The Natural Human Diet

NF-Nov15 The Problem with the Paleo Diet Argument copy.jpg

Our epidemics of dietary disease have prompted a great deal of research into what humans are meant to eat for optimal health. In 1985, an influential article highlighted in my video The Problem With the Paleo Diet Argument was published proposing that our chronic diseases stem from a disconnect between what our bodies ate while evolving during the Stone Age (about 2 million years ago) and what we're stuffing our face with today. The proposal advocated for a return towards a hunter-gatherer type diet of lean meat, fruits, vegetables, and nuts.

It's reasonable to assume our nutritional requirements were established in the prehistoric past. However, the question of which prehistoric past we should emulate remains. Why just the last 2 million? We've been evolving for about 20 million years since our last common great ape ancestor, during which our nutrient requirements and digestive physiology were set down. Therefore our hunter-gatherer days at the tail end probably had little effect. What were we eating for the first 90% of our evolution? What the rest of the great apes ended up eating--95 percent or more plants.

This may explain why we're so susceptible to heart disease. For most of human evolution, cholesterol may have been virtually absent from the diet. No bacon, butter, or trans fats; and massive amounts of fiber, which pulls cholesterol from the body. This could have been a problem since our body needs a certain amount of cholesterol, but our bodies evolve not only to make cholesterol, but also to preserve it and recycle it.

If we think of the human body as a cholesterol-conserving machine, then plop it into the modern world of bacon, eggs, cheese, chicken, pork, and pastry; it's no wonder artery-clogging heart disease is our #1 cause of death. What used to be adaptive for 90% of our evolution--holding on to cholesterol at all costs since we weren't getting much in our diet--is today maladaptive, a liability leading to the clogging of our arteries. Our bodies just can't handle it.

As the editor-in-chief of the American Journal of Cardiology noted 25 years ago, no matter how much fat and cholesterol carnivores eat, they do not develop atherosclerosis. We can feed a dog 500 eggs worth of cholesterol and they just wag their tail; a dog's body is used to eating and getting rid of excess cholesterol. Conversely, within months a fraction of that cholesterol can start clogging the arteries of animals adapted to eating a more plant-based diet.

Even if our bodies were designed by natural selection to eat mostly fruit, greens and seeds for 90% of our evolution, why didn't we better adapt to meat-eating in the last 10%, during the Paleolithic? We've had nearly 2 million years to get used to all that extra saturated fat and cholesterol. If a lifetime of eating like that clogs up nearly everyone's arteries, why didn't the genes of those who got heart attacks die off and get replaced by those that could live to a ripe old age with clean arteries regardless of what they ate? Because most didn't survive into old age.

Most prehistoric peoples didn't live long enough to get heart attacks. When the average life expectancy is 25 years old, then the genes that get passed along are those that can live to reproductive age by any means necessary, and that means not dying of starvation. The more calories in food, the better. Eating lots of bone marrow and brains, human or otherwise, would have a selective advantage (as would discovering a time machine stash of Twinkies for that matter!). If we only have to live long enough to get our kids to puberty to pass along our genes, then we don't have to evolve any protections against the ravages of chronic disease.

To find a population nearly free of chronic disease in old age, we don't have to go back a million years. In the 20th century, networks of missionary hospitals in rural Africa found coronary artery disease virtually absent, and not just heart disease, but high blood pressure, stroke, diabetes, common cancers, and more. In a sense, these populations in rural China and Africa were eating the type of diet we've been eating for 90% of the last 20 million years, a diet almost exclusively of plant foods.

How do we know it was their diet and not something else? In the 25 year update to their original paleo paper, the authors tried to clarify that they did not then and do not now propose that people adopt a particular diet just based on what our ancient ancestors ate. Dietary recommendations must be put to the test. That's why the pioneering research from Pritikin, Ornish, and Esselstyn is so important, showing that plant-based diets can not only stop heart disease but have been proven to reverse it in the majority of patients. Indeed, it's the only diet that ever has.

For more on the absence of Western diseases in plant-based rural populations, see for example:

I've touched on "paleo" diets in the past:

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: Nathan Rupert / Flickr

Original Link

The Natural Human Diet

NF-Nov15 The Problem with the Paleo Diet Argument copy.jpg

Our epidemics of dietary disease have prompted a great deal of research into what humans are meant to eat for optimal health. In 1985, an influential article highlighted in my video The Problem With the Paleo Diet Argument was published proposing that our chronic diseases stem from a disconnect between what our bodies ate while evolving during the Stone Age (about 2 million years ago) and what we're stuffing our face with today. The proposal advocated for a return towards a hunter-gatherer type diet of lean meat, fruits, vegetables, and nuts.

It's reasonable to assume our nutritional requirements were established in the prehistoric past. However, the question of which prehistoric past we should emulate remains. Why just the last 2 million? We've been evolving for about 20 million years since our last common great ape ancestor, during which our nutrient requirements and digestive physiology were set down. Therefore our hunter-gatherer days at the tail end probably had little effect. What were we eating for the first 90% of our evolution? What the rest of the great apes ended up eating--95 percent or more plants.

This may explain why we're so susceptible to heart disease. For most of human evolution, cholesterol may have been virtually absent from the diet. No bacon, butter, or trans fats; and massive amounts of fiber, which pulls cholesterol from the body. This could have been a problem since our body needs a certain amount of cholesterol, but our bodies evolve not only to make cholesterol, but also to preserve it and recycle it.

If we think of the human body as a cholesterol-conserving machine, then plop it into the modern world of bacon, eggs, cheese, chicken, pork, and pastry; it's no wonder artery-clogging heart disease is our #1 cause of death. What used to be adaptive for 90% of our evolution--holding on to cholesterol at all costs since we weren't getting much in our diet--is today maladaptive, a liability leading to the clogging of our arteries. Our bodies just can't handle it.

As the editor-in-chief of the American Journal of Cardiology noted 25 years ago, no matter how much fat and cholesterol carnivores eat, they do not develop atherosclerosis. We can feed a dog 500 eggs worth of cholesterol and they just wag their tail; a dog's body is used to eating and getting rid of excess cholesterol. Conversely, within months a fraction of that cholesterol can start clogging the arteries of animals adapted to eating a more plant-based diet.

Even if our bodies were designed by natural selection to eat mostly fruit, greens and seeds for 90% of our evolution, why didn't we better adapt to meat-eating in the last 10%, during the Paleolithic? We've had nearly 2 million years to get used to all that extra saturated fat and cholesterol. If a lifetime of eating like that clogs up nearly everyone's arteries, why didn't the genes of those who got heart attacks die off and get replaced by those that could live to a ripe old age with clean arteries regardless of what they ate? Because most didn't survive into old age.

Most prehistoric peoples didn't live long enough to get heart attacks. When the average life expectancy is 25 years old, then the genes that get passed along are those that can live to reproductive age by any means necessary, and that means not dying of starvation. The more calories in food, the better. Eating lots of bone marrow and brains, human or otherwise, would have a selective advantage (as would discovering a time machine stash of Twinkies for that matter!). If we only have to live long enough to get our kids to puberty to pass along our genes, then we don't have to evolve any protections against the ravages of chronic disease.

To find a population nearly free of chronic disease in old age, we don't have to go back a million years. In the 20th century, networks of missionary hospitals in rural Africa found coronary artery disease virtually absent, and not just heart disease, but high blood pressure, stroke, diabetes, common cancers, and more. In a sense, these populations in rural China and Africa were eating the type of diet we've been eating for 90% of the last 20 million years, a diet almost exclusively of plant foods.

How do we know it was their diet and not something else? In the 25 year update to their original paleo paper, the authors tried to clarify that they did not then and do not now propose that people adopt a particular diet just based on what our ancient ancestors ate. Dietary recommendations must be put to the test. That's why the pioneering research from Pritikin, Ornish, and Esselstyn is so important, showing that plant-based diets can not only stop heart disease but have been proven to reverse it in the majority of patients. Indeed, it's the only diet that ever has.

For more on the absence of Western diseases in plant-based rural populations, see for example:

I've touched on "paleo" diets in the past:

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: Nathan Rupert / Flickr

Original Link

How to Design Saturated Fat Studies to Hide the Truth

NF-Oct4 Saturated Fat Studies Set up to Fail.jpeg

Where do the international consensus guidelines to dramatically lower saturated fat consumption come from? (I show the list in my video, The Saturated Fat Studies: Buttering Up the Public). They came from literally hundreds of metabolic ward experiments, which means you don't just ask people to change their diets, you essentially lock them in a room--for weeks if necessary--and have total control over their diet. You can then experimentally change the level of saturated fat consumed by subjects however you want to, and see the corresponding change in their cholesterol levels. And the results are so consistent that you can create an equation, the famous Hegsted Equation, where you can predict how much their cholesterol will go up based on how much saturated fat you give them. So if you want your LDL cholesterol to go up 50 points, all you have to do is eat something like 30% of your calories in saturated fat. When you plug the numbers in, the change in cholesterol shoots up as predicted. The experiments match the predictions. You can do it at home with one of those home cholesterol testing kits, eat a stick of butter every day, and watch your cholesterol climb.

These ward experiments were done in 1965; meaning we've known for 50 years that even if you keep calorie intake the same, increases in saturated fat intake are associated with highly significant increases in LDL bad cholesterol. Your good cholesterol goes up a bit too, but that increase is smaller than the increase in bad, which would translate into increased heart disease risk.

So if you feed vegetarians meat even just once a day, their cholesterol jumps nearly 20% within a month. To prevent heart disease, we need a total cholesterol under 150, which these vegetarians were, but then even just eating meat once a day, and their cholesterol shot up 19%. The good news is that within just two weeks of returning to their meat-free diet, their cholesterol dropped back down into the safe range. Note that their HDL good cholesterol hardly moved at all, so their ratio went from low risk of heart attack to high risk in a matter of weeks with just one meat-containing meal a day. And indeed randomized clinical trials show that dietary saturated fat reduction doesn't just appear to reduce cholesterol levels, but also reduces the risk of subsequent cardiovascular events like heart attacks.

So we have randomized clinical trials, controlled interventional experiments--our most robust forms of evidence--no wonder there's a scientific consensus to decrease saturated fat intake! You'll note, though, that the Y-axis in these studies seen in my video The Saturated Fat Studies: Set Up to Fail is not cholesterol, but change in cholesterol. That's because everyone's set-point is different. Two people eating the same diet with the same amount of saturated fat can have very different cholesterol levels. One person can eat ten chicken nuggets a day and have an LDL cholesterol of 90; another person eating ten a day could start out with an LDL of 120. It depends on your genes. But while our genetics may be different, our biology is the same, meaning the rise and drop in cholesterol is the same for everyone. So if both folks cut out the nuggets, the 90 might drop to 85, whereas the 120 would drop to 115. Wherever we start, we can lower our cholesterol by eating less saturated fat, but if I just know your saturated fat intake--how many nuggets you eat, I can't tell you what your starting cholesterol is. All I can say with certainty is that if you eat less, your cholesterol will likely improve.

But because of this extreme "interindividual variation"--this wide variability in baseline cholesterol levels for any given saturated fat intake--if you take a cross-section of the population, you can find no statistical correlation between saturated fat intake and cholesterol levels, because it's not like everyone who eats a certain set amount of saturated fat is going to have over a certain cholesterol. So there are three ways you could study diet and cholesterol levels: controlled feeding experiments, free-living dietary change experiments, or cross-sectional observations of large populations. As we know, there is a clear and strong relationship between change in diet and change in serum cholesterol in the interventional designs, but because of that individual variability, in cross-sectional designs, you can get zero correlation. In fact, if you do the math, that's what you'd expect you'd get. In statistical parlance, one would say that a cross-sectional study doesn't have the power for detecting such a relationship. Thus because of that variability, these kinds of observational studies would seem an inappropriate method to study this particular relationship. So since diet and serum cholesterol have a zero correlation cross-sectionally, an observational study of the relationship between diet and coronary heart disease incidence will suffer from the same difficulties. So again, if you do the math, observational studies would unavoidably show nearly no correlation between saturated fat and heart disease. These prospective studies can be valuable for other diseases, but the appropriate design demonstrating or refuting the role of diet and coronary heart disease is a dietary change experiment.

And those dietary change experiments have been done; they implicate saturated fat, hence the lower saturated guidelines from basically every major medical authority. In fact, if we lower saturated fat enough, we may be able to reverse heart disease, opening up arteries without drugs or surgery. So with this knowledge, how would the meat and dairy industry prove otherwise? They use the observational studies that mathematically would be unable to show any correlation.

All they need now is a friendly researcher, such as Ronald M. Krauss, who has been funded by the National Dairy Council since 1989, also the National Cattleman's Beef Association, as well as the Atkins Foundation. Then they just combine all the observational studies that don't have the power to provide significant evidence, and not surprisingly, as published in their 2010 meta-analysis, no significant evidence was found.

The 2010 meta-analysis was basically just repackaged for 2014, using the same and similar studies. As the Chair of Harvard's nutrition department put it, their conclusions regarding the type of fat being unimportant are seriously misleading and should be disregarded, going as far as suggesting the paper be retracted, even after the authors corrected a half dozen different errors.

It's not as though they falsified or fabricated data--they didn't have to. They knew beforehand the limitations of observational studies, they knew they'd get the "right" result and so they published it, helping to "neutralize the negative impact of milk and meat fat by regulators and medical professionals." And it's working, according to the dairy industry, as perceptions about saturated fat in the scientific community are changing. They even go so far to say this is a welcome message to consumers, who may be tired of hearing what they shouldn't eat. They don't need to convince consumers, just confuse them. Confusion can easily be misused by the food industry to promote their interests.

It's like that infamous tobacco industry memo that read, "Doubt is our product since it's the best means of competing with the body of fact that exist in the mind of the general public." They don't have to convince the public that smoking is healthy to get people to keep consuming their products. They just need to establish a controversy. Conflicting messages in nutrition cause people to become so frustrated and confused they may just throw their hands up in the air and eat whatever is put in front of them, which is exactly what saturated fat suppliers want, but at what cost to the public's health?


If that "Doubt is our product" memo sounded familiar, I also featured it in my Food Industry Funded Research Bias video. More on how industries can design deceptive studies in BOLD Indeed: Beef Lowers Cholesterol? and How the Egg Board Designs Misleading Studies.

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.

Image Credit: Taryn / Flickr

Original Link

The Saturated Fat Studies: Buttering Up the Public

NF-Sept29 The Saturated Fat Studies Buttering Up the Public.jpeg

Time magazine's cover exhorting people to eat butter could be viewed as a desperate attempt to revive dwindling print sales, but they claimed to be reporting on real science--a systematic review and meta-analysis published in a prestigious journal that concluded that current evidence does not clearly support cardiovascular guidelines that encourage cutting down on saturated fat, like the kind found in meat and dairy products like butter.

No wonder it got so much press, since reducing saturated fat intake is a major focus of most dietary recommendations worldwide, aiming to prevent chronic diseases including coronary heart disease. So, to quote the Center for Science in the Public Interest, "What gives? Evidently, shaky science...and a mission by the global dairy industry to boost sales."

They interviewed an academic insider, who noted that some researchers are intent on showing saturated fat does not cause heart disease, which can be seen in my video The Saturated Fat Studies: Buttering Up the Public. In 2008, the global dairy industry held a meeting where they decided that one of their main priorities was to "neutralize the negative impact of milk fat by regulators and medical professionals." And when they want to do something, they get it done. So they set up a major, well-funded campaign to come up with proof that saturated fat does not cause heart disease. They assembled scientists who were sympathetic to the dairy industry, provided them with funding, encouraged them to put out statements on milk fat and heart disease, and arranged to have them speak at scientific meetings. And the scientific publications we've seen emerging since the Mexico meeting have done just what they set out to do.

During this meeting, the dairy industry discussed what is the key barrier to increasing worldwide demand for dairy. There's global warming issues and other milks competing out there, but number one on the list is the "Negative messages and intense pressure to reduce saturated fats by governments and non- governmental organizations." In short, the negative messages are outweighing the positive, so indeed, their number one priority is to neutralize the negative image of milk fat among regulators and health professionals as related to heart disease.

So if we are the dairy industry, how are we going to do it? Imagine we work for Big Butter. We've got quite the challenge ahead of us. If we look at recommendations from around the globe, there is a global scientific consensus to limit saturated fat intake with most authoritative bodies recommending getting saturated fat at least under 10% of calories, with the prestigious U.S. Institute of Medicine and the European Food Safety Authority recommending to push saturated fat consumption down as low as possible.

The latest guidelines from the American Heart Association and the American College of Cardiology recommend reducing trans fat intake, giving it their strongest A-grade level of evidence. And they say the same same for reducing saturated fat intake. Since saturated and trans fats are found in the same place, meat and dairy, cutting down on foods with saturated fat will have the additional benefit of lowering trans fat intake. They recommend pushing saturated fat intake down to 5 or 6%. People don't realize how small that is. One KFC chicken breast could take us over the top. Or, two pats of butter and two cubes of cheese and we're done for the day--no more dairy, meat, or eggs. That'd be about 200 calories, so they are in effect saying 90% of our diet should be free of saturated fat-containing foods. That's like the American Heart Association saying, "two meals a week can be packed with meat, dairy, and junk, but the entire rest of the week should be unprocessed plant-foods." That's how stringent the new recommendations are.

So this poses a problem for Big Cheese and Chicken. The top contributors of cholesterol-raising saturated fat is cheese, ice cream, chicken, non-ice cream desserts like cake and pie, and then pork. So what are these industries to do? See The Saturated Fat Studies: Set Up to Fail.

For those unfamiliar with Trans Fat in Meat and Dairy (and refined vegetable oils), that's why I made a video about it.

The U.S. National Academy of Sciences Institute of Medicine "as low as possible" position, echoed by the European Food Safety Authority, is described in my video: Trans Fat, Saturated Fat, and Cholesterol: Tolerable Upper Intake of Zero.

What happened when a country tried to put the lower saturated fat guidance into practice? See the remarkable results in Dietary Guidelines: From Dairies to Berries.

Don't think the dietary guidelines process could be undermined by underhanded corporate tactics? Sad but true:

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.

Image Credit: Johnathan Nightingale / Flickr

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.

Image Credit: BruceBlaus

Image Credit: [Nakhorn Yuangkratoke] © 123RF.com

Original Link

What to Eat to Protect Against Kidney Cancer

NF-Sept8 Can Diet Protect Against Kidney Cancer_.jpeg

58,000 Americans are diagnosed with kidney cancer every year, and 13,000 die. And the numbers have been going up. Approximately 4 percent of cases are hereditary, but what about the other 96 percent? The only accepted risk factor has been tobacco use, but cigarette smoking has been declining.

Nitrosamines are one of the most potent carcinogens in cigarette smoke. One hot dog has as many nitrosamines and nitrosamides as five cigarettes. And these carcinogens are also found in fresh meat as well: beef, chicken and pork. So even though smoking rates have dropped, perhaps the rise in kidney cancer over the last few decades may have something to do with meat consumption. But would kidney cancer just be related to the processed meats like bacon, sausage, hot dogs and cold cuts that have nitrate and nitrite additives, or fresh meat as well?

The NIH-AARP study featured in my video Can Diet Protect Against Kidney Cancer? is the largest prospective study on diet and health ever performed--about 500,000 followed for nine years. In addition to examining nitrate and nitrite intake from processed meat, they also looked at intake from other sources such as fresh meat, eggs and dairy. Nitrite from animal sources, not just processed meats, was associated with an increased risk of kidney cancer, and total intake of nitrate and nitrite from processed meat sources was also associated with kidney cancer risk. The researchers found no associations with nitrate or nitrite intake from plant sources, but nitrates from processed meat was associated with cancer.

When meat producers advertise their bacon or lunch meat as "uncured," this means no nitrites or nitrates added. But if you look at the small print you'll see something like, "except for celery juice." That's just a sneaky way to add nitrites. Processed meat producers ferment the nitrates in celery to create nitrites, then add it to the meat; a practice even the industry admits "may be viewed as incorrect at best or deceptive at worst."

But that same fermentation of nitrates to nitrites can happen thanks to bacteria on our tongue when we eat vegetables. So why are nitrates and nitrites from vegetables on our tongue harmless, but nitrates and nitrites from vegetables in meat linked to cancer? The actual carcinogens are not nitrites, but nitrosamines and nitrosamides. In our stomach, to turn nitrites into nitros-amines, and nitros-amides we need amines and amides, which are concentrated in animal products. And vitamin C and other antioxidants in plant foods block the formation of these carcinogens in our stomach. That's why we can safely benefit from the nitrates in vegetables without the cancer risk. In fact some of the highest nitrate vegetables like arugula, kale, and collards are associated with decreased risk of kidney cancer. The more plants, it appears, the better.

Plant-based diets and fiber-rich diets are recommended to prevent cancer directly, as well as chronic conditions associated with kidney cancer, such as obesity, high blood pressure and diabetes. It's similar to sodium intake and kidney cancer. Sodium intake increases kidney disease risk, but that's not just because sodium intake increases blood pressure. It appears the salt is associated with increased cancer risk even independently of hypertension. What about plant-based diets? Turns out the protective association remains even in people who are not obese and have normal blood pressure. So overall, plant-based and fiber-rich diets appear to do both: decrease cancer risk directly and indirectly.

I briefly address kidney health in Preventing Kidney Failure Through Diet and Treating Kidney Failure Through Diet, but have a whole series of more in-depth videos dealing with various kidney issues.

More on the fascinating nitrate/nitrite story in my 17-part series about improving athletic performance with nitrate-rich vegetables such as beets and arugula. Here are a few short highlights:

More on carcinogens caused by cooking meat in videos like:

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.

Image Credit: RDSVS / Flickr

Original Link

Paleo Diet May Undermine Benefit of CrossFit Exercise

NF-Sept6 Paleo Diets May Negate Benefits of Exercise.jpeg

Much of the low-carb and paleo reasoning revolves around insulin. To quote a paleo blogger, "carbohydrates increase insulin, the root of all evil when it comes to dieting and health." So the logic follows that because carbs increase insulin, we should stick mostly to meat, which is fat and protein with no carbs, so no increase in insulin, right?

Wrong.

We've known for half a century that if you give someone just a steak: no carbs, no sugar, no starch; their insulin goes up. Carbs make our insulin go up, but so does protein.

In 1997 an insulin index of foods was published, ranking 38 foods to determine which stimulates higher insulin levels. Researchers compared a large apple and all its sugar, a cup of oatmeal packed with carbs, a cup and a half of white flour pasta, a big bun-less burger with no carbs at all, to half of a salmon fillet. As you can see in the graph in my video Paleo Diets May Negate Benefits of Exercise, the meat produced the highest insulin levels.

Researchers only looked at beef and fish, but subsequent data showed that that there's no significant difference between the insulin spike from beef, chicken, or pork--they're all just as high. Thus, protein and fat rich foods may induce substantial insulin secretion. In fact, meat protein causes as much insulin release as pure sugar.

So, based on the insulin logic, if low-carbers and paleo folks really believed insulin to be the root of all evil, then they would be eating big bowls of spaghetti day in and day out before they would ever consume meat.

They are correct in believing that having hyperinsulinemia, high levels of insulin in the blood like type 2 diabetics have, is not a good thing, and may increase cancer risk. But if low-carb and paleo dieters stuck to their own insulin theory, then they would be out telling everyone to start eating plant-based. Vegetarians have significantly lower insulin levels even at the same weight as omnivores. This is true for ovo-lacto-vegetarians, lacto-vegetarians, and vegans. Meat-eaters have up to 50% higher insulin levels.

Researchers from the University of Memphis put a variety of people on a vegan diet (men, women, younger folks, older folks, skinny and fat) and their insulin levels dropped significantly within just three weeks. And then, just by adding egg whites back to their diet, their insulin production rose 60% within four days.

In a study out of MIT, researchers doubled participants' carbohydrate intake, and their insulin levels went down. Why? Because the researchers weren't feeding people jellybeans and sugar cookies, they were feeding people whole, plant foods, lots of whole grains, beans, fruits, and vegetables.

What if we put someone on a very-low carb diet, like an Atkins diet? Low carb advocates such as Dr. Westman assumed that it would lower insulin levels. Dr. Westman is the author of the new Atkins books, after Dr. Atkins died obese with, according to the medical examiner, a history of heart attack, congestive heart failure, and hypertension. But, Dr. Westman was wrong in his assumption. There are no significant drop in insulin levels on very low-carb diets. Instead, there is a significant rise in LDL cholesterol levels, the number one risk factor for our number one killer, heart disease.

Atkins is an easy target though. No matter how many "new" Atkins diets that come out, it's still old news. What about the paleo diet? The paleo movement gets a lot of things right. They tell people to ditch dairy and doughnuts, eat lots of fruits, nuts, and vegetables, and cut out a lot of processed junk food. But a new study published in the International Journal of Exercise Science is pretty concerning. Researchers took young healthy people, put them on a Paleolithic diet along with a CrossFit-based, high-intensity circuit training exercise program.

If you lose enough weight exercising, you can temporarily drop our cholesterol levels no matter what you eat. You can see that with stomach stapling surgery, tuberculosis, chemotherapy, a cocaine habit, etc. Just losing weight by any means can lower cholesterol, which makes the results of the Paleo/Crossfit study all the more troubling. After ten weeks of hardcore workouts and weight loss, the participants' LDL cholesterol still went up. And it was even worse for those who started out the healthiest. Those starting out with excellent LDL's (under 70), had a 20% elevation in LDL cholesterol, and their HDL dropped. Exercise is supposed to boost our good cholesterol, not lower it.

The paleo diet's deleterious impact on blood fats was not only significant, but substantial enough to counteract the improvements commonly seen with improved fitness and body composition. Exercise is supposed to make things better.

On the other hand, if we put people instead on a plant-based diet and a modest exercise program, mostly just walking-based; within three weeks their bad cholesterol can drop 20% and their insulin levels 30%, despite a 75-80% carbohydrate diet, whereas the paleo diets appeared to "negate the positive effects of exercise."

I touched on paleo diets before in Paleolithic Lessons, and I featured a guest blog on the subject: Will The Real Paleo Diet Please Stand Up?

but my favorite paleo videos are probably The Problem With the Paleo Diet Argument and Lose Two Pounds in One Sitting: Taking the Mioscenic Route.

I wrote a book on low carb diets in general (now available free full-text online) and touched on it in Atkins Diet: Trouble Keeping It Up and Low Carb Diets and Coronary Blood Flow.

And if you're thinking, but what about the size of the cholesterol, small and dense versus large and fluffy? Please see my video Does Cholesterol Size Matter?

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.

Image Credit: Vincent Lit / Flickr

Original Link

Chicken Big: The Correlation Between Poultry and Obesity

Aug30.jpg

Vegetarians have considerably lower obesity rates compared to meat-eaters, but why? Is it because they're not eating meat or because they're eating more plants? Or maybe they're just eating fewer calories or exercising more? A study out of the Netherlands controlled for all of that and is profiled in my video, Chicken Big: Poultry and Obesity.

Researchers effectively studied men and women who ate the same number of calories a day, ate the same amount of vegetables, fruits, grains and did the same amount of exercise, but ate different amounts of meat. Men and women who ate less than a small serving of meat a day were on average not overweight, but the more meat they ate, the heavier they were. By one and a half servings a day, they crossed the threshold of a BMI of 25 to become officially classified as overweight.

Which type of meat was the worst? I previously profiled a study of hundreds of thousands of men and women which showed that poultry consumption appeared to be the worst (see Meat and Weight Gain in the PANACEA Study). But maybe it was reverse causation, meaning obesity lead to greater chicken consumption and not the other way around. The new study controlled for that, adjusting for dieting habits, yet found the same thing. Chicken consumption was most associated with weight gain in both men and women, and it didn't take much. Compared to those who didn't eat any chicken at all, those eating about 20 or more grams of chicken a day had a significantly greater increase in their body mass index. That's around one chicken nugget, or a single chicken breast once every two weeks compared to no chicken at all.

Why poultry though? We don't know, but here are some possible contributing factors:

Other surprising discoveries in the field include:

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.

Original Link

How Big Food Twists the Science

Aug18.jpg

Just like mosquitos are the vectors of spread for malaria, a landmark article published last year in one of the most prestigious medical journals, Lancet, described large food corporations as the vectors of spread for chronic disease. Unlike "infectious disease epidemics, however, these corporate disease vectors implement sophisticated campaigns to undermine public health interventions." Most mosquitoes don't have as good PR firms.

A key message was that "alcohol and ultra-processed food and drink industries use similar strategies as the tobacco industry to undermine effective public health policies and programs." What they mean by ultra-processed is things like burgers, frozen meals, chicken nuggets, fish sticks, potato chips, doughnuts and soda pop.

But how is the food industry like the tobacco industry? The "first strategy is to bias research findings." For example, Philip Morris implemented the Whitecoat project to hire doctors to publish ghost-written studies purporting to negate links between secondhand smoke and harm, publishing biased cherry-picked scientific reports to deny harm and suppress health information. In my video Food Industry-Funded Research Bias, you can see the actual industry memo describing the Whitecoat Project, designed to reverse the scientific "misconception" that secondhand smoke is harmful.

Similarly, funding from these large food corporations biases research. Studies show systematic bias from industry funding, so we get the same kind of tactics--supplying misinformation, use of supposedly conflicting evidence and hiding negative data.

The same scientists-for-hire that downplayed the risks of secondhand smoke are the same hired by the likes of the National Confectioner's Association to say candy cigarettes are A-OK as well. Of course, they declared "no conflict of interest."

The similarities between strategies used by the tobacco, alcohol, and food and drink corporations are unsurprising in view of the flow of people, funds and activities across these industries, which also have histories of joint ownership--like Philip Morris owned both Kraft and Miller Brewing.

So what's their strategy? As a former FDA commissioner described:

"The tobacco industry's strategy was embodied in a script written by the lawyers. Every tobacco company executive in the public eye was told to learn the script backwards and forwards, no deviation was allowed. The basic premise was simple-- smoking had not been proven to cause cancer. Not proven, not proven, not proven--this would be stated insistently and repeatedly. Inject a thin wedge of doubt, create controversy, never deviate from the prepared line. It was a simple plan and it worked."

Internal industry memos make this explicit, stating "doubt is our product, since it is the best means of competing with the body of fact that exists in the mind of the general public." The internal industry memos list objective number one as "to set aside in the minds of millions the false conviction that cigarette smoking causes lung cancer and other diseases; a conviction based on fanatical assumptions, fallacious rumors, unsupported claims and the unscientific statements and conjectures of publicity-seeking opportunists... [We need] to lift the cigarette from the cancer identification as quickly as possible, and to establish--once and for all--that no scientific evidence has ever been produced, presented or submitted to prove conclusively that cigarette smoking causes cancer," similar to what's now coming out from the food industry, from the same folks that brought us smoke and candy.

This is part of a series of "political" blogs which includes my video, Collaboration with the New Vectors of Disease. Why don't I just "stick to the science"? When there are billions of dollars at stake, the body of evidence can be skewed and manipulated. Funders can determine which studies are performed, how they're performed and whether or not they get published at all. That's why I think it's important to take a broader view to account for the ways the scientific method can be perverted for profit.

Here are some examples:

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.

Original Link

GMO Soy and Breast Cancer

July12.jpg

In response to concerns raised about the toxicity of Monsanto's roundup pesticide, which ends up in GMO foods (See Is Monsanto's Roundup Pesticide Glyphosate Safe?), Monsanto's scientists countered that these in vitro experiments used physiological irrelevant concentrations, meaning dripping roundup on cells in a petri dish at levels far above what would be realistically found in the human body.

Sure, it's probably not a good idea to mix up your alcohol with your roundup and chug the stuff, or try to commit suicide by drinking or injecting it. And there are rare cases of Parkinson's reported after getting directly sprayed with it, or working for years in a pesticide production plant, but that's not your typical consumer exposure.

As shown in my video GMO Soy and Breast Cancer, some of the researchers responded to the accusation claiming they used the kinds of concentrations that are used out in the fields. Therefore every little droplet we spray worldwide is above the threshold concentration they found to cause adverse effects. Monsanto's folks responded saying, "Yes, that's the concentration we spray, but that's not the concentration that human cells are bathing in. Once it gets into drinking water or food, it's highly diluted." And, they're quick to point out, if we look at people with the greatest exposure--pesticide workers--the vast majority of studies show no link between the use of Roundup and cancer or non-cancer diseases. There are a few suggestive findings suggesting a link with non-Hodgkin's lymphoma. One study of pesticide applicators suggested an association with multiple myeloma, and one study of the children of pesticide applicators found a tentative association with ADHD, but again these are folks experiencing a much greater exposure level than the general population that may just get a few parts per million in their food. But there had never been any studies done on the tiny levels found circulating in people's bodies, until now.

In a study out of Thailand, the maximum residue levels were set at parts per million (the concentrations found within human bodies is measured in parts per billion). The study found glyphosate can activate estrogen receptors at a few parts per trillion, increasing the growth of estrogen receptor positive human breast cancer cells in a petri dish. These results indicate "that truly relevant concentrations of the pesticide found on GMO soybeans possesses estrogenic activity."

But consumption of soy is associated with lower breast cancer risk (See BRCA Breast Cancer Genes and Soy), and improved breast cancer survival (See Breast Cancer Survival and Soy).

That may be because most GMO soy in the U.S. is fed to chickens, pigs, and cows as livestock feed, whereas most of the major soy food manufacturers use non-GMO soy. Or it could be because the benefits of eating any kind of soy may far outweigh the risks, but why accept any risk at all when we can choose organic soy products, which by law exclude GMOs.

The bottom-line is that there is no direct human data suggesting harm from eating GMOs, though in fairness such studies haven't been done, which is exactly the point that critics counter. This is why we need mandatory labeling on GMO products so that public health researchers can track whether GMOs are having any adverse effects.

It is important to put the GMO issue in perspective though. As I've shown (See Lifestyle Medicine: Treating the Causes of Disease), there are dietary and lifestyle changes we can make that could eliminate most heart disease, strokes, diabetes, and cancer. Millions of lives could be saved. A healthy enough diet can even reverse our number one killer, heart disease. So, I'm sympathetic to the biotech industry's exasperation about GMO concerns when we still have people dropping dead from everything else they're eating. As one review concluded "consumption of genetically modified food entails risk of undesirable effects... similar to the consumption of traditional food." In other words, buying the non-GMO Twinkie isn't doing our body much of a favor.

For more on the public health implications of genetically engineered crops in our food supply, check out the these videos:

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: Nesbitt_Photo / Flickr

Original Link