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Review: Black Currant, Borage, Evening Primrose, and Flaxseed Oils: Sources of ALA and GLA (Omega-3 and -6 Fatty Acids)
What It Is:
ALA (alpha-linolenic acid) is an omega-3 essential fatty acid. GLA (gamma-linolenic acid) is an essential omega-6 fatty acid manufactured by the body from the essential fatty acid linoleic acid. An essential fatty acid is one that must be supplied by the diet, since the body cannot manufacture it or cannot manufacture enough of it. Both ALA and GLA are polyunsaturated fats ("good" fats, as opposed to saturated fats which increase the risk of heart disease). ALA and GLA are found in the seed oils of certain plants.
ALA is an omega-3 fatty acid that, to a limited extent, can be converted in the body into two other important omega-3's - EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). Of all the plant seeds, flaxseed (also known as flax seed or linseed) contains the highest concentration of ALA -in fact, 55% of the oil in flaxseed is ALA. Phytoplankton and algae are also rich sources. The oil from hemp and black currant seeds also contain, respectively, 19% and 13% ALA. Soybean oil, canola oil, and walnuts also contain some ALA. The body has a limited ability to manufacture both EPA and DHA from ALA (only about 10% is converted), and even this is lessened if the diet is too high in omega-6 fatty acids, because they compete with omega 3's for certain enzymes as they are metabolized.
GLA is an omega-6 fatty acid. The body ordinarily is able to produce sufficient GLA from the essential fatty acid linoleic acid (LA), which is found in foods containing oils from corn, sunflower, safflower, soy, peanut and other plants, including flaxseed. However, GLA production may be reduced in several conditions (advanced age, diabetes, high alcohol intake, eczema, cyclic mastitis, viral infections, excessive saturated fat intake, elevated cholesterol, and some vitamin/mineral deficiencies). In such cases, supplements may be beneficial. Seed oils from black currant, borage, and evening primrose are among the few that are rich in GLA. Hemp seed oil also contains a small amount. All of these oils are also rich in linoleic acid.
What It Does:
ALA:
The Mediterranean diet, which is associated with a lower risk of coronary artery disease and certain types of cancer, is high in ALA. However, the beneficial effects of EPA and DHA (which include cardiovascular benefits and reduced pain associated with rheumatoid arthritis and menstrual cramps) have not been seen with ALA alone. There is preliminary evidence that ALA might be useful in bipolar disorder. Flaxseed oil (the most common source of ALA) has no well-documented specific medical uses but may best be used to provide essential fatty acids, especially for people who are not getting EPA or DHA from fish/marine oils. Flaxseeds themselves contain fiber and lignans that are phytoestrogens and may be useful in preventing cancer. However, flaxseed oil contains little or no lignan because it is bound to the fiber, which is lost when the oil is pressed from the seeds. However, some specially processed flaxseed oils contain lignans, which are reintroduced after the oil is pressed.
The other common source of ALA in supplements is black currant oil, which has a mixture of both ALA and GLA and may, consequently, have anti-inflammatory effects due to its GLA content described below.
GLA:
GLA may be useful in diseases that involve inflammation. GLA is useful in treating breast pain associated with the menstrual cycle (cyclic mastalgia). It appears to be helpful in about 50% of women studied, vs. less than half that for placebo. However, it may not be effective in more severe cases involving actual breast cysts or lumps. GLA may also be helpful in reducing other PMS symptoms. GLA is used in Europe to treat diabetic neuropathy and eczema - although the evidence that it works for these conditions is mixed. It may also have some benefit in treating rheumatoid arthritis (especially as purified GLA and when combined with traditional treatments) and Raynaud's phenomenon. Many other potential uses, including some in conjunction with fish oils, have been explored, but evidence is either weak or very preliminary. Linoleic acid, which the body can convert into GLA, may also have a role in treating symptoms of multiple sclerosis.
Most clinical studies of GLA, such as those on breast pain and diabetic neuropathy, used evening primrose oil, the most popular and widely available source of GLA on the market. Experts now believe that the American diet contains too little omega-3 fatty acids and too much omega-6 fatty acids. These two compete with each other for certain enzymes needed in their metabolism. Consequently, too much omega-6 fatty acids in the diet will interfere with the body's conversion of ALA into DHA and EPA and may contribute to an increased risk of heart disease and cancer. While the ratio of omega-6's to omega-3's in the American diet is believed to be as high as 14:1 (14 grams of omega 6's for every gram of omega-3's), a ratio of no more than 3:1 (3 grams of omega-6's for every 1 gram of omega-3) is recommended.
What It Is:
ALA (alpha-linolenic acid) is an omega-3 essential fatty acid. GLA (gamma-linolenic acid) is an essential omega-6 fatty acid manufactured by the body from the essential fatty acid linoleic acid. An essential fatty acid is one that must be supplied by the diet, since the body cannot manufacture it or cannot manufacture enough of it. Both ALA and GLA are polyunsaturated fats ("good" fats, as opposed to saturated fats which increase the risk of heart disease). ALA and GLA are found in the seed oils of certain plants.
ALA is an omega-3 fatty acid that, to a limited extent, can be converted in the body into two other important omega-3's - EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). Of all the plant seeds, flaxseed (also known as flax seed or linseed) contains the highest concentration of ALA -in fact, 55% of the oil in flaxseed is ALA. Phytoplankton and algae are also rich sources. The oil from hemp and black currant seeds also contain, respectively, 19% and 13% ALA. Soybean oil, canola oil, and walnuts also contain some ALA. The body has a limited ability to manufacture both EPA and DHA from ALA (only about 10% is converted), and even this is lessened if the diet is too high in omega-6 fatty acids, because they compete with omega 3's for certain enzymes as they are metabolized.
GLA is an omega-6 fatty acid. The body ordinarily is able to produce sufficient GLA from the essential fatty acid linoleic acid (LA), which is found in foods containing oils from corn, sunflower, safflower, soy, peanut and other plants, including flaxseed. However, GLA production may be reduced in several conditions (advanced age, diabetes, high alcohol intake, eczema, cyclic mastitis, viral infections, excessive saturated fat intake, elevated cholesterol, and some vitamin/mineral deficiencies). In such cases, supplements may be beneficial. Seed oils from black currant, borage, and evening primrose are among the few that are rich in GLA. Hemp seed oil also contains a small amount. All of these oils are also rich in linoleic acid.
What It Does:
ALA:
The Mediterranean diet, which is associated with a lower risk of coronary artery disease and certain types of cancer, is high in ALA. However, the beneficial effects of EPA and DHA (which include cardiovascular benefits and reduced pain associated with rheumatoid arthritis and menstrual cramps) have not been seen with ALA alone. There is preliminary evidence that ALA might be useful in bipolar disorder. Flaxseed oil (the most common source of ALA) has no well-documented specific medical uses but may best be used to provide essential fatty acids, especially for people who are not getting EPA or DHA from fish/marine oils. Flaxseeds themselves contain fiber and lignans that are phytoestrogens and may be useful in preventing cancer. However, flaxseed oil contains little or no lignan because it is bound to the fiber, which is lost when the oil is pressed from the seeds. However, some specially processed flaxseed oils contain lignans, which are reintroduced after the oil is pressed.
The other common source of ALA in supplements is black currant oil, which has a mixture of both ALA and GLA and may, consequently, have anti-inflammatory effects due to its GLA content described below.
GLA:
GLA may be useful in diseases that involve inflammation. GLA is useful in treating breast pain associated with the menstrual cycle (cyclic mastalgia). It appears to be helpful in about 50% of women studied, vs. less than half that for placebo. However, it may not be effective in more severe cases involving actual breast cysts or lumps. GLA may also be helpful in reducing other PMS symptoms. GLA is used in Europe to treat diabetic neuropathy and eczema - although the evidence that it works for these conditions is mixed. It may also have some benefit in treating rheumatoid arthritis (especially as purified GLA and when combined with traditional treatments) and Raynaud's phenomenon. Many other potential uses, including some in conjunction with fish oils, have been explored, but evidence is either weak or very preliminary. Linoleic acid, which the body can convert into GLA, may also have a role in treating symptoms of multiple sclerosis.
Most clinical studies of GLA, such as those on breast pain and diabetic neuropathy, used evening primrose oil, the most popular and widely available source of GLA on the market. Experts now believe that the American diet contains too little omega-3 fatty acids and too much omega-6 fatty acids. These two compete with each other for certain enzymes needed in their metabolism. Consequently, too much omega-6 fatty acids in the diet will interfere with the body's conversion of ALA into DHA and EPA and may contribute to an increased risk of heart disease and cancer. While the ratio of omega-6's to omega-3's in the American diet is believed to be as high as 14:1 (14 grams of omega 6's for every gram of omega-3's), a ratio of no more than 3:1 (3 grams of omega-6's for every 1 gram of omega-3) is recommended.