Brown Fat: Losing Weight Through Thermogenesis

Sept 21 Brown Fat Thermo copy.jpeg

During World War I, it was discovered that many of the chemicals for new explosives had toxic or even lethal effects on the workers in the munitions factories. Chemicals such as di-nitro-phenol (DNP) can boost metabolism so much that workers were too often found wandering along the road after work, covered in sweat with temperatures of 106 to 109 degrees Fahrenheit before they died. Even after death, their temperatures kept going up, as if they were having a total body meltdown. At subacute doses, however, workers claimed to have grown thin to a notable extent after several months working with the chemical.

That got some Stanford pharmacologists excited about the "promising metabolic applications" of DNP. Our resting metabolic rate jumps up 30% after one dose of DNP, and therefore, it becomes an actual fat-burning drug. People started losing weight, as you can see in my video Brown Fat: Losing Weight Through Thermogenesis, with no apparent side effects. They felt great... and then thousands of people started going blind and users started dropping dead from hyperpyrexia, fatal fever due to the heat created by the burning fat. Of course, it continued to be sold. Ad copy read:

"Here, at last, is a [weight] reducing remedy that will bring you a figure men admire and women envy, without danger to your health or change in your regular mode of living....No diet, no exercise!"

It did work, but the therapeutic index--the difference between the effective dose and the deadly dose--was razor thin. It was not until thousands suffered irreversible harm that it got pulled from the market and remained unavailable. Unavailable, that is, until it was brought back by the internet for those dying to be thin.

There is, however, a way our body naturally burns fat to create heat. When we're born, we go from a nice tropical 98.6 in our mother's womb straight to room temperature, just when we're still all wet and slimy. As an adaptive mechanism to maintain warmth, the appearance of a unique organ around 150 million years ago allowed mammals to maintain our high body temperatures.

That unique organ is called brown adipose tissue, or BAT, and its role is to consume fat calories by generating heat in response to cold exposure. The white fat in our bellies stores fat, but the brown fat, located up between our shoulder blades, burns fat. BAT is essential for thermogenesis, the creation of heat in newborns, but has been considered unnecessary in adults who have higher metabolic rates and increased muscle mass for shivering to warm us up when we get chilled. We used to think brown tissue just shrank away when we grew up, but, if it was there, then it could potentially make a big difference for how many calories we burn every day.

When PET scans were invented to detect metabolically active tissues like cancer, oncologists kept finding hot spots in the neck and shoulder regions that on CT scans turned out not to be cancer, just fat. Then, some observant radiologists noticed they appeared in patients mostly during the cold winter months. When they looked closer at tissue samples taken from people who had undergone neck surgery, they found it: brown fat in adults.

The common message from a number of studies is that BAT is present and active in adults, and the more we have and the more active it is, the thinner we are. And we can rapidly activate our fat-burning brown fat by exposure to cold temperatures. For example, if you hang out in a cold room for two hours in your undies and put your legs on a block of ice for four minutes every five minutes, you can elicit a marked increase in energy expenditure, thanks to brown fat activation. So, the studies point to a potential "natural" intervention to stimulate energy expenditure: Turn down the heat to burn calories (and reduce the carbon footprint in the process).

Thankfully, for those of us who would rather not lay our bare legs on blocks of ice, our brown fat can also be activated by some food ingredients such as those that are covered in my Boosting Brown Fat Through Diet video.


I briefly touch on the role cold temperatures can play in weight loss in The Ice Diet and talk more about calories in (Nutrient-Dense Approach to Weight Management) and calories out (How Much Exercise to Sustain Weight Loss).

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:

Original Link

Fish Consumption and Suicide

Sept 12 Fish Consumption copy.jpeg

Depression is a serious and common mental disorder responsible for the majority of suicides. As I've covered in Antioxidants & Depression, intake of fruits, vegetables, and naturally occurring antioxidants have been found to be protectively associated with depression. Therefore, researchers have considered that "it may be possible to prevent depression or to lessen its negative effects through dietary intervention."

But not so fast. Cross-sectional studies are snapshots in time, so we don't know "whether a poor dietary pattern precedes the development of depression or if depression causes poor dietary intake." Depression and even treatments for depression can affect appetite and dietary intake. Maybe people who feel crappier just eat crappier, instead of the other way around.

What we need is a prospective study (a study performed over time) where we start out with people who are not depressed and follow them for several years. In 2012, we got just such a study, which ran over six years. As you'll see in my video Fish Consumption and Suicide, those with higher carotenoid levels in their bloodstream, which is considered a good indicator of fruit and vegetable intake, had a 28% lower risk of becoming depressed within that time. The researchers conclude that having low blood levels of those healthy phytonutrients may predict the development of new depressive symptoms. What about suicide?

Worldwide, a million people kill themselves every year. Of all European countries, Greece appears to have the lowest rates of suicide. It may be the balmy weather, but it may also have something to do with their diet. Ten thousand people were followed for years, and those following a more Mediterranean diet pattern were less likely to be diagnosed with depression. What was it about the diet that was protective? It wasn't the red wine or fish; it was the fruit, nuts, beans, and effectively higher plant to animal fat ratio that appeared protective. Conversely, significant adverse trends were observed for dairy and meat consumption.

A similar protective dietary pattern was found in Japan. A high intake of vegetables, fruits, mushrooms, and soy products was associated with a decreased prevalence of depressive symptoms. The healthy dietary pattern was not characterized by a high intake of seafood. Similar results were found in a study of 100,000 Japanese men and women followed for up to 10 years. There was no evidence of a protective role of higher fish consumption or the long-chain omega 3s EPA and DHA against suicide. In fact, they found a significantly increased risk of suicide among male nondrinkers with high seafood omega 3 intake. This may have been by chance, but a similar result was found in the Mediterranean. High baseline fish consumption with an increase in consumption were associated with an increased risk of mental disorders.

One possible explanation could be the mercury content of fish. Could an accumulation of mercury compounds in the body increase the risk of depression? We know that mercury in fish can cause neurological damage, associated with increased risk of Alzheimer's disease, memory loss, and autism, but also depression. Therefore, "the increased risk of suicide among persons with a high fish intake might also be attributable to the harmful effects of mercury in fish."

Large Harvard University cohort studies found similar results. Hundreds of thousands were followed for up to 20 years, and no evidence was found that taking fish oil or eating fish lowered risk of suicide. There was even a trend towards higher suicide mortality.

What about fish consumption for the treatment of depression? When we put together all the trials done to date, neither the EPA nor DHA long-chain omega-3s appears more effective than sugar pills. We used to think omega-3 supplementation was useful, but several recent studies have tipped the balance the other way. It seems that "[n]early all of the treatment efficacy observed in the published literature may be attributable to publication bias," meaning the trials that showed no benefit tended not to get published at all. So, all doctors saw were a bunch of positive studies, but only because a bunch of the negative ones were buried.

This reminds me of my Is Fish Oil Just Snake Oil? video. Just like we thought omega-3 supplementation could help with mood, we also thought it could help with heart health, but the balance of evidence has decidedly shifted. I still recommend the consumption of pollutant-free sources of preformed long-chain omega 3s for cognitive health and explain my rationale in Should We Take DHA Supplements to Boost Brain Function? and Should Vegans Take DHA to Preserve Brain Function?


For more on the neurotoxic nature of mercury-contaminated seafood, see:

What can we do to help our mood? See:

What about antidepressant drugs? Sometimes they can be absolutely life-saving, but other times they may actually do more harm than good. See my controversial video Do Antidepressant Drugs Really Work?.

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:

Original Link

Fish Consumption and Suicide

Sept 12 Fish Consumption copy.jpeg

Depression is a serious and common mental disorder responsible for the majority of suicides. As I've covered in Antioxidants & Depression, intake of fruits, vegetables, and naturally occurring antioxidants have been found to be protectively associated with depression. Therefore, researchers have considered that "it may be possible to prevent depression or to lessen its negative effects through dietary intervention."

But not so fast. Cross-sectional studies are snapshots in time, so we don't know "whether a poor dietary pattern precedes the development of depression or if depression causes poor dietary intake." Depression and even treatments for depression can affect appetite and dietary intake. Maybe people who feel crappier just eat crappier, instead of the other way around.

What we need is a prospective study (a study performed over time) where we start out with people who are not depressed and follow them for several years. In 2012, we got just such a study, which ran over six years. As you'll see in my video Fish Consumption and Suicide, those with higher carotenoid levels in their bloodstream, which is considered a good indicator of fruit and vegetable intake, had a 28% lower risk of becoming depressed within that time. The researchers conclude that having low blood levels of those healthy phytonutrients may predict the development of new depressive symptoms. What about suicide?

Worldwide, a million people kill themselves every year. Of all European countries, Greece appears to have the lowest rates of suicide. It may be the balmy weather, but it may also have something to do with their diet. Ten thousand people were followed for years, and those following a more Mediterranean diet pattern were less likely to be diagnosed with depression. What was it about the diet that was protective? It wasn't the red wine or fish; it was the fruit, nuts, beans, and effectively higher plant to animal fat ratio that appeared protective. Conversely, significant adverse trends were observed for dairy and meat consumption.

A similar protective dietary pattern was found in Japan. A high intake of vegetables, fruits, mushrooms, and soy products was associated with a decreased prevalence of depressive symptoms. The healthy dietary pattern was not characterized by a high intake of seafood. Similar results were found in a study of 100,000 Japanese men and women followed for up to 10 years. There was no evidence of a protective role of higher fish consumption or the long-chain omega 3s EPA and DHA against suicide. In fact, they found a significantly increased risk of suicide among male nondrinkers with high seafood omega 3 intake. This may have been by chance, but a similar result was found in the Mediterranean. High baseline fish consumption with an increase in consumption were associated with an increased risk of mental disorders.

One possible explanation could be the mercury content of fish. Could an accumulation of mercury compounds in the body increase the risk of depression? We know that mercury in fish can cause neurological damage, associated with increased risk of Alzheimer's disease, memory loss, and autism, but also depression. Therefore, "the increased risk of suicide among persons with a high fish intake might also be attributable to the harmful effects of mercury in fish."

Large Harvard University cohort studies found similar results. Hundreds of thousands were followed for up to 20 years, and no evidence was found that taking fish oil or eating fish lowered risk of suicide. There was even a trend towards higher suicide mortality.

What about fish consumption for the treatment of depression? When we put together all the trials done to date, neither the EPA nor DHA long-chain omega-3s appears more effective than sugar pills. We used to think omega-3 supplementation was useful, but several recent studies have tipped the balance the other way. It seems that "[n]early all of the treatment efficacy observed in the published literature may be attributable to publication bias," meaning the trials that showed no benefit tended not to get published at all. So, all doctors saw were a bunch of positive studies, but only because a bunch of the negative ones were buried.

This reminds me of my Is Fish Oil Just Snake Oil? video. Just like we thought omega-3 supplementation could help with mood, we also thought it could help with heart health, but the balance of evidence has decidedly shifted. I still recommend the consumption of pollutant-free sources of preformed long-chain omega 3s for cognitive health and explain my rationale in Should We Take DHA Supplements to Boost Brain Function? and Should Vegans Take DHA to Preserve Brain Function?


For more on the neurotoxic nature of mercury-contaminated seafood, see:

What can we do to help our mood? See:

What about antidepressant drugs? Sometimes they can be absolutely life-saving, but other times they may actually do more harm than good. See my controversial video Do Antidepressant Drugs Really Work?.

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:

Original Link

Fish Consumption and Suicide

Sept 12 Fish Consumption copy.jpeg

Depression is a serious and common mental disorder responsible for the majority of suicides. As I've covered in Antioxidants & Depression, intake of fruits, vegetables, and naturally occurring antioxidants have been found to be protectively associated with depression. Therefore, researchers have considered that "it may be possible to prevent depression or to lessen its negative effects through dietary intervention."

But not so fast. Cross-sectional studies are snapshots in time, so we don't know "whether a poor dietary pattern precedes the development of depression or if depression causes poor dietary intake." Depression and even treatments for depression can affect appetite and dietary intake. Maybe people who feel crappier just eat crappier, instead of the other way around.

What we need is a prospective study (a study performed over time) where we start out with people who are not depressed and follow them for several years. In 2012, we got just such a study, which ran over six years. As you'll see in my video Fish Consumption and Suicide, those with higher carotenoid levels in their bloodstream, which is considered a good indicator of fruit and vegetable intake, had a 28% lower risk of becoming depressed within that time. The researchers conclude that having low blood levels of those healthy phytonutrients may predict the development of new depressive symptoms. What about suicide?

Worldwide, a million people kill themselves every year. Of all European countries, Greece appears to have the lowest rates of suicide. It may be the balmy weather, but it may also have something to do with their diet. Ten thousand people were followed for years, and those following a more Mediterranean diet pattern were less likely to be diagnosed with depression. What was it about the diet that was protective? It wasn't the red wine or fish; it was the fruit, nuts, beans, and effectively higher plant to animal fat ratio that appeared protective. Conversely, significant adverse trends were observed for dairy and meat consumption.

A similar protective dietary pattern was found in Japan. A high intake of vegetables, fruits, mushrooms, and soy products was associated with a decreased prevalence of depressive symptoms. The healthy dietary pattern was not characterized by a high intake of seafood. Similar results were found in a study of 100,000 Japanese men and women followed for up to 10 years. There was no evidence of a protective role of higher fish consumption or the long-chain omega 3s EPA and DHA against suicide. In fact, they found a significantly increased risk of suicide among male nondrinkers with high seafood omega 3 intake. This may have been by chance, but a similar result was found in the Mediterranean. High baseline fish consumption with an increase in consumption were associated with an increased risk of mental disorders.

One possible explanation could be the mercury content of fish. Could an accumulation of mercury compounds in the body increase the risk of depression? We know that mercury in fish can cause neurological damage, associated with increased risk of Alzheimer's disease, memory loss, and autism, but also depression. Therefore, "the increased risk of suicide among persons with a high fish intake might also be attributable to the harmful effects of mercury in fish."

Large Harvard University cohort studies found similar results. Hundreds of thousands were followed for up to 20 years, and no evidence was found that taking fish oil or eating fish lowered risk of suicide. There was even a trend towards higher suicide mortality.

What about fish consumption for the treatment of depression? When we put together all the trials done to date, neither the EPA nor DHA long-chain omega-3s appears more effective than sugar pills. We used to think omega-3 supplementation was useful, but several recent studies have tipped the balance the other way. It seems that "[n]early all of the treatment efficacy observed in the published literature may be attributable to publication bias," meaning the trials that showed no benefit tended not to get published at all. So, all doctors saw were a bunch of positive studies, but only because a bunch of the negative ones were buried.

This reminds me of my Is Fish Oil Just Snake Oil? video. Just like we thought omega-3 supplementation could help with mood, we also thought it could help with heart health, but the balance of evidence has decidedly shifted. I still recommend the consumption of pollutant-free sources of preformed long-chain omega 3s for cognitive health and explain my rationale in Should We Take DHA Supplements to Boost Brain Function? and Should Vegans Take DHA to Preserve Brain Function?


For more on the neurotoxic nature of mercury-contaminated seafood, see:

What can we do to help our mood? See:

What about antidepressant drugs? Sometimes they can be absolutely life-saving, but other times they may actually do more harm than good. See my controversial video Do Antidepressant Drugs Really Work?.

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:

Original Link

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.

Original Link

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.

Original Link

Foods that Affect Testosterone Levels

Foods that Affect Testosterone Levels.jpeg

A number of studies suggest that exposure to industrial pollutants may affect sexual function, for example, loss of libido, sexual dysfunction, and impotence. This may be due to effects on testosterone levels. In a study of men who ate a lot of contaminated fish, an elevation in PCB levels in the blood was associated with a lower concentration of testosterone levels. These pollutants are found predominantly in fish, but also meat and dairy. The lowest levels are found in plants (see Dietary Pollutants May Affect Testosterone Levels).

Testosterone doesn't just play a role in the determination of secondary sex characteristics like facial hair at puberty. It also regulates normal sexual functioning and the overall physical and psychological well-being of adult men. Abnormally low levels of testosterone can lead to decreased physical endurance and memory capacity, loss of libido, drop in sperm count, loss of bone density, obesity, and depression.

Endocrine-disrupting compounds that build up in fish may be able to mimic or block hormone receptors, or alter rates of synthesis or breakdown of sex steroid hormones. In children, these pollutants may actually impair sexual development. Boys who are exposed may grow up with smaller penises (although only by about two-thirds of an inch shorter at most). Researchers have tried exposing cells from aborted fetal human penises to these kinds of dietary pollutants, and gene expression related to genital development is indeed affected at real-life exposure levels. We're not sure if the effects on penis length are due to the pro-estrogenic effects of the toxins, though, or the anti-testosterone effects.

You've heard of save the whales? Well, male reproductive organs may be at risk from environmental hazards as well.

I previously addressed how we discovered the endocrine disruptor phenomenon in Alkylphenol Endocrine Disruptors and Allergies, as well as where they're found (Dietary Sources of Alkylphenol Endocrine Disruptors).

For more on sustaining male virility, see Male Fertility and Diet, The Role of Diet in Declining Sperm Counts, and Dairy Estrogen and Male Fertility.

I've talked about the role a plastics chemical may play in male sexual functioning (BPA Plastic and Male Sexual Dysfunction). But it's not just toxins, it's the total diet (Survival of the Firmest: Erectile Dysfunction and Death), and not only in men (Cholesterol and Female Sexual Dysfunction). My latest on the topic is Best Foods to Improve Sexual Function.

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: Sally Plank / Flickr. Image has been modified.

Original Link

Foods that Affect Testosterone Levels

Foods that Affect Testosterone Levels.jpeg

A number of studies suggest that exposure to industrial pollutants may affect sexual function, for example, loss of libido, sexual dysfunction, and impotence. This may be due to effects on testosterone levels. In a study of men who ate a lot of contaminated fish, an elevation in PCB levels in the blood was associated with a lower concentration of testosterone levels. These pollutants are found predominantly in fish, but also meat and dairy. The lowest levels are found in plants (see Dietary Pollutants May Affect Testosterone Levels).

Testosterone doesn't just play a role in the determination of secondary sex characteristics like facial hair at puberty. It also regulates normal sexual functioning and the overall physical and psychological well-being of adult men. Abnormally low levels of testosterone can lead to decreased physical endurance and memory capacity, loss of libido, drop in sperm count, loss of bone density, obesity, and depression.

Endocrine-disrupting compounds that build up in fish may be able to mimic or block hormone receptors, or alter rates of synthesis or breakdown of sex steroid hormones. In children, these pollutants may actually impair sexual development. Boys who are exposed may grow up with smaller penises (although only by about two-thirds of an inch shorter at most). Researchers have tried exposing cells from aborted fetal human penises to these kinds of dietary pollutants, and gene expression related to genital development is indeed affected at real-life exposure levels. We're not sure if the effects on penis length are due to the pro-estrogenic effects of the toxins, though, or the anti-testosterone effects.

You've heard of save the whales? Well, male reproductive organs may be at risk from environmental hazards as well.

I previously addressed how we discovered the endocrine disruptor phenomenon in Alkylphenol Endocrine Disruptors and Allergies, as well as where they're found (Dietary Sources of Alkylphenol Endocrine Disruptors).

For more on sustaining male virility, see Male Fertility and Diet, The Role of Diet in Declining Sperm Counts, and Dairy Estrogen and Male Fertility.

I've talked about the role a plastics chemical may play in male sexual functioning (BPA Plastic and Male Sexual Dysfunction). But it's not just toxins, it's the total diet (Survival of the Firmest: Erectile Dysfunction and Death), and not only in men (Cholesterol and Female Sexual Dysfunction). My latest on the topic is Best Foods to Improve Sexual Function.

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: Sally Plank / Flickr. Image has been modified.

Original Link

Estrogen in Meat, Dairy, and Eggs

Sept13.jpg

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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Is Insecticidal GMO Corn Safe?

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Recently the prominent science journal Nature editorialized that we are now swimming in information about genetically modified crops, but that much of the information is wrong--on both sides of the debate. "But a lot of this incorrect information is sophisticated, backed by legitimate-sounding research and written with certitude," adding that with GMOs, "a good gauge of a statement's fallacy is the conviction with which it is delivered."

To many in the scientific community, GMO concerns are dismissed as one big conspiracy theory. In fact, one item in a psychological test of belief in conspiracy theories asked people if they thought food companies would have the audacity to be dishonest about genetically modified food. The study concluded that many people were cynical and skeptical with regard to advertising tricks, as well as the tactics of organizations like banks and alcohol, drug, and tobacco companies. That doesn't sound like conspiracy theory to me; that sounds like business as usual.

We must remember there is a long legacy of scientific misconduct. Throw in a multi-billion dollar industry, and one can imagine how hard it is to get to the truth of the matter. There are social, environmental, economic, food security, and biodiversity arguments both pro and con about GMOs, but those are outside my area of expertise. I'm going to stick to food safety. And as a physician, I'm a very limited veterinarian--I only know one species (us!). So, I will skip the lab animal data and ask instead: What human data do we have about GMO safety?

One study "confirmed" that DNA from genetically modified crops can be transferred into humans who eat them, but that's not what the study found, just that plant DNA in general may be found in the human bloodstream, with no stipulations of harm (See Are GMOs Safe? The Case of Bt Corn).

Another study, however, did find a GMO crop protein in people. The "toxin" was detected in 93 percent of blood samples of pregnant women, 80 percent of umbilical cord blood samples, and 69 percent of samples from non-pregnant women. The toxin they're talking about is an insecticidal protein produced by Bt bacteria whose gene was inserted into the corn's DNA to create so-called Bt-corn, which has been incorporated into animal feed. If it's mainly in animal feed, how did it get into the bodies of women? They suggest it may be through exposure to contaminated meat.

Of course, why get GMO's second-hand when you can get them directly? The next great frontier is transgenic farm animals. A genetically modified salmon was first to vie for a spot at the dinner table. And then in 2010, transgenic cows, sheep, goats and pigs were created, genetically modified for increased muscle mass, based on the so-called mighty mouse model. Frankenfurters!

But back to children of the corn and their mothers. When they say it's a toxin, it's a toxin to corn worms, not necessarily to people. In fact I couldn't find any data linking BT toxin to human harm, which is a good thing since it's considered one of the few pesticides considered so non-toxic that it's sprayed on organic fruits and vegetables.

For more on on the public health implications of genetically modified crops, see:

I did a similar "controversial issue" video series on gluten. See:

For those interested in the genetic engineering of livestock, I published a few papers myself on the topic:

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: Jen Wilton / Flickr

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