Polyunsaturated fatty acids are made out of a hydrocarbonated chain of variable length with several double bonds. Polyunsaturated omega 3 fatty acids and polyunsaturated omega 6 fatty acids are different in the position of the first double bond (omega).
These two fatty acids are needed by the body but cannot manufacture them. They can only be derived from proper diet. Sufficient polyunsaturated fatty acids contribute to lower blood cholesterol levels. Brain requires very high content of this fatty acid but is dependent on the dietary intake alone to have the adequate supply. Dietary lack of essential polyunsaturated fatty acid can affect the cerebral development, brain function and the fight against diseases.
On Diseases
Among the fatty acids, it is the omega-3 polyunsaturated fatty acid or PUFA that is the most effective in the body’s fight against diseases and among the omega-3 PUFA it is the fish oil and the docosahexaenoic acid (DHA) that are the most effective.
Several studies proved that omega-3 fatty acids have anti-inflammatory properties and is very helpful in the management of autoimmune diseases. Coronary heart disease, major depression, aging and cancer are characterized by proinflammatory cytokine. Similarly, arthritis, Crohn's disease, ulcerative colitis and lupus erythematosis are autoimmune diseases also characterized by proinflammatory leukotriene. Study showed that lower omega-3 levels are associated with increased risk of coronary artery disease (CAD), increases in cardiac events in CAD patients, and depression.
It was proven that dietary supplementation with fish oils in several inflammatory and autoimmune diseases in humans, including rheumatoid arthritis, Crohn's disease, ulcerative colitis, psoriasis, lupus erythematosus, multiple sclerosis and migraine headaches is very beneficial.
On Depression
Over the years, the rate of depression has been increasing globally. Although several factors have been recognized as contributory, medically, it was theorized that this increasing rate has been caused by the unbalanced intake of polyunsaturated omega 3 fatty acid (found in fish, vegetables and game) and the polyunsaturated omega 6 fatty acid (cereal oil).
DHA and AA (arachidonic acid) are the major polyunsaturated fatty acids in the membranes of brain and retinal cells. Deficiency in dietary n-3 fatty acids could result to reduced visual acuity and impaired learning ability. Adding DHA and AA to milk replacer-formulas significantly improves mental development and maturation of visual function. In adults, low intakes of fish or of n-3 PUFA in have been associated with increased risks of depression and Alzheimer disease.
The omega-3 polyunsaturated acid or DHA plays a very important role in the nervous system especially since it is found in very high concentration in cell membranes. In infants it is needed for the growth and functional development of the brain. Deficiency could result in various mental disorders or learning and cognitive disorders. For adults, DHA maintains normal brain function and insufficient DHA may result in schizophrenia and depression.
Depressed patients had significantly lower concentrations of total omega-3 and DHA, and higher ratios of arachidonic acid (AA) to DHA, AA to eicosapentaenoic acid (EPA), and n-3 to n-6.
Two studies found that when the level of polyunsaturated omega 3 fatty acids or the ratio omega 3/6 was low it caused a higher severity of depression. Polyunsaturated omega 3 fatty acids are associated with different levels of major depression because of their role in the membrane fluidity and their function as precursor of pro-inflammatory cytokinesis and eicosanoids disturbing neurotransmission. And n-3 PUFA has been found to be very effective as an added treatment, and in some cases the only treatment, in several psychiatric disorders.
In a study on 30 patients with bipolar disorder, supplementation of n-3 PUFA created longer period of remission and better prognosis. And in another recent study on depressed patients, after 4 weeks, 6 out of 10 patients who received fatty acids became better than those receiving placebo.
Evidence collected from different countries also showed that suicide, more so violent suicide, is affected by fish-oil intake (rich in n-3 polyunsaturated fatty acids) or the lack thereof. A recent study concluded that lifelong intake of fish oil (rich in n-3 PUFA) was able to induce an antidepressant effect with EPA and DHA concentration increased in the cerebral cortex and hippocampus.
On Postpartum Depression
DHA is transferred by mothers to their babies as they develop in the womb. Thus it is important for both mothers and their babies to have sufficient DHA during this period. For the fetus, DHA is needed for a complete neurological development. And for the mothers, without sufficient DHA the risk of suffering major depression in the postpartum depression is highly increased.
In a recent study, the contents of DHA were measured in the plasma phospholipids of 112 women at delivery and 32 weeks postpartum. The results proved that DHA is lower in the 'possibly depressed' group compared to the non-depressed group. Lactating women were more likely to suffer from depressive symptoms than non-lactating women. Sufficient DHA during the postpartum period lessens the development of depressive symptoms.
DHA content of mother’s milk and their seafood consumption can therefore predict whether the mother would suffer postpartum depression. In a study using reports from 23 countries, it was found that both lower DHA content in mothers’ milk and lower seafood consumption are consistent with higher rates of postpartum depression. Sufficient dietary intake of DHA, such as seafood, would therefore help mothers and their babies.