fish, mercury, omega 3s, and heart disease

An intriguing new study published in the American Journal of Clinical Nutrition, took a look at fish consumption, mercury levels, and blood levels of long chain omega 3 fatty acids from fish, in relationship to heart disease in Scandanavian men. You can read the abstract (and the full paper) here . Basically what they found was that eating more fish raised both blood levels of EPA and DHA, but also increased measured mercury levels. Those with the highest levels of omega-3s and the lowest levels of mercury, compared with those with the highest mercury levels and lowest levels of omega-3s had a greater than 3 fold difference in diagnosis of heart and vascular disease. The authors noted: “Our model indicated that even a small change in fish consumption (ie, by increasing S-PUFA by 1%–blood levels of EPA+DHA–) would prevent 7% of MIs (heart attacks), despite a small increase in mercury exposure. However, at a high hair-mercury content, the modeled beneficial effect of PUFA on MI risk was counteracted by methylmercury.”

Although not stated in the paper, it still seems to me like the safest way to get your EPA and DHA is from high quality fish oils–those that have been molecularly distilled to remove environmental contaminants, such as PCBs and dioxins–mercury is never an issue, even in low quality fish oils, as it stays in the fish protein, and does not come out in the oil. But many low quality fish oils are also oxidized (rancid), which can increase oxidative stress in the body significantly. As noted in a recent post about the meta-analysis (desk research) which stated that fish oils supplements were of ‘no value’–see that post for all the reasons that this was a very poor ‘study of studies’–not the least of which reasons is that many of those studies used over the counter fish oils and didn’t analyze them for content, rancidity, or toxins. Not all fish oils are created equal. When you do eat fish, choose small fish, like sardines, herring (pickled is fine if you like them), anchovies, mackerel. And NEVER farmed fish–unless the are certified organic, with a natural food chain established, rather then feeding them pellets of grain (which are often GMO corn and soy). Virtually all tilapia (a marketing term for perch) are farm raised, and their fatty acid profile is closer to that of bacon than to that of fish. Caveat Emptor!

fish oil has no impact on heart disease?

An article published in the Journal of the American Medical Association (JAMA), has been widely publicized in the media, for its conclusion that ‘fish oil doesn’t help heart disease”. You can read the full abstract here:  Now, let’s take a look at these ‘findings”.  First of all this is a type of research called ‘meta-analysis’, in which no actual clinical research at all is done. It simply takes a look at lots of articles published on a particular subject, and tries to draw conclusions. I call this “armchair research”.  Particularly when many studies with different research designs are studied together, results can be very misleading. But there are also some assumptions that bear looking at. In case you didn’t click on the link to read the abstract, these were the conclusions of the meta-analysis: “Omega-3 fatty acid supplementation was not associated with a lower risk of all-cause mortality, cardiac death, sudden death, myocardial infarction, or stroke.

I have collected an enormous amount of data that strongly suggest multiple benefits from the consumption of omega-3 fatty acids for cardiovascular disease, cancer, neurological disease, auto-immune diseases, and even in bone, skin and lung health. There is no question that the dietary ratio of omega-3 to omega-6 fats is a major factor in how susceptible people are to chronic inflammation, which underlies most chronic modern maladies. Good quality (molecularly distilled, preserved by potent fat soluble antioxidants) fish oil is, in my opinion, much safer than actually eating fish, as it contains many fewer environmental contaminants, such as mercury, PCBs, dioxins, etc.  It also takes a long time for it to be incorporated into cell membranes and other body structures, so it is not something that produces dramatic effects in less than a year, and many of the studies analyzed in this meta-analysis, were shorter than one year–and these were not separated out from the analysis of longer studies.

Another key point is that there was some heterogeneity in study design, including in dosage of omega-3 fatty acid used and patient populations. There is much uncertainty regarding the potency and purity of the over-the-counter supplements.  The majority of people taking omega-3 supplements are taking cheap, poor-quality, low-potency, and often even rancid products.  The public doesn’t know any different, and unfortunately very few of these studies actually analyzed the products that were used. Moreover, the control groups were exposed to varying amounts of fish oils, and this could account for a lack of effect seen between experimental and control groups. Another issue is that when placebo controls were used, due to the fish odor of omega-3 fatty acid supplements, complete blinding of fish oil studies may not be feasible. This imperfect blinding was not considered in the quality assessment of the studies.

Most of the restenosis studies only presented data among those who completed their follow-up angiogram. Consequently, restenosis data were generally analyzed using a modified intention-to-treat, which may result in biased results (in other words, if someone felt great and didn’t come back for their folowup angiogram, they were counted as a non-responder).

Finally, due to the lack of individual-level data, they did not estimate the change in risk of mortality or cardiovascular outcomes over time. In other words did the folks taking a therapeutic dosage get better results?  How much EPA and DHA were people consuming?  Of course this is essential information.  Availability of individual-level data would also have allowed us to examine which subgroups may derive the greatest benefit from the use of these agents. This study adds nothing to our understanding of the role of omega-3 fatty acids in reducing risk of heart disease, and creates a lot of confusion in the minds of consumers (and doctors), who don’t understand research design. Remember the old adage about computers, which applies equally to meta-analysis studies: “GIGO”.  Garbage in, Garbage out. Oh, and you can’t compare completely different types of studies and draw any valid conclusions. Better to go do an actual study. But that requires a lot more money, a lot more thought, and a lot more work. There seems to have been a spate of “supplements don’t work” publications in scientific journals lately, which this one adds to. But the people who experience benefits of high quality supplements in their own bodies over time are not likely to believe them.

those with low vitamin D levels twice as likely to die

A recent study suggests that vitamin D may be one of our most crucial nutrients to health and long life continues to mount:

CHICAGO – New research linking low vitamin D levels with deaths from heart disease and other causes bolsters mounting evidence about the “sunshine” vitamin’s role in good health.

Patients with the lowest blood levels of vitamin D were about two times more likely to die from any cause during the next eight years than those with the highest levels, the study found. The link with heart-related deaths was particularly strong in those with low vitamin D levels.

Science used to believe that vitamin D was simply needed to prevent rickets, a disease of soft bones, and that people needed only 200-400 international units (IUs) for this. In the past decade we’ve learned that vitamin D is crucial to the health of every cell in the body, and that heart health, brain health, immune system health, and cancer prevention all rely heavily on robust levels of this vitamin in our bodies. Not only that, we’re learning that nutrition scientists were off by a factor of 10 in how much is optimal. In other words, we need 2,000 to 4,000 (and in some cases 6,000) IU of vitamin D daily for optimal blood levels (above 50 ng/ml). What wasn’t known for a long time is that a healthy human exposed to summer (or tropical winter) sun for 30 to 60 minutes, depending on how dark or light skinned we are, will make between 10 and 10 THOUSAND IUs of vitamin D. When we started subtracting sun exposure (or using sunscreen) from our lives some 30 years ago, we shut off the tap of the “sunshine vitamin”, and our food “fortifications” and multivitamin pills had far too little vitamin D to make up for it. I recommend to everybody to take at least 2,000 IU daily, and after a few months, to ask their doctor to order a 25-hydroxy vitamin D level–this number may be more important to your health than knowing your cholesterol level or your blood pressure–and for optimal health, you want it to be between 50 and 100 ng/ml, even though 30 is considered “adequate”–and you wouldn’t believe how many millions of people are well below 30!