissue damage. This vitamin has also been the subject of a study looking at protective effects against major cardiovascular events in middle aged men but supplementation does not increase protection (12) Surprisingly one report suggested vitamin E supplementation might even increase the risk of lung cancer for already at-risk individuals.(13)

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Vitamin K is required for the complete synthesis of a number of important proteins involved in blood coagulation (various coagulation factors) , vascular biology and bone metabolism (14). In somewhat of a developing theme, vitamin K supplementation was explored as a means to prevent or reduce the incidence of cardiovascular disease. This makes sense as vitamin K deficiency is associated with the stiffening of arteries (15). Despite this, there is no good evidence that vitamin K supplementation will stop cardiac events occurring in the first place (16). The science also refutes fairy common claims that vitamin K supplements can slow cancerous tumour growth (17).

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Overall, studies which look at standard supplementation (rather than the effects of over-supplementation) have produced few promising results. Unless you are deficient in a particular vitamin then supplementation has no detectable benefit to your health. The only possible exception to this is vitamin C supplementation in regards to common cold duration. Additionally, vitamin C supplementation may help in the prevention of common colds when individuals are exercising rigorously in cold environments (18, 19). This seems like a super specific scenario but if you plan on skiing naked for a prolonged period of time than maybe pop a vitamin C tab or two (but not three…that’s just getting silly)

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*Tactical dong strap*

 


Daily multivitamins are potentially harmful

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I’m going to take aim at Berocca here as an example. Berocca is an effervescing tablet that you plop into a glass of water and it releases all it’s tasty, healthy vitamins and minerals (we know the truth berocca you scum bag!). Now, unlike VITL, who I assume have done their research on vitamin absorption, the people behind Berocca have added a ludicrously large % of your RDA (Recommended Daily Allowance) for many of the vitamins. I mean, 1071% of your recommended daily allowance of B1! That is mental for a number of reasons.

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A quick excerpt from the brilliant website quackwatch.org about RDAs:

”The RDAs have been published by the National Research Council approximately every five years since 1943. They are defined as “the levels of intake of essential nutrients that, on the basis of scientific knowledge, are judged by the Food and Nutrition Board to be adequate to meet the known nutrient needs of practically all healthy persons.” Neither the RDAs nor the Daily Values listed on food labels are “minimums” or “requirements.” They are deliberately set higher than most people need. The reason quacks say that the RDAs are too low is obvious: if you believe you need more than can be obtained from food, you are more likely to buy supplements”

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The doses in VITL stay within recommended limits
The doses in VITL stay within recommended limits

 

1000 % of your RDA is 900 % too much!

Firstly I have already shown you that for the average healthy person, supplementing with any vitamin doesn’t provide protection against diseases or make you ‘healthier’ in general. 

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Secondly, vitamins are only required in limited quantity. The phrase ‘more is better’ is almost always wrong when applied to biology. Any additional vitamins taken in are excreted as waste so those doses are needlessly high.

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Finally, those super high percentages may hide a sinister detail. Not only are excess vitamins pointless they have also been linked to increased risk of a variety of diseases. Over-dosing on some of the vitamins can also induce a specific set of symptoms depending on the vitamin as summarised below.

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Major studies looking into the effects of long term vitamin supplementation have produced surprising but solid data.

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General Mutlivitamin Tablets: Two large meta-studies, headed by the same researchers, that had access to data from hundreds of thousands of people (more likely to show a true effect) found that individuals taking daily multivitamins had an INCREASED RISK OF MORTALITY in comparison to people who don’t (20,21). Mortality of course covers death from all causes so those people taking multivitamins daily have an increased risk of dying in general. That’s pretty bleak. Other studies have looked at certain vitamins in particular and their effects on the incidence rates of specific diseases. The situation is no less bleak unfortunately…

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Vitamin A: As the table further up the article shows, vitamin A can be found in green leafy veg, oranges and milk to name just a few sources. Carrots are also a great source. You only need to eat half a carrot to obtain you recommended daily allowance. Now these studies are specific to smokers but beta-carotene (form of vitamin A) was explored for it’s therapeutic value in lung cancer development. Shockingly those smokers on beta carotene supplements saw a 28% increased incidence of lung cancer (which is already comparatively high in smokers), a huge increase! So unexpected was this result that the trial was terminated ahead of schedule. (22, 23)

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The horror!
The horror!

 

Vitamin E: A large number of studies have been conducted concerning Vitamin E supplementation and, like vitamin A, the results are rather disturbing. A study trying to determine if vitamin E could be used to reduce cancer and cardiovascular disease uncovered an increased risk of heart failure in patients taking ‘excessive amounts’ of vitamin E (this why those crazy high % RDAs in some products are dangerous!). These patients all had existing vascular disease or diabetes mellitus (24). Perhaps excessive vitamin E exacerbates circulatory problems that surface with both vascular disease and chronic diabetes.

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Another study produced a similar finding to the Vitamin A meta-studies in that vitamin E supplementation correlated with increased mortality (25). This was a large study involving over 100,000 individuals. The conclusion says it all:

”High-dosage (> or =400 IU/d) vitamin E supplements may increase all-cause mortality and should be avoided.”

Of relevance to men, a more recent 2011 study with 35,000 participants  showed that vitamin E supplementation significantly increased the risk of prostate cancer (26)

Ultimately, the science refutes the phrase ‘you can’t have too much of a good thing’. Multivitamins and specific vitamin supplements have been linked with an increased risk of death in general, prostate cancer in men, skin cancer in women and  heart failure in those already at risk.

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Admittedly, these trials expose participants to vitamin levels far above their recommended allowance but that shows us how potentially dangerous it is for companies to make products (for daily consumption) with 5 or 10 times the recommended levels. 

 


Summary: Do you need daily multivitamin supplements?

 

For the average person, the simple answer is a resounding no. All your vitamin needs are met by your diet.

In fact, it should be an aggressive  ‘no’ because you may in fact actually be damaging your health. If you do still wish to take daily vitamins then for the love of god at least check the % RDA on the back and stay away from those products that provide 1000% of your RDA in one daily serving.

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”2000 percent of my RDA? F*ck that sh*t!”

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Whats important to remember is that although the evidence shows that vitamin supplements, in general, will not make you ‘healthier’ this is all assuming you have a fairly balanced life style and diet to begin with. If you are known to have a deficiency in a particular vitamin then supplementing may still be helpful as long as you stay within recommended daily intakes. Of course, listen to your doctor.

Finally, as an added note: I’ve written this article without touching on fitness or training at all. Not many studies focus on this topic and it would be a very short article if I did. The story is much the same as has been told above. Unless you have a legitimate reason to take vitamins, taking extra won’t effect your general health or really impact your training in any meaningful way. Vitamins are peddled all over fitness and body-building websites just like at health food equivalents but now you know that they are a TOTAL WASTE OF MONEY. 

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My only advice, and this applies to all supplements, is that actual food should always come first. That’s the whole idea of a supplement, to supplement what you are are (or are not) getting through your diet. Your money would be much better spent on frequent purchases of fruit and vegetables.

Any questions? Feel free to reach me at ed@scienceguysupplements.com

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Thanks for reading,

ScienceGuy

 


Text References 

I recommend using Google Scholar to quickly find these studies in full detail.

1) University of Bristol (2002). “Pantothenic Acid”. Retrieved 16 September 2012.

2) National Academy of Sciences. Institute of Medicine. Food and Nutrition Board, ed. (1998). “Chapter 6 – Niacin”. Dietary Reference Intakes for Tjiamine, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin and Choline. Washington, D.C.: National Academy Press.

3) Bailey, Lynn B. (2009). Folate in Health and Disease, Second Edition. CRC Press. p. 198

4) Li Y, Huang T, Zheng Y, Muka T, Troup J, Hu FB (2016). “Folic Acid Supplementation and the Risk of Cardiovascular Diseases: A Meta-Analysis of Randomized Controlled Trials”. J Am Heart Assoc. 5 (8)

5) Holick MF (March 2006). “High prevalence of vitamin D inadequacy and implications for health”. Mayo Clin. Proc. 81 (3): 353–73.

6) Holick, M.F. The Vitamin D Deficiency Pandemic: a Forgotten Hormone Important for Health. Health Reviews. 2010; 32: 267-283.

7) Douglas RM, Hemilä H, Chalker E, Treacy B (2007). Hemilä H, ed. “Vitamin C for preventing and treating the common cold”. Cochrane Database Syst Rev (3): CD00098

8) Heimer KA, Hart AM, Martin LG, Rubio-Wallace S (May 2009). “Examining the evidence for the use of vitamin C in the prophylaxis and treatment of the common cold”. J Am Acad Nurse Pract. 21 (5): 295–300

9) Fulan H, Changxing J, Baina WY, Wencui Z, Chunqing L, Fan W, Dandan L, Dianjun S, Tong W, Da P, Yashuang Z (October 2011). “Retinol, vitamins A, C, and E and breast cancer risk: a meta-analysis and meta-regression”. Cancer Causes Control. 22(10): 1383–96.

10) Ye Y, Li J, Yuan Z (2013). “Effect of antioxidant vitamin supplementation on cardiovascular outcomes: a meta-analysis of randomized controlled trials”. PLoS ONE. 8 (2): e56803.

11) Stratton J, Godwin M (June 2011). “The effect of supplemental vitamins and minerals on the development of prostate cancer: a systematic review and meta-analysis”. Fam Pract. 28 (3): 243–52.

12) Rimm E, Stamper M, et al.(May 1993). ”Vitamin E consumption and the risk of coronary heart disease in men” The New England Journal of Medicine . 328 (20) 1450-1456.

13) Heionen OP, Albanes D (April 1994). ”The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers” The New England Journal of Medicine. 330:1029-1035

14) “Vitamin K Overview”. University of Maryland Medical Center.

15) Maresz K (2015). “Proper Calcium Use: Vitamin K2 as a Promoter of Bone and Cardiovascular Health”. Integrative Medicine (Encinitas, Calif.) (Review). 14 (1): 34–9.

16) Hartley L, Clar C, Ghannam O, Flowers N, Stranges S, Rees K (2015). “Vitamin K for the primary prevention of cardiovascular disease”. Cochrane Database Syst Rev (Systematic review). (9)

17) Ades TB, ed. (2009). “Vitamin K”. American Cancer Society Complete Guide to Complementary and Alternative Cancer Therapies (2nd ed.). American Cancer Society. pp. 558–563.

18) Douglas RM, Hemilä H (June 2005). “Vitamin C for Preventing and Treating the Common Cold”. PLoS Medicine. 2(6):

19) Hemilä H, Chalker E (January 2013). “Vitamin C for preventing and treating the common cold”. Cochrane Database of Systematic Reviews. 1

20) Bjelakovic G, Nikolova D, Simonetti RG, et al. Antioxidant supplements for prevention of gastrointestinal cancers: a systematic review and meta-analysis. Lancet. 2004 Oct 2-8;364(9441):1219-28.

21) Bjelakovic G, Nikolova D, Gluud LL, et al. Mortality in randomized trials of antioxidant supplements for primary and secondary prevention: systematic review and meta-analysis. JAMA. 2007 Feb 28;297(8):842-57.

22) Omenn GS, Goodman GE, Thornquist MD, et al. Risk factors for lung cancer and for intervention effects in CARET, the Beta-Carotene and Retinol Efficacy Trial. Journal of the National Cancer Institute. 1996 Nov 6;88(21):1550-9.

23) The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers. The Alpha-Tocopherol, Beta Carotene Cancer Prevention Study Group. The New England Journal of Medicine. 1994 Apr 14;330(15):1029-35

24) Lonn E, Bosch J, Yusuf S, et al. Effects of long-term vitamin E supplementation on cardiovascular events and cancer: a randomized controlled trial. JAMA. 2005 Mar 16;293(11):1338-47.

25) Miller ER, Pastor-Barriuso R, Dalal D, et al. Meta-analysis: high-dosage vitamin E supplementation may increase all-cause mortality. Annals of Internal Medicine. 2005 Jan 4;142(1):37-46.

25) Klein EA, Thompson IM Jr, Tangen CM, et al. Vitamin E and the risk of prostate cancer: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA. 2011 Oct 12;306(14):1549-56.

Table References

1) Penniston KL, Tanumihardjo SA (2006). “The acute and chronic toxic effects of vitamin A”. The American Journal of Clinical Nutrition. 83 (2): 191–201.

2) “Thiamin, vitamin B1: MedlinePlus Supplements”. U.S. Department of Health and Human Services, National Institutes of Health.

3) Hardman, J.G.; et al., eds. (2001). Goodman and Gilman’s Pharmacological Basis of Therapeutics (10th ed.). p. 992.

4) Brunton, Laurence L.; Lazo, John S.; Parker, Keith, eds. (2005). Goodman & Gilman’s The Pharmacological Basis of Therapeutics(11th ed.). New York: McGraw-Hill.

5) Pantothenic acid, dexpanthenol: MedlinePlus Supplements”. MedlinePlus. Retrieved 5 October 2009.

6) Perry, T. A.; Weerasuriya, A.; Mouton, P. R.; Holloway, H. W.; Greig, N. H. (2004). “Pyridoxine-induced toxicity in rats: a stereological quantification of the sensory neuropathy”. Exp. Neurol. 190 (1): 133–144.

7) FAO; WHO (2002), “ch. 4, Folate and Folic Acid”, Human Vitamin and Mineral Requirements

8) The Dark Side Of Linus Pauling’s Legacy, Quackwatch

9) Masterjohn, C (2007). “Vitamin D toxicity redefined: vitamin K and the molecular mechanism”. Med Hypotheses. 68 (5): 1026–34. doi:10.1016/j.mehy.2006.09.051.

10) Gaby, Alan R. (2005). “Does vitamin E cause congestive heart failure? (Literature Review & Commentary)”. Townsend Letter for Doctors and Patients.

11) Rohde LE; de Assis MC; Rabelo ER (2007). “Dietary vitamin K intake and anticoagulation in elderly patients”. Curr Opin Clin Nutr Metab Care. 10 (1): 1–5.

The truth about Fish Oil

Many cupboards across the country are home to a little tub of those squishy yellow fish oil pills.

Over the last decade or so, fish oil capsules have become exceptionally popular and now take pride of place on any health supplement shop shelf.

Eating fish is  generally considered healthy. Fish, in general, is low in saturated fats and less calorific than red meats. Populations that consume large amounts of fish also have lower incidence of heart disease. Additionally, high consumption of red meat has been linked with increased risk of bowel cancer (1) – further promoting the eating of fish is therefore good for public health.

The idea for a long time has been that the oils and fats in fish is what really sets it apart from other meat products – hence why we now see fish oil supplements.

But what is the truth about eating fish oils regularly? Will you really be ‘healthier’? Are fish oils protective against heart disease for example?

Lets find out…but first a bit of background about what fish oils actually are.

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What are ‘Fish Oils’?

 

Fish oil is simply an oily substance derived from the tissues of ‘oily’ fish. The most oily fish are sardines, mackerel, salmon, halibut and tuna. Lots of other fish also contain these oils but to a lesser degree (2).

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 The major components of fish oil are the omega-3 fatty acids:

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Eicosapentaenoic acid (EPA)

Docosahexaenoic acid (DHA)

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An additional type of fatty acid is also important in human health but found in nuts, not oily fish:

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α-linolenic acid (ALA)

.Both EPA and DHA are described as ‘essential’ – we have to obtain these fatty acids from our diets, we cannot make them ourselves (3). ‘Fatty’ fish such as salmon and sardines are great sources of both of these compounds. If you aren’t a fan of fish, flax seeds, pumpkin seeds and walnuts are just a few other dietary sources from which you can obtain high levels of EPA and DHA.

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A handy conversion schematic from Dr. Ben King at drbenking.com

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Omega-3 fatty acids are important for normal metabolic function and are especially important for growth in infants (4). DHA is found in large quantities in the brain where it acts as a major structural component (5).  Aside from structural function, DHA and EPA are thought to play an important role in brain health – good evidence suggest omega-3s are important in maintaining mood stability and show potential in combating depression (discussed more below).

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As with a lot of popular supplements – many remarkable health benefits have been attributed to omega-3s and the broader term of ‘fish oils’. As always, as I have shown you before, when we dig deeper we see that many common claims about supplements either exaggerate the truth or are entirely made up. Some supplements have very weak literature and research behind them, fish oils however have been researched in depth for a number of years so we can draw firmer conclusions regarding their therapeutic efficacy.

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Are there health benefits: What does the science say?

 

At some point or another, fish oils have been said to cure or alleviate an extremely wide range of maladies and diseases. I won’t cover them all here as the list is practically endless and mostly made up. Instead I will focus on common diseases and pathologies which have the most research behind them concerning fish oils as a therapeutic supplements.

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.Cardiovascular Disease

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CVD and fish oils go hand in hand. Aside from widely cited ‘mental boosting’ effects, the next benefit on the list of fish oil supplements is almost almost cardiovascular health. We know that dietary fat intake is very important for cardiovascular health and can be a major indicator of risk of heart attack. In general, we know that trans fats are especially bad when it comes to heart health and that polyunsaturated fats are a much better choice and may even be protective against heart disease if eaten in moderation (6). It therefore makes sense that so much research has investigated the effects of omega-3 fatty acids and CV health and disease risk.

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Basic anatomy of the heart – many of these components can be adversely affected by cardiovascular disease

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Most of that research sends a clear message: Fish oil supplements do not protect against heart attacks of strokes. Although some individual papers have shown potential benefit – i.e. two papers from 1999 and 2009 (7,8) suggesting fish oils may have beneficial effects on certain abnormal heart rhythms. However, since then meta studies have refuted that specific claim (9) and also gone on to conclude that…

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”Omega-3 Fatty Acid supplementation did not reduce the chance of death, cardiac death, heart attack or stroke”

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This is the conclusion of a 2012 meta-study (Journal of the American Medical Association) which analysed the data from 20 separate studies and well over 60,000 patients (10). This is a good amount of data so we can be confident in this conclusion as it stands.

It is important to note that although fish oil doesn’t seem to prevent death from heart attacks of stroke it does appear to have beneficial effects for previous sufferers of heart attacks and other people with a history of cardiovascular disease. Omega-3s possess modest anti-inflammatory properties (11) and it is probably because of this that a cohort of heart attack survivors that received daily fish oil supplements for 6 months showed improved heart function overall and lower markers of systemic inflammation than their control counterparts (12). Furthermore, omega-3 fatty acid supplementation greater than one gram a day for at least a year may be protective against cardiac death, sudden death, and myocardial infarction in people who have a history of cardiovascular disease.

Another meta study also concluded that there was ‘tentative’ evidence of an anti-inflammatory effect  from fish oil supplementation. More data will be needed to take a stronger position on this in the future.

Although not directly heart protective in healthy individuals the current evidence suggests fish oil supplements may benefit those who have a history of heart disease and/or have suffered a heart attack.

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Prostate Cancer

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I’ve decided to mainly write about prostate cancer here as this is the type of cancer with the most relevant studies. Omega-3s are often touted as having a strong anti-cancer effect but as I have said before: Just because a compound kills or inhibits the growth of cancer cells in vitro (in a cell culture dish) does not mean it qualifies as a cancer therapy by itself.

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More true advice has never been given

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Some studies have shown that fish oils rich in Omega-3s do inhibit tumour cell growth in vitro. This effect was deemed strong enough to suggest that a diet rich in Omega-3 fatty acids be used alongside traditional breast cancer treatments (13) – this may actually prove beneficial (this does not endorse Omega-3 fatty acids as a treatment by itself in any way).

But what about studies where they gave actual patients with cancer Omega-3 supplements or looked directly at Omega-3 blood concentrations? This has been mostly done with prostate cancer patients.

The area remains controversial due to the publication of a few papers with conflicting results.

One paper demonstrated that increased DHA in the blood was associated with a reduction in prostate cancer risk (14). However, two other papers have shown almost the exact opposite. One group showed that increased levels of DHA and EPA was associated with an increased risk of more aggressive prostate cancer (15).  Another group presented evidence that suggested a link between high blood levels of omega -3 fatty acids and an increased risk of prostate cancer (16).

These papers have all been published in the last few years, starting in 2012, so this is a an actively contested research  topic that has yet to see a solid consensus emerge. As such we can say that overall, given the available data, the effects of omega-3 supplementation on cancer, including prostate cancer, is currently inconclusive. 

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Alzheimer’s Disease

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It is unlikely that dietary intervention will prevent Alzheimer’s and even more unlikely that symptoms will be reversed once they manifest. A 2012 Cochrane meta-analysis (17) pooled the data from studies when individuals over the age of 60 had been given fish oils as a supplement. They found that taking fish oil supplements did not provide protection against the development of Alzheimer’s in the over 60s.

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In their words…

“Our analysis suggests that there is currently no evidence that omega-3 fatty acid supplements provide a benefit for memory or concentration in later life”.

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It is important to note that this meta-study specifically looked at those over the age of 60 as Alzheimer’s is typically a disease of old age. This study is therefore limited in a number of ways. It cannot tell us whether fish oil supplementation in younger years may ultimately prove protective against Alzheimer’s in old age. Although this remains unlikely, fatty acids are important brain components and do play a role in mood and brain function so there may be an as of yet, undiscovered link.

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Mental Health

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Overall, studies and meta-studies in this area have expressed the need for many more randomised controlled studies in order to increase the data pool and that the data is, in general, limited. The major review that suggested this need for more data also showed that omega-3s were an effective adjunctive therapy for depressive (but not manic) symptoms in bipolar disorder (18).

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The most recent meta-study in this area from 2014, an analysis of 11 studies, looked at treating depression in patients diagnosed with Major Depressive Disorder (MDD) and those with depression but without a diagnosis of MDD.

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They concluded…

‘The use of omega-3 PUFA is effective in patients with diagnosis of MDD and on depressive patients without diagnosis of MDD.”

Omega 3 fish oil supplements appear to be effective in treating depression. More data more establish this more strongly in the future.

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Hypertension (High Blood Pressure)

Omega-3s may have a small beneficial effect on hypertension by lowering blood pressure (19). The effect currently shown in studies is small and appears to only effect individuals with hypertension. Studies which failed to replicate the blood pressure reduction may be due to dosage issues. Additionally, DHA and EPA don’t seem to have the same efficacy with DHA having potentially greater effects.

This area is worth exploring in greater detail with more data before a solid conclusion can be drawn.

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Are there any dangers associated with fish oil supplements?

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A 2013 review on fish oil supplement dangers concluded…

”appear mild at worst and are unlikely to be of clinical significance”

This is true of eating fish in general…not just taking fish oil supplements.

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Mercury

Heavy metal accumulation can be a problem with fish and predatory fish at the top of the food chain have higher levels of mercury due  to bio-accumulation over time. Mercury levels can range from very low to worryingly high in a single serving of fish. Usually from 10 ppb (parts per billion) of mercury all the way up to 1,000 (20). Luckily your average fish oil supplement contains 2 ppb mercury- well within tolerable limits (21).

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The process of bio-accumulation means large predatory fish have greater levels of environmental toxins in their system than smaller prey fish. Original image from jessbanda.wordpress.com

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Dioxins and dioxin like chemicals

Chronic exposure to low levels of dioxins may be carcinogenic and the chemical is classified as a human carcinogen (22).  There is also evidence that uterine exposure to dioxins leads to subtle developmental issues in children. In a similar fashion to mercury, chemicals like dioxin bio accumulate in fish so that the concentrations in the fish are much greater than the surrounding environment. In reputable brands of  fish oil supplements, dioxins will not be found. Always buy your supplements from reputable brands and suppliers.

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Vitamin A

The liver and liver products of fish (i.e. cod liver oil) contain omega-3, but also the active form of vitamin A.

High intake of vitamin A can lead to dangerous Hypervitaminosis A.

I have covered the role of vitamins in health extensively here.

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% Recommended Daily Allowances

FDA guidelines state that it is  safe to take up to 3000 mg of omega-3 per day. However, that is pure omega-3 oil not 3000 mg of fish oil.

Fish oil contain varying levels of omega-3 which should be labelled clearly on the back of the packaging.

A typical 1000 mg fish oil pill contains about 200-400 mg of omega-3 fatty acids. You would have to take over ten pills a day to be over recommended allowances – no chance of that.

.Ultimately taking fish oil supplements from a reputable producer and seller is no more dangerous than consuming fish frequently.

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The Final Word

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Dissecting out exactly what certain molecules and compounds are doing in the body is always tricky. This is certainly true of supplements. There is no doubt that supplements are a great idea for those deficient in a particular nutrient but the benefits of taking more of a particular nutrient when you are already meeting requirements are much harder to determine. This is a common theme running through supplement use in general.

Overall fish oils (Omega-3s) are physiologically important and play a number of key roles in the body. The science suggests that  supplementing with fish oils is no where near as ‘powerful’ as some manufactures would have you believe…

Currently the data suggests there is no clear protective effect against…

Risk of cancer

Risk of stroke

Risk of heart attack

Development of Alzheimer’s Disease

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However! There is some evidence that Omega-3s are effective in…

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Treating certain types or depression – more data would be ideal

Increasing general heart function following a heart attack

General reduction in markers of  systemic inflammation

May have small beneficial effects on hypertension

Although there are some minor risk associated with high fish oil intake (potential heavy metal ingestion), this risk is no greater than when simply eating fish. On this topic, researchers at Harvard’s School of Public Health said…

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 ”The benefits of fish intake generally far outweigh the potential risks.”

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I myself really enjoy eating fish – mainly salmon and tuna. I also eat mixed nuts frequently which include walnuts. All good sources of Omega-3 fatty acids. I also always have a tub of fish oil capsules handy at home. I do not take them every day but if I haven’t got hold of fresh fish for a week or two I will go ahead and supplement for a few days with capsules.

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If you fancy doing the same, grab them for cheap down below. Also, check out the Microalgae Capsules – the vegetarian alternative to fish oil capsules.

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Thanks for reading!

-ScienceGuy

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References

 

  1. Zhu, H; et al. (2013). “Red and processed meat intake is associated with higher gastric cancer risk: a meta-analysis of epidemiological observational studies.”. PLOS ONE. 8 (8)
  2. Kris-Etherton, Penny M.; William S. Harris, Lawrence J. Appel (2002). “Fish Consumption, Fish Oil, Omega-3 Fatty Acids, and Cardiovascular Disease”. Circulation. 106 (21): 2747–57.
  3. Moghadasian, Mohammed H. (2008). “Advances in Dietary Enrichment with N-3 Fatty Acids”. Critical Reviews in Food Science and Nutrition. 48 (5): 402–10.
  4. Freemantle E, Vandal M, Tremblay-Mercier J, Tremblay S, Blachère JC, Bégin ME, Brenna JT, Windust A, Cunnane SC (2006). “Omega-3 fatty acids, energy substrates, and brain function during aging”. Prostaglandins, Leukotrienes and Essential Fatty Acids. 75 (3): 213–20.
  5. “Nutrition for the Brain” (PDF)/DHA in Brain and Retina Structure” (PDF)
  6. Zaloga GP, Harvey KA, Stillwell W, Siddiqui R (2006). “Trans Fatty Acids and Coronary Heart Disease”. Nutrition in Clinical Practice. 21 (5): 505–512.
  7. Charnock John S (1999). “The role of omega-3 polyunsaturated fatty acid-enriched diets in the prevention of ventricular fibrillation” Asia Pacific Journal of Clinical Nutrition. 8 (3): 226–30.
  8. Li GR, Sun HY, Zhang XH, Cheng LC, Chiu SW, Tse HF, Lau CP (2009). “Omega-3 polyunsaturated fatty acids inhibit transient outward and ultra-rapid delayed rectifier K+currents and Na+current in human atrial myocytes”. Cardiovasc Res. 81 (2): 286–93.
  9. Khawaja, Owais; Gaziano, J. Michael; Djoussé, Luc (2012-02-01). “A meta-analysis of omega-3 fatty acids and incidence of atrial fibrillation”. Journal of the American College of Nutrition. 31 (1): 4–13.
  10. Rizos, E. C.; Ntzani, E. E.; Bika, E; Kostapanos, MS; Elisaf, MS (2012). “Association Between Omega-3 Fatty Acid Supplementation and Risk of Major Cardiovascular Disease Events: A Systematic Review and Meta-analysis”. Journal of the American Medical Association. 308 (10): 1024–33.
  11. Wall R, Ross RP, Fitzgerald GF, Stanton C (2010). “Fatty acids from fish: the anti-inflammatory potential of long-chain omega-3 fatty acids”. Nutr Rev. 68 (5): 280–89.
  12. Heydari B, Abdullah S (2016) Effect of Omega-3 Acid Ethyl Esters on Left Ventricular Remodelling After Acute Myocardial Infarction: The OMEGA-REMODEL Randomised Clinical TrialCirculation2;134(5):378
  13. Jiajie Liu and David W. L. Ma (2014).’‘The Role of n-3 Polyunsaturated Fatty Acids in the Prevention and Treatment of Breast Cancer” Nutrients. 6(11): 5184–5223.
  14. Heinze, VM; Actis, AB (February 2012). “Dietary conjugated linoleic acid and long-chain n-3 fatty acids in mammary and prostate cancer protection: a review”. International journal of food sciences and nutrition. 63 (1): 66–78.
  15. Chua ME, Sio MC, Sorongon MC, Morales ML (May–June 2013). “The relevance of serum levels of long chain omega-3 polyunsaturated fatty acids and prostate cancer risk: a meta-analysis”. Canadian Urological Association Journal. 7 (5–6): E333–43.
  16. Brasky TM, Darke AK, Song X, et al. (August 2013). “Plasma phospholipid fatty acids and prostate cancer risk in the SELECT trial”. J. Natl. Cancer Inst. 105 (15): 1132–41.
  17. Sydenham E, Dangour A, Lim W (2012) ”Omega 3 fatty acid for the prevention of cognitive decline and dementia” Cochrane Database of Systematic Reviews
  18. Grosso, G.; Pajak, A.; Marventano, S.; Castellano, S.; Galvano, F.; Bucolo, C.; Caraci, F. (2014). “Role of Omega-3 Fatty Acids in the Treatment of Depressive Disorders: A Comprehensive Meta-Analysis of Randomized Clinical Trials”. PLoS ONE. 9 (5)
  19. Miller PE, Van Elswyk M, Alexander DD (July 2014). “Long-chain omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid and blood pressure: a meta-analysis of randomized controlled trials”. American Journal of Hypertension. 27 (7): 885–96
  20. Mercury Levels in Commercial Fish and Shellfish (1990–2010) U.S. Food and Drug Administration. Accessed 14 January 2017
  21. Top 10 Fish Oil Supplements – LabDoor”. LabDoor. Accessed  14 January 2017
  22. Steenland K, Bertazzi P. (2004) ‘‘Dioxin Revisited: Developments Since the 1997 IARC Classification of Dioxin as a Human Carcinogen”. Environmental Health Perspectives. 112 (13) 1265-1268