SB 646 raises unnecessary alarm on prenatal vitamin safety

OPINION – Certain metals occur naturally with essential nutrients. Policies must protect pregnant women from contaminants and nutritional gaps, not frighten them into nutritional deficiency.

A recent opinion piece in MedPage Today, by Dr. Shilpa Mathew, “Toxic Metals Have No Place in Prenatal Vitamins,” makes an important point—every expectant parent wants the safest possible start for their baby. Safety must always be the first priority—any discussion of regulation should begin with the shared goal of protecting pregnant women and their babies. And we can all agree: prenatal vitamins should contain as little heavy metals as possible, and manufacturers should be transparent.

In making this important point, Dr. Mathew also gives the false impression that manufacturers of prenatal vitamins can simply eliminate the presence of heavy metals in their products. If only it were that simple.

Some essential nutrients—calcium, iron, magnesium, zinc—come from natural sources that can contain trace amounts of heavy metals. This doesn’t mean these products are unsafe, just like leafy greens such as spinach and broccoli—which also contain heavy metals—aren’t unsafe. Rather, it means these essential minerals occur in nature alongside tiny amounts of elements like lead, cadmium, and arsenic, even when carefully sourced and manufactured. Responsible companies already invest in reducing those levels to the lowest possible amounts, and continued innovation can further reduce these levels without nutrient loss.

That’s why California’s SB 646, which just passed the California State Legislature without any objection, while well-intentioned, may do more harm than good. The bill would require publishing raw test results for heavy metals to consumers without adequate explanation of what they represent. Although brand owner websites would be required to include a brief statement explaining the results, a single statement may be insufficient to provide consumers with the necessary context for such a complex issue. Some consumers may not even read the statement at all, leaving them only with heavy metal testing data that would alarm and discourage them from using prenatal vitamins.

According to a 2019 study in JAMA Network Open, pregnant women didn’t meet nutrient needs from diet alone:

• 84% of pregnant women didn’t get enough iron;
• 53% didn’t get enough magnesium;
• 21% didn’t get enough calcium.

And when eating for two, the “healthy” foods recommended—leafy greens for folate, cold-water fish for omega-3s, legumes for zinc—can actually deliver more heavy metals than a prenatal supplement when consumed in needed amounts.

The concern with SB 646 is twofold:

Dissuading women from consuming critical supplements: Without sufficient context, raw lab numbers will appear alarming, leading some pregnant women to take prenatal vitamins that contain insufficient nutrients, or, in the worst-case, to avoid taking prenatal vitamins altogether.

Encouraging misleading “clean label” marketing and the removal of essential minerals: Some brands have elected to lower or eliminate the levels of critical nutrients—such as calcium, iron, folate, zinc, and magnesium—in their products so that they can reduce their heavy metal numbers. The result? A prenatal vitamin that appears to be superior on paper from lower heavy metal results, but which is nutritionally deficient compared to those that contain sufficient levels of nutrients. Instead, the focus should be on the dual goal of providing complete nutrition and reducing heavy metals through careful sourcing and advanced purification.

We should absolutely hold supplement manufacturers to the highest safety standards, and we should expect transparency. But transparency must come with education, explaining why trace amounts can be unavoidable, how they compare to what’s in everyday foods, and why certain nutrients are too important to leave out. Public trust also depends on acknowledging past contamination issues and demonstrating how responsible companies already exceed safety standards.

A truly healthy pregnancy means providing all the essential nutrients a baby needs and minimizing unnecessary risks. Any policy should protect both priorities—because pregnant women deserve clear information, not fear; and complete nutrition, not compromised formulas. We urge Governor Newsom to veto this bill and legislators to reconsider the unintended impact it will have on prenatal health.

Steve Mister is President and CEO for the Council for Responsible Nutrition.