From The May 1997 Issue of Nutrition Science News
by Richard N. Podell, M.D.
More than half of all patients who visit general physicians suffer from symptoms triggered or made worse by stress--headaches, ulcers, fatigue or even emotional distress. Two research studies demonstrated that essential fatty acid nutritional supplements can increase resistance to stress--and its debilitating and costly side effects.
The first study, published in the Journal of Clinical Investigation in 1996, tested the anti- stress power of docosahexaenoic acid (DHA), an omega-3 fatty acid most commonly derived from fish oil but also found in algae. Eicosapentaenoic acid (EPA), a close cousin of DHA, may be effective in reducing heart disease risk and treating rheumatoid arthritis and intestinal inflammations like Crohn's disease. DHA has different beneficial properties and appears to be particularly important in brain biochemistry. For instance, it is involved in the maturation of brain cells during gestation and infancy.
The DHA study involved 41 healthy fourth-year medical students. They took either fish-oil capsules containing 1.5 g to 1.8 g of DHA daily or a placebo made mainly of soybean oil. They underwent psychological testing, first during summer vacation, and again three months later during final exams.
Not surprisingly, the control group showed increased feelings of aggression during the exams compared to their scores during summer vacation. However, the students taking DHA showed a modest decrease in this negative emotion. The authors speculate that reducing the tendency toward anger and hostility might be another way that a diet high in fish and omega-3 fats could protect against heart attacks.
The second study, published in the Journal of Human Hypertension in 1989, found similar beneficial results from a different fat, gamma linolenic acid (GLA). GLA is a component of borage oil, primrose oil and black currant seed oil.
Thirty healthy Canadian university students volunteered to take either nine borage oil capsules (containing 1.3 g per day of GLA) or an olive oil placebo. Each student received a standard psychological stress test known as the Stroop color-word conflict test, both before and after 28 days of supplements.
The Stroop test consists of 200 words such as "red" or "green," each printed in a color different from the one it actually signifies. Thus, the word "red" might be printed in green ink and the word "green" in red ink. Subjects proceed through the list as rapidly as possible for two minutes, calling out the color of the ink. The test's deliberately mixed message typically stresses people and induces physical changes including rapid heart rate, increased blood pressure and cold fingers due to blood vessel spasms.
Students taking the placebo showed little change in their vulnerability to stress. However, those taking high-GLA borage oil showed reduced stress vulnerability after 28 days of supplementation.
The Bottom Line
Both studies demonstrate that stress vulnerability is not "just" psychological. How we eat affects our ability to resist stress. If this is true for young, healthy students, how much more so might it be for older or sick people? It's unfortunate that neither study looked at subjects' red blood cell fatty acid levels--a relatively inexpensive test offered by several suppliers. Measuring people's fatty acid profiles might make it possible to recommend fatty acid supplements that better meet their needs.
These reports are scientifically important, but they also illustrate changing attitudes toward nutrition. The borage oil study appeared in the Journal of Human Hypertension, a respected but little-read journal. No one since has bothered to repeat the study to either confirm or refute it. And I never see the article footnoted in the journals I read.
The DHA study was published in the Journal of Clinical Investigation -- JCI to those in academic medicine. While not well-known to the public, no journal ranks higher in prestige within the halls of academia.
Will the JCI's pedigree save the DHA article from obscurity? Perhaps not. Few practicing physicians read the journal. But the fact that the journal editors accepted a paper on DHA and stress--and earmarked it for quick publication--shows how much respect nutrition research has gained.
We still have much guesswork in our nutritional prescriptions, but the scientific basis for our field is getting stronger every month. In academic medicine, at least, the leaders are noticing.
Richard Podell, M.D., is clinical professor of family medicine at the UMDNJ-Robert Wood Johnson Medical School in New Brunswick, N.J. He is the author of Patient Power: How to Protect Yourself Against Medical Error (Fireside, 1996).
Hamazaki, Tomohito, et al.
The effect of docosahexaenoic acid on aggression in young adults: A placebo-controlled double-blind study
Journal of Clinical Investigation, 97: 1129-34,1996.
Mills, D., et al.
Dietary fatty acid supplementation alters stress reactivity and performance in man
Journal of Human Hypertension, j3: 111-16, 1989.
Neuringer, M., et al.
Biochemical and functional effects of prenatal and postnatal w3 fatty acid deficiency on retina and brain in rhesus monkeys
Proceedings of the National Academy of Science, 83: 4021-25, 1986.
McLennan, P., et al.
Dietary fish oil prevents ventricular fibrillation following coronary artery occlusion and reperfusion
American Heart Journal, 116: 709-17, 1988.
Mills, D, & Ward, R.
Effects of essential fatty acid administration on cardiovascular responses to stress
Proceedings of the Society of Experimental Biology and Medicine 182: 127-31, 1986
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