A high intake of omega-3 essential fatty acids may reduce the risk of age-related macular degeneration (AMD) by up to 38%, a new meta-analysis suggests.

Pooling the data from nine studies, researchers from the University of Melbourne in Australia report that the benefits were most pronounced against late (more advanced) AMD, while eating fish twice a week was associated with a reduced risk of both early and late AMD.

The meta-analysis, which included 88,974 participants and 3,203 people with AMD, was published in the journal Archives of Ophthalmology.

Since omega-3 fatty acids, and particularly DHA (docosahexaenoic acid), play an important role in the layer of nerve cells in the retina, “a diet rich in omega-3 fatty acids and fish, as a proxy for long-chain omega-3 fatty acid intake, has therefore been hypothesized as a means to prevent AMD,” wrote lead author Elaine Chong.

Chong and co-workers searched seven databases to identify randomized controlled trials (RCTs) and prospective cohort, case-control and cross-sectional studies. Only nine studies—three prospective cohorts, three cross-sectional, three case-control studies—met the inclusion criteria.

Combining the results showed that a high dietary intake of omega-3 EPA (eicosapentaenoic acid) was associated with a 23% reduction in the risk of early AMD, whereas DHA was associated with a 30% reduction.

In terms of advanced AMD, the researchers report that a high dietary intake of omega-3 was associated with a 38% reduction in risk. Consuming fish at least twice a week was linked to 24% and 33% reduction in early and late AMD, respectively.

Archives of Ophthalmology 126(6):826-833, 2008

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Low-dose resveratrol may slow ageing

Resveratrol, a polyphenol found in red wine, may mimic the effects of calorie restriction and inhibit various aspects of the ageing process, according to a new study.

The study adds to a growing body of research linking resveratrol and red wine consumption to a range of beneficial health effects, including brain and mental health and cardiovascular health.

Red wine and resveratrol have been lauded as the answer to the “French paradox,” the question that asks why people who live in some regions of France where diets are soaked with saturated fats and washed down with a glass of wine, have a low incidence of heart disease.

Previous in vitro and in vivo studies with resveratrol suggest that the compound may help prevent the negative effects of high-calorie diets and have anti-inflammatory and anti-cancer potential.

Critics of resveratrol’s benefits state that in order to gain support from dietary sources, one would have to drink 350 to 1,250 liters of red wine. Moreover, they believe that resveratrol supplements would not be effective since a daily dose of 2,500 mg would be required to mimic the effects observed in other studies.

“Resveratrol is active in much lower doses than previously thought and mimics a significant fraction of the profile of caloric restriction at the gene expression level,” said researcher Tomas Proila from the University of Wisconsin-Madison.

The amount of resveratrol in a bottle of red wine can vary between types of grapes and growing seasons, and can vary between 0.2 and 5.8 mg per liter. But nearly all dark red wines—merlot, cabernet, zinfandel, shiraz and pinot noir—contain resveratrol.

The new study, published in the open-access journal Public Library of Science One, suggests that low doses of resveratrol in the diet of middle-aged mice may influence genetic issues involving aging and may provide special protection for the heart.

“Our findings that a low dose of resveratrol partially mimics calorie restriction at the gene expression level and leads to prevention of some age-related parameters suggests that clinical trials with resveratrol should be conducted to test the relevance of these findings in humans,” wrote lead author Jamie Barger. “Because cardiac disease is a major contributor to age-related mortality, positive findings could lead to a novel and important approach to improve the quality of human life.”

The researchers fed middle-aged mice (14 months) a control diet, a low dose of resveratrol or a calorie-restricted diet, and followed the animals until old age (30 months). They found that animals in the calorie-restriction and low-dose resveratrol groups had altered gene expression profiles in 90% and 92%, respectively, in the heart.

The new findings, say the study’s authors, were associated with prevention of the decline in heart function associated with ageing. In short, a glass of wine or food or supplements that contain even small doses of resveratrol are likely to represent “a robust intervention in the retardation of cardiac ageing,” wrote the authors.

“There must be a few master biochemical pathways activated in response to caloric restriction, which in turn activate many other pathways,” said Proila. “And resveratrol seems to activate some of these master pathways as well.”

Public Library of Science One Published online ahead of print.

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