And much of the fiber data are just from test tube studies. In one, for example, researchers used simulated intestinal conditions, complete with “flasks” of feces, and both soluble and insoluble dietary fiber were able to bind up large amounts of mercury, cadmium, and lead to such an extent that they may have been able to block absorption in the small intestine. But, when our good gut flora then eat the fiber, some of the heavy metals may be re-released down in the colon, so it’s not completely fail safe. And, as with thiamine, there haven’t been controlled human studies.
But where is thiamine found? At 1:47 in my video How to Lower Lead Levels with Diet: Thiamine, Fiber, Iron, Fat, Fasting?, I feature a list of some of the healthiest sources of thiamine-rich foods that also contain fiber, which include highly concentrated, super healthy foods like beans and greens—foods we should all be eating anyway. So, even if thiamine- and fiber-rich foods don’t actually lower lead levels, we’ll still end up healthier.
What happened when iron was put to the test? It failed to improve the cognitive performance of lead-exposed children and failed to improve behavior or ADH symptoms, which is no surprise, because it also failed to bring down lead levels, as did zinc supplementation. It turns out that while iron may limit the absorption of lead, “it may also inhibit excretion of previously absorbed lead” that’s already in your body. What’s more, iron may not even inhibit lead absorption in the first place. That was based on rodent studies, and it turns out we’re not rodents.
We get the same story with zinc. It may have helped to protect rat testicles, but didn’t seem to help human children. “Nevertheless, iron is routinely prescribed in children with lead poisoning.” But, “given the lack of scientific evidence supporting the use of iron [supplementation] in…children with lead poisoning, its routine use should be re-examined.” Though, obviously, supplementation may help if you have an iron deficiency.
High fat intake has been identified as a nutritional condition that makes things worse for lead-exposed children. In fact, dietary fat has been associated with higher lead levels in cross-sectional, snapshot-in-time type studies, and there is a plausible biological mechanism: Dietary fat may boost lead absorption by stimulating extra bile, which in turn may contribute to lead absorption, but you really don’t know until you put it to the test.
In addition to testing iron, researchers also tested fat. They gave a group of intrepid volunteers a cocktail of radioactive lead and then, with a Geiger counter, measured how much radiation the subjects retained in their bodies. Drinking the lead with iron or zinc didn’t change anything, but adding about two teaspoons of vegetable oil boosted lead absorption into the body from about 60 percent up to around 75 percent, as you can see at 4:17 in my video.
The only thing that seemed to help, dropping lead absorption down to about 40 percent, was eating a light meal with the lead drink. What was the meal? Coffee and a donut. I think this is the first donut intervention I’ve ever seen with a positive outcome! Could it have been the coffee? Unlikely, because if anything, coffee drinking has been associated with a tiny increase in blood lead levels. If fat makes things worse, and the one sugar they tried didn’t help, the researchers figured that what made the difference was just eating food—any food—and not taking in lead on an empty stomach. And, indeed, if you repeat the study with a whole meal, lead absorption doesn’t just drop from 60 percent to 40 percent—it drops all the way down to just 4 percent! That’s extraordinary. That means it’s 15 times worse to ingest lead on an empty stomach.
Lead given 12 hours before a meal was absorbed at about 60 percent, so most of it was absorbed. When the same amount of lead was given three hours after a meal and also seven hours after a meal, most of it was absorbed at those times, too. But, if you get some food in your stomach within a few hours of lead exposure, you can suppress the absorption of some or nearly all of the lead you ingested, which you can see at 0:11 in my video How to Lower Lead Levels with Diet: Breakfast, Whole Grains, Milk, Tofu?.
This is why it’s critical to get the lead out of our tap water. Although it’s estimated that most of our lead exposure comes from food, rather than water, it’s not what we eat that matters, but what we absorb. If 90 percent of the lead in food is blocked from absorption by the very fact that it’s in food, 10 to 20 times more lead could be absorbed into your bloodstream simply by consuming the same amount of lead in water drank on an empty stomach.
And, since children empty their stomachs faster than adults because kids “have more rapid gastric emptying times,” the timing of meals may be even more important. With little tummies emptying in as few as two hours after a meal, offering midmorning and midafternoon snacks in addition to breakfast and regular meals may cut down on lead absorption in a contaminated environment. And, of course, we should ensure that children wash their hands prior to eating.
So, do preschoolers who eat breakfast have lower levels of lead in their blood? In the first study of its kind, researchers found that, indeed, children who ate breakfast regularly did appear to have lower lead levels, supporting recommendations to provide regular meals and snacks to young children at risk for lead exposure.
Is there anything in food that’s particularly protective? Researchers tested all sorts of foods to find out, and it turns out the “effect of a meal was probably largely due to its content of calcium and phosphate salts but lead uptake was probably further reduced by phytate which is plentiful in whole cereals,” but if calcium and phosphates are protective, you’d think dairy would work wonders. And, indeed, they started giving milk “to workers to prevent lead exposure” ever since calcium was shown to inhibit lead absorption in rats. But, in humans, there’s something in milk that appeared to increase lead uptake, and it wasn’t the fat because they found the same problem with skim milk.
“For over a century milk was recommended unreservedly to counteract lead poisoning in industry,” but this practice was abandoned in the middle of the last century once we learned that milk’s “overall effect is to promote the absorption of lead from the intestinal tract.” What’s the agent in milk that promotes the absorption of lead from the gut? It may be the milk sugar, lactose, though the “mechanism by which lactose enhances lead absorption is not clear.”
The bottom line? “In the past…milk was used as a prophylactic agent to protect workers in the lead industry. Recent studies, however, suggest that this practice is unjustified and may even be harmful.” So, giving people whole grains may offer greater protection against lead uptake.
However, the most potently calcium and phytate-rich food would be tofu. Isolated soy phytonutrients may have a neuroprotective effect, at least this was the case in petri dish-type studies. As you can see at 3:45 in my video, if you add a little lead to nerve cells, you can kill off about 40 percent of them, but if you then give more and more soy phytonutrients, you can ameliorate some of the damage. This is thought to be an antioxidant effect. If you add lead to nerve cells, you can get a big burst of free radicals, but less and less as you drip on more soy compounds.
Nevertheless, even if this worked outside of a lab, cutting down on the toxic effects of lead is nice, but cutting down on the levels of lead in your body is even better. “Because tofu has high content of both calcium and phytic acid phytate…it is biologically plausible that tofu may inhibit lead absorption and retention, thus reducing blood lead levels.” But you don’t know, until you put it to the test.
Tofu consumption and blood lead levels were determined for about a thousand men and women in China. For every nine or so ounces of tofu consumed a week, there appeared to be about four percent less lead in their bloodstream. Those who ate up to two and a half ounces a day had only half the odds of having elevated lead levels, compared to those eating less than about nine ounces a week. Those consuming nearly four ounces a day appeared to cut their odds by more than 80 percent. This was just a cross-sectional study, or snapshot in time, so it can’t prove cause and effect. What you need is an interventional study where you randomize people into two groups, giving half of them some food to see if it drives down lead levels. I cover this in my video Best Food for Lead Poisoning: Chlorella, Cilantro, Tomatoes, Moringa?.
Where does all this lead exposure come from anyway? Check out the first five videos on this series:
For more about blocking lead absorption, as well as what to eat to help rid yourself of the lead you’ve already built up, see:
Or, even better, don’t get exposed in the first place. Find out more in these videos:
Some of my other videos on lead include:
And what about lead levels in women? See:
In health,
Michael Greger, M.D.
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