Choosing to Have a Normal Blood Pressure

Oct 5 Blood Pressure copy.jpeg

For the first 90% of our evolution, humans ate diets containing less than a quarter teaspoon of salt a day. Why? Because we ate mostly plants. Since we went millions of years without salt shakers, our bodies evolved into salt-conserving machines, which served us well until we discovered salt could be used to preserve foods. Without refrigeration, this was a big boon to human civilization. Of course, this may have led to a general rise in blood pressure, but does that matter if the alternative is starving to death since all your food rotted away? But where does that leave us now, when we no longer have to live off pickles and jerky? We are genetically programmed to eat ten times less salt than we do now. Even many "low"-salt diets can be considered high-salt diets. That's why it's critical to understand what the concept of "normal" is when it comes to salt.

As I discuss in my video High Blood Pressure May Be a Choice, having a "normal" salt intake can lead to a "normal" blood pressure, which can help us to die from all the "normal" causes, like heart attacks and strokes.

Doctors used to be taught that a "normal" systolic blood pressure (the top number) is approximately 100 plus age. Babies start out with a blood pressure around 95 over 60, but then as we age that 95 can go to 120 by our 20s, then 140 in our 40s, and keep climbing as we age. (140 is the official cut-off above which one technically has high blood pressure.) That was considered normal, since everyone's blood pressure creeps up as we get older. And if that's normal, then heart attacks and strokes are normal too, since risk starts rising once we start getting above the 100 we had as a baby.

If blood pressures over 100 are associated with disease, maybe they should be considered abnormal. Were these elevated blood pressures caused by our abnormally high salt intake--ten times more than what our bodies were designed to handle? Maybe if we ate a natural amount of salt, our blood pressures would not go up with age and we'd be protected. Of course, to test that theory you'd have to find a population in modern times that doesn't use salt, eat processed food, or go out to eat. For that, you'd have to go deep into the Amazon rainforest.

Meet the Yanomamo people, a no-salt culture with the lowest salt intake ever reported. That is, they have a totally normal-for-our-species salt intake. So, what happens to their blood pressure on a no- or low-salt diet as they age? They start out with a blood pressure of about 100 over 60 and end up with a blood pressure of about 100 over 60. Though theirs is described as a salt-deficient diet, that's like saying they have a diet deficient in Twinkies. They're the ones, it seems, who are eating truly normal salt intakes, which leads to truly normal blood pressures. Those in their 50s have the blood pressure of a 20-year-old. What was the percentage of the population tested with high blood pressure? Zero. However, elsewhere in Brazil, up to 38% of the population may be affected. The Yanomamos probably represent the ultimate human example of the importance of salt on blood pressure.

Of course, there could have been other factors. They didn't drink alcohol, ate a high-fiber and plant-based diet, got lots of exercise, and had no obesity. There are a number of plant-based populations eating little salt who experience no rise of blood pressure with age, but how do we know what exactly is to blame? Ideally, we'd do an interventional trial. Imagine if we took people literally dying from out-of-control high blood pressure (so called malignant hypertension) where you go blind from bleeding into your eyes, your kidneys shut down, and your heart fails, and then we withhold from these patients blood pressure medications so their fate is certain death. Then, what if we put them on a Yanomamo level of salt intake--that is, a normal-for-the-human-species salt intake--and, if instead of dying, they walked away cured of their hypertension? That would pretty much seal the deal.

Enter Dr. Walter Kempner and his rice and fruit diet. Patients started with blood pressures of 210 over 140, which dropped down to 80 over 60. Amazing stuff, but how could he ethically withhold all modern blood pressure medications and treat with diet alone? This was back in the 1940s, and the drugs hadn't been invented yet.

His diet wasn't just extremely low salt, though; it was also strictly plant-based and extremely low in fat, protein, and calories. There is no doubt that Kempner's rice diet achieved remarkable results, and Kempner is now remembered as the person who demonstrated, beyond any shadow of doubt, that high blood pressure can often be lowered by a low enough salt diet.

Forty years ago, it was acknowledged that the evidence is very good, if not conclusive, that a low enough reduction of salt in the diet would result in the prevention of essential hypertension (the rising of blood pressure as we age) and its disappearance as a major public health problem. It looks like we knew how to stop this four decades ago. During this time, how many people have died? Today, high blood pressure may kill 400,000 Americans every year--causing a thousand unnecessary deaths every day.


I have a whole series of videos on salt, including Sprinkling Doubt: Taking Sodium Skeptics with a Pinch of Salt, The Evidence That Salt Raises Blood Pressure, Shaking the Salt Habit and Sodium & Autoimmune Disease: Rubbing Salt in the Wound.

Canned foods are infamous for their sodium content, but there are no-salt varieties. Learn more with my video Canned Beans or Cooked Beans?. Cutting down on sodium is one of the ways we could be Improving on the Mediterranean Diet. Beyond heart health, reducing salt intake could also help our kidneys (How to Treat Kidney Stones with Diet) but if you cut down on salt, won't everything taste like cardboard? See Changing Our Taste Buds.

For more on hypertension, see How to Prevent High Blood Pressure with Diet, How to Treat High Blood Pressure with Diet, and How Not to Die from High Blood Pressure. What if you already eat healthfully and still can't get your pressures down? Try adding hibiscus tea (Hibiscus Tea vs. Plant-Based Diets for Hypertension) and ground flaxseeds (Flax Seeds for Hypertension) to your diet, and, of course, make sure you're exercising regularly (Longer Life Within Walking Distance).

Dr. Kempner and his rice diet are so fascinating they warrant an entire video series. Check out Kempner Rice Diet: Whipping Us Into Shape, Drugs and the Demise of the Rice Diet, Can Diabetic Retinopathy Be Reversed?, and Can Morbid Obesity be Reversed Through 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:

Original Link

Choosing to Have a Normal Blood Pressure

Oct 5 Blood Pressure copy.jpeg

For the first 90% of our evolution, humans ate diets containing less than a quarter teaspoon of salt a day. Why? Because we ate mostly plants. Since we went millions of years without salt shakers, our bodies evolved into salt-conserving machines, which served us well until we discovered salt could be used to preserve foods. Without refrigeration, this was a big boon to human civilization. Of course, this may have led to a general rise in blood pressure, but does that matter if the alternative is starving to death since all your food rotted away? But where does that leave us now, when we no longer have to live off pickles and jerky? We are genetically programmed to eat ten times less salt than we do now. Even many "low"-salt diets can be considered high-salt diets. That's why it's critical to understand what the concept of "normal" is when it comes to salt.

As I discuss in my video High Blood Pressure May Be a Choice, having a "normal" salt intake can lead to a "normal" blood pressure, which can help us to die from all the "normal" causes, like heart attacks and strokes.

Doctors used to be taught that a "normal" systolic blood pressure (the top number) is approximately 100 plus age. Babies start out with a blood pressure around 95 over 60, but then as we age that 95 can go to 120 by our 20s, then 140 in our 40s, and keep climbing as we age. (140 is the official cut-off above which one technically has high blood pressure.) That was considered normal, since everyone's blood pressure creeps up as we get older. And if that's normal, then heart attacks and strokes are normal too, since risk starts rising once we start getting above the 100 we had as a baby.

If blood pressures over 100 are associated with disease, maybe they should be considered abnormal. Were these elevated blood pressures caused by our abnormally high salt intake--ten times more than what our bodies were designed to handle? Maybe if we ate a natural amount of salt, our blood pressures would not go up with age and we'd be protected. Of course, to test that theory you'd have to find a population in modern times that doesn't use salt, eat processed food, or go out to eat. For that, you'd have to go deep into the Amazon rainforest.

Meet the Yanomamo people, a no-salt culture with the lowest salt intake ever reported. That is, they have a totally normal-for-our-species salt intake. So, what happens to their blood pressure on a no- or low-salt diet as they age? They start out with a blood pressure of about 100 over 60 and end up with a blood pressure of about 100 over 60. Though theirs is described as a salt-deficient diet, that's like saying they have a diet deficient in Twinkies. They're the ones, it seems, who are eating truly normal salt intakes, which leads to truly normal blood pressures. Those in their 50s have the blood pressure of a 20-year-old. What was the percentage of the population tested with high blood pressure? Zero. However, elsewhere in Brazil, up to 38% of the population may be affected. The Yanomamos probably represent the ultimate human example of the importance of salt on blood pressure.

Of course, there could have been other factors. They didn't drink alcohol, ate a high-fiber and plant-based diet, got lots of exercise, and had no obesity. There are a number of plant-based populations eating little salt who experience no rise of blood pressure with age, but how do we know what exactly is to blame? Ideally, we'd do an interventional trial. Imagine if we took people literally dying from out-of-control high blood pressure (so called malignant hypertension) where you go blind from bleeding into your eyes, your kidneys shut down, and your heart fails, and then we withhold from these patients blood pressure medications so their fate is certain death. Then, what if we put them on a Yanomamo level of salt intake--that is, a normal-for-the-human-species salt intake--and, if instead of dying, they walked away cured of their hypertension? That would pretty much seal the deal.

Enter Dr. Walter Kempner and his rice and fruit diet. Patients started with blood pressures of 210 over 140, which dropped down to 80 over 60. Amazing stuff, but how could he ethically withhold all modern blood pressure medications and treat with diet alone? This was back in the 1940s, and the drugs hadn't been invented yet.

His diet wasn't just extremely low salt, though; it was also strictly plant-based and extremely low in fat, protein, and calories. There is no doubt that Kempner's rice diet achieved remarkable results, and Kempner is now remembered as the person who demonstrated, beyond any shadow of doubt, that high blood pressure can often be lowered by a low enough salt diet.

Forty years ago, it was acknowledged that the evidence is very good, if not conclusive, that a low enough reduction of salt in the diet would result in the prevention of essential hypertension (the rising of blood pressure as we age) and its disappearance as a major public health problem. It looks like we knew how to stop this four decades ago. During this time, how many people have died? Today, high blood pressure may kill 400,000 Americans every year--causing a thousand unnecessary deaths every day.


I have a whole series of videos on salt, including Sprinkling Doubt: Taking Sodium Skeptics with a Pinch of Salt, The Evidence That Salt Raises Blood Pressure, Shaking the Salt Habit and Sodium & Autoimmune Disease: Rubbing Salt in the Wound.

Canned foods are infamous for their sodium content, but there are no-salt varieties. Learn more with my video Canned Beans or Cooked Beans?. Cutting down on sodium is one of the ways we could be Improving on the Mediterranean Diet. Beyond heart health, reducing salt intake could also help our kidneys (How to Treat Kidney Stones with Diet) but if you cut down on salt, won't everything taste like cardboard? See Changing Our Taste Buds.

For more on hypertension, see How to Prevent High Blood Pressure with Diet, How to Treat High Blood Pressure with Diet, and How Not to Die from High Blood Pressure. What if you already eat healthfully and still can't get your pressures down? Try adding hibiscus tea (Hibiscus Tea vs. Plant-Based Diets for Hypertension) and ground flaxseeds (Flax Seeds for Hypertension) to your diet, and, of course, make sure you're exercising regularly (Longer Life Within Walking Distance).

Dr. Kempner and his rice diet are so fascinating they warrant an entire video series. Check out Kempner Rice Diet: Whipping Us Into Shape, Drugs and the Demise of the Rice Diet, Can Diabetic Retinopathy Be Reversed?, and Can Morbid Obesity be Reversed Through 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:

Original Link

Optimal Bowel Movement Frequency

Optimal Bowel Movement Frequency.jpeg

Lasting for 3,000 years, ancient Egypt was one of the greatest ancient civilizations--with a vastly underestimated knowledge of medicine. They even had medical subspecialties. The pharaohs, for example, had access to dedicated physicians to be "guardian[s] of the royal bowel movement," a title alternately translated from the hieroglyphics to mean "Shepherd of the Anus." How's that for a resume builder?

Today, the primacy of the bowel movement's importance continues. Some have called for bowel habits to be considered a vital sign on how the body is functioning, along with heart rate, blood pressure, and breathing rate. Medical professionals may not particularly relish hearing all about their patients' bowel movements, but it is a vital function that nurses and doctors need to assess.

Surprisingly, the colon has remained relatively unexplored territory, one of the body's final frontiers. For example, current concepts of what "normal" stools are emanated primarily from the records of 12 consecutive bowel movements in 27 healthy subjects from the United Kingdom, who boldly went where no one had gone before. Those must have been some really detailed records.

It's important to define what's normal. When it comes to frequency, for example, we can't define concepts like constipation or diarrhea unless we know what's normal. Standard physiology textbooks may not be helpful in this regard. One text implies that anything from one bowel movement every few weeks or months to 24 in just one day can be regarded as normal. Once every few months is normal?

Out of all of our bodily functions, we may know the least about defecation. Can't we just ask people? It turns out people tend to exaggerate. There's a discrepancy between what people report and what researchers find when they record bowel habits directly. It wasn't until 2010 when we got the first serious look. In my video, How Many Bowel Movement's Should You Have Everyday? you'll see the study that found that normal stool frequency was between three per week and three per day, based on the fact that that's where 98% of people tended to fall. But normal doesn't necessarily mean optimal.

Having a "normal" salt intake can lead to a "normal" blood pressure, which can help us to die from all the "normal" causes like heart attacks and strokes. Having a normal cholesterol level in a society where it's normal to drop dead of heart disease--our number-one killer--is not necessarily a good thing. Indeed, significant proportions of people with "normal bowel function" reported urgency, straining, and incomplete defecation, leading the researchers of the 2010 study to conclude that these kinds of things must be normal. Normal, maybe, if we're eating a fiber-deficient diet, but not normal for our species. Defecation should not be a painful exercise. This is readily demonstrable. For example, the majority of rural Africans eating their traditional fiber-rich, plant-based diets can usually pass without straining a stool specimen on demand. The rectum may need to accumulate 4 or 5 ounces of fecal matter before the defecation reflex is fully initiated, so if we don't even build up that much over the day, we'd have to strain to prime the rectal pump.

Hippocrates thought bowel movements should ideally be two or three times a day, which is what we see in populations on traditional plant-based diets. These traditional diets have the kind of fiber intakes we see in our fellow Great Apes and may be more representative of the type of diets we evolved eating for millions of years. It seems somewhat optimistic, though, to expect the average American to adopt a rural African diet. We can, however, eat more plant-based and bulk up enough to take the Hippocratic oath to go two or three times a day.

There's no need to obsess about it. In fact, there's actually a "bowel obsession syndrome" characterized in part by "ideational rambling over bowel habits." But three times a day makes sense. We have what's called a gastrocolic reflex, which consists of a prompt activation of muscular waves in our colon within 1 to 3 minutes of the ingestion of the first mouthfuls of food to make room for the meal. Even just talking about food can cause our brains to increase colon activity. This suggests the body figured that one meal should be about enough to fill us up down there. So maybe we should eat enough unprocessed plant foods to get up to three a day--a movement for every meal.

I know people are suckers for poop videos--I'm so excited to finally be getting these up! There actually is a recent one--Diet and Hiatal Hernia--that talks about the consequences of straining on stool. Hernias are better than Bed Pan Death Syndrome, though, which is what I talk about in in my video, Should You Sit, Squat, or Lean During a Bowel Movement?

Here are some older videos on bowel health:

For more on this concept of how having "normal" health parameters in a society where it's normal to drop dead of heart attacks and other such preventable fates, see my video When Low Risk Means High Risk.

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. This image has been modified.

Original Link

Optimal Bowel Movement Frequency

Optimal Bowel Movement Frequency.jpeg

Lasting for 3,000 years, ancient Egypt was one of the greatest ancient civilizations--with a vastly underestimated knowledge of medicine. They even had medical subspecialties. The pharaohs, for example, had access to dedicated physicians to be "guardian[s] of the royal bowel movement," a title alternately translated from the hieroglyphics to mean "Shepherd of the Anus." How's that for a resume builder?

Today, the primacy of the bowel movement's importance continues. Some have called for bowel habits to be considered a vital sign on how the body is functioning, along with heart rate, blood pressure, and breathing rate. Medical professionals may not particularly relish hearing all about their patients' bowel movements, but it is a vital function that nurses and doctors need to assess.

Surprisingly, the colon has remained relatively unexplored territory, one of the body's final frontiers. For example, current concepts of what "normal" stools are emanated primarily from the records of 12 consecutive bowel movements in 27 healthy subjects from the United Kingdom, who boldly went where no one had gone before. Those must have been some really detailed records.

It's important to define what's normal. When it comes to frequency, for example, we can't define concepts like constipation or diarrhea unless we know what's normal. Standard physiology textbooks may not be helpful in this regard. One text implies that anything from one bowel movement every few weeks or months to 24 in just one day can be regarded as normal. Once every few months is normal?

Out of all of our bodily functions, we may know the least about defecation. Can't we just ask people? It turns out people tend to exaggerate. There's a discrepancy between what people report and what researchers find when they record bowel habits directly. It wasn't until 2010 when we got the first serious look. In my video, How Many Bowel Movement's Should You Have Everyday? you'll see the study that found that normal stool frequency was between three per week and three per day, based on the fact that that's where 98% of people tended to fall. But normal doesn't necessarily mean optimal.

Having a "normal" salt intake can lead to a "normal" blood pressure, which can help us to die from all the "normal" causes like heart attacks and strokes. Having a normal cholesterol level in a society where it's normal to drop dead of heart disease--our number-one killer--is not necessarily a good thing. Indeed, significant proportions of people with "normal bowel function" reported urgency, straining, and incomplete defecation, leading the researchers of the 2010 study to conclude that these kinds of things must be normal. Normal, maybe, if we're eating a fiber-deficient diet, but not normal for our species. Defecation should not be a painful exercise. This is readily demonstrable. For example, the majority of rural Africans eating their traditional fiber-rich, plant-based diets can usually pass without straining a stool specimen on demand. The rectum may need to accumulate 4 or 5 ounces of fecal matter before the defecation reflex is fully initiated, so if we don't even build up that much over the day, we'd have to strain to prime the rectal pump.

Hippocrates thought bowel movements should ideally be two or three times a day, which is what we see in populations on traditional plant-based diets. These traditional diets have the kind of fiber intakes we see in our fellow Great Apes and may be more representative of the type of diets we evolved eating for millions of years. It seems somewhat optimistic, though, to expect the average American to adopt a rural African diet. We can, however, eat more plant-based and bulk up enough to take the Hippocratic oath to go two or three times a day.

There's no need to obsess about it. In fact, there's actually a "bowel obsession syndrome" characterized in part by "ideational rambling over bowel habits." But three times a day makes sense. We have what's called a gastrocolic reflex, which consists of a prompt activation of muscular waves in our colon within 1 to 3 minutes of the ingestion of the first mouthfuls of food to make room for the meal. Even just talking about food can cause our brains to increase colon activity. This suggests the body figured that one meal should be about enough to fill us up down there. So maybe we should eat enough unprocessed plant foods to get up to three a day--a movement for every meal.

I know people are suckers for poop videos--I'm so excited to finally be getting these up! There actually is a recent one--Diet and Hiatal Hernia--that talks about the consequences of straining on stool. Hernias are better than Bed Pan Death Syndrome, though, which is what I talk about in in my video, Should You Sit, Squat, or Lean During a Bowel Movement?

Here are some older videos on bowel health:

For more on this concept of how having "normal" health parameters in a society where it's normal to drop dead of heart attacks and other such preventable fates, see my video When Low Risk Means High Risk.

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. This image has been modified.

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

Why Certain Plant Compounds May Mimic Dietary Restriction

NF-Sep3 Xenohormesis- What doesn't kill plants may make us stronger.jpg

A new concept, called xenohormesis, has arisen to explain the mystery of why so many plant molecules interact with and modulate key regulators of our physiology in ways that are beneficial to our health (explained further in my video, Xenohormesis: What Doesn't Kill Plants May Make Us Stronger).

Basically, hormesis is the biological principle of "no pain, no gain." Mild stresses like exercise can trigger a protective response that leads to strengthened defenses in the long run. But instead of exposing ourselves to the stressor to trigger our bodies' defenses and shore up protection against future stressors, why not let plants take the hit? Let the plants get stressed because, incredibly, the stress response molecules in plants may activate the same protective responses in humans. Xenohormesis "explains how environmentally stressed plants produce bioactive compounds that can confer stress resistance and survival benefits to animals that consume them." We can piggyback off of their sophisticated stress response. Indeed, the majority of known health-beneficial effects of edible plants are attributable to the pharmacologically active substances of plants' stress responses.

Hormesis may be why dietary restriction can lead to lifespan extension. The mild stress placed upon the body by not eating enough may activate a wide variety of protective pathways within the body, ramping up anti-inflammatory and antioxidant defenses. Our bodies are preparing themselves for the coming famine they think is about to occur. So is there a way to exploit the benefits of dietary restriction to prevent chronic disease? Obviously, "chronically restricting food intake is not a realistic health strategy for the majority of people--it's hard for most people to even cut food intake 10-20%, [given the powerful evolutionary drive to eat]. A more feasible alternative may be to activate dietary restriction-induced stress response pathways by other means."

In other words, xenohormesis.

If we starve plants, they do the same thing mammals do: activate preservation pathways. So let's let the plant face the adversity to create the molecules that trigger cell stress resistance, alter metabolism, and improve disease resistance, and then just come along and appropriate them for the same uses in our own bodies.

The reason phytonutrients like resveratrol in grapes, curcumin in the spice turmeric, and ECGC in green tea are called "dietary restriction mimetics" is that they mimic the physiological effects of dietary restriction. This may be no coincidence, because the plants produced these compounds to save their own green butts from scarcity. So instead of having to walk around starving all the time, thanks to xenohormesis, we may be able to let the plants bear the brunt and enable us to harness other species' hardships as a means to promote our own health.

If this subject interests you, make sure you see my video where I introduce the topic: Appropriating Plant Defenses.

I previously introduced the concept of hormesis in my videos Enhanced Athletic Recovery Without Undermining Adaptation and Is Liquid Smoke Carcinogenic?

How else might we get the benefits of dietary restriction without starving ourselves? See:

In health,
Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my videos for free by clicking here and watch my full 2012 - 2015 presentations Uprooting the Leading Causes of Death, More than an Apple a Day, From Table to Able, and Food as Medicine.

Image Credit: KylaBorg / Flickr

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How Humans Benefit From Stressed Plants

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Plants live the ultimate sedentary lifestyle--most of us usually think of plants more as objects than as organisms. Because plants can't move, they've had to evolve a whole other way to escape threats to their well-being. Plants can "sense and respond dynamically to all sorts of stimuli: chemical concentrations in the air and soil, water, touch, motion, vibration, pathogens, predators, and, of course, light." How do they respond? Biochemically. They manufacture, from scratch, a dizzying array of compounds to deal with specific threats.

If we get too hot, we can move into the shade. If plants get too hot, they're stuck--they are the shade! As a result, "the complexity of the plant stress response humbles that of animals. Plants and their stress response have been evolving for almost a billion years." And in that time they've created a whole chemistry lab of protective substances, some of which can induce similarly protective responses in those of us who eat them.

The "best grapes in terms of health benefit often grow in relatively dry, sun-exposed, infertile soil. Similarly, drought-stressed strawberries have more antioxidants and phytonutrients. Indeed, commonly consumed foods like lettuce and fruits can be nutritionally enhanced by cold stress, light stress, water deficit, or nutrient deficit stress." Why are stressed plants often the healthiest?

Studies (such as those highlighted in my video, Appropriating Plant Defenses) suggest that plants and animals largely share the same molecular pathways in order to respond to stress, so it's conceivable that a molecule produced in plants can also be effective in people. Plants have DNA; humans have DNA. The UV rays in sunlight can damage the DNA in plants in the same way it can damage our DNA (by creating free radicals). Plants figured out how to cook up all these complex antioxidants, and instead of reinventing the wheel, animals can just expropriate those antioxidants from plants and commandeer them for the same purpose.

We get attacked by bacteria; plants get attacked by bacteria. When a particular fungus is getting muscled in on by bacteria, it creates a molecule called penicillin--provided free for us.

When plants get infected, they produce aspirin (See Aspirin Levels in Plant Foods), which can come in handy when we get infected. Plants heal wounds; we heal wounds, using similar fatty-acid signaling systems. It is "increasingly evident that plants and animals differ less than we thought in how we respond to stimuli, sharing elements of fatty acid, protein, steroidal, neurotransmitter, free radical, nitric oxide, and even plant growth hormone signaling systems." So in a sense, we're just opening up nature's drug store when we pull out the crisper in our fridge.

This whole co-evolution concept reminds me of Human Neurotransmitters In Plants and The Broccoli Receptor: Our First Line of Defense.

More on the power of plants in Power Plants.

Some of the wilder things that Phytochemicals: The Nutrition Facts Missing from the Label can do are explored in:

We evolved eating a lot of plants: Paleolithic Lessons.

In health,
Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my videos for free by clicking here and watch my full 2012 - 2015 presentations Uprooting the Leading Causes of Death, More than an Apple a Day, From Table to Able, and Food as Medicine.

Image Credit: Hernan Pinera / Flickr

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How a Tick Bite Can Lead to Food Allergies

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In the beginning, Aristotle defined two forms of life on planet Earth: plants and animals. Two thousand years later, the light microscope was invented and we discovered tiny, single-celled organisms like amoebas. Then, the electron microscope was invented and we discovered bacteria. Finally, in 1969, biologists recognized fungi as a separate category, and we've had at least five kingdoms of life ever since.

In my video, Higher Quality May Mean Higher Risk, I talk about the potential downsides of consuming proteins from within our own kingdom, such as the impact our fellow animal proteins can have on boosting our liver's production of a cancer-promoting hormone called IGF-1.

In Eating Outside Our Kingdom, I talked about other potential advantages of preferably dipping into the plant and mushroom kingdoms for dinner, not only from a food safety perspective (we're more likely to get infected by animal pathogens than Dutch Elm Disease), but because of the potential for cross-reactivity between animal and human proteins. Our immune system is more likely to get confused between a chicken leg and our own legs than it is with a banana, so there may be less potential to trigger an autoimmune reaction, like degenerative brain diseases or inflammatory arthritis (See Diet & Rheumatoid Arthritis). In attacking some foreign animal meat protein, some of our own similarly composed tissues may get caught in the crossfire.

It's not just proteins. If you remember the Neu5Gc story (see Inflammatory Meat Molecule Neu5GC), sialic acid in other animals may cause inflammation in our arteries (see Nonhuman Molecules Lining Our Arteries) and help breast tumors and other human cancers to grow (see How Tumors Use Meat to Grow: Xeno-Autoantibodies). Now a new twist has been added to the story.

The reason Neu5Gc triggers inflammation is because humans lost the ability to make it two million years ago, and so when our body is exposed to it through animal products, it's treated as a foreign molecule, causing inflammation. But there's also another oligosaccharide called alpha-gal that humans, chimps, and apes lost the ability to make 20 million years ago, but is still made by a variety of animals, including many animals we eat.

Anti-gal antibodies may be involved in a number of detrimental processes that may result in allergic, autoimmune, and autoimmune-like diseases, such as auto-immune thyroid disorders. We see higher levels of anti-gal antibodies in Crohn's disease victims. These antibodies even react against about half of human breast tumors, and we can find them in atherosclerotic plaques in people's necks. However, those are all mostly speculative risks. We do know that alpha-gal is a major obstacle to transplanting pig organs into people, like kidneys, because our bodies reject alpha-gal as foreign. In fact, alpha-gal is thought to be the major target for human anti-pig antibodies.

It's interesting that if we look at those that abstain from pork for whatever reason, they have fewer swine-specific immune cells in their bloodstream. Researchers speculate that oral intake of pork could ferry swine molecules into the bloodstream via gut-infiltrating lymphocytes to prime the immune response. So we can have an allergic reaction to eating pig kidneys too, but such severe meat allergies were considered rare, until an unusual report surfaced. First described in 2009, the report included details on 24 cases of meat allergies triggered by tick bites.

Within a year, it was obvious that the cases should be counted in hundreds rather than dozens. By 2012, there were thousands of cases across a large area of the southern and eastern U.S., and new cases are now popping up in several countries around the world.

The culprit, the lone star tick, so-called because females have a white spot on their back, are famous for causing Masters' disease, a disease similar to Lyme syndrome, also known as STARI (southern tick associated rash illness). But thanks to the lone star tick steadily expanding its range (even as far as Long Island, NY), it's not necessarily just so Southern any more.

What is the relevance of tick bites to the production of allergy-causing anti-meat antibodies to alpha-gal? Good question. What we know is that if you get bitten by one of these ticks, you can develop an allergy to meat (See Alpha Gal and the Lone Star Tick). This appears to be the first example of a response to an external parasite giving rise to an important form of food allergy. We don't know the exact mechanism, but it may be because there's something in the tick saliva that's cross-reacting with alpha-gal, or because the tick is injecting you with animal allergens from its last meal.

What role may these tick-bite induced allergies play in the development of chronic hives and other allergic skin reactions in children? See Tick Bites, Meat Allergies, and Chronic Urticaria.

Here's some videos unearthing the IGF-1 story:

Neu5Gc is what opened up this whole can of worms:

I wonder if alpha gal is playing a role in the improvements in arthritis and Crohn's on plant-based diets: Dietary Treatment of Crohn's Disease and Diet & Rheumatoid Arthritis.

In health,
Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my videos for free by clicking here and watch my full 2012 - 2015 presentations Uprooting the Leading Causes of Death, More than an Apple a Day, From Table to Able, and Food as Medicine.

Image Credit: USGS Bee Inventory and Monitoring Lab / Flickr

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Exploiting Autophagy to Live Longer

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Thanks to advances in modern medicine, we are living longer lives, but we're doing it by lengthening the morbidity phase. In other words, we live longer, but sicker, lives (see my video: Americans Are Live Longer, but Sicker Lives). So, traditional medicine increases the number of old people in bad health. Ideally, though, we'd extend lifespan by slowing aging to delay the onset of deterioration, rather than extending the period of deterioration.

That's exactly what a new compound appears to do. It sounds like science fiction. A bacteria in a vial of dirt taken from a mysterious island creating a compound that prolongs life. And not in the traditional medical sense. Researchers in a study profiled in my video, Why Do We Age?, called it rapamycin--named after the bacteria's home, Easter Island, which is known locally as Rapa Nui. Rapamycin inhibits an enzyme called TOR, or "target of rapamycin." TOR may be a master determinant of lifespan and aging. The action of TOR has been described as the engine of a speeding car without brakes.

Rather than thinking of aging as slowly rusting, a better analogy may be a speeding car that enters the low-speed zone of adulthood and damages itself because it does not and cannot slow down. Why don't living organisms have brakes? Because they've never needed them. In the wild, animals don't live long enough to experience aging. Most die before they even reach adulthood. The same used to be true for humans. For example, just a few centuries ago, average life expectancy in London was less than 16 years old.

Therefore, living beings need to grow as fast as possible to start reproduction before they die from external causes. The best evolutionary strategy may be to run at full speed. However, once we pass the finish line, once we win the race to pass on our genes, we're still careening forward at an unsustainable pace, all thanks to this enzyme TOR. In our childhood, TOR is an engine of growth, but in adulthood, it is the engine of aging. "Nature simply selects for the brightest flame, which in turn casts the darkest shadow."

Sometimes, though, even in our youth, our bodies need to turn down the heat. When we were evolving, there were no grocery stores; periodic famine was the norm. So sometimes even young people had to slow down or they might never even make it to reproductive age. So we did evolve one braking mechanism: caloric restriction. Caloric restriction may extend lifespan mainly through the inhibition of TOR.

When food is abundant, TOR activity goes up, prompting the cells in our body to divide. When TOR detects that food is scarce, it shifts the body into conservation mode, slowing down cell division and kicking in a process called autophagy, from the Greek auto meaning "self," and phagy meaning "to eat." Autophagy essentially means eating yourself. Our body realizes there isn't much food around and starts rummaging through our cells looking for anything we don't need. Defective proteins, malfunctioning mitochondria, stuff that isn't working anymore, and cleans house. Clears out all the junk and recycles it into fuel or new building materials, renewing our cells.

So caloric restriction has been heralded as a fountain of youth. The potential health and longevity benefits of such a diet regimen may be numerous, but symptoms may include dropping our blood pressure too low, loss of libido, menstrual irregularities, infertility, loss of bone, cold sensitivity, loss of strength, slower wound healing, and psychological conditions such as depression, emotional deadening, and irritability. And you walk around starving all the time! There's got to be a better way, and there is. Check out my video Caloric Restriction vs. Animal Protein Restriction.

More tips for preserving youthful health:

-Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death, More Than an Apple a Day, and From Table to Able.

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