DHA

Discover august 1996 
Courtesy Josef Gutter

Breakthroughs-HEALTH

Bottle-Fed Eyes

WHILE MANY OF US SEEK TO CUT fat from our diet, some babies may not be getting enough to stay healthy. Over the last decade, scientists have found that babies born prematurely need supplements of certain fatsÑin particular a group of polyunsaturated fats called omega-threes, in order for their vision to develop normally. Infants usually get these fats in their last months in the womb, so premature babies don't get a full dose. Now vision researcher Eileen Birch and her colleagues at the Retina Foundation of the Southwest in Dallas have found that all babies apparently need the fats even a few months after birth. And, says Birch, not just any fatty acid in this group will do. She tbinks all babies need one called DHA. Wlthout it, their vision suffers.
Human milk contains DHA, says Birch, but at least a third of American babies drink only formula from birth, and formula lacks this fat. DHA is a crucial building block of the membranes of nerve cells in the retina and brain (and also of red blood cell membranes because it is believed to keep those membranes fluid and permeable. This is important because nerve cells depend on the efficient passage of molecules across their membranes to generate the signals that transmit visual information from the retina to the brain. Those membranes develop rapidly from the final three months of pregnancy to six months after birth, after which they're essentially set for life. If babies don't get enough DHA during this dtical period, another fatty acid takes its place, one that makes the cell membranes less fluid AÑand one that may therefore impair the transmission of nerve signals.
Birch and her colleagues studied 162 infants, none of whom were born prematurely, for one year. The researchers found that babies fed formula without DHA had poorer vision than babies who were given a DHA supplement. The difference between the two groups, Birch says, is equivalent to about one line on an eye chart. "It's not as though it's putting them in a poorly performing group," Birch says. "They're just slightly below average, and the kids with the supplement are slightly above average."
Birch says the Food and Drug Administration will decide by next spring if DHA is necessary for infant development. She expects the FDA will indeed mandate that DHA be added to infant formula.

Nutrition Science News ~ May 1997—Vol. 2, No. 5

Nutrition Science News ~ May 1997ÑVol. 2, No. 5

DOCTOR'S INSIGHT

STRESS_REDUCING FATTY ACIDS ALSO MAY DEFUSE HEALTH RISKS

by Richard N. Podell, M.D.

More than half of all patients who visit general physicians suffer from symptoms triggered or made worse by stressÑ headaches, ulcers, fatigue or even emotional distress. Two research studies demonstrated that essential fatty acid nutritional supplements can increase resistance to stressÑ and its debilitating and costly side effects.

The first study, published in the Journal of Clinical Investigation in 1996, tested the antistress 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 arth' ritis and intestinal inflammations like Crohn's disease. DHA has differ' ent 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 Co| lor-Word Conflict Test, | both before and after 28 I 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 levelsÑa 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 Joumal of Human Hypertension, a respected but little-read joumal. No one since has bothered to repeat the study to either confirm or refute it. And I never see the article footnoted in the joumals I read.

The DHA study was published in the Journal of Clinical InvesagononÑJCI to those in academic medicine. While not wellknown to the public, no joumal ranks higher in prestige within the halls of academia.

Will the JCl's pedigree save the DHA article from obscurity? Perhaps not. Few practicing physicians read the journal. But the fact that the joumal editors accepted a paper on DHA and stress and earmarked it for quick publicationÑshows 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).