From University of Maryland, Medical Center

Omega-3 fatty acids

Overview

Omega-3 fatty acids are considered essential fatty acids: They are necessary for human health but the body can?t make them — you have to get them through food. Omega-3 fatty acids can be found in fish, such as salmon, tuna, and halibut, other seafood including algae and krill, some plants, and nut oils. Also known as polyunsaturated fatty acids (PUFAs), omega-3 fatty acids play a crucial role in brain function, as well as normal growth and development. They have also become popular because they may reduce the risk of heart disease. The American Heart Association recommends eating fish (particularly fatty fish such as mackerel, lake trout, herring, sardines, albacore tuna, and salmon) at least 2 times a week.

Research shows that omega-3 fatty acids reduce inflammation and may help lower risk of chronic diseases such as heart disease, cancer, and arthritis. Omega-3 fatty acids are highly concentrated in the brain and appear to be important for cognitive (brain memory and performance) and behavioral function. In fact, infants who do not get enough omega-3 fatty acids from their mothers during pregnancy are at risk for developing vision and nerve problems. Symptoms of omega-3 fatty acid deficiency include fatigue, poor memory, dry skin, heart problems, mood swings or depression, and poor circulation.

It is important to have the proper ratio of omega-3 and omega-6 (another essential fatty acid) in the diet. Omega-3 fatty acids help reduce inflammation, and most omega-6 fatty acids tend to promote inflammation. The typical American diet tends to contain 14 – 25 times more omega-6 fatty acids than omega-3 fatty acids, which many nutritionally oriented physicians consider to be way too high on the omega-6 side.

The Mediterranean diet, on the other hand, has a healthier balance between omega-3 and omega-6 fatty acids. Many studies have shown that people who follow this diet are less likely to develop heart disease. The Mediterranean diet emphasizes foods rich in omega-3 fatty acids, including whole grains, fresh fruits and vegetables, fish, olive oil, garlic, as well as moderate wine consumption.

Uses

Clinical evidence is strongest for heart disease and problems that contribute to heart disease, but omega-3 fatty acids may also be used for:

More under the link below,

From Harvard Public Health Review:

While vitamin D?s role in strengthening bones is well established, its links to cancer and immune-system malfunctions have only recently emerged. At the Harvard School of Public Health, nutrition experts say large segments of the population don?t get enough vitamin D and are urging the U.S. Food and Drug Administration to raise the daily recommended dose, from 400 international units to 800. For an update on what?s known so far about this important nutrient, the Harvard Public Health Review spoke with HSPH Professor of Nutrition and Epidemiology Edward Giovannucci.

Q: What are the documented benefits of vitamin D?

A: Vitamin D?s best-known role is in building strong bones. We?ve seen plenty of advertising urging people to take calcium to strengthen bones, but people also need to know that calcium can?t do the job well if they?re low on vitamin D. The two micronutrients work

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http://www.hsph.harvard.edu/review/spring07/spr07vitaminD.html