Comparing Pollutant Levels Between Different Diets

Comparing Pollutant Levels Between Different Diets.jpeg

The results of the CHAMACOS (Center for the Health Assessment of Mothers and Children of Salinas) study were published recently. This study of a California birth cohort investigated the relationship between exposure to flame retardant chemical pollutants in pregnancy and childhood, and subsequent neurobehavioral development. Why California? Because California children's exposures to these endocrine disruptors and neurotoxins are among the highest in the world.

What did they find? The researchers concluded that both prenatal and childhood exposures to these chemicals "were associated with poorer attention, fine motor coordination, and cognition" (particularly verbal comprehension) by the time the children reached school age. "This study, the largest to date, contributes to growing evidence suggesting that PBDEs [polybrominated diphenyl ethers, flame retardant chemicals] have adverse impacts on child neurobehavioral development." The effects may extend into adolescence, again affecting motor function as well as thyroid gland function. The effect on our thyroid glands may even extend into adulthood.

These chemicals get into moms, then into the amniotic fluid, and then into the breast milk. The more that's in the milk, the worse the infants' mental development may be. Breast milk is still best, but how did these women get exposed in the first place?

The question has been: Are we exposed mostly from diet or dust? Researchers in Boston collected breast milk samples from 46 first-time moms, vacuumed up samples of dust from their homes, and questioned them about their diets. The researchers found that both were likely to blame. Diet-wise, a number of animal products were implicated. This is consistent with what's been found worldwide. For example, in Europe, these flame retardant chemical pollutants are found mostly in meat, including fish, and other animal products. It's similar to what we see with dioxins--they are mostly found in fish and other fatty foods, with a plant-based diet offering the lowest exposure.

If that's the case, do vegetarians have lower levels of flame retardant chemical pollutants circulating in their bloodstreams? Yes. Vegetarians may have about 25% lower levels. Poultry appears to be the largest contributor of PBDEs. USDA researchers compared the levels in different meats, and the highest levels of these pollutants were found in chicken and turkey, with less in pork and even less in beef. California poultry had the highest, consistent with strict furniture flammability codes. But it's not like chickens are pecking at the sofa. Chickens and turkeys may be exposed indirectly through the application of sewer sludge to fields where feed crops are raised, contamination of water supplies, the use of flame-retarded materials in poultry housing, or the inadvertent incorporation of fire-retardant material into the birds' bedding or feed ingredients.

Fish have been shown to have the highest levels overall, but Americans don't eat a lot of fish so they don't contribute as much to the total body burden in the United States. Researchers have compared the level of PBDEs found in meat-eaters and vegetarians. The amount found in the bloodstream of vegetarians is noticeably lower, as you can see in my video Flame Retardant Pollutants and Child Development. Just to give you a sense of the contribution of chicken, higher than average poultry eaters have higher levels than omnivores as a whole, and lower than average poultry eaters have levels lower than omnivores.

What are the PBDE levels in vegans? We know the intake of many other classes of pollutants is almost exclusively from the ingestion of animal fats in the diet. What if we take them all out of the diet? It works for dioxins. Vegan dioxin levels appear markedly lower than the general population. What about for the flame retardant chemicals? Vegans have levels lower than vegetarians, with those who've been vegan around 20 years having even lower concentrations. This tendency for chemical levels to decline the longer one eats plant-based suggests that food of animal origin contributes substantially. But note that levels never get down to zero, so diet is not the only source.

The USDA researchers note that there are currently no regulatory limits on the amount of flame retardant chemical contamination in U.S. foods, "but reducing the levels of unnecessary, persistent, toxic compounds in our diet is certainly desirable."

I've previously talked about this class of chemicals in Food Sources of Flame Retardant Chemicals. The same foods seem to accumulate a variety of pollutants:

Many of these chemicals have hormone- or endocrine-disrupting effects. See, for example:

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:

Image Credit: Mitchell Haindfield / Flickr. This image has been modified.

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Comparing Pollutant Levels Between Different Diets

Comparing Pollutant Levels Between Different Diets.jpeg

The results of the CHAMACOS (Center for the Health Assessment of Mothers and Children of Salinas) study were published recently. This study of a California birth cohort investigated the relationship between exposure to flame retardant chemical pollutants in pregnancy and childhood, and subsequent neurobehavioral development. Why California? Because California children's exposures to these endocrine disruptors and neurotoxins are among the highest in the world.

What did they find? The researchers concluded that both prenatal and childhood exposures to these chemicals "were associated with poorer attention, fine motor coordination, and cognition" (particularly verbal comprehension) by the time the children reached school age. "This study, the largest to date, contributes to growing evidence suggesting that PBDEs [polybrominated diphenyl ethers, flame retardant chemicals] have adverse impacts on child neurobehavioral development." The effects may extend into adolescence, again affecting motor function as well as thyroid gland function. The effect on our thyroid glands may even extend into adulthood.

These chemicals get into moms, then into the amniotic fluid, and then into the breast milk. The more that's in the milk, the worse the infants' mental development may be. Breast milk is still best, but how did these women get exposed in the first place?

The question has been: Are we exposed mostly from diet or dust? Researchers in Boston collected breast milk samples from 46 first-time moms, vacuumed up samples of dust from their homes, and questioned them about their diets. The researchers found that both were likely to blame. Diet-wise, a number of animal products were implicated. This is consistent with what's been found worldwide. For example, in Europe, these flame retardant chemical pollutants are found mostly in meat, including fish, and other animal products. It's similar to what we see with dioxins--they are mostly found in fish and other fatty foods, with a plant-based diet offering the lowest exposure.

If that's the case, do vegetarians have lower levels of flame retardant chemical pollutants circulating in their bloodstreams? Yes. Vegetarians may have about 25% lower levels. Poultry appears to be the largest contributor of PBDEs. USDA researchers compared the levels in different meats, and the highest levels of these pollutants were found in chicken and turkey, with less in pork and even less in beef. California poultry had the highest, consistent with strict furniture flammability codes. But it's not like chickens are pecking at the sofa. Chickens and turkeys may be exposed indirectly through the application of sewer sludge to fields where feed crops are raised, contamination of water supplies, the use of flame-retarded materials in poultry housing, or the inadvertent incorporation of fire-retardant material into the birds' bedding or feed ingredients.

Fish have been shown to have the highest levels overall, but Americans don't eat a lot of fish so they don't contribute as much to the total body burden in the United States. Researchers have compared the level of PBDEs found in meat-eaters and vegetarians. The amount found in the bloodstream of vegetarians is noticeably lower, as you can see in my video Flame Retardant Pollutants and Child Development. Just to give you a sense of the contribution of chicken, higher than average poultry eaters have higher levels than omnivores as a whole, and lower than average poultry eaters have levels lower than omnivores.

What are the PBDE levels in vegans? We know the intake of many other classes of pollutants is almost exclusively from the ingestion of animal fats in the diet. What if we take them all out of the diet? It works for dioxins. Vegan dioxin levels appear markedly lower than the general population. What about for the flame retardant chemicals? Vegans have levels lower than vegetarians, with those who've been vegan around 20 years having even lower concentrations. This tendency for chemical levels to decline the longer one eats plant-based suggests that food of animal origin contributes substantially. But note that levels never get down to zero, so diet is not the only source.

The USDA researchers note that there are currently no regulatory limits on the amount of flame retardant chemical contamination in U.S. foods, "but reducing the levels of unnecessary, persistent, toxic compounds in our diet is certainly desirable."

I've previously talked about this class of chemicals in Food Sources of Flame Retardant Chemicals. The same foods seem to accumulate a variety of pollutants:

Many of these chemicals have hormone- or endocrine-disrupting effects. See, for example:

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:

Image Credit: Mitchell Haindfield / Flickr. This image has been modified.

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Children’s Supplements Found Contaminated With Pollutants

NF-May19 PCBs in Children's Fish Oil Supplements.jpeg

A number of case-control studies have found that giving kids cod liver oil supplements may increase their risk of asthma later in life. Case-control studies are done by asking about past behavior in cases (those with asthma) versus controls (those without asthma) to see if certain past behaviors are more likely among the disease group. The problem is that asking people to remember what they were doing years ago, when most people can't remember what they had for breakfast last week, is unreliable. When interpreting the results from case-control studies, we also can't rule out something called reverse causation. Maybe cod liver oil doesn't lead to asthma, but asthma led to the use of cod liver oil.

It would therefore be nice to see a cohort study. In a cohort study, researchers would take people without asthma and follow them over time to see if those taking cod liver oil are more likely to develop it. Because people without the disease and their diets are followed over time, cohort studies bypass the problems of recall bias and reverse causation.

In 2013, we finally got one such study. 17,000 people free of asthma were followed over 11 years. Researchers knew who was taking cod liver oil and who wasn't, and then sat back and watched to see who got asthma over the subsequent 11 years. The researchers found that cod liver oil intake was indeed significantly associated with the development of asthma. They thought it might be the excessive vitamin A in the cod liver oil that was causing the problem, but there are also a number of substances in fish oil we may not want our children exposed to.

Researchers from Philadelphia University, highlighted in my video PCBs in Children's Fish Oil Supplements, recently looked at 13 over-the-counter children's dietary supplements containing fish oil to assess potential exposure to PCBs, toxic industrial pollutants that have contaminated our oceans. PCBs were detected in all products. Could we just stick to the supplements made from small, short-lived fish like anchovies instead of big predator fish like tuna to reduce the impact of biomagnification? Or use purified fish oils? No, the researchers found no significant difference in PCB levels whether the supplements were labeled as molecularly distilled or how high up the food chain the fish were.

The researchers concluded that while children's dietary supplements containing the long-chain omega-3's from fish oils may claim to benefit young consumers, "daily ingestion of these products may provide a vector for contaminant exposure that may off-set the positive health effects." What positive health benefits are they talking about?

Researchers publishing in the journal, Early Human Development, found that infants given DHA-fortified formula may have better development of their eyes and brains compared to infants getting non DHA-fortified formula. What was the source of the DHA? Not fish, but algae-derived DHA. In that way we can get the benefits of omega 3's without the contaminant risks. But of course, breast milk is the gold standard, significantly better than either of the formula fed infants. So the best source of omega-3's is mom.

It's bad enough when supplement manufacturers exploit adults when they're sick and vulnerable with pills that are often useless or worse, but taking advantage of our parental drive to do what's best for our children with contaminated products that may make them sick, makes me sick.

More on supplements in:

And speaking of which, Is Fish Oil Just Snake Oil?

Also check out these videos on fish oil and DHA: Omega-3's and the Eskimo Fish Tale and Should We Take EPA and DHA Omega-3 For Our Heart?

What about omega 3's for our child's growing brain? See my video Mercury vs. Omega-3s for Brain Development

We can also be exposed to PCBs in food. See Food Sources of PCB Chemical Pollutants.

More on the polluted aquatic food chain in:

What can we do to lower the risk of childhood asthma and other allergic-type diseases? 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 year-in-review presentations Uprooting the Leading Causes of Death, More Than an Apple a Day, From Table to Able, and Food as Medicine.

Image Credit: Lars Plougmann / Flickr

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No More Than a Quart a Day of Hibiscus Tea

NF-May17 How Much Hibiscus Tea is Too Much?.jpeg

Over the counter antacids are probably the most important source for human aluminum exposure in terms of dose. For example, Maalox, taken as directed, can exceed the daily safety limit more than 100-fold, and nowhere on the label does it say to not take it with acidic beverages such as fruit juice. Washing an antacid down with orange juice can increase aluminum absorption 8-fold, and citric acid-the acid found naturally concentrated in lemon and limes--is even worse.

Just as sour fruits can enhance the absorption of iron (a good thing), the same mechanism they may enhance the absorption of aluminum (a bad thing). This raises the question of what happens when one adds lemon juice to tea? Previously, I concluded that the amount of aluminum in tea is not a problem for most people because it's not very absorbable (See Is There Too Much Aluminum in Tea?). What if we add lemon? Researchers publishing in the journal Food and Chemical Toxicology found no difference between tea with lemon, tea without lemon, or no tea at all in terms of the amount of aluminum in the bloodstream, suggesting that tea drinking does not significantly contribute to aluminum getting inside the body.

The researchers used black tea, green tea, white tea, oolong tea, but what about the "red zinger" herbal tea, hibiscus? The reason hibiscus tea is called "sour tea" is because it has natural acids in it like citric acid. Might these acids boost the absorption of any hibiscus's aluminum? While a greater percentage of aluminum gets from the hibiscus into the tea water than from the other teas, there's less aluminum overall.

The real question is whether the aluminum then gets from the tea water into our bodies. We don't have that data, so to be on the safe side we should assume the worst: that hibiscus tea aluminum, unlike green and black tea aluminum, is completely absorbable. In that case, based on this data and the World Health Organization weekly safety limit, we may not want to drink more than 15 cups of hibiscus tea a day, (based on someone who's about 150 pounds). If you have a 75 pound 10-year-old, a half-gallon a day may theoretically be too much. Recent, more extensive testing highlighted in my video, How Much Hibiscus Tea is Too Much?, suggests that levels may reach level twice as high. Therefore, to be safe, no more than about two quarts a day for adults, or one quart a day for kids or pregnant women. Hibiscus tea should be completely avoided by infants under six months--who should only be getting breast milk--as well as kids with kidney failure, who can't efficiently excrete it.

There is also a concern about the impressive manganese level in hibiscus tea. Manganese is an essential trace mineral, a vital component of some of our most important antioxidant enzymes, but we probably only need about two to five milligrams a day. Four cups of hibiscus tea can have as much as 17 milligrams, with an average of about ten. Is that a problem?

One study from the University of Wisconsin found that women given 15 milligrams of manganese a day for four months, saw, if anything, an improvement in their anti-inflammatory, anti-oxidant enzyme activity. Another study using 20 milligrams a day similarly showed no adverse short-term effects, and importantly showed that the retention of dietary manganese is regulated. Our bodies aren't stupid; if we take in too much manganese, we decrease the absorption and increases the excretion. Even though tea drinkers may get ten times the manganese load (10 or 20 milligrams a day) the levels in their blood are essentially identical. There is little evidence that dietary manganese poses a risk.

These studies were conducted with regular tea, though, so we don't know about the absorption from hibiscus. To err on the side of caution we should probably not routinely exceed the reference dose of ten milligrams per day, or about a quart a day for adults and a half-quart for a 75 pound child.

I've actually changed my consumption. Given the benefits of the stuff, I was using it as a substitute for drinking water, drinking around two quarts a day. I was also blending the hibiscus petals in, not throwing them away, effectively doubling the aluminum content, and increasing manganese concentrations by about 30%. So given this data I've cut back to no more than a quart of filtered hibiscus tea a day.

Lemon can actually boost the antioxidant content of green and white tea. See Green Tea vs. White. For a comparison of their cancer-fighting effects in vitro, Antimutagenic Activity of Green Versus White Tea.

Before that I covered another potential downside of sour tea consumption in Protecting Teeth From Hibiscus Tea, and before that a reason we should all consider drinking it in: Hibiscus Tea vs. Plant-Based Diets for Hypertension.

For more on the iron absorption effect, see my video Risks Associated with Iron Supplements.

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 Uprooting the Leading Causes of Death, More Than an Apple a Day, From Table to Able, and Food as Medicine.

Image Credit: mararie / Flickr

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How to Reduce Exposure to Alkylphenols Through Your Diet

NF-Apr28 Dietary Sources of Alkylphenol Endocrine Disruptors.jpg

Alkylphenols are industrial chemicals that are found in hair products, spermicides, cleaning products and detergents. They are considered endocrine disruptors. For more information on alkylphenols, check out my video Alkylphenol Endocrine Disruptors and Allergies.

Concern about alkylphenols first surfaced decades ago when a group at Tufts observed an excessive proliferation of human breast cancer cells in certain types of plastic containers, something that would normally only be seen if the cells were exposed to some type of estrogen. They identified an alkylphenol leaching from the plastic as the culprit, having "estrogen-like properties when tested in the human breast tumor cells." Excessive proliferation of human breast cancer cells is never good, so countries in Europe started banning and restricting the use of these chemicals. However, the U.S. EPA has been slow to respond.

A half million tons of alkylphenols continue to spew out into the environment every year, so much so that now that they come down in the rain and then accumulate up the food chain.

One study, highlighted in my video, Dietary Sources of Alkylphenol Endocrine Disruptors, examined the Japanese food supply to find out which foods had these potentially allergy-exacerbating endocrine disruptors. The researchers found that chicken and fish had the highest levels. Water animals and birds concentrate these compounds to levels several thousands of times greater than those in the environment because these are fat-soluble chemicals. "Therefore, they can easily contaminate foods of animal origin, which are thought to represent the most important source of human exposure to many organic pollutants," not just the alkylphenols. Another research group also found that fish was the worst.

Which kind of fish? Anchovies, mackerel, salmon and cod seem to have the highest levels. In fact, salmon was the only food found contaminated with nonylphenol diethoxylate, which is even more potent than regular nonylphenol. The levels of contamination in fish were at the concentrations that start to make breast cancer cells go crazy in vitro.

These findings are consistent with the fact that seafood consumption has been associated with severe asthma, current and severe rhinoconjunctivitis, (seasonal pollen allergies), and current and severe eczema (an allergic-type disease of the skin) in adolescent populations around the globe.

If these synthetic xenoestrogens are playing a role, what about natural phytoestrogens, such as those found in soy foods? It turns out that in patients with asthma, consumption of a diet with moderate to high amounts of soy phytoestrogens is associated with better lung function and better asthma control. If anything then, it's these chemical pollutants, which come down in the rain, contaminate the soil, the plants, and then concentrate up the food chain in the fat of animals. We're now the animals at the top of the food chain, like the polar bear or bald eagle, building up higher levels of these synthetic xenoestrogens.

Thankfully, there aren't many cannibals around anymore. However, there is one group that continues to feed off human tissues--babies (See The Wrong Way to Detox). Alkylphenols have been found to concentrate in human breast milk, particularly in women who eat fish. The highest levels of these endocrine-disrupting pollutants were recorded in milk samples from mothers who said they ate fish at least twice a week, consistent with the fact that seafood consumption represents an important source of alkylphenol intake. Even these "slightly elevated levels of endocrine disruptors in the milk of mothers with a seafood-rich diet may be associated with adverse effects on neurological development, fetal and postnatal growth, and memory functions on breastfed infants, because these contaminants may interfere with the endocrine [hormonal] system."

Since these toxins concentrate in fat, the highest concentrations may be found in straight animal fat, such as chicken fat, lard, tallow, or fish oil. Consumption of fish oil capsules and processed fish products has been associated with alkylphenol concentration in mothers' milk, again due to bioaccumulation up the food chain. And then we recycle the leftover remains of farm animals into farm animal feed, so the levels can get higher and higher in animal products.

As one commentator noted, while these pollutants do contaminate human milk, they also contaminate cow's milk--humans and cows live in the same polluted world. In fact, infant formula was found to be over five times more contaminated, so breast is still best, absolutely. But these kinds of studies are important in order to provide good suggestions for food choices to nursing mothers to prevent excess exposure to these pollutants in their infants.

We can kind of cut out the middlefish and move lower down the food chain in hopes of decreasing our exposure to industrial toxins.

Endocrine disruptors have also been linked to conditions such as male infertility (Male Fertility and Diet and Xenoestrogens and Sperm Counts) and early onset of puberty (Protein, Puberty, and Pollutants and Xenoestrogens and Early Puberty).

What other industrial pollutants build up in the aquatic fish chain? See, for example:

Farmed Fish vs. Wild Caught. Which is worse?

How Long to Detox from Fish Before Pregnancy? If it's too late, How Fast Can Children Detoxify from PCBs?

-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 Uprooting the Leading Causes of Death, More Than an Apple a Day, and From Table to Able.

Image Credit: Andrea Pokrzywinski / Flickr

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Alkylphenol Endocrine Disruptors and Allergies

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In my video Preventing Childhood Allergies, I noted a study in Japan that found higher maternal intake of meat during pregnancy was significantly associated with about three times the odds of both suspected and physician-diagnosed eczema. The researchers suggest that certain components of meat may affect the fetal immune system. But what about the moms, themselves? A plant-based diet may also help alleviate allergies in adults. See Say No to Drugs by Saying Yes to More Plants and Preventing Allergies in Adulthood.

Seasonal allergies have exploded in Japan in the past few decades, starting with the first reported case in 1964 and now affecting millions every year. We've seen a rising prevalence of allergic diseases around the industrialized world in past decades, but perhaps nothing quite this dramatic.

Some have suggested that profound changes in the Japanese diet may have played a role. Over the latter half of the century total meat, fish, and milk intake rose hundreds of percent in Japan, so researchers decided to look into dietary meat and fat intake and the prevalence of these seasonal pollen allergies. No association with overall fat, but "higher meat intake was significantly associated with an increased prevalence."

Saturated fat wasn't associated with increased prevalence either, so what other constituents in meat may be to blame? The researchers considered the cooked meat carcinogens, the heterocyclic amines, the polycyclic aromatic hydrocarbons, and the nitrosamines.

A new review, highlighted in my video, Alkylphenol Endocrine Disruptors and Allergies, however, raised an intriguing possibility. There's a class of industrial pollutants called alkylphenols, recognized as common toxic endocrine disrupting chemicals that tend to accumulate in the human body and may be associated with allergic diseases. A variety of studies have shown how they may exacerbate allergen-induced inflammation, "suggesting that alkylphenol exposure may influence the onset, progression, and severity of allergic diseases." These toxic xenoestrogens can be found in human breast milk, in our body fat, in our urine, in our bloodstream, and even in the umbilical cord blood going to our babies. How did it get there? Through contaminated food.

It all goes back to a famous study about the reduction of penis size and testosterone levels in alligators living in a contaminated environment. I don't know what you do for a day job, but these researchers observed that a population of juvenile alligators living on one lake in Florida exhibited a "significantly smaller penis size" and lower blood concentrations of testosterone compared to animals on some different lake. The most important difference between the two lakes was that Lake Stubby was fed by relatively polluted waters. They attributed the "short penis phenomenon" to estrogen-mimicking (xenoestrogenic) environmental metabolites of DDT that still pollute our Earth. This seminal work introduced the concept of endocrine disruptors. Environmental xenoestrogens might result in feminization of exposed male animals. And that's just the shriveled tip of the iceberg.

Since then, endocrine-disrupting chemicals have been implicated in the dramatic rise over the last 50 years of diseases like breast cancer, prostate cancer, testicular cancer, diabetes, obesity, and fertility (such as dropping normal sperm counts), genital birth defects such as penile malformations, preterm birth, neurobehavioral disorders in children linked to thyroid disruption, and earlier breast development in young girls. Because genes do not change fast enough to explain these increases, environmental causes must be involved. Since our greatest exposure to the environment is through our gut, it's no surprise that our greatest exposure to these endocrine-disrupting chemicals is through diet.

To find out which foods may contain these alkylphenol endocrine disruptors, check out my video Dietary Sources of Alkylphenol Endocrine Disruptors.

More on endocrine disruptors in:

A different class of chemicals has been found to be associated with smaller penis size in humans. See Chicken Consumption and the Feminization of Male Genitalia.

-Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videoshere and watch my live year-in-review presentations Uprooting the Leading Causes of Death, More Than an Apple a Day, and From Table to Able.

Image Credit: Mark Freeth / Flickr

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What to Eat to Reduce Our Toxic Exposure

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It is not very common that a single molecule attracts enough interest to merit international scientific conferences of its own. "Ah receptor," however, "belongs to the rare elite of such molecules." Ah receptors are an important factor in how our immune system works. For background, see my video, The Broccoli Receptor: Our First Line of Defense. The latest conference offered "new reports about the way plant-derived compounds in our diet are necessary for a fully functioning immune system of the gut." One study in particular out of the journal Nature, "expanded our understanding of how diet impacts immunity and health by showing that a plant-derived nutrient profoundly shapes the capacity for intestinal immune defense." And intestinal defense not only protects us against the pathogens we may ingest, but also against toxic chemicals.

We're constantly exposed to a wide range of toxins, from such sources as cigarette smoke, exhaust fumes, furnace gases, cooked meat and fish, cow's milk, and even mother's milk (because of what mothers themselves are exposed to) as seen in my video Counteracting the Effects of Dioxins Through Diet. Many of these pollutants exert their toxic effects through the Ah receptor system. For example, dioxins invade the body mainly through the diet (where we get more than 90% of our exposure) as it concentrates through the food chain, presenting a serious health concern. But there are phytonutrients in fruits, vegetables, tea, red wine, and beans that block the effects of dioxins at levels close to what we find in people's bloodstream. Just three apples or about a tablespoon of red onion a day may cut dioxin toxicity in half. And the half-life of these phytonutrients in the body is only about 25 hours, so we have to keep eating these health-promoting foods day after day.

At first we just thought that it was only cruciferous vegetables that could dock in these receptors and fend off toxins, but does that make evolutionary sense? As Lora V. Hooper from the Howard Hughes Medical Institute notes, "Given the variety and flexibility of most mammalian diets, a specific dependence on cruciferous vegetables for optimal intestinal immune function would seem overly restrictive. Rather, it seems likely that many other foods contain compounds with similar immune-stimulatory properties."

Indeed, "the search for foods containing similar immunomodulatory compounds has begun." We now know that a wide variety of natural plant compounds can counteract the chemical pollution to which we're all exposed. There is actually one animal product that has also been shown to potentially block the cancer-causing effects of dioxins: camel urine. Camel urine--but not cow urine--was found to inhibit the effects of a known carcinogenic chemical. Importantly, the researchers emphasize that virgin camel urine showed the highest degree of inhibition, performing better than pregnant camel urine, for example. So the next time our kids don't want to eat their fruits and veggies, we can just say, "It's either that, or camel pee."

I report different mechanisms but similar outcomes in Plants vs. Pesticides and Eating Green to Prevent Cancer. So this all suggests a double benefit of eating lower on the food chain, since it would also entail lower exposure to toxic contaminants in the first place (Industrial Pollutants in Vegans).

How Chemically Contaminated Are We? Check out the CDC Report on Environmental Chemical Exposure. Where are dioxins found so we can avoid them in the first place? See Dioxins in the Food Supply.

-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 Uprooting the Leading Causes of Death, More Than an Apple a Day, and From Table to Able.

Images thanks to Feliciano Guimaraes / Flickr

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