What Do All the Blue Zones Have in Common?

Do Flexitarians Live Longer.jpg

What accounts for the benefits of a Mediterranean-style diet? An anatomy of health effects was published, and the single most important component was the high consumption of plant foods. In contrast, fish and seafood consumption, the only animal foods promoted in the Mediterranean diet, did not seem to help.

If you look at four of the major dietary quality scoring systems, which have all been associated with extending lifespan and lowering heart disease and cancer mortality, they all share only four things in common: more fruit, more vegetables, more whole grains and more nuts and beans. They are all built on a common core of a diet rich in plant foods, whereas opposite food patterns, rich in animal foods and poor in plant-based foods (in other words, the Western diet), is associated with higher risks. So we need to optimize the food environment to support whole grains, vegetables, fruit and plant-based proteins.

That's one of the things all the so-called Blue Zones have in common: the longest living populations have not only social support and engagement and daily exercise, but nutritionally they all center their diets around plant foods, reserving meat mostly for special occasions. In fact, the population with perhaps the highest life-expectancy in the world, the California Adventist vegetarians, doesn't eat any meat at all.

So if the primary benefits of the Mediterranean diet are due to all the whole plant foods, what if you went back to the famous PREDIMED study and created a "provegetarian" scoring system? We know vegetarians live longer, but because a pure vegetarian diet might not easily be embraced by many individuals, maybe it would be easier to swallow if we just tell people more plant-based foods and less animal-based foods. But would just moving along the spectrum towards more plants actually enable people to live longer? Researchers thought of this food pattern as a "gentle approach" to vegetarianism, figuring that if it improved survival it would be an easily understandable message for health promotion: more plant foods, less animal foods.

On this scoring system, you get points for eating fruit, vegetables, nuts, grains, beans, olive oil and potatoes, but get docked points for any animal fats, eggs, fish, dairy or any type of meat or meat products. Of course that means you get a higher score the more potato chips and French fries you eat. That's why I prefer the term "whole-food, plant-based diet" since it's defined by what you eat, not by what you don't eat. When I taught at Cornell I had "vegan" students who apparently were trying to live off French fries and beer; vegan does not necessarily mean health-promoting.

But did the provegetarian scoring system work? Regardless of healthy versus unhealthy, if you give points to people for any kind of plant food, processed or not, and detract points for any kind of animal product consumption, people with higher scores live longer. The maximum provegetarian score is 60, but even just scoring 40 or more was associated with a 40 percent drop in mortality. In fact, there were so few deaths in the highest category of adherence to the provegetarian diet, they had to merge the two upper categories for their analysis. This is evidence that simple advice to increase the consumption of plant-derived foods with reductions in the consumption of foods from animal sources confers a survival advantage. You can view the graph in my video Do Flexitarians Live Longer?

The researchers conclude, "this modest change is realistic, affordable, and achievable because a sizable proportion of their population was already eating that way. So one can get significant survival benefit without a radical shift to the exclusive consumption of plant foods, a more gradual and gentle approach which is more easily translatable into public policy." A 41 percent drop in mortality rates in the United States would mean saving the lives of hundreds of thousands of Americans every year.

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

I've done a few videos on the health of so-called semi-vegetarians or flexitarians ("flexible" vegetarians). See how they rate in:

The Provegetarian Score reminds me of the animal to vegetable protein ratio in Prostate Cancer Survival: The A/V Ratio. My favorite dietary quality index is the one in Calculate Your Healthy Eating Score. How do you rate? Even the healthiest among us may be able to continue to push the envelope.

In health,

Michael Greger, M.D.

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

Image Credit: Sally Plank / Flickr. This image has been modified.

Original Link

What Do All the Blue Zones Have in Common?

Do Flexitarians Live Longer.jpg

What accounts for the benefits of a Mediterranean-style diet? An anatomy of health effects was published, and the single most important component was the high consumption of plant foods. In contrast, fish and seafood consumption, the only animal foods promoted in the Mediterranean diet, did not seem to help.

If you look at four of the major dietary quality scoring systems, which have all been associated with extending lifespan and lowering heart disease and cancer mortality, they all share only four things in common: more fruit, more vegetables, more whole grains and more nuts and beans. They are all built on a common core of a diet rich in plant foods, whereas opposite food patterns, rich in animal foods and poor in plant-based foods (in other words, the Western diet), is associated with higher risks. So we need to optimize the food environment to support whole grains, vegetables, fruit and plant-based proteins.

That's one of the things all the so-called Blue Zones have in common: the longest living populations have not only social support and engagement and daily exercise, but nutritionally they all center their diets around plant foods, reserving meat mostly for special occasions. In fact, the population with perhaps the highest life-expectancy in the world, the California Adventist vegetarians, doesn't eat any meat at all.

So if the primary benefits of the Mediterranean diet are due to all the whole plant foods, what if you went back to the famous PREDIMED study and created a "provegetarian" scoring system? We know vegetarians live longer, but because a pure vegetarian diet might not easily be embraced by many individuals, maybe it would be easier to swallow if we just tell people more plant-based foods and less animal-based foods. But would just moving along the spectrum towards more plants actually enable people to live longer? Researchers thought of this food pattern as a "gentle approach" to vegetarianism, figuring that if it improved survival it would be an easily understandable message for health promotion: more plant foods, less animal foods.

On this scoring system, you get points for eating fruit, vegetables, nuts, grains, beans, olive oil and potatoes, but get docked points for any animal fats, eggs, fish, dairy or any type of meat or meat products. Of course that means you get a higher score the more potato chips and French fries you eat. That's why I prefer the term "whole-food, plant-based diet" since it's defined by what you eat, not by what you don't eat. When I taught at Cornell I had "vegan" students who apparently were trying to live off French fries and beer; vegan does not necessarily mean health-promoting.

But did the provegetarian scoring system work? Regardless of healthy versus unhealthy, if you give points to people for any kind of plant food, processed or not, and detract points for any kind of animal product consumption, people with higher scores live longer. The maximum provegetarian score is 60, but even just scoring 40 or more was associated with a 40 percent drop in mortality. In fact, there were so few deaths in the highest category of adherence to the provegetarian diet, they had to merge the two upper categories for their analysis. This is evidence that simple advice to increase the consumption of plant-derived foods with reductions in the consumption of foods from animal sources confers a survival advantage. You can view the graph in my video Do Flexitarians Live Longer?

The researchers conclude, "this modest change is realistic, affordable, and achievable because a sizable proportion of their population was already eating that way. So one can get significant survival benefit without a radical shift to the exclusive consumption of plant foods, a more gradual and gentle approach which is more easily translatable into public policy." A 41 percent drop in mortality rates in the United States would mean saving the lives of hundreds of thousands of Americans every year.

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

I've done a few videos on the health of so-called semi-vegetarians or flexitarians ("flexible" vegetarians). See how they rate in:

The Provegetarian Score reminds me of the animal to vegetable protein ratio in Prostate Cancer Survival: The A/V Ratio. My favorite dietary quality index is the one in Calculate Your Healthy Eating Score. How do you rate? Even the healthiest among us may be able to continue to push the envelope.

In health,

Michael Greger, M.D.

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

Image Credit: Sally Plank / Flickr. 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 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

Improving Employee Diets Could Save Companies Millions

Plant-Based Workplace Intervention.jpg

The food, alcohol, and tobacco industries have been blamed for "manufacturing epidemics" of chronic disease, but they're just trying to sell more product like everyone else. And so if that means distorting science, creating front groups, compromising scientists, blocking public health policies... they're just trying to protect their business.

It's not about customer satisfaction, but shareholder satisfaction. How else could we have tobacco companies, for example, "continuing to produce products that kill one in two of their most loyal customers?"

Civil society organizations concerned with public health have earned a reputation for being "anti-industry," but the issue is not industry, but that sector of industry whose products are harmful to public health. We like the broccoli industry. In fact, the corporate world might end up leading the lifestyle medicine revolution.

As shown in my video, Plant-Based Workplace Intervention, the annual cost attributable to obesity alone among full-time employees is estimated at 70 billion dollars, primarily because obese employees are not as productive on the job. Having healthy employees is good for the bottom-line. Every dollar spent on wellness programs may offer a $3 return on investment. And if you track the market performance of companies that strive to nurture a culture of health, they appear to outperform their competition.

That's why companies like GEICO are exploring workplace dietary interventions (see my video, Slimming the Gecko). The remarkable success at GEICO headquarters led to an expansion of the program at corporate offices across the country, with test sites from San Diego to Macon, Georgia. Given that previous workplace studies have found that workers who ate a lot of animal protein had nearly five times the odds of obesity, whereas those that ate mostly plant protein appeared protected, obese and diabetic employees were asked to follow a plant-based diet of whole grains, vegetables, beans, and fruit while avoiding meat, dairy, and eggs. Compliance wasn't great. Fewer than half really got their animal product consumption down, but there were definitely improvements such as significant reductions in saturated fat, an increase in protective nutrients, and even noted weight loss, lower blood cholesterol levers, and better blood sugar control in diabetics.

And this was with no calorie counting, no portion control, and no exercise component. The weight reduction appears to result from feeling fuller earlier, due to higher dietary fiber intake. The difference in weight loss could also be the result of an increase in the thermic effect of food, allowing a small extra edge for weight loss in the vegan group. Those eating plant-based diets tend to burn off more calories in heat.

Eating plants appears to boost metabolism. This may be due to increased insulin sensitivity in cells, allowing cells to metabolize carbohydrates more quickly rather than storing them as body fat. "As a result, vegan diets have been shown to increase postprandial calorie burn by about 16%, up to three hours after consuming a meal."

Imagine how much money companies that self-insure their employees could save! See, for example:

Find out more on some of the potential downsides of corporate influence 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:

Image Credit: Ryan McGuire / Pixabay. This image has been modified.

Original Link

Improving Employee Diets Could Save Companies Millions

Plant-Based Workplace Intervention.jpg

The food, alcohol, and tobacco industries have been blamed for "manufacturing epidemics" of chronic disease, but they're just trying to sell more product like everyone else. And so if that means distorting science, creating front groups, compromising scientists, blocking public health policies... they're just trying to protect their business.

It's not about customer satisfaction, but shareholder satisfaction. How else could we have tobacco companies, for example, "continuing to produce products that kill one in two of their most loyal customers?"

Civil society organizations concerned with public health have earned a reputation for being "anti-industry," but the issue is not industry, but that sector of industry whose products are harmful to public health. We like the broccoli industry. In fact, the corporate world might end up leading the lifestyle medicine revolution.

As shown in my video, Plant-Based Workplace Intervention, the annual cost attributable to obesity alone among full-time employees is estimated at 70 billion dollars, primarily because obese employees are not as productive on the job. Having healthy employees is good for the bottom-line. Every dollar spent on wellness programs may offer a $3 return on investment. And if you track the market performance of companies that strive to nurture a culture of health, they appear to outperform their competition.

That's why companies like GEICO are exploring workplace dietary interventions (see my video, Slimming the Gecko). The remarkable success at GEICO headquarters led to an expansion of the program at corporate offices across the country, with test sites from San Diego to Macon, Georgia. Given that previous workplace studies have found that workers who ate a lot of animal protein had nearly five times the odds of obesity, whereas those that ate mostly plant protein appeared protected, obese and diabetic employees were asked to follow a plant-based diet of whole grains, vegetables, beans, and fruit while avoiding meat, dairy, and eggs. Compliance wasn't great. Fewer than half really got their animal product consumption down, but there were definitely improvements such as significant reductions in saturated fat, an increase in protective nutrients, and even noted weight loss, lower blood cholesterol levers, and better blood sugar control in diabetics.

And this was with no calorie counting, no portion control, and no exercise component. The weight reduction appears to result from feeling fuller earlier, due to higher dietary fiber intake. The difference in weight loss could also be the result of an increase in the thermic effect of food, allowing a small extra edge for weight loss in the vegan group. Those eating plant-based diets tend to burn off more calories in heat.

Eating plants appears to boost metabolism. This may be due to increased insulin sensitivity in cells, allowing cells to metabolize carbohydrates more quickly rather than storing them as body fat. "As a result, vegan diets have been shown to increase postprandial calorie burn by about 16%, up to three hours after consuming a meal."

Imagine how much money companies that self-insure their employees could save! See, for example:

Find out more on some of the potential downsides of corporate influence 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:

Image Credit: Ryan McGuire / Pixabay. This image has been modified.

Original Link

Lipotoxicity: How Saturated Fat Raises Blood Sugar

NF-Nov24 Lipotoxicity How Saturated Fat Raises Blood Sugar copy.jpg

The reason those eating plant-based diets have less fat buildup in their muscle cells and less insulin resistance may be because saturated fats appear to impair blood sugar control the most.

The association between fat and insulin resistance is now widely accepted. Insulin resistance is due to so-called ectopic fat accumulation, the buildup of fat in places it's not supposed to be, like within our muscle cells. But not all fats affect the muscles the same. The type of fat, saturated vs. unsaturated, is critical. Saturated fats like palmitate, found mostly in meat, dairy and eggs, cause insulin resistance, but oleate, found mostly in nuts, olives and avocados may actually improve insulin sensitivity.

What makes saturated fat bad? Saturated fat causes more toxic breakdown products and mitochondrial dysfunction, and increases oxidative stress, free radicals and inflammation, establishing a vicious cycle of events in which saturated fat induces free radicals, causes dysfunction in the little power plants within our muscle cells (mitochondria), which then causes an increase in free radical production and an impairment of insulin signaling. I explain this in my video Lipotoxicity: How Saturated Fat Raises Blood Sugar.

Fat cells filled with saturated fat activate an inflammatory response to a far greater extent. This increased inflammation from saturated fat has been demonstrated to raise insulin resistance through free radical production. Saturated fat also has been shown to have a direct effect on skeletal muscle insulin resistance. Accumulation of saturated fat increases the amount of diacyl-glycerol in the muscles, which has been demonstrated to have a potent effect on muscle insulin resistance. You can take muscle biopsies from people and correlate the saturated fat buildup in their muscles with insulin resistance.

While monounsaturated fats are more likely to be detoxified or safely stored away, saturated fats create those toxic breakdown products like ceramide that causes lipotoxicity. Lipo- meaning fat, as in liposuction. This fat toxicity in our muscles is a well-known concept in the explanation of trigger for insulin resistance.

I've talked about the role saturated and trans fats contribute to the progression of other diseases, like autoimmune diseases, cancer and heart disease, but they can also cause insulin resistance, the underlying cause of prediabetes and type 2 diabetes. In the human diet, saturated fats are derived from animal sources while trans fats originate in meat and milk in addition to partially hydrogenated and refined vegetable oils.

That's why experimentally shifting people from animal fats to plant fats can improve insulin sensitivity. In a study done by Swedish researchers, insulin sensitivity was impaired on the diet with added butterfat, but not on the diet with added olive fat.

We know prolonged exposure of our muscles to high levels of fat leads to severe insulin resistance, with saturated fats demonstrated to be the worst, but they don't just lead to inhibition of insulin signaling, the activation of inflammatory pathways and the increase in free radicals, they also cause an alteration in gene expression. This can lead to a suppression of key mitochondrial enzymes like carnitine palmitoyltransferase, which finally solves the mystery of why those eating vegetarian have a 60 percent higher expression of that fat burning enzyme. They're eating less saturated fat.

So do those eating plant-based diets have less fat clogging their muscles and less insulin resistance too? There hasn't been any data available regarding the insulin sensitivity or inside muscle cell fat of those eating vegan or vegetarian... until now. Researchers at the Imperial College of London compared the insulin resistance and muscle fat of vegans versus omnivores. Those eating plant-based diets have the unfair advantage of being much slimmer, so they found omnivores who were as skinny as vegans to see if plant-based diets had a direct benefit, as opposed to indirectly pulling fat out of the muscles by helping people lose weight in general.

They found significantly less fat trapped in the muscle cells of vegans compared to omnivores at the same body weight, better insulin sensitivity, better blood sugar levels, better insulin levels and, excitingly, significantly improved beta-cell function (the cells in the pancreas that make the insulin). They conclude that eating plant-based is not only expected to be cardioprotective, helping prevent our #1 killer, heart disease, but that plant-based diets are beta-cell protective as well, helping also to prevent our seventh leading cause of death, diabetes.

This is the third of a three-part series, starting with What Causes Insulin Resistance? and The Spillover Effect Links Obesity to Diabetes.

Even if saturated fat weren't associated with heart disease, its effects on pancreatic function and insulin resistance in the muscles would be enough to warrant avoiding it. Despite popular press accounts, saturated fat intake remains the primary modifiable determinant of LDL cholesterol, the #1 risk factor for our #1 killer-heart disease. See The Saturated Fat Studies: Buttering Up the Public and The Saturated Fat Studies: Set Up to Fail.

How low should we shoot for in terms of saturated fat intake? As low as possible, according to the U.S. National Academies of Science Institute of Medicine: Trans Fat, Saturated Fat, and Cholesterol: Tolerable Upper Intake of Zero.

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: Andrew Malone / Flickr

Original Link

Lipotoxicity: How Saturated Fat Raises Blood Sugar

NF-Nov24 Lipotoxicity How Saturated Fat Raises Blood Sugar copy.jpg

The reason those eating plant-based diets have less fat buildup in their muscle cells and less insulin resistance may be because saturated fats appear to impair blood sugar control the most.

The association between fat and insulin resistance is now widely accepted. Insulin resistance is due to so-called ectopic fat accumulation, the buildup of fat in places it's not supposed to be, like within our muscle cells. But not all fats affect the muscles the same. The type of fat, saturated vs. unsaturated, is critical. Saturated fats like palmitate, found mostly in meat, dairy and eggs, cause insulin resistance, but oleate, found mostly in nuts, olives and avocados may actually improve insulin sensitivity.

What makes saturated fat bad? Saturated fat causes more toxic breakdown products and mitochondrial dysfunction, and increases oxidative stress, free radicals and inflammation, establishing a vicious cycle of events in which saturated fat induces free radicals, causes dysfunction in the little power plants within our muscle cells (mitochondria), which then causes an increase in free radical production and an impairment of insulin signaling. I explain this in my video Lipotoxicity: How Saturated Fat Raises Blood Sugar.

Fat cells filled with saturated fat activate an inflammatory response to a far greater extent. This increased inflammation from saturated fat has been demonstrated to raise insulin resistance through free radical production. Saturated fat also has been shown to have a direct effect on skeletal muscle insulin resistance. Accumulation of saturated fat increases the amount of diacyl-glycerol in the muscles, which has been demonstrated to have a potent effect on muscle insulin resistance. You can take muscle biopsies from people and correlate the saturated fat buildup in their muscles with insulin resistance.

While monounsaturated fats are more likely to be detoxified or safely stored away, saturated fats create those toxic breakdown products like ceramide that causes lipotoxicity. Lipo- meaning fat, as in liposuction. This fat toxicity in our muscles is a well-known concept in the explanation of trigger for insulin resistance.

I've talked about the role saturated and trans fats contribute to the progression of other diseases, like autoimmune diseases, cancer and heart disease, but they can also cause insulin resistance, the underlying cause of prediabetes and type 2 diabetes. In the human diet, saturated fats are derived from animal sources while trans fats originate in meat and milk in addition to partially hydrogenated and refined vegetable oils.

That's why experimentally shifting people from animal fats to plant fats can improve insulin sensitivity. In a study done by Swedish researchers, insulin sensitivity was impaired on the diet with added butterfat, but not on the diet with added olive fat.

We know prolonged exposure of our muscles to high levels of fat leads to severe insulin resistance, with saturated fats demonstrated to be the worst, but they don't just lead to inhibition of insulin signaling, the activation of inflammatory pathways and the increase in free radicals, they also cause an alteration in gene expression. This can lead to a suppression of key mitochondrial enzymes like carnitine palmitoyltransferase, which finally solves the mystery of why those eating vegetarian have a 60 percent higher expression of that fat burning enzyme. They're eating less saturated fat.

So do those eating plant-based diets have less fat clogging their muscles and less insulin resistance too? There hasn't been any data available regarding the insulin sensitivity or inside muscle cell fat of those eating vegan or vegetarian... until now. Researchers at the Imperial College of London compared the insulin resistance and muscle fat of vegans versus omnivores. Those eating plant-based diets have the unfair advantage of being much slimmer, so they found omnivores who were as skinny as vegans to see if plant-based diets had a direct benefit, as opposed to indirectly pulling fat out of the muscles by helping people lose weight in general.

They found significantly less fat trapped in the muscle cells of vegans compared to omnivores at the same body weight, better insulin sensitivity, better blood sugar levels, better insulin levels and, excitingly, significantly improved beta-cell function (the cells in the pancreas that make the insulin). They conclude that eating plant-based is not only expected to be cardioprotective, helping prevent our #1 killer, heart disease, but that plant-based diets are beta-cell protective as well, helping also to prevent our seventh leading cause of death, diabetes.

This is the third of a three-part series, starting with What Causes Insulin Resistance? and The Spillover Effect Links Obesity to Diabetes.

Even if saturated fat weren't associated with heart disease, its effects on pancreatic function and insulin resistance in the muscles would be enough to warrant avoiding it. Despite popular press accounts, saturated fat intake remains the primary modifiable determinant of LDL cholesterol, the #1 risk factor for our #1 killer-heart disease. See The Saturated Fat Studies: Buttering Up the Public and The Saturated Fat Studies: Set Up to Fail.

How low should we shoot for in terms of saturated fat intake? As low as possible, according to the U.S. National Academies of Science Institute of Medicine: Trans Fat, Saturated Fat, and Cholesterol: Tolerable Upper Intake of Zero.

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: Andrew Malone / 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

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