Vitamins, Minerals and Dietary Supplements
What is gamma-linolenic acid? Why do we need it?
Gamma-linolenic acid, or GLA, is a type of fatty acid that comes from two main sources: It can be produced in the body from other essential acids, or it can be derived from the oils of certain plants such as black currant and evening primrose. In fact, evening primrose oil is often marketed as gamma-linolenic acid.
In the body, GLA is used in the production of hormone-like substances called prostaglandins, which are believed to be involved in several metabolic processes, including regulation of the immune system. Laboratory studies have suggested that GLA can shrink the size of cancerous tumors and cause "subjective" improvement in people with cancer, although the results of these studies remain the subject of some dispute. GLA has also been suggested as a remedy for a variety of conditions, including arthritis, skin problems, high blood pressure and premenstrual syndrome.
How much gamma-linolenic acid should I take?
As of this writing, the optimal daily intake of gamma-linolenic acid is unknown. Many trials often use dosages of 3,000 to 6,000 milligrams of evening primrose oil, which translates roughly to 270 milligrams to 540 milligrams of GLA.
What forms of gamma-linolenic acid are available?
Evening primrose oil (which contains sizable amounts of gamma-linolenic acid) is available primary in supplement form, as is black currant oil. GLA supplements are available in liquid and capsule form; an injectable form is also being studied in Europe. Several substances, in addition to GLA, are necessary for the body to make prostaglandins. As a result, some researchers suggest that people take supplements of magnesium, zinc, vitamin C, niacin and vitamin B6 along with GLA or evening primrose oil.
What can happen if I take too much gamma-linolenic acid? Are there any interactions I should be aware of? What precautions should I take?
While gamma-linolenic acid does not appear to be toxic, there have been reports that it can aggravate the symptoms of temporal lobe epilepsy. It should not be taken by people who use anticonvulsant medications. Long-term use of GLA may lead to blood clots or decreased immune function. As always, make sure to consult with a licensed health care provider before taking gamma-linolenic acid or any other dietary supplement or herbal remedy.
- Fetrow CW, Avila JR. Professional's Handbook of Complementary and Alternative Medicines. Springhouse, PA: Springhouse Corp., 1999.
- Joe LA, Hart LL. Evening primrose oil in rheumatoid arthritis. Ann Pharmacother 1993;27:1475-7.
- Phinney S. Potential risk of prolonged gamma-linolenic acid use. Ann Intern Med 1994;120:692.
- Vaddadi KS. The use of gamma-linolenic acid and linoleic acid to differentiate between temporal lobe epilepsy and schizophrenia. Prostaglandins Med 1981;6:375-9.
- Van der Merwe CF, Booyens J. Oral gamma-linolenic acid in 21 patients with untreatable malignancy. An ongoing pilot open clinical trial. Br J Clin Pract 1987;41:907-15.