Eating to Block Lead Absorption

Intake of certain nutrients has been associated with lower lead levels in the body. For example, women with higher intake of thiamine, also called vitamin B1, tended to have lower blood lead levels, and the same was found for lead-exposed steel workers—and not just with thiamine, as “content of dietary fiber, iron, or thiamine intake each correlated inversely with blood lead concentrations in workers…” The thinking is that the fiber might glom onto the lead and flush it out of the body, the iron would inhibit the lead absorption, and the thiamine may accelerate lead removal through the bile. So, researchers suggest that eating lots of iron, fiber and especially thiamine-rich foods “may induce rapid removal and excretion of the lead from the tissues.” But thiamine’s never been put to the test by giving it to people to see if their lead levels drop. The closest I could find is a thiamine intervention for lead-intoxicated goats.
 

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.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

 

What About the Sodium in Miso?

According to the second World Cancer Research Fund/American Institute for Cancer Research expert report, “[s]alt is a probable cause of stomach cancer,” one of the world’s leading cancer killers. If the report’s estimate of an 8 percent increase in risk for every extra gram of salt a day is correct, then in a country like the United Kingdom, nearly 1,700 cases of stomach cancer happen every year just because of excess salt intake, as you can see at 0:27 in my video Is Miso Healthy?, and, in a country like the United States, it would be thousands more annually.

The risk of stomach cancer associated with salt intake appears on par with smoking or heavy alcohol use, but may only be half as bad as opium use or increased total meat consumption, as you can see at 0:43 in my video. These findings were based on a study of more than a half million people, which may explain why those eating meatless diets appear to have nearly two-thirds lower risk.

We know dietary salt intake is directly associated with the risk of stomach cancer, and the higher the intake, the higher the risk. A meta-analysis went one step further and looked at specific salt-rich foods: pickled foods, salted fish, processed meat, and miso soup. Habitual consumption of pickled foods, salted fish, and processed meat were each associated with about a 25 percent greater risk of stomach cancer. The pickled foods may explain why Korea, where the pickled cabbage dish kimchi is a staple, appears to have the highest stomach cancer rates in the world, as you can see at 1:39 in my video. But researchers found there was no significant association with the consumption of miso soup. This may be because the carcinogenic effects of the salt in miso soup are counteracted by the anti-carcinogenic effects of the soy, effectively canceling out the risk. And, if we made garlicky soup with some scallions thrown in, our cancer risk may drop even lower, as you can see at 2:06 in my video.

Cancer isn’t the primary reason people are told to avoid salt, though. What about miso soup and high blood pressure? Similar to the relationship between miso and cancer, the salt in miso pushes up our blood pressures, but miso’s soy protein may be relaxing them down. If we compare the effects of soy milk to cow’s milk, for example, and, to make it even more fair, compare soy milk to skim cow’s milk to avoid the saturated butter fat, soy milk can much more dramatically improve blood pressure among women with hypertension, as you can see at 2:43 in my video. But would the effect be dramatic enough to counter all the salt in miso? Japanese researchers decided to put it to the test.

For four years, they followed men and women in their 60s, who, at the start of the study, had normal blood pressure, to see who was more likely to be diagnosed with hypertension in that time: those who had two or more bowls of miso soup a day or those who had one or less. Two bowls a day may add a half teaspoon of salt to one’s daily diet, yet those who had two or more bowls of miso soup every day appeared to have five times lower risk of becoming hypertensive. So, maybe the anti-hypertensive effects of the soy in the miso exceed the hypertensive effects of the salt.


Indeed, miso paste, a whole soy food, can be used as a “green light” source of saltiness when cooking. That’s why I used it in my pesto recipe in How Not to Die and in my How Not to Die Cookbook. It can help you in Shaking the Salt Habit.

Not convinced that salt is bad for you? Check out these videos:

Not convinced that soy is good for you? See:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

Plant vs. Animal Food Purines for Preventing Gout

More than 2,000 years ago, “Hippocrates described gout as a disease of kings primarily because it was the wealthy who could afford the ‘rich’ foods, which seemed to precipitate gouty attacks.” Today, however, we can all eat like kings and acquire some diseases of royalty ourselves. That’s why I produced my video Preventing Gout Attacks with Diet.

Gout is caused by needle-sharp crystals of uric acid in our joints. Uric acid comes from the breakdown of purines, which are the breakdown product of genetic material—DNA, the foundation of all life. So, “there is no such thing as a purine-free diet, but foods do vary in their purine content.” It was long thought that people with gout just needed to stay away from all high-purine foods, whether from animals, like organ meats, or plants, like beans, but this strategy proved ineffective. Yes, all uric acid comes from the breakdown of purines, so limiting meat makes sense, but plant sources “have largely been exonerated.”

“The association of gout with alcohol intake and increased dietary purine consumption had been known since ancient times, but there were no prospective trial data” to back it up until fairly recently. The Harvard Health Professionals Follow-Up Study, which followed about 50,000 men for a dozen years, found that alcohol intake was “strongly associated with an increased risk of gout.” In terms of food, they found “an increased risk of gout with higher meat consumption or seafood consumption,” but not with higher consumption of purine-rich plant foods. Perhaps this is because the purines in plants are less bioavailable? So, though it had been suggested that gout sufferers should moderate purine-rich animal and plant foods, their “results suggest that this type of dietary restriction may be applicable to purines of animal origin but not to purine-rich vegetables.”

Although it was not surprising that meat, including seafood, had significant associations with the incidence of gout, this lack of effect of purine-rich plant foods was new. There don’t appear to be any long-term studies showing purine-rich plant foods increase risk, though there are still some guidelines continuing to disseminate those outdated recommendations.

Not only has the intake of purine-rich plants not been associated with high uric acid levels, but the vegetables gout sufferers are specifically told to stay away from—mushrooms, peas, beans, lentils, and cauliflower—were actually found to be protective. This may be because foods rich in fiber, folate, and vitamin C appear to protect against uric acid buildup and gout. “Fiber,” for example, “has been recognized as having a potential role in binding uric acid in the gut for excretion.”

Lack of association between purine-rich vegetables and urate could be due to the co-packaging of these “beneficial plant components (such as vitamin C, dietary fiber or some phytochemicals), which may have masked an effect of purine on [uric acid]. Vegetable intake, regardless of purine content, may also be protective as it may increase [uric acid] excretion.”

By changing the pH of our urine, we can change uric acid clearance. Eating an alkaline diet, which was a vegetarian diet in the case of the study I profile in my video, was found “effective for removing uric acid from the body.” Those eating the alkaline diet excreted significantly more uric acid than those eating the acidic diet. As such, uric acid levels in the blood of those eating the acid-forming diet rose within days.

So, one would assume uric acid levels are lower in vegetarians, and, indeed, those eating vegetarian diets long-term were found to have significantly lower levels in their blood. To prove cause and effect, though, you need to do an interventional trial, where you take people, change their diets, and see what happens. Researchers took ten guys to study the build-up of uric acid in their kidneys, kept them on a standard Western diet for five days, and measured their relative supersaturation for uric acid. Then, they tried a vegetarian diet for five days. The result? Within days, the intake of the vegetarian diet led to a 93 percent decline in the risk of uric acid crystallization.

You can do it the other way, too: Take a bunch of people with gout, feed them a big meal of meat, and see if you can trigger an attack. Seven patients were put in a hospital, “stabilized on a low-purine diet and then challenged with a meat-laden dinner.” In response, their uric acid levels shot up, and they started getting gout attacks. Then they added alcohol, and their uric acid levels shot up even further. In all, the researchers were able to trigger gout attacks in six out of the seven patients with just single meals.

Now, some meats have less purines than others. For those who aren’t squeamish, inches-long superworms, for example, have particularly low purine levels.

Not all animal foods increase gout risk, though. Low-fat dairy products were found to be protective. Given that, we would predict vegans to be at a disadvantage, which is indeed what was found, though all groups tested—meat eaters, fish eaters, vegetarians, and vegans—were within the normal range of around 3.5 to 7.

Should gout patients add milk to their diets? Well, although drinking the equivalent of ten cups of skim milk at a time appears to have an acute lowering effect on uric acid levels, in the long term over months, at the equivalent of two cups a day, there was not a statistically significant lowering effect. Gout patients were given skim milk powder for three months, and it did not appear to help. Though soymilk has also been associated with a lower risk of uric acid buildup, there are no interventional trials to back that up.

The bottom line is that we now have good research on how to reduce risk of gout “without the use of drug treatments through modification of diet.” That’s important, because allopurinol is the “drug of choice.” It’s considered generally safe, but what does it mean when doctors talk about a relatively safe drug? Well, about “2% of patients develop hypersensitivity reactions, which can sometimes be severe and fatal with a mortality rate of ~20%”—and that’s the safe drug. The other leading drug, colchicine, has “no clear-cut distinction between nontoxic, toxic, and lethal doses.”


A better choice is through diet, and these videos show you how sweet that diet choice can be:

And, for alkalinizing your urine, see How to Treat Kidney Stones with Diet and Testing Your Diet with Pee and Purple Cabbage.

Uric acid is double-edged sword, as both high and low levels are associated with increased mortality. If our uric acid levels are too high, we can get gout; if they’re too low, it may increase our risk of neurodegenerative diseases such as Alzheimer’s and Parkinson’s. This is presumed to be because uric acid acts as a powerful brain antioxidant. See my videos Miocene Meteorites and Uric Acid and Parkinson’s Disease and the Uric Acid Sweet Spot for more on this.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations: