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he main emphasis on this short and somewhat overpriced
book is omega-3 fatty acids, particularly docosahexaenoic acid (DHA, 22:6).
This lipid is synthesized in humans, albeit at a slow rate, from
linolenic acid, an essential fatty acid that cannot be made in the body
but must be supplied in the diet. DHA is a primary building block
in the synaptic membranes of the human brain and retina. Deficiency of
DHA can cause depression and impairment of brain development.
Consumption of seafood, which is a rich source of DHA, is highly
significantly (p<0.005) negatively correlated across cultures with
lifetime rates of depression. The authors also speculate about possible
roles of omega-3 fatty acids and other lipid molecules in postpartum
depression, bipolar affective disorder, neurodegenerative diseases,
so-called attention deficit hyperactivity disorder (ADHD), and schizophrenia.
Interestingly, schizophrenic patients seem to be at reduced risk for rheumatoid arthritis, inflammatory disorders, and cerebrovascular disease. These topics and the role of lipids in various brain disorders are currently under intense investigation. While it is clear that dietary omega-3 fatty acids may be beneficial in cardiovascular disease, there is as yet no conclusive evidence for a role of omega-3 in any clinical brain disorder. Other articles discuss apolipoprotein E (a protein molecule that transports cholesterol), the lipid hypothesis of schizophrenia, eicosapentaenoic acid (EPA, 20:5), and phospholipids. Like DHA, apolipoprotein E is also a hot topic because the ε4 allele is a risk factor for Alzheimer's disease. The theory that low cholesterol levels may trigger depression or aggressive behavior is also discussed.
The articles are review papers written at a level appropriate for an audience of biochemists, nutritionists, or physicians. Perhaps understandably, each author is an enthusiastic and occasionally unskeptical advocate of the particular lipid molecule he or she is studying. Their infectious enthusiasm is no doubt born of the tremendous benefits that taking omega-3 fish oil supplements would have for public health if their hypotheses turn out to be correct.
