Evening primrose oil, St. John’s wort, fenugreek, echinacea and aloe vera were the Top 5 most-researched herbs on the National Center for Complementary and Alternative Medicine, National Institutes of Health, website in 2012.

Here’s what the center says consumers need to know about those herbs:

• Evening primrose oil, used as a folk or traditional remedy for eczema, rheumatoid arthritis and menopause symptoms, is not adequately supported with evidence for treating these conditions.

• Research on the effectiveness of St. John’s wort for depression is conflicting. There is public interest in St. John’s wort to treat depression, but the Food and Drug Administration has not approved its use as medicine. St. John’s wort is known to affect the metabolism of some drugs, such as antiviral medicines, antidepressants, birth control pills and certain antiseizure medicines, and it can cause serious side effects.

• Fenugreek is sometimes used as a folk or traditional remedy for diabetes and loss of appetite, and to stimulate milk production in breast-feeding women, but there’s not enough scientific evidence to support its use for these or any health condition. Given its historical use for inducing childbirth, women should use caution when taking fenugreek during pregnancy.

• Overall, scientific evidence on echinacea for colds is inconclusive. Limited evidence suggests some echinacea preparations might reduce the length or severity of colds in adults, but four NCCAM-funded clinical trials indicated that echinacea did no such thing. Few side effects have been reported in clinical trials of echinacea, but some people may have allergic reactions.

• Topical use of aloe vera gel generally appears safe, and a few small studies suggest that it may help heal burns and abrasions. Aloe contains strong laxative compounds. In 2002, the U.S. Food and Drug Administration required all over-the-counter oral aloe laxative products be removed from the market or reformulated because manufacturers did not provide the necessary safety data.

— Anne Aurand, The Bulletin