A recent study by the National Health and Nutritional Examination Survey shows that herbal supplements appeared to cause an increase in blood levels of lead among women of childbearing age. The participants were men and women 20 years and older.

With the widespread use of these so called "natural" alternative medicines in the United States, this finding is a concern. Since many of these herbal supplements effects are not fully proven, they could end up doing more harm to patients than good, especially in women who could potentially expose fetuses to lead while still growing in the uterus.

Herbal supplement survey

Participants were asked if they used any supplements within the last month. Some supplements have previously been shown to contain lead (1.5 mcg/day or more) or have been associated with heavy metal poisoning. These include Echinacea, ginkgo, ginseng, St. John’s wort, and other traditional herbs such as those used in Ayurvedic and Chinese medicine.


The study found that 4.3% of the participants used an herbal supplement within the last month. Of those who reported herb use, 31% men and 28% were using 2 or more in the last month. In the end, elevated average levels of lead were found in both sexes. Increased levels were also found with older age, lower socioeconomic status, being born in Mexico, smoking, poor kidney function, and living in a home built before 1978. Decreased lead levels were seen in participants who took calcium supplements. This is probably due to the ability of calcium to remove lead from the blood. Heavier people were also less likely to have high lead levels.

Women who used any herbal supplement had levels 10% higher than women who did not. For supplements such as St. John’s wort and other traditional herbs, the levels were 20% higher. In an analysis of childbearing aged women 16-45, those who used supplements had levels in the range of 10-40% higher than women who did not.


People using herbal supplements, especially women trying to conceive, should be aware of the possible risks associated with lead exposure from herbal supplements. Exposure of a fetus to high lead concentrations in the uterus could result in neurological defects, lower birth weight, premature birth, and an increased incidence of minor congenital anomalies. Adverse effects may even occur at lower levels than previously thought. All patients should consult their physician before beginning any such treatment.

At IVF1, it is recommended that all couples that are attempting to conceive avoid all herbal supplements.