Estrogen in Meat, Dairy, and Eggs


Estrogen hormones can be thousands of times more estrogenic than typical endocrine-disrupting chemicals. Dietary exposure to natural sex steroids (in meat, dairy, and eggs) is "therefore highly relevant in the discussion of the impact of estrogens on human development and health." And chicken estrogen is identical to human estrogen--they're identical molecules. So it doesn't matter if it ends up in our drinking supply from women taking birth control pills excreting it in their urine, or cows excreting it into their milk. The source doesn't matter; the quantity does.

If you check out my video Estrogen in Meat, Dairy, and Eggs, you can see that a child's exposure to estrogens in drinking water is about 150 times lower than exposure from cow's milk, so our day-to-day estrogen exposure levels are more likely determined by whether or not we happen to eat dairy products that day.

Human urine is "often cited as the main source of natural and synthetic estrogens in the aquatic environment," but the level of estrogen even in the urine of heavy meat-eaters, who have significantly higher levels, pales in comparison to the estrogen excreted by the farm animals themselves. Pig, sheep, cattle, and chickens produce literally tons of estrogen every year.

Women may excrete 16 mg every day, but farm animals may release ten times more, or in the case of pregnant cows, thousands of times more. Animal waste may contribute an estimated 90% of total estrogens in the environment. Five gallons of runoff water contaminated with chicken manure may contain a birth control pill's worth of estrogen.

Estrogen levels in poultry litter are so high that when farmers feed chicken manure to their animals to save on feed costs, it may trigger premature development. Poultry manure has among the highest hormone content, quadruple the total estrogens, and nine times more 17-beta estradiol, the most potent estrogen and a "complete" carcinogen, as it exerts both tumor initiating and tumor promoting effects.

From a human health standpoint, do we really care about feminized fish, or the appearance of "intersex roaches"? The problem is that the hormones get into the food supply. Endogenous steroid hormones in food of animal origin are unavoidable as they occur naturally in these products. It's not a matter of injected hormones, which are banned in places like Europe in order to protect consumers' health. Sex steroid hormones are part of animal metabolism, and so all foodstuffs of animal origin contain these hormones, which have been connected with several human health problems. (See Why Do Vegan Women Have 5x Fewer Twins?)

What effects might these female hormones have on men? See Dairy Estrogen and Male Fertility.

The implications of this relatively new practice of milking cows even when they're pregnant is further explored in:

More on xenoestrogens in:

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--2013: Uprooting the Leading Causes of Death, More Than an Apple a Day, 2014: From Table to Able: Combating Disabling Diseases with Food, 2015: Food as Medicine: Preventing and Treating the Most Dreaded Diseases with Diet, and my latest, 2016: How Not To Die: The Role of Diet in Preventing, Arresting, and Reversing Our Top 15 Killers.

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How to Suppress the Aging Enzyme TOR

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Over the last decade, more than 5,000 papers have been published about TOR, an engine-of-aging enzyme inhibited by the drug rapamycin. (What is TOR? Check out my videos Why Do We Age? and Caloric Restriction vs. Animal Protein Restriction.) Rapamycin has been used experimentally to extend lifespan, but is already in use clinically to prevent the rejection of kidney transplants. Patients who received rapamycin due to renal transplantation had a peculiar "side effect," a decrease in cancer incidence. In a set of 15 patients who had biopsy proven Kaposi's sarcoma (a cancer that often affects the skin), all cutaneous sarcoma lesions disappeared in all patients within three months after starting rapamycin therapy.

TOR functions as a master regulator of cellular growth and proliferation. For example, TOR is upregulated in nearly 100% of advanced human prostate cancers (See Prevent Cancer From Going on TOR). So, reductions in cancerous lesions after rapamycin therapy make sense. TOR may also be why dairy consumption has been found to be a major dietary risk factor for prostate cancer. We used to think it was just the hormones in milk, but maybe prostate cancer initiation and progression is also promoted by cow's milk stimulation of TOR.

Our understanding of mammalian milk has changed from a simple food to a "species-specific endocrine signaling system," which activates TOR, promoting cell growth and proliferation and suppressing our body's internal housecleaning mechanisms. Normally, milk-mediated TOR stimulation is restricted only to infancy where we really need that constant signal to our cells to grow and divide. So from an evolutionary perspective, "the persistent 'abuse' of the growth-promoting signaling system of cow's milk by drinking milk over our entire life span may maintain the most important hallmark of cancer biology, sustained proliferative signaling."

TOR appears to play a role in breast cancer, too. Higher TOR expression has been noted in breast cancer tumors, associated with more aggressive disease, and lower survival rate among breast cancer patients. Altered TOR expression could explain why women hospitalized for anorexia may end up with only half the risk of breast cancer. Severe caloric restriction in humans may confer protection from invasive breast cancer by suppressing TOR activation.

We don't have to starve ourselves to suppress TOR; just reducing animal protein intake can attenuate overall TOR activity. Moreover, diets emphasizing plants, especially cruciferous vegetables, have both decreased TOR activation from animal proteins and provide natural plant-derived inhibitors of TOR found in broccoli, green tea, soy, turmeric, and grapes, along with other fruits and vegetables such as onions, strawberries, blueberries, mangoes and the skin of cucumbers.

The downregulation of TOR may be one reason why plant-based in general are associated with lower risk for many cancers. "Are we finally on the threshold of being able to fundamentally alter human aging and age-related disease?" asks researchers in the journal Nature. Only time will tell, but if the pace and direction of recent progress are any indication, the next 5,000 studies on TOR should prove very interesting indeed.

More on dairy and prostate cancer in Prostate Cancer and Organic Milk vs. Almond Milk.

This story continues in my video: Saving Lives By Treating Acne With Diet.

-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.

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How Fruits and Vegetables Can Prevent Asthma

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Asthma is the most common chronic disease in children and the prevalence is increasing around the world. Despite this, most research dollars are spent on adult chronic disease. "One might ask," a group of researchers posited "whether this is because our politicians and senior administrators feel themselves to be more likely to suffer from the latter, and thus ignore allergic diseases as they mostly impact children and young adults" - who don't vote.

An enormous study about asthma and allergies in childhood, highlighted in my video, Preventing Asthma with Fruits and Vegetables, was published that includes more than a million children in nearly a hundred countries, making it the most comprehensive survey of asthma and allergies ever undertaken. The researchers found striking worldwide variations in the prevalence and severity of asthma, allergies, and eczema--a 20 to 60-fold difference in prevalence of symptoms of asthma, allergic runny nose, and atopic eczema around the world. The large variability suggests a crucial role of local characteristics that are determining the differences in prevalence between one place and another.

What kind of environmental factors? Why does the prevalence of itchy eyes and runny noses range anywhere from 1% in India, for example, and up to 45% of kids elsewhere? There were some associations with regional air pollution and smoking rates, but the most significant associations were with diet. Adolescents showed a consistent pattern of decreases in symptoms of wheeze (current and severe), allergic rhinoconjunctivitis, and atopic eczema with increases in per capita consumption of plant foods. The more their calories and protein came from plant sources, the less allergies they tended to have.

In general, there seems to be an association between an increase in asthma prevalence and a decrease in consumption of fresh fruits, green vegetables, and other dietary sources of antioxidants, helping to explain why the prevalence of asthma and respiratory symptoms are lower in populations with high intake of foods of plant origin. High intakes of fat and sodium, and low intakes of fiber and carbohydrates, are linked with asthma, while traditional and vegetarian diets are associated with lower rates. For example, if we look closer within India, in a study of more than 100,000 people, "those who consumed meat (daily or occasionally) were more likely to report asthma than those who were strictly vegetarian." This also meant avoiding eggs.

Eggs have been associated (along with soft drink consumption) with increased risk of respiratory symptoms and asthma in schoolchildren. On the other hand, consumptions of soy foods and fruits were associated with reduced risk of respiratory symptoms. In fact, removing eggs and dairy from the diet may improve lung function in asthmatic children in as little as eight weeks. Therefore, it may be a combination of eating fewer animal foods and more plants.

High vegetable intake, for example, has been found protective in children, potentially cutting the odds of allergic asthma in half. And fruit has also shown a consistent protective association for current and severe wheeze and runny nose in adolescents, and for current and severe asthma, allergies, and eczema in children.

Why is this? I've talked about the endocrine-disrupting industrial pollutants (see Dietary Sources of Alkylphenol Endocrine Disruptors) building up in the meat supply that may increase the risk of allergic disease, but the increase in asthma may be a combination of both a more toxic environment and a more susceptible population. One review notes that, "The dietary changes which have occurred over recent years may have led to a reduction in these natural antioxidant defenses, resulting in a shift of the antioxidant status of the whole population and leading to increased susceptibility to oxidant attack and airway inflammation."

In adults, for example, the risk of airway hyper-reactivity may increase seven-fold among those with the lowest intake of vitamin C from plant foods, while those with the lowest intake of saturated fats may have a 10-fold protection, presumably because of saturated fat's role in triggering inflammation.

The protective effect of plant-based food may also be mediated through effects on intestinal microflora. It turns out that differences in the indigenous intestinal flora might affect the development and priming of the immune system in early childhood. Kids with allergies, for example, tend to be less likely to harbor lactobacilli, the good bacteria that's found in fermented foods, and naturally on many fruits and vegetables. Lactobacillus probiotics may actually help with childhood asthma, which may help explain why children raised on largely organic vegetarian diets may have a lower prevalence of allergic reactions. Infants raised this way tend to have more good lactobacilli in their guts compared to controls, though they were also more likely to have been born naturally, breastfed longer, and not been given antibiotics, so we can't really tell if it's the diet until we put it to the test (See Treating Asthma with Fruits and Vegetables).

More on preventing allergic diseases can be found in my videos Preventing Childhood Allergies and Preventing Allergies in Adulthood.

More on protecting lung function with fruits and vegetables can be found in Preventing COPD With Diet.

Surprised probiotics can affect immune function? Check out my video Preventing the Common Cold with Probiotics? And if you think that is wild, wait until you see Gut Feelings: Probiotics and Mental Health.

What might be in plants that's so beneficial? See Anti-inflammatory Antioxidants.

What might be in animal products that is harmful to lung function? There are endocrine-disrupting industrial pollutants that build up in the food chain that may be playing a role. See my video Alkylphenol Endocrine Disruptors and Allergies. Also there's an inflammatory omega-6 fatty acid found predominantly in chicken and eggs that may contribute to inflammation as well. See Inflammatory Remarks About Arachidonic Acid.

Choosing fragrance-free personal care products may also help reduce airway reactivity: Throw Household Products Off the Scent.

I compare the efficacy of plants to pills (Treating Asthma With Plants vs. Supplements?) and explore the role an entire diet filled with plants might play in Treating Asthma and Eczema With Plant-Based Diets.

-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.

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How Contaminated Are Our Children?

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In a study highlighted in my video, California Childen Are Contaminated, researchers analyzed the diets of California children ages two through seven to determine the cancer and non-cancer health effects from food contaminant exposures. It turns out food may be the primary route of exposure to toxic heavy metals, persistent pollutants, and pesticides. "Though food-borne toxic contaminants are a concern for all ages, they are of greatest concern for children, who are disproportionately impacted because they're still developing and have greater intake of food and fluids relative to their weight. Pediatric problems that have been linked to preventable environmental toxin exposures include cancer, asthma, lead poisoning, neurobehavioral disorders, learning and developmental disabilities, and birth defects."

The good news is that changing one's diet can change one's exposure. Quoting from the study, "A diet high in fish and animal products, for example, results in greater exposure to persistent pollutants like DDT and dioxins and heavy metals than does a plant-based diet because these compounds bioaccumulate up the food chain." Plants are at the bottom of the food chain. The sample of California kids, however, was not eating a plant-based diet. Cancer benchmark levels were exceeded by all 364 children for arsenic, the banned pesticide dieldrin, a metabolite of DDT called DDE, and dioxins.

Children exceeded safety levels by a greater margin than adults. This is especially of concern for children because all of these compounds are suspected endocrine disruptors and thus may impact normal development. Cancer risk ratios were exceeded by over a factor of 100 for both arsenic and dioxins.

Which foods were the worse? For preschoolers, the number one food source of arsenic was poultry, though for their parents, it was tuna. The number one source of lead was dairy, and for mercury it was seafood. And the number one source of the banned pesticides and dioxins was dairy. (See Preventing Parkinson's Disease With Diet.)

The researchers also recommended children should eat lower quantities of chips, cereal, crackers, and other crispy carbs to reduce acrylamide intake.

The California study didn't split up the groups by gender, but a similar study in Europe found that men had higher levels of some of these pollutants than women. For example, levels of the banned pesticide chlordane were higher in men, but women who never breastfed were right up there alongside men, with the lowest levels found in women who breastfed over 12 months. Therefore, it is likely that the lactation-related reduction in blood pollutant levels partly explains the lower body burdens among women compared with men. So cows can lower their levels by giving some to us, then we can pass it along to our children.

What non-cancer effects might some of these pollutants have? They can affect our immune system. Studies clearly demonstrate the "ability of dioxins and related compounds to have a long-lasting and deleterious impact on immune function." This manifests as increased incidences of respiratory infections, ear infections, cough, and sore throat. At first, most of the data was for during infancy, but now we have follow-up studies showing that the immunosuppressive effects of these toxins may persist into early childhood, so we should try to reduce our exposure as much as possible. Because these pollutants accumulate in animal fat, consuming a plant-based diet-decreasing meat, dairy, and fish consumption-may reduce exposure for children and adults alike.

These findings should come as no surprise to those who saw my video Pollutants in California Breast Tissue. For an overview see CDC Report on Environmental Chemical Exposure and President's Cancer Panel Report on Environmental Risk.

Pollutant exposure may affect the ability to have children in the first place (Male Fertility and Diet and Meat Hormones & Female Infertility). Such a delay, though, may allow one an opportunity to reduce one's toxic burden through dietary change (Hair Testing for Mercury Before Considering Pregnancy and How Long to Detox From Fish Before Pregnancy?).

During pregnancy, pollutants can be transferred directly (DDT in Umbilical Cord Blood), and after pregnancy through breastfeeding (The Wrong Way to Detox). Once our kids are contaminated, How Fast Can Children Detoxify from PCBs? The chemicals have implications for older children too: Protein, Puberty, and Pollutants.

Seafood is not the only source of toxic heavy metals. See:

Videos on primary food sources of other industrial pollutants include:

There are some things we can eat, though, to counteract some of the toxins:

-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.

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How to Reduce Exposure to Alkylphenols Through Your Diet

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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.

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