| Pharmacol Res 1999 Sep;40(3):211-25 |
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Health benefits of docosahexaenoic acid.
Horrocks LA, Yeo YK
Docosa Foods Ltd, 1275 Kinnear Road, Columbus, OH 43212-1155, USA,
Docosahexaenoic acid (DHA) is essential for the growth and functional
development of the brain in infants. DHA is also required for maintenance of
normal brain function in adults. The inclusion of plentiful DHA in the diet
improves learning ability, whereas deficiencies of DHA are associated with
deficits in learning. DHA is taken up by the brain in preference to other
fatty acids. The turnover of DHA in the brain is very fast, more so than is
generally realized. The visual acuity of healthy, full-term, formula-fed
infants is increased when their formula includes DHA. During the last 50
years, many infants have been fed formula diets lacking DHA and other
omega-3 fatty acids. DHA deficiencies are associated with foetal alcohol
syndrome, attention deficit hyperactivity disorder, cystic fibrosis,
phenylketonuria, unipolar depression, aggressive hostility, and
adrenoleukodystrophy. Decreases in DHA in the brain are associated with
cognitive decline during aging and with onset of sporadic Alzheimer disease.
The leading cause of death in western nations is cardiovascular disease.
Epidemiological studies have shown a strong correlation between fish
consumption and reduction in sudden death from myocardial infarction. The
reduction is approximately 50% with 200 mg day(-1)of DHA from fish. DHA is
the active component in fish. Not only does fish oil reduce triglycerides in
the blood and decrease thrombosis, but it also prevents cardiac arrhythmias.
The association of DHA deficiency with depression is the reason for the
robust positive correlation between depression and myocardial infarction.
Patients with cardiovascular disease or Type II diabetes are often advised
to adopt a low-fat diet with a high proportion of carbohydrate. A study with
women shows that this type of diet increases plasma triglycerides and the
severity of Type II diabetes and coronary heart disease. DHA is present in
fatty fish (salmon, tuna, mackerel) and mother's milk. DHA is present at low
levels in meat and eggs, but is not usually present in infant formulas. EPA,
another long-chain n-3 fatty acid, is also present in fatty fish. The
shorter chain n-3 fatty acid, alpha-linolenic acid, is not converted very
well to DHA in man. These longchain n-3 fatty acids (also known as omega-3
fatty acids) are now becoming available in some foods, especially infant
formula and eggs in Europe and Japan. Fish oil decreases the proliferation
of tumour cells, whereas arachidonic acid, a longchain n-6 fatty acid,
increases their proliferation. These opposite effects are also seen with
inflammation, particularly with rheumatoid arthritis, and with asthma. DHA
has a positive effect on diseases such as hypertension, arthritis,
atherosclerosis, depression, adult-onset diabetes mellitus, myocardial
infarction, thrombosis, and some cancers. Copyright 1999 Academic Press
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