The four main heavy metals that can cause health issues are mercury, lead, arsenic, and cadmium. The U.S. Food & Drug Administration1 monitors levels of these “big four” heavy metals in food and drinking water, but some sources inevitably fall through the cracks. (Take the high levels of lead in the water in Flint, Michigan, for example.) Here are four sources of heavy metals to look out for and avoid consuming in high doses. In 2016, the Environmental Working Group performed an analysis of pregnant women who eat fish to examine their exposure to mercury. They measured mercury levels in hair samples of 254 women eating about as much fish as the U.S. government recommends for pregnant mothers. About 30 percent of women had mercury levels over the safe limit set by the EPA, considered too high for pregnant women. Using even stricter limits recommended by other experts, the researchers found that 60 percent of women had excessive mercury levels in their hair. Frequent fish eaters had 11 times more mercury than a group who rarely ate fish. Whether you’re pregnant or not, you’ll want to avoid eating mercury-laden fish. Generally, smaller fish that are lower down on the food chain—such as sardines, anchovies, and mackerel—tend to be lower in heavy metals. Larger fish such as shark, swordfish, tuna, sea bass, halibut, and marlin tend to accumulate more mercury from the ocean over time and should be avoided in high quantities. Not much research has looked into heavy metals in bone broth. There was one small (and non-peer reviewed) 2013 study2 measured the levels of lead in broth made from the bones of organic chickens. The broth was found to have “markedly high lead concentrations” compared to water cooked in the same cookware. This isn’t to say you should avoid bone broth altogether, but like with anything else, consume it in moderation. I am unaware of any commercially available bone broth or collagen powder that test for lead levels. More recently, cadmium has also been identified in e-cigarettes. A 2019 study3 found concentrations of other heavy metals (such as lead and copper) in certain vapors produced by e-cigarettes too. Some states like California are looking to label these products as potentially carcinogenic, similar to the labeling required in Canada. Young children tend to be at a higher risk for arsenic exposure and the FDA cautions4 that rice formulas should not be the only source, or even the first source, of nutrition for an infant. Barley, multigrain, and oats are preferred nutrition sources. Adults buying rice can refer to this Consumer Reports resource to find grains that are less likely to contain heavy metals. One key takeaway: “White basmati rice from California, India, and Pakistan, and sushi rice from the U.S. on average has half of the inorganic-arsenic amount of most other types of rice.” A cutting-edge nutrition deep dive taught by 20+ top health & wellness experts
