Friday Favorites: How to Lower Heavy Metal Levels with Diet

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

We’ve previously explored the issue of lead contamination in calcium supplements like bonemeal, but it wasn’t just bonemeal. Substantial quantities of lead were found in other, more common, over-the-counter supplements. Still, testing revealed continued public health concern over bonemeal, but thankfully it’s not as popular these days. So, most of us are not likely to get directly exposed to the lead in bonemeal any more, but we may get indirectly exposed through the animals we eat.

In the U.S., five billion pounds of meat and bonemeal are produced as slaughterhouse by-products every year. What do we do with these millions of tons every year? We feed it back to farm animals, particularly chickens. Now, most of the lead in the bonemeal passes right through the animals into their waste, but then we take that waste (cow, pig, and chicken feces) and feed it back to the animals again. You guessed it! So, you can see how the levels of contaminants might build up in their bodies.

I’ve talked previously about what that might mean for making something like chicken soup, but the original concern about these kinds of feeding practices, feeding cows to cows, and pigs and chickens, was the spread of prion diseases, like mad cow disease. But it’s not just prions that this kind of recycling can magnify, but other toxic substances, including lead. So, a more plant-based diet may be able to lower lead exposure, and an even more plant-based diet could theoretically lower exposure even more. But you’ve got to put it to the test.

But should we expect to find a benefit? Yes, lead is one of the toxins found in meat, but half of our dietary exposure probably comes from plant foods. Dietary modeling studies in Europe suggest that vegetarians would be exposed to about the same amount of lead compared to the general population, with the exception of those who eat a lot of wild game, which can end up with a thousand times more lead than most other foods.

In fact, a vegetarian diet may even be higher in lead. But, it’s not what you eat; it’s what you absorb. As we learned from the cadmium story, the uptake of toxic heavy metals from animal food sources into human intestinal lining cells may be higher than from vegetable sources. That’s how you have a vegetarian with some of the lowest concentrations of lead and cadmium in her blood, despite higher concentrations in her diet. But you don’t know, until you…put it to the test.

There seemed to be a tendency towards higher fecal elimination of lead following a change to a vegetarian diet, with nine subjects on average tripling their elimination of lead, three unaffected, and four dropping by about half. But the study only lasted a few months, and the difference wasn’t statistically significant. So, let’s try a year. A shift towards a diet characterized by large amounts of raw vegetables, fruits, and unrefined foods, whole grains, with the exclusion of meat, poultry, fish, and eggs (though it did include fermented dairy, like a type of soured milk), as well as cutting back on processed foods and junk. They took clippings of hair before and after the shift, and got significant reductions in heavy metals, including cutting their lead level nearly in half. Check this out: this is how much mercury, cadmium, and lead they had oozing from their body into their hair when they started, and within three months, their toxic heavy metal levels went down, and stayed down. How do we know it wasn’t just a coincidence? Because they went back up a few years later after the study was over, after they went back to more of their regular diet, and their mercury, cadmium, and lead levels shot back up to where they were before.

Same thing with a different group after two years. The drop in mercury is easy to explain, presumably due to the drastic drop in fish consumption, and the drop in alcoholic beverages may have contributed to the drop in lead, but it also could have been a cadmium-like effect, where the decrease in hair lead content could be due to the dietary shift resulting in less absorption of lead into the body in the first place.

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Image credit: Kristina DeMuth. Image has been modified.

Motion graphics by Avocado Video.