Gamma-Linolenic Acid (GLA)

Gamma-linolenic acid (GLA) is an essential fatty acid that comes primarily from plant-based oils. Linoleic acid, which is found in cooking oils and processed foods, is converted into GLA in the body. GLA supplements are available in the form of evening primrose oil, black currant seed oil, and borage oil, which also provide linoleic acid. For example, evening primrose oil is 72 percent linoleic acid. The average North American diet provides more than 10 times the necessary amount of linoleic acid.

People who have diabetes are less able than healthy individuals to convert linoleic acid to GLA. Other conditions that appear to reduce the body's ability to convert linoleic acid to GLA include aging, alcoholism, atopic dermatitis, premenstrual syndrome, rheumatoid arthritis, cancer, and cardiovascular disease. Aging also appears to reduce conversion of linoleic acid to GLA. If you are an older person or have one of these conditions, you may want to talk to your provider about supplementing your diet with GLA.

If you have rheumatoid arthritis, you may benefit from GLA supplementation. It may enable you to take less non-steroidal anti-inflammatory drugs, which can cause stomach and intestinal problems. However, more research is needed to establish the proper dosage for long-term use.

Research has shown that GLA may help prevent cardiovascular disease by dilating blood vessels, lowering blood pressure, and preventing atherosclerosis.

Cancer is another condition where GLA may be useful. Studies in people with colon cancer, breast cancer, and melanoma show that GLA inhibits the growth of tumors and the spread of cancer.

For hemodialysis patients with uremic skin symptoms, studies show that skin conditions improved when the subjects used evening primrose oil supplements. Studies suggest that GLA is also helpful in increasing bone density and calcium absorption in people who have osteoporosis.

Uses

• Rheumatoid arthritis. GLA may reduce inflammation.
• Diabetes. GLA supplementation assists nerve function and helps prevent nerve damage caused by diabetes.
• Cancer. GLA may help suppress tumor growth and spread of cancer, particularly in colon cancer, breast cancer, and melanoma.
• Heart disease. GLA may help prevent heart disease by inhibiting plaque formation, dilating blood vessels, and lowering blood pressure.
• Eyes. GLA is beneficial in Sjφgren's syndrome and may be useful in other dry eye conditions.
• GLA supplements may help the symptoms of many conditions that occur with aging. It can also reduce the symptoms of alcoholism, atopic dermatitis, and osteoporosis.
• Menstrual problems (painful menstruation or no menstruation). Essential fatty acids such as those found in flaxseed, evening primrose, and borage oils reduce inflammation and support hormone production. Dosage is 1,000 to 1,500 mg one or two times per day.

Dietary Sources

GLA is found in the plant-seed oils of evening primrose, black currant, borage, and fungal oils. GLA is also found in human milk and, in small amounts, in a wide variety of common foods, particularly organ meats.

Other Forms

GLA supplements are available in several forms, including evening primrose oil, black current seed oil, borage oil, and borage oil capsules

Several manufacturing methods can destroy the nutrient value of GLA products. Some preferred methods use proprietary names for their process, generically known as "modified atmospheric packing methods." Generally, a high-quality oil will be certified as organic by a reputable third party, packaged in light-resistant containers, refrigerated, and marked with a freshness date.

How to Take It

There is no recommended dietary allowance (RDA) for GLA.

A recommended dosage for rheumatoid arthritis is 1.4 g per day. As the cost of oils can be high, and lower doses are usually effective, an acceptable clinical dosage of evening primrose, black currant, or borage oil would be 1,500 mg once or twice daily.

Studies have shown that up to 2.8 g of GLA per day is well tolerated. A healthy person eating a normal diet should consume fewer saturated fats and more polyunsaturated fats. Avoid products that contain hydrogenated fats. Discuss your total fat intake with your health care provider if you are thinking about taking GLA supplements.

Precautions

GLA from dietary sources appears to be nontoxic. Talk to your health care provider about your regular diet, so he or she can help you decide if you should take GLA supplements, and what kind of supplements are best for you. Remember that GLA supplements are fats and contain a lot of calories.

Possible Interactions

If you are taking psychotherapeutic medications to treat schizophrenia, talk with your health care provider before taking evening primrose oil which contains gamma-linolenic acid. It can interact with these medications and increase the risk of seizures. For the same reason, you should avoid taking this herb with antidepressant medications (medicines to treat depression), particularly tricyclic antidepressants, and anticonvulsant medications that are used to treat seizure disorders.

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