Estrogen in Meat, Dairy, and Eggs

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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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Dietary Estrogens and Male Fertility

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In my video, The Role of Diet in Declining Sperm Counts, I discussed the association between high saturated fat intake and reduced semen quality. But what's the connection? One of the most recent papers on the topic found that a significant percentage of the saturated fat intake in the study was derived from dairy products. Residues of industrial chemicals may bioaccumulate up the food chain into animal fat, and some of these lipophilic (fat-loving) chemicals may have hormone-disrupting abilities.

The U.S. Environmental Protection Agency performed a national survey of persistent, bioaccumulative, and toxic pollutants in the U.S. milk supply (highlighted in my video, Dairy Estrogen and Male Fertility). The EPA team noted that since milk fat is likely to be among the highest dietary sources of exposure to these pollutants, it's important to understand the levels in the dairy supply. The team tested milk from all over the country and found a veritable witches brew of chemicals. They estimate that dairy products alone contribute about 30% to 50% of our dioxin exposure. And "like dioxin, other toxic pollutants tend to be widely dispersed in the environment, bioaccumulated through the food chain and ultimately result in low-level contamination in most animal fats."

This may explain higher pollutant concentrations in fish eaters. Xenoestrogens like polychlorinated biphenyls (PCBs) are associated with the fats of fish or animal flesh and cannot be fully removed by washing and cooking, and so can accumulate in our fat, too. Xenoestrogens are chemicals with demasculinizing or feminizing effects. But even in a non-polluted world, animal foods also have actual estrogen, which are unavoidable constituents of animal products. All foodstuff of animal origin contains estradiol, which is at least 10,000-fold more potent than most xenoestrogens. Dietary exposure--meat, dairy products and eggs--to these natural sex steroids is therefore highly relevant, as the hormones in these animals are identical to our own.

Estrogens are present in meat and eggs, but the major sources are milk and dairy products. By drinking a glass of milk, a child's intake of estradiol is 4,000 times the intake of xenoestrogens in terms of hormone activity. Modern genetically-improved dairy cows can lactate throughout their pregnancy. The problem is that during pregnancy, estrogen levels can jump as much as 30-fold.

Cheese intake has specifically been associated with lower sperm concentration, whereas dairy food intake in general has been associated with abnormal sperm shape and movement. Lower sperm concentrations by themselves may just represent a potential suppression of sperm production due to higher estrogen levels, but abnormal shape and movement suggests that dairy intake may be implicated in actual direct testicular damage.

While milk products supply most of our ingested female sex steroids, eggs are a considerable source as well, contributing about as much as meat and fish. This could be expected, as eggs are produced directly in the hens' ovaries.

Meat may also contain added hormones. In the U.S. anabolic sex steroids may be administered to animals for growth promotion, a practice banned in Europe twenty-five years ago. A study in New York found progressively lower sperm counts associated with processed meat consumption. However, similar studies in Europe after the ban found the same thing, so it may not be the implanted hormones, but rather a consequence of other meat components, such as the saturated fat raising cholesterol levels.

We've known for decades that men with high cholesterol levels show abnormalities in their "spermiograms": decreased sperm concentration, about a third of the normal sperm movement, and half the normal sperm shape. Twenty-five years later, we're finding the same thing. In the largest study to date, higher blood cholesterol levels were associated with a significantly lower percentage of normal sperm. Cholesterol was also associated with reductions in semen volume and live sperm count. These results highlight the role of fats in the blood in male fertility, and should be of concern given the rising prevalence of obesity and cholesterol problems. Although a healthier diet may be associated with healthier sperm counts, cholesterol-lowering statin drugs do not seem to help.

What about the phytoestrogens in soy? See The Effect of Soy on Precocious Puberty.

More on hormones in dairy in:

Neurotoxic chemicals in the dairy supply have been blamed for neurological conditions as well. See my video Preventing Parkinson's Disease with Diet.

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.

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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.

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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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Male Fertility and Dietary Pollutants

 

 

 

 

 

 

 

 

Male Fertility and Diet

Infertility affects 10–15 percent of couples attempting to conceive, and in about half the cases the problem is in the man. A recent Harvard study found that increasing saturated fat intake just 5 percent was associated with a 38 percent lower sperm count, but why? It may be because of endocrine-disrupting industrial pollutants that build up in animal fat, particularly fish, as I describe in my video Xenoestrogens & Sperm Counts, but male fertility is not just about the number of sperm, but also how well they work.

A recent study, featured in my 5-min video Male Fertility and Diet, found that successful pregnancy and fertilized egg implantation outcomes are decreased in patients reporting a more frequent intake of meat. The researchers blame industrial pollutants and steroids present in animal products. They conclude that couples having trouble conceiving must be advised about the dramatic effects diet may play on treatment success for both men and women, consistent with previous findings that “frequent intake of fat-laden foods like meat products or milk may negatively affect semen quality in humans, whereas some fruits or vegetables may maintain or improve semen quality.” Vegetable consumption was also found protective in this new study, which may be because of the antioxidant and nutrient content.

The reason why maternal beef consumption may alter a man’s testicular development and adversely affect his future reproductive capacity is thought to be due to the anabolic steroids implanted into the animals. However, as an accompanying editorial to a study exploring this phenomenon pointed out, the steroids could also be interacting with other xenobiotics—industrial chemicals present in meat—such as pesticides and dioxin-like pollutants, and even chemicals that may be present in the plastic wrap (see Dioxins in the Food Supply). For more on the hormones used in meat production, see my video Anabolic Steroids in Meat.

Heavy metals may also play a role. Lead and cadmium exposure, as measured by levels in the bloodstream, were associated with a significantly longer time to conceive. Where might exposure be coming from? Common types of seafood from fish markets and supermarkets were sampled. The highest cadmium levels were found in tuna; highest lead levels in scallops and shrimp. The greatest risk from different metals resided in different fish. Thus, the risk information given to the public (mainly about mercury) does not present a complete picture. There are other toxic metals in fish as well.

For more on heavy metal exposure (dietary as opposed to auditory), see:

The only beverage associated with infertility in women was soft drinks, though this may be from an indirect route, since soda is linked to obesity and obesity is then linked to reduced fertilization rates. However, Harvard researchers conducted a study on one really direct route: “The Effectiveness of Coca Cola As a Spermicidal Agent in Vaginal Douching.” Diet coke apparently had the strongest effect. What about Coke versus Pepsi? Tax-payer money hard at work for this head-to-head test. Neither of them really worked—Coke nor Pepsi—though they explain their methods for preparing the "sperm-cola mixtures" differed from the Harvard group. Bottom line: soda probably isn’t good for you going into any orifice.

For more on both male and female infertility, see my videos Soy Hormones & Male Infertility and Meat Hormones & Female Infertility.

-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 and More Than an Apple a Day.

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