John's wort is widely used in the U.S. as a dietary supplement for treating
mild to moderate depression and to relieve depression-related anxiety. It has
not been shown to be effective in treating patients with severe depression.
Exactly how St. John's wort works is not
completely known. It is also not clearly understood which of its chemical
components are most responsible for its effects. Most supplements are made from
a concentrated extract of St. John's wort. Most clinical studies that have been
performed have used products standardized to contain a specific amount of the
plant chemical hypericin, or more recently, another plant chemical hyperforin.
These compounds currently serve as markers to evaluate the quality of St.
John's wort in a product. While the flower, leaves, and stem, collectively
referred to as the "aerial" (above-ground) portion of St. John's wort plant
have been used medicinally, the flowers are known to have the highest
concentration of hypericin.
As the St. John's wort plant grows, it
naturally accumulates the heavy metal cadmium from its environment. Cadmium is
carcinogenic to humans and builds up in the kidneys, where it may be toxic.
While the amount of cadmium likely to be found in a dose of St. John's wort
supplement should not be sufficient to cause disease, it contributes to total
daily cadmium intake. There is a relatively small safety margin between cadmium
exposure in the normal diet and exposure that can produce deleterious effects.
It is therefore preferable to identify products with the lowest cadmium levels.
Extracts, although concentrated, actually tend to have lower levels of cadmium
than raw herb because some of the cadmium is removed as part of the extraction
Neither the FDA nor any other federal or
state agency routinely tests St. John's wort products, or other supplements,
for quality prior to sale. In addition, since March 1999 FDA has required
products to state the plant parts used, although it has not been generally
ConsumerLab.com, as part of its mission to
independently evaluate products that affect health, wellness, and nutrition,
purchased many of the St. John's wort dietary supplements sold in the U.S. and
tested them for quality of ingredients and levels of cadmium.
Testing & Results:
In October and November 2000, ConsumerLab.com purchased a total of 21
brands of St. John's wort products. Eighteen of the products claimed to contain
only standardized extracts. The remaining three claimed to be combinations of
extract and raw herb. All but three of the products made claims of hypericin
content. Two products made claims for both hypericin and hyperforin levels. All
but four of the 21 products also identified the portion of the St. John's wort
plant used, such as the flower, flower and leaves, or, more generally "aerial"
The products were tested to determine
whether they possessed 100% of their claimed amounts of St. John's wort and
claimed levels of hypericin and/or hyperforin. If the hypericin or hyperforin
levels were not clearly labeled, products were held to specific minimum
standards selected by ConsumerLab.com that are consistent with most clinical
research with St. John' wort. Products were also required to meet purity
requirements for cadmium.
Among the twenty-one
seven did not pass.
Four products had levels of hypericin
ranging from 77% to 85% of that stated on their labels or, if not stated, used
as a minimum for this review. These included two of the three products claiming
a mixture of extract and raw herb.
One of the two products claiming to
contain hyperforin did not contain the claimed amount. It contained only 21.7%
of the claimed amount of hyperforin.
Five products contained levels of
cadmium that exceeded acceptable levels for this review. Three of these
products had levels of cadmium more than twice the acceptable amount. Although
none of these five products would alone pose a serious health risk, they
represent avoidable sources of cadium exposure. This group included all three
extract/raw herb products, as well as two other products that had insufficient
All five products claiming to be made from
"flowers" passed. In addition, four out of 5 products labeled as made from
"flowers and leaves" passed. Among the 7 products made from "aerial" portions,
i.e., any combination of flower, leaves, and stems, only 2 products passed.
While consumers are commonly advised to
look for products that state their hypericin or hyperforin content on the
labels, such claims were no guarantee as to the quality of the products.
Ironically, all 3 products that did not claim a specific hypericin or
hyperforin level passed, while 5 of 18 products stating their hypericin or
hyperforin levels failed. Products most likely to have passed testing in this
review claim to be made from St. John's wort "flower" or "flower and leaves."
Products less likely to have passed this review were labeled as containing
"aerial" plant parts (a more general term as it may include stems for example)
and were also more likely to contain raw herb as an ingredient.
Listed alphabetically by name below are the
products that passed ConsumerLab.com's independent testing of St. John's Wort
(Information in order of Product Name,
Amount per Pill, and Manufacturer or Distributor)
Tech Hypericum perforatum St. John's Wort 300 mg, Standardized Extract,
Standardized to contain 0.3% Hypericin (300 mg extract/capsule) Carefully
Manufactured by Vitamin World, Inc.
Nature's Bounty® Herbal
Harvest® St. John's Wort 300mg, Standardized to contain 0.3% Hypericin (300
mg extract/capsule) Carefully Manufactured by: Nature's Bounty,
Nutrilite® St. John's Wort with Lemon Balm (300 mg
extract/capsule) Mfd. By Nutrilite, a Division of Access Business