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.
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 mid-morning and mid-afternoon snacks in addition to breakfast and regular meals may cut down on lead absorption in a contaminated environment.
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.
No comments:
Post a Comment