Yesterday, a patient I’m seeing for atrial fibrillation told me that he was taking fish oil supplements that his eye doctor had recommended and sold to him for dry eyes. This patient reads my blog and knows that I strongly recommend not taking fish oil supplements (unless your triglycerides are >500). At the time I told him I didn’t know the literature on fish oil and dry eyes but that I was skeptical of any proven benefit.
Despite insufficient evidence establishing the effectiveness of omega-3s, clinicians and their patients have been inclined to try the supplements for a variety of conditions with inflammatory components, including dry eye. “This well-controlled investigation conducted by the independently-led Dry Eye Assessment and Management (DREAM) Research Group shows that omega-3 supplements are no better than placebo for typical patients who suffer from dry eye.”
I suspect that one by one the various alleged benefits of fish oil supplements will be proven to be nonexistent. I’m not sure the general public will stop buying snake or fish oil then but I feel like one by one I’m getting my patients off them. Doing my part to save the ocean bottom-feeders.
N.B. I’m writing this while flying to Miami to begin the great Galapagos adventure and the Voyage of the Samba.
If by now you are still taking fish oil supplements despite my last post on the topic I present three more reasons to stop wasting your money and destroying the ocean’s ecosystem.
The first nail: No Reason To Take Fish Oil Pills
A Cochrane review showing shows there is little or no effect of omega 3 supplements on our risk of experiencing heart disease, stroke or death.
This is the most extensive systematic assessment of effects of omega-3 fats on cardiovascular health to date. Moderate- and high-quality evidence suggests that increasing EPA and DHA has little or no effect on mortality or cardiovascular health (evidence mainly from supplement trials). Previous suggestions of benefits from EPA and DHA supplements appear to spring from trials with higher risk of bias. Low-quality evidence suggests ALA may slightly reduce CVD event risk, CHD mortality and arrhythmia.
Second Nail. Peruvian Anchoveta: Put Them On A Pizza Not in A Pill
Paul Greenberg’s recently published book, The Omega Principle, emphasizes the damage the fish oil supplement business is doing to the ocean environment,
GREENBERG: So omega-3 supplements come from this critical layer of the ocean biosphere that are small – what are called pelagic fish. They’re the silvery, little fish like anchovies and herring and other fish called menhaden that most people haven’t heard of, but it’s actually the most caught fish in the lower 48 of the United States. These fish are really essential for ecosystem dynamics in the ocean.
So the way that oceans work is that all the energies coming from the sun – it goes – all that energy is processed by plankton, by phytoplankton. And it’s really these fish that are – these little fish that are used for omega-3 supplements that transfer the energy from plankton to larger fish. So in other words, you know, you have the solar energy going into the plankton. The little fish then eat the plankton. And then they are in turn eaten by larger fish. So if you harvest this middle layer – if you overharvest this middle layer of anchovies, of herring, of menhaden – if you take them out of the picture, there’s no way for the energy to be transferred from phytoplankton up to larger predators. So I guess that’s my main concern here.
So in particular, where are the omega-3 supplements coming from? Most of the omega-3 supplement oil is coming from a fish called a Peruvian anchoveta. And it is the most caught fish in the world. In some years, Peruvian anchoveta harvests have equaled as much as 10 million metric tons. Just to give you some perspective, that’s like one-eighth of all the fish caught in the world. And the crazy thing about it is that those fish are completely, totally edible. I’ve eaten them. They’re delicious. You can have them on a pizza. You could do anything with them. But 99 percent of those Peruvian anchoveta are ground up into animal feed, boiled down into oil and turned into supplements. So to me, to my mind, that is not necessarily the wisest use to be made of this really, really important source both for the ecology of the ocean but also for humans
Nail Three. Save the Krill!
The supplement industry is incredibly creative in their marketing. As the uselessness of fish oil supplementation has become clear, supplement manufacturers have begun touting krill oil as superior to fish oil.
Claims like the following are all over the internet:
Krill have an edge over your ordinary fish – when you take a krill oil supplement, you also get astaxanthin along with your DHA and EPA. It’s an antioxidant. In terms of antioxidant power of potency, it’s been found to be 500x to 6,000x stronger than regular vitamins like vitamin E and vitamin C.
This is just hogwash. There is no good clinical evidence to support any health claim for krill oil in general or astaxanthin in particular. Please read my post on the failure of anti-oxidant supplements and vitamins and recognize that claims of antioxidant power do not indicate any health benefit.
A technical paper from Greenpeace review the importance of krill to to the marine ecosystem in the Antarctic and this paper, entitled “License to Krill” details the problem.
Do you want to be responsible for starving penguins, whales and seals??!
the bottom line on fish oil supplements is that the most recent scientific evidence does not support any role for them in preventing heart attack, stroke, or death. There are potential down sides to taking them, including contaminants and the impact on the marine ecosystem. I don’t take them and I advise my patients to avoid them (unless they have triglyceride levels over 500.)
The skeptical cardiologist has a confession to make: he’s been adding ground flaxseed to his typical late morning full fat yoghurt plus berries and almonds.
Adding flaxseed seems dangerously close to dietary behaviour I have been advising against: supplementing instead of eating real food.
Also, I am philosophically opposed to going out of my way to eat any edible that is consistently promoted as a “super food” or a “functional food.” To me, these are meaningless terms and marketing blather
When I began writing this post in 2017 I was getting my flaxseed from Stober Farms (Est. 1901) who had been producing “for over 100 years the finest flax in the world.” Stober Farms provided me with “organic Golden Flax Seed which has been Cold-Milled Processed.”
Stober Farms (who have since mysteriously gone into bankruptcy) also informed me:
Flax is digested most effectively when ground. Some grinding methods generate heat when milled, spurring early omega-3 oxidation. Stober Farms uses a unique cold-milled process, which gently grinds the seed without significantly raising the temperature. This proprietary method preserves the nutrients, flavor and extends the shelf life to 22 months.
Honestly, I don’t recall exactly why I began “flaxing” but I suspect I felt it was a good way to boost the fat content in my full fat yoghurt (yes, I am now spelling yoghurt with an h) and berries and perhaps sufficiently satiate me that it would be the only food I would need to consume until dinner or late afternoon.
Two tablespoon (14 grams) is what I typically imprecisely add. These tablespoons provide 75 kcal of energy which comes from 3 grams of protein, 6 grams of fat, and 4 grams of carbs. Three of the four carb grams are soluble fibre.
About half of the fat in flaxseed is in the form of alpha-linolenic acid (ALA)(18:3) an omega-3 polyunsaturated (PUFA) fat. Flaxseed oil contains five times more ALA than walnut oil or canola oil, which are the next highest sources of ALA.
Is Flaxseed A Super Functional Food?
Many seemingly authoritative sites on the internet proclaim that flaxseed is incredibly healthy. For example, Healthline.com’s “Authority Nutrition” (they must be authoritative as authority is in their name) presents their 10 health benefits of eating flaxseed “backed by science” and concludes:
They can be used to improve digestive health, lower blood pressure and bad cholesterol, reduce the risk of cancer and may benefit people with diabetes.
But typical of Authority Nutrition’s overblown claims these are not truly proven by science. The studies cited are weak; typically short-term tests of biomarkers or animal studies or human studies with very small numbers. Most importantly. these studies , which are often funded by flaxseed promoters are highly likely to be biased in favor of positive results.
Most websites tout the cardiovascular benefits of the omega-3 PUFA in flaxseed, the high percentage of soluble fibre and the benefits of a chemical which cannot be named (due to a name which is too difficult to pronounce), SDG.
Omega-3 PUFAs and fibre I’ve touched on previously (and positively) but what about the mysterious and unpronounceable SDF. Per a 2010 review article
Flaxseed is the richest source of the lignan secoisolariciresinol diglucoside (SDG). After ingestion, SDG is converted to secoisolariciresinol, which is further metabolised to the mammalian lignans enterodiol and enterolactone. A growing body of evidence suggests that SDG metabolites may provide health benefits due to their weak oestrogenic or anti-oestrogenic effects, antioxidant activity, ability to induce phase 2 proteins and/or inhibit the activity of certain enzymes, or by mechanisms yet unidentified.
Like so many putative wonder phytochemicals, SDG has a “growing body of evidence” for lots of things but actual proof that it does anything worthwhile in humans is lacking and awaits well done randomized clinical trials
Poorly researched articles on flaxseed are highly likely to tout its anti-inflammatory properties. These properties are seen in rats but unfortunately haven’t been proven in my favorite species, Homo Sapiens , Flaxseed doesn’t seem to decrease the inflammatory marker CRP in humans as reported in this systematic review and meta-analysis.
ALA and Cardiovascular Disease
As I’ve indicated in previous posts, evidence supports fatty fish consumption as beneficial in reducing cardiovascular disease presumably by increasing levels of marine omega-3 PUFAs in the body.
The value of fish oil supplementation, however, is not proven (see here).
How does ALA compare to the seafood omega 3s in preventing cardiovascular disease (CVD)?
Their introductory paragraph nicely lays out why ALA could be very important to public health:
A large body of evidence supports a potential protective effect of seafood omega-3 (n−3) fatty acids, particularly EPA (20:5n−3) and DHA (22:6n−3), on coronary heart disease (CHD. However, fewer studies have evaluated how the plant-derived omega-3 fatty acid α-linolenic acid (ALA; 18:3n−3) relates to risk of CHD and other cardiovascular disease (CVD) outcomes, and the results have been inconsistent As an essential fatty acid that cannot be synthesized by humans, ALA is mainly consumed from plant sources, including soybeans, walnuts, and canola oil. Compared with seafood omega-3 fatty acids, ALA from plant sources is more affordable and widely available globally. Thus, whether ALA can reduce the risk of CVD is of considerable public health importance.
If plant-derived ALA can provide our omage-3 PUFA needs then perhaps we can stop stripping the ocean of all the menhaden.
In the Harvard analysis when all 27 studies were combined the authors found a significant risk reduction of 14% in CVD events with flaxseed.
There were lots of issues with the data which I won’t bore you with leading the authors to conclude that “ALA consumption may be beneficial “. They emphasized the need for additional well-designed observational studies and randomized clinical trials in the area.
Since observational studies cannot prove causality, I await a good randomized clinical trial of ALA supplementation before I can recommend ALA supplementing to prevent heart disease.
After Performing This Review Is The Skeptical Cardiologist Still “Flaxing”?
I am. Because I’ve found that when I consume flaxseed I feel 20 years younger, full of vitality. and with a youthful golden sheen to my hair, nails and skin.
Actually, that last sentence is untrue.
I’m still adding ground flaxseed to my yoghurt but not with any expectation that it is reducing my risk of heart attack and definitely not because I perceive it as a super or functional food.
I like the taste, the convenience, and the extra (presumably healthy) calories it provides but I’m still an advocate of just eating real food rather than trying to identify specific nutrients, nutraceuticals or supplements and add them to your diet.
N.B. I did not touch on omega-6/omega-3 ratios in the diet. I’ve been examining that inflammatory (enjoy the pun) topic for years and once I come across a good study that adds to understanding in the area I will likely publish a post on it.