Connor sees ample evidence that long-chain n-3s have a critical bearing on intellectual performance in humans. He cites a well-controlled study of premature infants fed by tube, either standard American infant formula or breast milk. The children given breast milk had significantly higher IQs, an advantage they maintained over the eight-year study. Their IQ superiority rests exclusively on docosahexaenoic acid, Connor insists. It's a known component of breast milk. While infant formulas sold in Japan and Europe contain docosahexaenoic acid, most American formulas do not.
N-3 fats may also have the ability to protect the brain from damage, or heal it once damage occurs. In Fish and Human Health (Academic Press, 1986), biochemist William E. M. Lands, Ph.D., cites a study demonstrating that fish oil reduced the degree of brain damage in cats experiencing cerebral stroke.
Nutrients for Neurotransmitters
The brain deploys a multitude of biochemicals to carry out its many cognitive tasks and make you happy, calm, alert, relaxed, energized, or motivated. Helping orchestrate every thought, feeling, and movement are the neurotransmitters, perhaps the best known of which is serotonin, whose functions include sleep regulation and anxiety reduction. Another key neurotransmitter is acetylcholine, essential in memory formation and maintenance. And count in dopamine, epinephrine, and norepinephrine, collectively called catecholamines, which control arousal and anxiety states.
Neurotransmitters are manufactured in the body from amino acids and other substances supplied by diet. Serotonin, for example, is manufactured from the amino acid tryptophan, which, like all other amino acids, is found in protein-rich foods. Dopamine and norepinephrine are derived from the amino acid tyrosine (which in turn can be made from the amino acid phenylalanine). Acetylcholine is made from the fatlike B vitamin choline, found in egg yolks and organ meats.
Ongoing research has begun to detail better how neurotransmitters are assembled from the foods we eat, how they decline with age, disease, environmental stress, or suboptimal dietary patterns. And science is only at the dawn of recognizing how dietary components, consumed in foods or as vitamin-like supplements, may help restore healthy levels of neurotransmitters.
Creation and utilization of acetyl-choline, so crucial to memory, is a complicated process dependent on numerous enzymes, hormones, and other neurotransmitters. Scientists do know that the devastation of Alzheimer's disease results from underproduction of acetylcholine due to death of the cholinergic neurons that make it.
So by consuming more choline than is normally found in the diet, can a healthy younger person perform better mentally? While the presence of extra choline does increase the amount of acetylcholine in certain areas of the brain, says Barbara Strupp, Ph.D., associate professor of psychology and nutritional sciences at Cornell University, "that doesn't mean it has any effect on learning. Just because you have more acetylcholine available doesn't mean more will be used," unless neurons are specifically calling on it.
It's different, however, in Alzheimer's patients. They have suffered neuron loss, which puts a burden on surrounding cells. "The remaining cells are firing more," says Strupp. "Maybe these people would benefit from megadoses of choline." Indeed, aging mice given choline supplements showed improvement on memory tests, and an increase in the number of dendritic spines, tiny branches on nerve cells by which they communicate with each other.
Gut Reactions
At the vanguard in choline research, as in much other research on the relationship between diet and performance, both mental and physical, is the U.S. Army. Even Napoleon knew that an army marches on its stomach, although if he were alive today he might update his famous dictum by declaring that an army thinks on its stomach, too. Can choline enhance the mental and physical skills of troops?
In Food Components to Enhance Performance, a groundbreaking report produced for the army by the National Academy of Sciences in 1994, researchers pulled together what's known about food and behavior. Choline supplementation, the report concludes, enhances memory and reaction time in animals, particularly aging animals. It also enhances memory in people, scant human studies show. The most concrete evidence of the benefits of choline supplementation concern physical performance. Choline supplementation minimizes fatigue. In one study cited in the report, choline given during a 20-mile run improved running time by five minutes.
Army researchers are also looking at the effects of supplemental tyrosine, the amino acid that is the precursor to the neurotransmitters dopamine, epinephrine (or adrenaline), and norepinephrine (noradrenaline). All three help regulate levels of arousal and anxiety, and are the major players in the brain's response to stress. Environmental stress depletes the blood of tyrosine, limiting the amount available for neurotransmitter manufacture. Performance flags. But when given tyrosine supplements, soldiers exposed to high altitudes or prolonged cold do not suffer the loss of memory, lightheadedness, headache, nausea, and general malaise such stresses normally bring on.
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