St. John's Wort Supplements Review
Initial Posting: 9/23/16
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Summary: What You Need to Know About St. John's Wort Supplements
- Does it help? Taking a supplement with the right type and amount of St. John's wort extract appears to be as effective in treating major depression of mild to moderate severity as standard antidepressant drugs, but with fewer side effects. St. John's wort is unlikely to help people who aren't truly depressed. (See What It Does)
- How much to take? Clinical trials suggest that an effective dose is 900 mg per day of a concentrated extract standardized to at least 0.3% hypericin and/or 1% to 3% hyperforin (see What to Consider When Buying and Using).
- Which product? Choose carefully, because 60% of the St. John's wort supplements selected for testing by ConsumerLab.com did not contain expected amounts of one or more key plant chemicals. There was enormous range in these amounts, indicating that you could get, for example, as much as 280 times more hyperforin from one product than from another. Four products were Approved by ConsumerLab.com, three of which are good choices and one of which was CL's Top Pick. Use our Results Table to see which products were, or were not, Approved, and to compare ingredients, test results, and prices.
- Don't get hurt! Although generally safe, St. John's wort can cause a range of side effects. It may cause mania in people with bipolar disorder and it may increase sensitivity to ultraviolet light, causing unexpected sunburn. Most importantly, St. John's wort can interact with a wide range of medications. See Concerns and Cautions for more information.
What It Is:
The parts of the St. John's wort plant (Hypericum perforatum) used medically include the aerial parts, i.e., those above ground -- the flower, leaves, and stem. St. John's wort contains at least seven constituents or groups of components that may contribute to its biological effects, including naphthodianthrons (e.g., hypericins), flavonoids (e.g., quercetin), bioflavonoids (e.g., biapigenin), xanthons, and phloroglucinol derivatives (e.g., hyperforin) (Nahrstedt 1997).
What It Does:
The vast majority of double-blind, placebo-controlled studies have found that St. John's wort extracts are as effective as standard antidepressant drugs (including antidepressants in the SSRI (Prozac) family) for treating major depression of mild to moderate severity -- and with significantly fewer side effects (Linde 2008; Szegedi, BMJ 2005). This level of depression does not refer to mere "blues" or "moodiness" but a more serious level of depression. However, for severe major depression (often requiring hospitalization), standard antidepressants are thought to be more effective than St. John's wort.
Nevertheless, three well-publicized human studies found no benefit with St. John's wort, although two of these studies found the antidepressant to which St. John's wort was compared wasalso ineffective for treating depression (Hypericum Depression Trial Study Group 2002; Shelton, JAMA 2001). These seemingly paradoxical clinical results may have been due to factors such as the products tested, the outcomes being measured, and the number of people involved in the studies.
St. John's wort does not cause euphoria and, like regular antidepressants, is unlikely to elevate mood in people who aren't truly depressed.
One study involving menopausal women with depression found that a combination of St. John's wort and black cohosh extracts improved both menopause symptoms and mood (Uebelhack, Obstet Gynecol 2006). St. John's wort is also sometimes tried for other conditions in which standard antidepressants might be recommended, such as anxiety, attention deficit disorder, PMS, seasonal affective disorder (SAD), chronic pain, insomnia, neuropathic pain, obsessive compulsive disorder, social phobia, and quitting smoking, but there is no reliable evidence as yet that it really works for these purposes.
For a while, St. John's wort was popular as a treatment for HIV infection. However, current evidence suggests that not only does it not help, but the herb can seriously impair the effect of standard HIV treatments. Even when used for depression, St. John's wort presents some significant safety risks, especially drug interactions. (See Concerns and Cautions).
Hyperforin and Hypericin: Active Ingredients?
Virtually all studies of St. John's wort have used extracts rather than whole herb and the content of most St. John's wort products are standardized to a substance called hypericin, one of the many chemical constituents noted above. Hypericin may not be the most important constituent, but products with standardized hypericin content of about 0.3% have proven to be effective in human studies.
Some other St. John's wort products are standardized to their hyperforin content, which has been shown to be a major antidepressant component of the plant (Zanoli, CNS Drug Rev 2004). Most of the early research on St. John's wort focused on hypericin and hyperforin, though newer studies suggest that the benefit of St. John's wort is based on synergistic interactions of multiple compounds present in the plant and not on the pharmacological activity of any one single compound (Butterweck, Wien Med Wochenschr 2007; Reichling, Forsch Komp Klass Natr 2003). (See ConsumerTips for Buying and Using for dosage information).
Quality Concerns and What CL Tested for:
During the growing season, St. John's wort may accumulate heavy metals from its environment. These include cadmium, a carcinogen and kidney toxin, and lead, which can impair mental functioning and may affect blood pressure. Although the levels of cadmium and lead in a supplement would be small and unlikely to cause disease on their own, the safety margin between exposure in the normal diet and the levels that can produce deleterious effects is relatively small. Therefore, choosing a product with low cadmium and lead levels is best. In 2010, ConsumerLab.com found that four products exceeded strict cadmium limits, with amounts ranging from 0.18 to 0.86 mcg per gram of St. John's wort; one of these products was also contaminated with lead, at 2.2 mcg per daily serving. In addition, three products contained only 23% to 36% of the expected amounts of hyperforin or hypericin. However, among 10 products selected for testing by ConsumerLab.com in 2013, contamination was not found and all products contained the expected phytochemicals. Only one product failed to pass the review and this was because its tablets failed to properly disintegrate in water.
No government agency is responsible for routinely testing St. John' wort supplements for their purity and contents. ConsumerLab.com independently evaluated several St. John's wort products to determine whether they contained the St. John's wort amount stated on their labels (based on listed or minimum expected amounts of hypericin and/or hyperforin), disintegrated properly, and did not contain significant amounts of arsenic, cadmium and lead. (See How Products Were Evaluated for information on testing methods and passing score.)