Alpha-linolenic acid is a type of omega-3 fatty acid found in plants. It is found in flaxseed oil, and in canola, soy, perilla, and walnut oils.
Alpha-linolenic acid is similar to the omega-3 fatty acids that are in fish oil, called eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Your body can change alpha-linolenic acid into EPA and DHA. However, some researchers suggest that less than 1% of ALA is converted to physiologically effective levels of EPA and DHA.
Omega-3 fatty acids -- especially EPA and DHA -- have been shown to reduce inflammation and may help prevent chronic diseases, such as heart disease and arthritis. They may also be important for brain health and development, as well as normal growth and development.
There is good evidence that fish oil containing EPA and DHA may help treat heart disease, prevent heart attack and stroke, and slightly reduce high blood pressure. Some researchers think the same may be true for alpha-linolenic acid. There is evidence that this may be so, but the evidence is not as strong as it is for fish oil.
Note: Alpha-linolenic acid is not the same as alpha-lipoic acid, an antioxidant that helps the body turn glucose into energy. This can be confusing because both alpha-linolenic acid and alpha-lipoic acid are sometimes abbreviated as ALA.
One of the best ways to help prevent and treat heart disease is to eat a diet that is low in saturated and trans fats, and rich in monounsaturated and polyunsaturated fats, particularly omega-3 fatty acids. The Mediterranean Diet -- which emphasizes whole grains, root and green vegetables, daily servings of fruit, fish and poultry, olive and canola oils, and alpha-linolenic acid (found in flaxseed oil) -- is an example.
There's some evidence that eating foods high in alpha-linolenic acid may help, too. One study suggests that people who eat a diet high in alpha-linolenic acid are less likely to have a fatal heart attack. Another study found that women who ate high levels of alpha-linolenic acid (1.5 g per day) had a 46% lower risk of sudden cardiac death than those who ate the lowest amount of alpha-linolenic acid (about half a gram per day). Other population studies show that as people eat more foods with alpha-linolenic acid, heart disease deaths go down.
Researchers don't know whether taking alpha-linolenic acid supplements would have the same effect as eating foods rich in alpha-linolenic acid.
People who follow a Mediterranean-style diet tend to have higher HDL ("good") cholesterol levels. In addition, walnuts -- which are rich in alpha-linolenic acid -- have been shown to lower cholesterol and triglycerides in people with high cholesterol. However, studies with flaxseed oil, which is high in alpha-linolenic acid, have been mixed. Some studies found that alpha-linolenic acid may help lower cholesterol, while others found it didn't. Researchers don't know whether alpha-linolenic acid supplements would have the same benefits as foods with alpha-linolenic acid.
High Blood Pressure
Several studies suggest that diets or supplements rich in omega-3 fatty acids lower blood pressure slightly in people with hypertension. One population study found that eating a diet rich in alpha-linolenic acid reduced the risk of high blood pressure by about 30%.
Preliminary research suggests that omega-3 fatty acid supplements (particularly perilla seed oil, which is rich in alpha-linolenic acid) may decrease inflammation and improve lung function in some people with asthma.
Preliminary studies suggest that higher intakes of ALA is linked with improvements in dry eye that are comparable to those seen with corticosteroids. ALA is also linked with lower inflammatory markers among patients with chronic obstructive pulmonary disease.
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