The Two Most Active Ingredients of the Mediterranean Diet

Which Parts of the Mediterranean Diet Extended Life.jpg

Olives and nuts are plant foods, and as such, are packed with antioxidants, raising the antioxidant level of our bloodstream resulting in lower fat oxidation and free radical DNA damage, but what's happening inside people's arteries?

Researchers measured the amount of atherosclerotic plaque in the neck arteries going to the brain in folks who for years were eating added nuts, added extra virgin olive oil or neither to their daily diets. In the control group, the plaque got worse, which is what happens when one continues to eat an artery-clogging diet, but there were no significant changes in the added extra virgin olive oil group, and the plaque in the added nut group appeared to get better. The nuts appeared to induce a regression of the disease, or at least a significant delay in the progression. The nut group was still suffering strokes, but only half as many, perhaps because the reduction in plaque height within the arteries on extra nuts was indicating a stabilization of the plaque, rendering them less likely to rupture. You can see these results in my video Which Parts of the Mediterranean Diet Extended Life?

Adding nuts to our diet may also improve endothelial function, boosting the ability of our arteries to dilate naturally by about 30 percent. If you look at the baseline adherence to Mediterranean diet principles and control for things like smoking and exercise, there were only two factors significantly associated with reduced heart attack and stroke risk: more vegetables and more nuts. No significant association with the olive oil, wine, fish or cutting back on soda and cookies. Among the individual components, only increased consumption of vegetables and nuts were related to reduced cardiovascular events.

On the one hand, cutting stroke risk in half just by eating a handful of nuts a day is pretty amazing, but those in the added nut group didn't appear to live any longer overall. This is in contrast to other studies that suggested that frequent nut consumption may extend life. For example, the Harvard health professionals studies, involving a whopping three million person-years of follow-up over decades, found nut consumption associated with fewer deaths from cancer, heart disease, respiratory disease and most importantly fewer deaths overall. This was confirmed by all the other big major prospective studies in a recent review.

So what's going on here with the study showing no longevity benefit from nuts? Did they just not wait long enough? Just because people were randomized to the nut group didn't mean they actually ate more nuts, and those randomized to the other groups didn't necessarily stay away.

If you re-analyze the data comparing the death rates of those who actually ate more nuts to those who actually didn't, nut consumption was indeed associated with significantly reduced risk of death. If you do the same kind of post hoc analysis with olive oil, even with the extra virgin, there is no benefit in terms of living longer. This is consistent with how Ancel Keys, the so-called Father of the Mediterranean diet, viewed olive oil. He thought of its benefit more as a way of just replacing animal fats; anything to get people to eat less lard and butter.

What is the best kind of nut? The greatest benefits were attributed to walnuts, particularly for preventing cancer deaths. Those eating more than three servings of walnuts a week appeared to cut their risk of dying from cancer in half.

Now it's just a matter of communicating the research to the public. All the major cancer groups emphasize a more plant-based diet, remarkably consistent with the World Health Organization guidelines for healthy eating. The far-reaching positive effects of a plant-based diet--including walnuts--may be the most critical message for the public.

Here are some of my previous videos on the Mediterranean diet:

Think the effects of adding a few nuts to one's daily diet are too good to believe? Check out my video Four Nuts Once a Month. For more on Walnuts and Artery Function check out the video, and for more on nuts and cancer prevention, see Which Nut Fights Cancer Better?

Nuts May Help Prevent Death and so may beans; see Increased Lifespan from Beans. What about Fruits and Longevity: How Many Minutes per Mouthful?

More on protecting ourselves from "brain attacks" in Preventing Strokes with Diet.

In health,

Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

Image Credit: garlandcannon / Flickr. This image has been modified.

Original Link

The Two Most Active Ingredients of the Mediterranean Diet

Which Parts of the Mediterranean Diet Extended Life.jpg

Olives and nuts are plant foods, and as such, are packed with antioxidants, raising the antioxidant level of our bloodstream resulting in lower fat oxidation and free radical DNA damage, but what's happening inside people's arteries?

Researchers measured the amount of atherosclerotic plaque in the neck arteries going to the brain in folks who for years were eating added nuts, added extra virgin olive oil or neither to their daily diets. In the control group, the plaque got worse, which is what happens when one continues to eat an artery-clogging diet, but there were no significant changes in the added extra virgin olive oil group, and the plaque in the added nut group appeared to get better. The nuts appeared to induce a regression of the disease, or at least a significant delay in the progression. The nut group was still suffering strokes, but only half as many, perhaps because the reduction in plaque height within the arteries on extra nuts was indicating a stabilization of the plaque, rendering them less likely to rupture. You can see these results in my video Which Parts of the Mediterranean Diet Extended Life?

Adding nuts to our diet may also improve endothelial function, boosting the ability of our arteries to dilate naturally by about 30 percent. If you look at the baseline adherence to Mediterranean diet principles and control for things like smoking and exercise, there were only two factors significantly associated with reduced heart attack and stroke risk: more vegetables and more nuts. No significant association with the olive oil, wine, fish or cutting back on soda and cookies. Among the individual components, only increased consumption of vegetables and nuts were related to reduced cardiovascular events.

On the one hand, cutting stroke risk in half just by eating a handful of nuts a day is pretty amazing, but those in the added nut group didn't appear to live any longer overall. This is in contrast to other studies that suggested that frequent nut consumption may extend life. For example, the Harvard health professionals studies, involving a whopping three million person-years of follow-up over decades, found nut consumption associated with fewer deaths from cancer, heart disease, respiratory disease and most importantly fewer deaths overall. This was confirmed by all the other big major prospective studies in a recent review.

So what's going on here with the study showing no longevity benefit from nuts? Did they just not wait long enough? Just because people were randomized to the nut group didn't mean they actually ate more nuts, and those randomized to the other groups didn't necessarily stay away.

If you re-analyze the data comparing the death rates of those who actually ate more nuts to those who actually didn't, nut consumption was indeed associated with significantly reduced risk of death. If you do the same kind of post hoc analysis with olive oil, even with the extra virgin, there is no benefit in terms of living longer. This is consistent with how Ancel Keys, the so-called Father of the Mediterranean diet, viewed olive oil. He thought of its benefit more as a way of just replacing animal fats; anything to get people to eat less lard and butter.

What is the best kind of nut? The greatest benefits were attributed to walnuts, particularly for preventing cancer deaths. Those eating more than three servings of walnuts a week appeared to cut their risk of dying from cancer in half.

Now it's just a matter of communicating the research to the public. All the major cancer groups emphasize a more plant-based diet, remarkably consistent with the World Health Organization guidelines for healthy eating. The far-reaching positive effects of a plant-based diet--including walnuts--may be the most critical message for the public.

Here are some of my previous videos on the Mediterranean diet:

Think the effects of adding a few nuts to one's daily diet are too good to believe? Check out my video Four Nuts Once a Month. For more on Walnuts and Artery Function check out the video, and for more on nuts and cancer prevention, see Which Nut Fights Cancer Better?

Nuts May Help Prevent Death and so may beans; see Increased Lifespan from Beans. What about Fruits and Longevity: How Many Minutes per Mouthful?

More on protecting ourselves from "brain attacks" in Preventing Strokes with Diet.

In health,

Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

Image Credit: garlandcannon / Flickr. This image has been modified.

Original Link

The Mediterranean Diet or a Whole Food Plant-Based Diet?

The Mediterranean Diet or a Whole Food Plant-Based Diet.jpg

Recent studies have shown that higher Mediterranean diet adherence scores are associated with a significant reduction of the risk of death, heart disease, cancer, and brain disease. The problem with population studies like these is that people who eat healthier may also live healthier, and so how do we know it's their diet? I examine this in The Mediterranean Diet or a Whole Food Plant-Based Diet?.

As the American Heart Association position states, "Before advising people to follow a Mediterranean diet, we need more studies to find out whether the diet itself or other lifestyle factors account for the lower deaths from heart disease." How do you do that? There are ways you can control for obvious things like smoking and exercise--which many of the studies did--but ideally you'd do an interventional trial, the gold standard of nutritional science. You change people's diets while trying to keep everything else the same and see what happens.

We got that kind of trial 20 years ago with the famous Lyon Diet Heart Study where about 600 folks who had just had their first heart attack were randomized into two groups. The control group received no dietary advice, apart whatever their doctors were telling them, while the experimental group was told to eat more of a Mediterranean-type diet, supplemented with a canola-oil based spread to give them the plant-based omega-3's they'd normally be getting from weeds and walnuts if they actually lived on a Greek isle in the 1950's.

The Mediterranean diet group did end up taking some of the dietary advice to heart. They ate more bread, more fruit, less deli meat, less meat in general, and less butter and cream; other than that, no significant changes in diet were reported in terms of wine, olive oil, or fish consumption. So, they ate less saturated fat and cholesterol, more plant-based omega 3's, but didn't have huge dietary changes. Even so, at the end of about four years, 44 individuals from the control group had a second heart attack, either fatal or nonfatal, but only 14 suffered another attack in the group that changed their diet. So they went from having a 4% chance of having a heart attack every year down to 1%.

A cynic might say that while there was less death and disease, the Mediterranean diet continued to feed their heart disease, so much so that 14 of them suffered new heart attacks while on the diet. Yes, their disease progressed a lot less than the regular diet group (about four times less), but what if there was a diet that could stop or reverse heart disease?

Dr. Caldwell Esselstyn and colleagues at the Cleveland Clinic recently published a case series of 198 consecutive patients with cardiovascular disease counseled to switch to a diet composed entirely of whole plant foods. Of the 198, 177 stuck to the diet, whereas the other 21 fell off the wagon, setting up kind of a natural experiment. What happened to the 21? This was such a sick group of patients that more than half suffered from either a fatal heart attack or needed angioplasty or a heart transplant. In that same time period of about four years, of the 177 that stuck to the plant-based diet, only one had a major event as a result of worsening disease. As Dean Ornish noted in his response to the latest trial, "a Mediterranean diet is better than what most people are consuming"...but even better may be a diet based on whole plant foods.

Dr. Esselstyn's was not a randomized trial, so it can't be directly compared to the Lyon study, and it included very determined patients. Not everyone is willing to dramatically change their diets, even if it may literally be a matter of life or death. In which case, rather than doing nothing, eating a more Mediterranean-type diet may cut risk for heart attack survivors by about two-thirds. Cutting 99% of risk would be better if Esselstyn's results were replicated in a controlled trial, but even a 70% drop in risk could save tens of thousands of lives every year.

For more on the Mediterranean diet, check out:

For more on Dr. Esselstyn's amazing work:

If the short-chain plant-based omega-3s in flax seeds and walnuts appear so beneficial, what about the long-chain omega-3's found in fish and fish oil? There are pros and cons. See, for example, Mercury vs. Omega-3s for Brain Development, Is Fish Oil Just Snake Oil?, and Omega-3's and the Eskimo Fish Tale.

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: wildpixel / Thinkstock. This image has been modified.

Original Link

The Mediterranean Diet or a Whole Food Plant-Based Diet?

The Mediterranean Diet or a Whole Food Plant-Based Diet.jpg

Recent studies have shown that higher Mediterranean diet adherence scores are associated with a significant reduction of the risk of death, heart disease, cancer, and brain disease. The problem with population studies like these is that people who eat healthier may also live healthier, and so how do we know it's their diet? I examine this in The Mediterranean Diet or a Whole Food Plant-Based Diet?.

As the American Heart Association position states, "Before advising people to follow a Mediterranean diet, we need more studies to find out whether the diet itself or other lifestyle factors account for the lower deaths from heart disease." How do you do that? There are ways you can control for obvious things like smoking and exercise--which many of the studies did--but ideally you'd do an interventional trial, the gold standard of nutritional science. You change people's diets while trying to keep everything else the same and see what happens.

We got that kind of trial 20 years ago with the famous Lyon Diet Heart Study where about 600 folks who had just had their first heart attack were randomized into two groups. The control group received no dietary advice, apart whatever their doctors were telling them, while the experimental group was told to eat more of a Mediterranean-type diet, supplemented with a canola-oil based spread to give them the plant-based omega-3's they'd normally be getting from weeds and walnuts if they actually lived on a Greek isle in the 1950's.

The Mediterranean diet group did end up taking some of the dietary advice to heart. They ate more bread, more fruit, less deli meat, less meat in general, and less butter and cream; other than that, no significant changes in diet were reported in terms of wine, olive oil, or fish consumption. So, they ate less saturated fat and cholesterol, more plant-based omega 3's, but didn't have huge dietary changes. Even so, at the end of about four years, 44 individuals from the control group had a second heart attack, either fatal or nonfatal, but only 14 suffered another attack in the group that changed their diet. So they went from having a 4% chance of having a heart attack every year down to 1%.

A cynic might say that while there was less death and disease, the Mediterranean diet continued to feed their heart disease, so much so that 14 of them suffered new heart attacks while on the diet. Yes, their disease progressed a lot less than the regular diet group (about four times less), but what if there was a diet that could stop or reverse heart disease?

Dr. Caldwell Esselstyn and colleagues at the Cleveland Clinic recently published a case series of 198 consecutive patients with cardiovascular disease counseled to switch to a diet composed entirely of whole plant foods. Of the 198, 177 stuck to the diet, whereas the other 21 fell off the wagon, setting up kind of a natural experiment. What happened to the 21? This was such a sick group of patients that more than half suffered from either a fatal heart attack or needed angioplasty or a heart transplant. In that same time period of about four years, of the 177 that stuck to the plant-based diet, only one had a major event as a result of worsening disease. As Dean Ornish noted in his response to the latest trial, "a Mediterranean diet is better than what most people are consuming"...but even better may be a diet based on whole plant foods.

Dr. Esselstyn's was not a randomized trial, so it can't be directly compared to the Lyon study, and it included very determined patients. Not everyone is willing to dramatically change their diets, even if it may literally be a matter of life or death. In which case, rather than doing nothing, eating a more Mediterranean-type diet may cut risk for heart attack survivors by about two-thirds. Cutting 99% of risk would be better if Esselstyn's results were replicated in a controlled trial, but even a 70% drop in risk could save tens of thousands of lives every year.

For more on the Mediterranean diet, check out:

For more on Dr. Esselstyn's amazing work:

If the short-chain plant-based omega-3s in flax seeds and walnuts appear so beneficial, what about the long-chain omega-3's found in fish and fish oil? There are pros and cons. See, for example, Mercury vs. Omega-3s for Brain Development, Is Fish Oil Just Snake Oil?, and Omega-3's and the Eskimo Fish Tale.

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: wildpixel / Thinkstock. This image has been modified.

Original Link

How a Low-Carb Diet is Metabolically Like Being Obese

NF-Nov22 The Spillover Effect copy.jpg

Free fatty acids (meaning fat circulating in the bloodstream not packaged into triglycerides) result in inflammation, toxic fat breakdown products, and oxidative stress, which can gum up the insulin receptor pathway and lead to insulin resistance in our muscles. Insulin resistance is what causes prediabetes and type 2 diabetes. I explain the process in my video What Causes Insulin Resistance? As the level of fat in the blood rises, the body's ability to clear sugar from the blood drops dramatically.

Where does this fat in our blood that's wreaking all this havoc come from? It comes from the fat that we eat and from the fat that we wear.

The number of fat cells we have stays constant in adulthood. The way researchers figured that out is by measuring the amount of radioactive carbon still trapped in our DNA from all the nuclear bomb tests. After massive weight loss, our fat cells shrink as they offload fat, but the number stays the same. Conversely, when we gain weight, our fat cells stretch as we pack more and more into each individual fat cell. So, when our belly, butt, or thighs get big, we're not adding more fat cells, we're just cramming more fat into each cell. At a certain point, our cells become so bloated that they spill fat back into the bloodstream.

This is called the spillover effect. Not only does an obese person have more fat, but they're constantly spilling that fat into their bloodstream. So that could be the link between obesity and diabetes. Fat is spilling out from our fat cells and gets lodged in our muscle cells, leading to the insulin resistance that promotes the onset of type 2 diabetes. I show this in my video The Spillover Effect Links Obesity to Diabetes.

The fat can also enter our bloodstream through our mouth. If you put people on a low carb diet, fat builds up in their muscle within two hours and insulin sensitivity drops. And the more fat found in the muscle, the lower the ability to clear sugar from the blood. It doesn't take years for this to happen, just hours after fatty foods go into our mouths. A fat-rich diet can increase fat in the blood and this increase is accompanied by a decrease in insulin sensitivity.

Studies clearly demonstrate that fat in the blood directly inhibit glucose transport and usage in our muscles, which is responsible for clearing about 85% of the glucose out of blood. These findings indicate that fat consumption can play an important role in the development of insulin resistance.

Normally we only have 10 to 50 micromoles of free fat floating around in our blood stream at any one time, but those who are obese have between 60 to 80. But, we can reach 80 just eating a high fat diet. So a skinny person eating a low-carb diet can have the same level of fat in their blood that obese people do. Similarly, being obese is like eating some horrible bacon and butter diet all day, because obese persons are constantly spilling fat into their bloodstream, no matter what goes in their mouth.

Are all types of fat the same? Find out the answer in my video Lipotoxicity: How Saturated Fat Raises Blood Sugar.

The fat leaking into our bloodstream may also contain fat-soluble pollutants that accumulated from our diet: Pollutants in Salmon and Our Own Fat.

The spillover effect may also help explain the increased heart disease risk associated with obesity: Low Carb Diets and Coronary Blood Flow.

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: [Eugene Bochkarev] © 123RF.com

Original Link

How a Low-Carb Diet is Metabolically Like Being Obese

NF-Nov22 The Spillover Effect copy.jpg

Free fatty acids (meaning fat circulating in the bloodstream not packaged into triglycerides) result in inflammation, toxic fat breakdown products, and oxidative stress, which can gum up the insulin receptor pathway and lead to insulin resistance in our muscles. Insulin resistance is what causes prediabetes and type 2 diabetes. I explain the process in my video What Causes Insulin Resistance? As the level of fat in the blood rises, the body's ability to clear sugar from the blood drops dramatically.

Where does this fat in our blood that's wreaking all this havoc come from? It comes from the fat that we eat and from the fat that we wear.

The number of fat cells we have stays constant in adulthood. The way researchers figured that out is by measuring the amount of radioactive carbon still trapped in our DNA from all the nuclear bomb tests. After massive weight loss, our fat cells shrink as they offload fat, but the number stays the same. Conversely, when we gain weight, our fat cells stretch as we pack more and more into each individual fat cell. So, when our belly, butt, or thighs get big, we're not adding more fat cells, we're just cramming more fat into each cell. At a certain point, our cells become so bloated that they spill fat back into the bloodstream.

This is called the spillover effect. Not only does an obese person have more fat, but they're constantly spilling that fat into their bloodstream. So that could be the link between obesity and diabetes. Fat is spilling out from our fat cells and gets lodged in our muscle cells, leading to the insulin resistance that promotes the onset of type 2 diabetes. I show this in my video The Spillover Effect Links Obesity to Diabetes.

The fat can also enter our bloodstream through our mouth. If you put people on a low carb diet, fat builds up in their muscle within two hours and insulin sensitivity drops. And the more fat found in the muscle, the lower the ability to clear sugar from the blood. It doesn't take years for this to happen, just hours after fatty foods go into our mouths. A fat-rich diet can increase fat in the blood and this increase is accompanied by a decrease in insulin sensitivity.

Studies clearly demonstrate that fat in the blood directly inhibit glucose transport and usage in our muscles, which is responsible for clearing about 85% of the glucose out of blood. These findings indicate that fat consumption can play an important role in the development of insulin resistance.

Normally we only have 10 to 50 micromoles of free fat floating around in our blood stream at any one time, but those who are obese have between 60 to 80. But, we can reach 80 just eating a high fat diet. So a skinny person eating a low-carb diet can have the same level of fat in their blood that obese people do. Similarly, being obese is like eating some horrible bacon and butter diet all day, because obese persons are constantly spilling fat into their bloodstream, no matter what goes in their mouth.

Are all types of fat the same? Find out the answer in my video Lipotoxicity: How Saturated Fat Raises Blood Sugar.

The fat leaking into our bloodstream may also contain fat-soluble pollutants that accumulated from our diet: Pollutants in Salmon and Our Own Fat.

The spillover effect may also help explain the increased heart disease risk associated with obesity: Low Carb Diets and Coronary Blood Flow.

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: [Eugene Bochkarev] © 123RF.com

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

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

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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

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