Posted by henryo on February 28, 2008, at 4:57:08
Low levels of DHA result in reduction of brain serotonin levels[2] and have been associated with ADHD, Alzheimer's disease, and depression, among other diseases, and there is mounting evidence that DHA supplementation may be effective in combating such diseases.
DHA is the most abundant essential fatty acid (polyunsaturated fatty acids, PUFAs) in the brain and retina. It comprises 40% of the PUFAs in the brain and 60% of the PUFAs in the retina. 50% of the weight of the neuron's plasma membrane is composed of DHA.
Of all the fatty acids, DHA has the largest effect on brain PUFA composition. DHA is found in three phospholipids: phosphatidylethanolamine, ethanolamine plasmalogens, and phosphatidylserine (PS). It modulates the carrier-mediated transport of choline, glycine, and taurine, the function of delayed rectifier potassium channels, and the response of rhodopsin contained in the synaptic vesicles, among many other functions.
DHA deficiency is associated with cognitive decline. PS controls apoptosis, and low DHA levels lower neural cell PS and increase neural cell death. DHA is depleted in the cerebral cortex of severely depressed patients.
Studies[4][5] were conducted on prisoners in England where the inmates were fed seafood which contains Omega-3 Fatty acids. The higher consumption of these fatty acids led to a drop in the assault rates. Another Finnish study found that prisoners who were convicted of violence had lower levels of omega3 fatty acids than prisoners convicted of nonviolent offenses. It was suggested that these kinds of fatty acids are responsible for the neuronal growth of the frontal cortex of the brain which, it is further alleged, is the seat of personal behavior.
Recent studies have suggested that fish oil may affect depression, and importantly, suicidaliy risk. One such study[6], took blood samples of 100 suicide-attempt patients and compared the blood samples to those of controls and found that levels of Eicosapentaenoic acid were significantly lower in the washed red blood cells of the suicide-attempt patients.
The American Heart Association recommends the consumption of 1g of fish oil daily, preferably by eating fish, for patients with coronary heart disease.[7]
The US National Institutes of Health lists three conditions for which fish oil and other omega-3 sources are most highly recommended: hypertriglyceridemia, secondary cardiovascular disease prevention and high blood pressure. It then lists 27 other conditions for which there less evidence. It also lists possible safety concerns: "Intake of 3 grams (3000mg) per day or greater of omega-3 fatty acids may increase the risk of bleeding, although there is little evidence of significant bleeding risk at lower doses. Very large intakes of fish oil/omega-3 fatty acids ("Eskimo" amounts) may increase the risk of hemorrhagic (bleeding) stroke."[8]
According to a study from Louisiana State University in September 2005, fish oil may help protect the brain from cognitive problems associated with Alzheimer's disease. [9]
A study from the Orygen Research Centre in Melbourne suggests that omega-3 fatty acids could also help delay or prevent the onset of schizophrenia. The researchers enlisted 81 'high risk' young people aged 13 to 24 who had previously suffered brief hallucinations or delusions and gave half of them capsules of fish oil while the other half received fish-tasting dummy subtitute. One year on, only three percent of those on fish oil had developed schizophrenia compared to 28 percent from those on the substitute - a very impressive result, but not yet published in a peer reviewed journal[1].
poster:henryo
thread:815125
URL: http://www.dr-bob.org/babble/20080221/msgs/815125.html