An introduction to dietary/supplemental omega-3 fatty acids for general health and prevention: Part 2.

January 1, 2005 Human Health and Nutrition Data 0 Comments

An introduction to dietary/supplemental omega-3 fatty acids for general health and prevention: Part 2.

Year: 2005
Authors: Moyad, MA
Publication Name: Urologic Oncology: Seminars and Original Investigations.
Publication Details: Volume 23, Page 36.


In Part 2 of this manuscript, an overview of the effects of the omega 3 fatty acids on Alzheimer and neurologic diseases, asthma and inflammatory disease, depression, osteoporosis, and maternal and child health is presented. The role of the omega’s in reducing inflammation stems from the conversion of EPA to the eicosanoids that are very anti-inflammatory and reducing the AA derived eicosanoids that produce inflammation. Several studies have reported anti-inflammatory effects of fish oil in patients with rheumatoid arthritis and include reductions in the pro-inflammatory CRP. Several randomized, placebo controlled, double-blind studies of fish oil in rheumatoid arthritis have been conducted using doses of omega 3’s between 1.6 and 7.1 g/d (average 3.5 g/d). Almost all of these trials showed some benefit of fish oil, including reduced duration of morning stiffness, number of tender or swollen joints, joint pain, time to fatigue, as well as increased grip strength, and decreased use of nonsteroidal anti-inflammatory drugs. ALA can reduce the inflammatory compound, CRP as much as 75% when compared to a ‘traditional Western style’ diet. In men and women with high blood cholesterol levels, the addition of a margarine rich in ALA (2.3% energy) to the diet for a period of two years significantly decreased CRP. These results and others suggest that dietary ALA intake is associated with lower levels of inflammation which may also explain the effect of ALA in preventing CVD. Evidence suggests that dietary intake of EPA and DHA is associated with a decreased risk for certain neuropsychiatric disorders – particularly Attention Deficit (Hyperactivity) Disorder (ADD/ADHD), Alzheimer’s Disease (AD) and Depression. Although preliminary, omega-3 fatty acids have shown considerable promise in reducing risk of AD. In one such study, the association between DHA levels in the blood and dementia in 899 men and women (average age 76) was examined. The participants, who were free of dementia at the start of the study, provided blood samples and underwent neuropsychological testing. After an average of nine years of follow-up, the researchers documented 99 cases of dementia, including 71 with AD. Men and women who consumed the highest level of DHA over the nine years, had a 47 % lower risk of developing dementia and 39 per cent lower risk of developing AD than those consuming lower DHA levels. Low levels of dietary EPA and DHA have also been linked to the severity of depression. For example, the regular use of cod liver oil has been correlated with lower levels of depressive symptoms in the general population. The prevalence of depressive symptoms among those who used cod liver oil daily was 2.5% versus 3.8% in the rest of the population. A comprehensive analysis of the literature in this area revealed a protective effect of DHA and EPA in mood disorders, particularly in depression. DHA is an important component of neural and retinal membranes and during the later part of gestation and early postnatal life, DHA accumulates rapidly in the brain and retina. Increased dietary requirements of omega 3 fatty acids, primarily DHA, are recommended in the last trimester of pregnancy and pregnant women are advised to consume 100–300 mg DHA/day. Higher visual acuity following DHA supplementation has been observed for both term and healthy pre-term infants. A meta-analysis review of data published from 1965-1999 focused on the effect of omega 3 supplementation on visual acuity in healthy pre-term infants and reported higher acuity in DHA supplemented groups. A second systematic review in healthy full term infants included twelve studies and reported higher visual acuity at 2 months of age in DHA supplemented infants versus non-supplemented infants. In a recent double-blinded, randomized controlled trial, 103 full-term infants were randomly allocated to consume formula at day 5 with no supplemented DHA, or with supplemented DHA and AA. Measures of visual acuity in the DHA supplemented group were significantly higher at ages 6, 17, 26, and 52 weeks. Red blood cell levels of DHA in the DHA group was found to be more than double and triple at ages 17 and 39 weeks, respectively. Supplementation with DHA during the first year of life appears to result in beneficial outcomes in visual function.

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