According to the National Center for Complementary and Alternative Medicine (NCCAM), five herbs were the most popular and searched-for in the NCCAM website in 2012. Here are some research-based information on these five herbal supplements, as stated by NCCAM.
Evening Primrose Oil
Although evening primrose oil has been used as a folk or traditional remedy for eczema, rheumatoid arthritis, and menopausal symptoms, there is not enough evidence to support the use of evening primrose oil for these conditions.
St. John's Wort
Study results on the effectiveness of St. John's wort for depression are conflicting. While there may be public interest in St. John's wort to treat depression, the Food and Drug Administration has not approved its use as an over-the-counter or prescription medicine for depression. Importantly, St. John's wort is known to affect metabolism of a number of drugs, such as antiviral medicines, antidepressants, birth control pills, and certain anti-seizure medicines, and can cause serious side effects.
Fenugreek
Fenugreek is sometimes used as a folk or traditional remedy for diabetes and loss of appetite, and to stimulate milk production in breastfeeding women. However, there is not enough scientific evidence to support the use of fenugreek for these or any health condition. Given its historical use for inducing childbirth, women should use caution when taking fenugreek during pregnancy.
Echinacea
Overall, the scientific evidence on echinacea for colds is inconclusive. There is limited evidence from some studies that some echinacea preparations might reduce the length or severity of colds in adults, but results from four NCCAM-funded clinical trials of echinacea for colds all indicated that echinacea did not reduce the length or severity of cold symptoms. Few side effects have been reported in clinical trials of echinacea, but some people may have allergic reactions.
Aloe Vera
Topical use: A few small studies suggest that topical aloe gel may help heal burns and abrasions. In general, topical use of aloe appears to be safe; one study, however, showed that aloe gel may inhibit healing of deep surgical wounds.
Oral use: Aloe latex contains strong laxative compounds, and in 2002, the U.S. Food and Drug Administration required that all over-the-counter aloe laxative products be removed from the U.S. market or reformulated because the companies that manufactured them did not provide the necessary safety data.
Source: NCCAM.gov