Chewing the Fat on Fatty Acids

By Joel Fuhrman, M.D.

Warning-Fish And Fish Oils Contain Large Concentrations Of Mercury, Dioxins, And PCBs!

The American diet is unquestionably low in omega-3 fat. Omega-3 fats are healthy fats that reduce inflammation, inhibit cancer development, and protect our blood vessels. The basic building block of omega-3 fat is alphalinolenic acid (ALA), and flaxseed is the food with the highest concentration of this much needed fat.

On the other hand, Americans consume huge amounts of omega-6 fats and oils. These are cancer-stimulating fats. If you feed mice a diet high in corn oil, their tumors will metastasize more aggressively. The omega-6 oils include safflower, sunflower, corn, peanut, and, yes, even olive oil. By extracting the oil from its protective housing, manufacturers have removed all the fiber, lignans, flavonoids, and protective phytochemicals that nature routinely packages along with these fats. As most of my readers know, I do not recommend extracted oils. One problem with using all polyunsaturated oils is that they are easily oxidized. Oxidized oils produce harmful substances called lipid peroxides and free radicals. These are present in all oil products, even in cold pressed, virgin olive oil. Both omega- 6 oils and omega-3-predominant oils such as flax oil can be easily oxidized. Flaxseed oil is particularly unstable when heated.

Nature’s special packaging of natural foods prevents rancidity and the formation of harmful chemical compounds. Therefore, it is always safest to consume fats the way they are found in nature, in raw nuts, seeds, and avocados.

In addition to omega-3 fats, flaxseed also contains very high levels of unique phytochemicals that powerfully inhibit prostate, breast, and colon cancer. However, these protective nutrients and lignans are not present in significant quantity in flaxseed oil, only in the whole seed. Unfortunately, the whole seeds are tiny and difficult to chew, and they pass through the body undigested, causing their beneficial nutrients to be lost. The solution is to buy ground flaxseed or grind the whole seeds before eating. Ground flaxseed is also susceptible to rancidity. In my house, we grind a pound at a time using our VitaMix and then store the ground flaxseed in the freezer to maintain stability of the fats before using. Every morning we simply scoop what we need out of the container and put the rest back into the freezer. If you buy ground flaxseed, remember to store it in the freezer after you’ve opened the vacuum-sealed package.

Of interest to those who eat a high-nutrient diet with the inclusion of lots of leafy greens is that greens are another rich source of ALA. Traditional nutritionists have not considered leafy greens a source of ALA because they reasoned people would not eat enough of them to get a significant contribution of omega-3 fat. But guess what? When you eat one pound of greens each day, you get two grams of ALA, which is as much as from your flaxseed or walnuts. Those individuals who are following my guidelines for excellent health and a slim waistline as outlined in my book, Eat To Live, are eating a diet with a favorable ratio of fatty acids. When these beneficial fats are consumed from whole food rather than from extracted oils, the beneficial long-term effect on one’s health is significant.

DHA From Fish And Fish Oils

Proponents of fish consumption have long touted the benefits of eicosapentaenoic acid (EPA) and docoshexanoic acid (DHA), two omega-3 fatty acids shown to exert health benefits. Most people think of fish as the primary source of these important fats. The amount of EPA and DHA can vary significantly in various fish. Some salmon have very little DHA, for example. More importantly, several studies have indicated that fish oil supplements are prone to toxic materials. For example, certain fish oils have been shown to contain large concentrations of dioxins and PCBs as a result of decades of corporate and municipal dumping of toxic waste and raw sewage into our oceans. These contaminants—combined with the lipid peroxide contamination that occurs as the oil ages—compromise the supposed health benefits of fish oil consumption. Fish and fish oils also contain mercury. Data from the Center for Disease Control indicates that one in twelve women of childbearing age in the United States has unsafe mercury levels. The major contributor to body mercury load is the consumption of fish and fish oils (not dental fillings, as some health writers have suggested). Multiple studies have illustrated that most of the body’s mercury load is from the consumption of fish.1

Mercury levels have been linked with infertility,2 neurologic and mental disorders, high blood pressure, and endocrine disorders.3 Mercury levels also are directly linked to the risk of heart attack. In an international case-controlled study, mercury levels were assessed in 684 European men within twenty-four hours of a first myocardial infarction and in 724 control subjects without a heart attack. A strong dose response pattern was observed, with a more than doubling of the risk for heart attack patients in the highest fifth of mercury levels, compared to the lowest.4 Fish and fish oil is obviously not the ideal way to decrease one’s risk of heart attack. Epidemiologic data on fish intake and fish-oil consumption is contradictory and inconsistent; some studies show a worsening of cardiac events that increases as fish consumption increases. Given the contamination issues with both fish and fish oils, the rancidity of fish oil, and documented immune system suppression from fish oil, we cannot consider fish or fish oils to be “health food.”

DHA is a beneficial fat, but we have to reconsider the source of how we find it. Almost all fish are relatively toxic, compared with other foods. After many years of reviewing the evidence and recording the mercury levels in my patients (which invariably correlate well with their fish consumption), I recommend that people consume little or no fish.

Healthful Alternatives

A common mistake people make when learning about the benefits of omega-3 fats is to start taking lots of fish oils. But these beneficial fats are produced not only by fish, we humans manufacture them as well. From the ALA found in flaxseed and walnuts, our bodies can manufacture the long-chain omega-3 fats EPA and DHA. The question remains— can we make sufficient or ideal levels of these long-chain fats without consuming fish and fish oils?

Our bodies can produce some EPA and DHA from the N-3 fat in flaxseed, leafy greens, and walnuts. For some people (especially those whose diet is superior), this production is sufficient. However, when I draw blood tests for fatty acid analysis on my patients, I find that a large percentage of those on vegetarian and vegan diets, as well as those who do not eat fish regularly, have lower than optimal levels of DHA. How can we assure optimal production of DHA fat for everyone, if we are hesitant about recommending and consuming fish? The answer is to take vegetable- derived DHA capsules (brand name Omega-Zen-3) which are now available.

These purified DHA supplements are extracted from microalgae grown in laboratory conditions, free of all contamination. These capsules enable you to get the health benefits of fish, without the mercury, pollution, and other risks. Most of the anti-cancer benefits of the N-3 oils are accounted for by the DHA component (rather than the EPA component), and the human body can retrograde manufacture EPA from DHA when DHA is supplemented. I advise most of my patients to take one of these clean DHA supplements once every other day.


My recommendations regarding nutritional supplementation are clear and simple:

  1. Take one tablespoon of ground flaxseed per day.
  2. Take one Omega-Zen-3 (the only totally vegetarian source of DHA) approximately every other day.
  3. Take two Dr. Fuhrman’s Gentle Care Formula per day (three daily if over 65, one if under 12).

This keeps the supplemental recommendations simple and inexpensive for most of my patients who follow my Eat to Live plan. One bottle of my Gentle Care Formula and one small bottle of Omega-Zen-3 lasts three months—a small price to pay to assure that all your nutritional bases are covered, with minimal supplementation.


1. Drexler H, Schaller KH. The mercury concentration in breast milk resulting from amalgam fillings and dietary habits. Environmental Research 1990;77(2):124-129. Carta P, Flore C, Ibba A, et al. Urinary and blood markers of internal mercury dose in workers from a chlorakali plant and in subjects not occupationally exposed: relation to dental amalgam and fish consumption. Med Lav 2002;93(3):176-183. Apostoli P, Colombi A, Buratti M, et al. Evaluation of the dose of mercury in exposed and control subjects. Med Lav 2002;93(3):159-175.

2. Choy CM, Yeung QS, Briton-Jones CM, et al. Relationship between semen parameters and mercury concentrations in blood and in seminal fluids from subfertile males in Hong Kong. Fertility Sterility 2002;78(2):426-428.

3. D’lakovich MP, Efimova NV. Assessments of health risks upon exposure to methylated mercury. Gig Sanit 2001;Mar-Apr;(2):49-51.

4. Guallar E, Sanz-Gallardo MI, Veer P, et al. Mercury, Fish Oils, and the Risk of Myocardial Infarction. N Engl J Med 2002; 347(22):1747-1754.

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