Like many over-the-counter supplements tested byConsumerLab.com these days, valerian products may not live up to what is promised on their labels.

When the company analyzed nine brands, they found that most contained little or none of the expected herbs; some had lead contamination.

Valerian is a common herbal sleep aid that’s also used for anxiety and stress. Of the nine different brands tested, only two passed ConsumerLab.com’s review.

One product contained no detectable key valerian compounds and four others had only 26.7 percent to 82.5 percent of amounts expected from ingredient listings.

Three products were contaminated with lead. The lead contamination wasn’t likely to cause toxicity alone but it’s best to avoid unnecessary lead exposure, the ConsumerLab.com report said.

If this all sounds familiar, it may be because ConsumerLab.com found similar problems when it reviewed valerian supplements in 2001, 2004, and 2006. Moreover, the company routinely shows through lab analysis that a wide range of other over-the-counter supplements frequently lack the ingredients listed on the labels or are contaminated with heavy metals.

To avoid lead, buy valerian root extract rather than the powder since the extraction process removes heavy metals. This is also the case with other herbs as well, like turmeric, said Tod Cooperman, president of ConsumerLab.com.

When buying a valerian product, the U.S. Food and Drug Administration requires labels to carry the following information:

• The species of valerian (look for Valeriana officinalis, though the claim of “valerian” should denote this species alone)
• The part of the plant used (it should be “root” and may also state “rhizonme”)
• The form of valerian used (e.g. root powder, extract or tincture)
• The amount of valerian per pill or dose in grams (g) or milligrams (mg)

Other buying tips from ConsumerLab.com:

It’s best if labels also indicate the concentration of total valerenic acids. Look for 0.8 percent valerenic acids for a 6:1 extract on a percent weight basis and no less than 0.4 percent for a 3:1 extract.

To treat insomnia, 600 mg of valerian extract up to two hours before bedtime is often used, although doses of extracts for various sleep disorders have ranged from 400 to 900 mg. You may need to take valerian every night for several weeks to achieve full sleep-enhancing benefits.

Many of the products in this review suggest lower doses of valerian (with lower amounts of valerenic acids) than those shown to work in clinical trials for insomnia. Such products may be less effective than higher dose products. Theoretically, lower doses of valerian may possibly suffice for products containing other ingredients believed to have tranquilizing or sedative effects, such as hops and lemon balm. But unless the product has been clinically tested, it is difficult to know whether such products are effective.

The brands tested included A. Vogel (Bioforce), Bluebonnet, CVS, Douglas Laboratories, Genestra (Seroyal), Mason, Nature’s Answer, Shaklee, Solaray, and Solgar.

To see which two products passed, read ConsumerLab.com’s report. Subscription required.