 You know the feeling you get when you learn something new about a health problem you've been trying to reverse? Maybe high blood pressure, diabetes, or heart disease? Well, there's nothing I like better than bringing you the information that will help you do just that. Welcome to the Nutrition Facts podcast, I'm your host, Dr. Michael Greger. Today we explore what dietary change can simultaneously help detoxify mercury, lead, and cadmium from the body. We've previously explored the issue of lead contamination in calcium supplements like bone meal, but it wasn't just bone meal, and substantial quantities of lead were found in other, more common, over-the-counter supplements. Still, testing revealed continued public health concern over bone meal, but thankfully it's not as popular these days. So many of us are not likely to get directly exposed to the lead in bone meal anymore, but may get indirectly exposed to the animals we eat. In the US, 5 billion pounds of meat and bone meal are produced to slaughter us byproducts 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 bone meal passes right through the animals into their waste, but then we take that waste, the cowpeg and chicken feces, and feed it back to the animals again, and 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 kind of feeding practices, of 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, more plant-based dye may be able to lower lead exposure, and even more plant-based dye 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 suggested vegetarians would be exposed 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 learn from the cadmium story, the uptake of toxic heavy metals from animal food sources into the human intestinal lining cells may be higher than that from vegetable sources. That's how you have a vegetarian with some of the lowest concentrations of lead in cadmium in their blood, despite higher concentrations in their 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, 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 food 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. And within three months, their toxic heavy metals 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 a regular diet. And they were at 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 could also have been a cadmium-like effect, where the decrease in hair-led content could be due to the dietary shift resulting in less absorption of lead into the body in the first place. In our next story, we live with one of the most concentrated sources of the toxic metal cadmium. Cadmium is known as a highly toxic metal, that represents a major hazard to human health. It sticks around in our body for decades because our body has no efficient way to get rid of it, and may contribute to a variety of illnesses, including heart disease, cancer, and diabetes. Most recently, data suggests cadmium exposure may impair cognitive performance even at levels once thought to be safe. Recent studies suggest cadmium exposure may produce adverse health effects at lower exposure levels than previously predicted, including increased risk of hormonal cancers. For example, researchers on Long Island estimated that about 40% of breast cancer in the US may be associated with elevated cadmium levels. Inhalation of cigarette smoke is one of the major routes for human exposure to cadmium. Seafood consumption is another dominant route of human exposure, even more so than from cigarette smoke. The highest levels, though, are found in organ meats, but how many horse kidneys can you eat? Because people eat so few organs, grains and vegetables actually end up contributing the largest amount. But wait a second. Whole grains and vegetables are among the major dietary sources of fiber, phytoestrogens, antioxidants that may protect against breast cancer. And indeed, even though the risk of breast cancer goes up as women consume more and more cadmium, even though on paper most cadmium comes from grains and vegetables, breast cancer risk goes down the more whole grains and vegetables women eat. So maybe the animal-sourced cadmium is somehow worse, or the benefits of the plant foods just overwhelm any adverse effects of the cadmium? This study may have helped solve the mystery. It's not what we eat, it's what we absorb. Cadmium bioavailability from animal-based foods may be higher than from vegetable-based foods. There appears to be something in plants that inhibits cadmium absorption. In fact, if you add kale to your boiled pig kidneys, you can cut down on toxic exposure. Just one tablespoon of pig kidney, we may exceed the daily safety limit, unless we eat kale, in which case we could eat a whole quarter cup. The pronounced effects of the inhibitory factors in kale points out the importance of vegetable foods in terms of prevention of health hazards from cadmium ingested as mixed diets in a real situation. Even if a vegetarian diet contains more lead in cadmium than a mixed diet, it's not certain that it'll give rise to higher uptake of the metals because the absorption of lead in cadmium is inhibited by plant compounds such as fiber and phytate. And it's not just in lab animals. Having whole grains in our stomach, up to three hours before we swallow lead, can eliminate 90% of absorption thought to be due to phytates and whole grains, beans, and nuts grabbing onto it. So vegetarians may have lower levels even though they have higher intakes. In fact, a significant decrease in the hair concentrations of lead in cadmium was seen after the change from an omnivorous to a vegetarian diet indicating a lower absorption of the metals. Here's that study. They took folks eating a standard Swedish diet and put them on a vegetarian diet. Lots of whole unrefined plant foods, no meat, poultry, fish, eggs, and junk food was discouraged. Within three months on a vegetarian diet, they're mercury levels, cadmium level, and lead levels in their bodies significantly dropped and stayed down for the rest of the year-long experiment. But then they came back three years later, three years after they stopped eating vegetarian. And what did they find? Their levels of mercury, cadmium, and lead shot back up. Since the cadmium in plants is based on the cadmium in soil, plant eaters that live in a really polluted area like Slovakia, which has some of the highest levels, the so-called black triangle of pollution, thanks to the chemical and smelting industries, those who eat lots of plants there can indeed build up higher cadmium levels, especially if you eat lots of plants. It's interesting, in spite of the significantly high blood-cadmium concentrations as a consequence of greater cadmium intake from polluted plants, all the antioxidants in those same plants were found to help inhibit the harmful effects of higher free radical production caused by the cadmium exposure. Still though, in highly polluted areas it might be a especially good idea not to smoke or eat too much seafood or organ meats, but even if we live in the Slovak Republic's black triangle of pollution, the benefits of whole plant foods would outweigh the risks. In highly polluted areas, zinc supplements may decrease cadmium absorption, but I'd recommend against multi-mineral supplements as they've been found to be contaminated with cadmium itself. Finally today, did you know that the toxic heavy metal contamination of Ayurvedic dietary supplements is, in most cases, intentional? How do toxic heavy metals get into Ayurvedic medicines in the first place? In most cases, high levels of metals in Ayurvedic traditional herbal preparations results from intentional incorporation of certain metallic preparations, like lead oxide, mercury sulfide, arsenic trioxide. Not to worry though, the heavy metals are claimed to be detoxified by, for example, heating and cooling the herbal mixtures in cow's urine. This is not just an India issue. Traditional medicines from around the world incorporate these poisons. In the Middle East, saut is used as a teething powder for infants. It's 51% lead, one of a number of black lead containing substances used as teething powder. Bakur is a Middle Eastern practice of burning lead sulfides to produce pleasant fumes to calm infants. They'll be calm alright. Traditional Latin American medicines include azarcon and gaita, almost pure lead used to treat constipation. In traditional Chinese herbal medicine, mercury is considered to have a tranquilizing and, if you can believe it, detoxifying effect. But wait a second, haven't these remedies been used for centuries? Sure, but that doesn't mean they're safe. In the West, let's not forget that bloodletting was among the most common medical practice performed by doctors for almost 2,000 years. We would love it if you could share with us your stories about reinventing your health through evidence-based nutrition. Go to nutritionfacts.org slash testimonials. We may share it on social media to help inspire others. Scenic graphs, charts, graphics, images, or studies mentioned here, please go to the Nutrition Facts Podcast landing page there you'll find all the detailed information you need, plus links to all the sources we cite for each of these topics. My last two books are How to Survive a Pandemic and the How Not to Diet Cookbook. Stay tuned for December 5, 2023 for the launch of my new one, How Not to Age. And of course, all the proceeds I received from the sales of all my books goes directly to charity. NutritionFacts.org is a non-profit, science-based public service where you can sign up for free daily updates and the latest in nutrition research via bite-sized videos and articles. Everything on the website is free. There are no ads, no corporate sponsorships, no kickbacks, strictly non-commercial, not selling anything. I just put up as public service as a labor of love as a tribute to my grandmother, whose own life was saved with evidence-based nutrition.