MONDAY, Feb. 9, 2004 (HealthDayNews) -- Some makers of the popular herbal supplement St. John's wort greatly exaggerate the levels of a major ingredient, a new Taiwanese study suggests.
It's the second study in recent months to question the accuracy of ingredients listed on labels of a supplement that is often used to treat depression.
"The study has implications more widely for labeling of drugs, particularly non-prescription drugs," says British medical risk management consultant Jonathan Berman. "If medical practitioners and patients are to make informed decisions concerning drug usage, it is important that they have accurate information."
However, a representative of the supplement industry says the Taiwanese researchers looked at a chemical that doesn't appear to contribute to the effects of the pills upon depression and anxiety.
In its supplement form, St. John's wort is extracted from plants in the wild with the same name. According to medical historians, humans have used the plant extracts for centuries to treat mental problems along with wounds, burns and insect bites.
Now, St. John's wort is a huge seller at health stores because of its supposed ability to treat depression and anxiety. Researchers disagree over whether it actually works; a $4 million federal study released in 2002 found it didn't improve symptoms in people with moderate depression.
In the new study, researchers examined the contents of five brands of St. John's wort sold over the counter at health stores in California. None of the brands were identified.
The findings appear in the February issue of the Journal of the Science of Food and Agriculture.
Manufacturers of St. John's wort typically claim a chemical known as hypericin makes up 0.3 percent of their products. For tablets, that usually amounts to 300 milligrams.
Some experts believe hypericin is the active ingredient in St. John's wort products, but its role isn't clear.
The labels of four of the St. John's wort brands in the study claimed to contain the standard level of hypericin, and another claimed to hold less because its tablets were smaller. But the researchers found only 1.7 percent to 38.5 percent of the claimed levels of hypericin in the brands.
Even when a related chemical called pseudohypericin was added to the totals, four of the five brands still had less of both chemicals combined than the levels of hypericin claimed by the manufacturers.
The findings on label inaccuracies reflect those of a study published last fall in the Canadian Journal of Clinical Pharmacology. Researchers looked at 54 samples of St. John's wort products available in the United States and Canada and found the labels, on average, reported double the true combined levels of hypericin and pseudohypericin.
St. John's wort is generally considered safe, but it has potential side effects, including dry mouth, gastrointestinal problems, fatigue and dizziness. The National Institutes of Health has warned that St. John's wort can affect the body's ability to absorb some drugs, including indinavir, used to treat AIDS, and cyclosporine, used in organ transplant patients.
Mark Blumenthal, executive director of the American Botanical Council, says manufacturers could do a better job of labeling their products to reflect the levels of both hypericin and pseudohypericin. But he adds that hypericin levels aren't important when it comes to the use of St. John's wort to treat depression.
"The real issue is whether the hypericin or total hypericin variation from the stated level on the label has any clinical or therapeutic significance," he says. "The answer is, probably not."
Blumenthal recommends that patients turn to St. John's wort brands that have been shown to successfully treat depression in clinical studies. Even if the doses aren't labeled correctly, they shouldn't be harmful, he says.
"It's probably OK to take them," he says. "The question is whether they'll get any benefit out of that. Ultimately, that would be up to the consumers' judgment three to six weeks after they start taking the product."
But even if incorrectly labeled doses of St. John's wort won't hurt anyone, their very existence can damage the trust of patients in the pharmaceutical industry, Berman says. That, in turn, may lead to more carelessness among patients about recommended doses of other drugs, he says.
"If there is a speed limit of 30 mph on a road near you, but you know that the local police force has radar traps that cannot distinguish between 25 mph and 45 mph, you might be tempted to drive at 40 on the basis that they cannot give you a ticket at that speed," he says. "This might then lead you more generally to drive at 40 in a 30 mph limit, which in another town (with better radar) might then lead to a speeding ticket -- not to mention the increased risk of traveling at 40."
More information
For more on St. John's wort, try this fact sheet from the National Center for Complementary and Alternative Medicine. Or visit Drug Digest.
