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Andrés Guerrero Serrano

sábado, 7 de septiembre de 2013

What Omega3s Can and Can't Do: The Truth About Omega-3s

(Extraído de thirdage.com)


Omega-3 supplements have become a health phenomenon, with claims that they can help protect against conditions as varied as heart disease and arthritis. And according to one survey, they are now the most commonly taken alternative supplement among adults. Here, from the National Center for Complementary and Alternative Medicine, a division of the National Institutes of Health, are some facts to consider before you jump on the omega-3 bandwagon:

First, know your terms. Commonly used dietary supplements that contain omega-3s include fish oil (which provides EPA and DHA) and flaxseed oil (which provides ALA). Algae oils are a vegetarian source of DHA.  But fish liveroils are not the same as fish oils. Although they contain omega-3 fatty acids,  fish liver oils also have vitamins A and D, which can be toxic in high doses.

Omega-3 fatty acids are important for a number of bodily functions, including muscle activity, blood clotting, digestion, fertility, and cell division and growth. DHA is important for brain development and function. ALA is an "essential" fatty acid, meaning that people must obtain it from food or supplements because the human body cannot manufacture it.

There has been a substantial amount of research on supplements of omega-3s, particularly those found in seafood and fish oil, and heart disease. The findings of individual studies have been inconsistent. In 2012, two combined analyses of the results of these studies didn’t find convincing evidence these omega-3s protect against heart disease. Eating seafood such as tuna and salmon a few times a week may provide some protection, but eating fish a lot doesn’t provide extra safety.

There is some evidence that omega-3s found in seafood and fish oil may be modestly helpful in relieving symptoms of rheumatoid arthritis. For most other conditions for which omega-3s have been studied, there are no definitive conclusions yet, or studies haven’t shown omega-3s to be beneficial.

There is conflicting evidence about whether omega-3 fatty acids found in seafood and fish oil might increase the risk of prostate cancer. Additional research on the association of omega-3 consumption and prostate cancer risk is under way. Although omega-3 fatty acid supplements don’t usually have negative side effects, they can cause minor symptoms such as belching, indigestion, or diarrhea.

Some more serious considerations: It’s not known whether people with fish or shellfish allergies can safely consume fish oil supplements. The Omega-3 supplements may extend bleeding time (the time it takes for a cut to stop bleeding). People who take drugs that affect bleeding time, such as anticoagulants ("blood thinners") or nonsteroidal anti-inflammatory drugs (NSAIDs), should discuss the use of omega-3 fatty acid supplements with a health care provider.

Other studies have been conducted on the effect of omega-3s on various disorders, including allergies, asthma, cachexia (severe weight loss) associated with advanced cancer, Crohn's disease, cystic fibrosis, diabetes, kidney disease, lupus, menstrual cramps, obesity, osteoporosis, and ulcerative colitis, as well as organ transplantation outcomes. So far, scientists can’t draw any conclusions about whether omega-3s are helpful for these conditions.

Further research is being done to see how omega-3s function in relation to various illnesses, including

Diseases of the brain or nervous system, such as cognitive decline and multiple sclerosis.

Mental and behavioral health problems, such as depression, borderline personality disorder, and schizophrenia.

Diseases of the eye, such as age-related macular degeneration) and dry eye syndrome. Studies have shown that people who eat diets rich in seafood are less likely to develop the advanced stage of AMD. However, a large NIH-sponsored study, called Age-Related Eye Disease Study 2 (AREDS2), indicated that supplements containing EPA and DHA did not slow the progression of AMD in people who were at high risk of developing the advanced stage of this disease.

If you’re considering using omega-3 supplements, a few words of caution:

*Do not use omega-3 supplements to replace conventional care or to postpone seeing a health care provider about a health problem.

Consult your health care provider before using the supplements. If you are pregnant, trying to become pregnant, or breastfeeding; if you take medicine that affects blood clotting; if you are allergic to fish or shellfish; or if you are considering giving a child an omega-3 supplement, it is especially important to consult your (or your child's) health care provider.

Look for published research studies on omega-3 supplements for the health condition that interests you. Information on evidence-based studies is available from NCCAM.

Tell all your health care providers about any complementary health approaches you use. Give them a full picture of what you do to manage your health. This will help ensure coordinated and safe care.

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