What Causes Diabetes?

What Causes Diabetes?.jpeg

After about age 20, we may have all the insulin-producing beta cells we're ever going to get. So if we lose them, we may lose them for good. Autopsy studies show that by the time type 2 diabetes is diagnosed, we may have already killed off half of our beta cells.

You can kill pancreatic cells right in a petri dish. If you expose the insulin-producing beta cells in our pancreas to fat, they suck it up and then start dying off. Fat breakdown products can interfere with the function of these cells and ultimately lead to their death. A chronic increase in blood fat levels can be harmful to our pancreas.

It's not just any fat; it's saturated fat. As you can see in my video, What Causes Diabetes?, predominant fat in olives, nuts, and avocados gives a tiny bump in death protein 5, but saturated fat really elevates this contributor to beta cell death. Therefore, saturated fats are harmful to beta cells. Cholesterol is, too. The uptake of bad cholesterol (LDL) can cause beta cell death as a result of free radical formation.

Diets rich in saturated fats not only cause obesity and insulin resistance, but the increased levels of circulating free fats in the blood (non-esterified fatty acids, or NEFAs) may also cause beta cell death and may thus contribute to the progressive beta cell loss we see in type 2 diabetes. These findings aren't just based on test tube studies. If researchers have infused fat into people's blood streams, they can show it directly impairing pancreatic beta cell function. The same occurs when we ingest it.

Type 2 diabetes is characterized by "defects in both insulin secretion and insulin action," and saturated fat appears to impair both. Researchers showed saturated fat ingestion reduces insulin sensitivity within hours. The subjects were non-diabetics, so their pancreases should have been able to boost insulin secretion to match the drop in sensitivity. But no, "insulin secretion failed to compensate for insulin resistance in subjects who ingested [the saturated fat]." This implies saturated fat impaired beta cell function as well, again just within hours after going into our mouth. "[I]ncreased consumption of [saturated fats] has a powerful short- and long-term effect on insulin action," contributing to the dysfunction and death of pancreatic beta cells in diabetes.

Saturated fat isn't just toxic to the pancreas. The fats found predominantly in meat and dairy--chicken and cheese are the two main sources in the American diet--are considered nearly "universally toxic." In contrast, the fats found in olives, nuts, and avocados are not. Saturated fat has been found to be particularly toxic to liver cells, contributing to the formation of fatty liver disease. If you expose human liver cells to plant fat, though, nothing happens. If you expose our liver cells to animal fat, a third of them die. This may explain why higher intake of saturated fat and cholesterol are associated with non-alcoholic fatty liver disease.

By cutting down on saturated fat consumption, we may be able to help interrupt these processes. Decreasing saturated fat intake can help bring down the need for all that excess insulin. So either being fat or eating saturated fat can both cause excess insulin in the blood. The effect of reducing dietary saturated fat intake on insulin levels is substantial, regardless of how much belly fat we have. It's not just that by eating fat we may be more likely to store it as fat. Saturated fats, independently of any role they have in making us fat, "may contribute to the development of insulin resistance and its clinical consequences." After controlling for weight, alcohol, smoking, exercise, and family history, diabetes incidence was significantly associated with the proportion of saturated fat in our blood.

So what causes diabetes? The consumption of too many calories rich in saturated fats. Just like everyone who smokes doesn't develop lung cancer, everyone who eats a lot of saturated fat doesn't develop diabetes--there is a genetic component. But just like smoking can be said to cause lung cancer, high-calorie diets rich in saturated fats are currently considered the cause of type 2 diabetes.

I have a lot of videos on diabetes, including:

Preventing the disease:

And treating it:

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

What Causes Diabetes?

What Causes Diabetes?.jpeg

After about age 20, we may have all the insulin-producing beta cells we're ever going to get. So if we lose them, we may lose them for good. Autopsy studies show that by the time type 2 diabetes is diagnosed, we may have already killed off half of our beta cells.

You can kill pancreatic cells right in a petri dish. If you expose the insulin-producing beta cells in our pancreas to fat, they suck it up and then start dying off. Fat breakdown products can interfere with the function of these cells and ultimately lead to their death. A chronic increase in blood fat levels can be harmful to our pancreas.

It's not just any fat; it's saturated fat. As you can see in my video, What Causes Diabetes?, predominant fat in olives, nuts, and avocados gives a tiny bump in death protein 5, but saturated fat really elevates this contributor to beta cell death. Therefore, saturated fats are harmful to beta cells. Cholesterol is, too. The uptake of bad cholesterol (LDL) can cause beta cell death as a result of free radical formation.

Diets rich in saturated fats not only cause obesity and insulin resistance, but the increased levels of circulating free fats in the blood (non-esterified fatty acids, or NEFAs) may also cause beta cell death and may thus contribute to the progressive beta cell loss we see in type 2 diabetes. These findings aren't just based on test tube studies. If researchers have infused fat into people's blood streams, they can show it directly impairing pancreatic beta cell function. The same occurs when we ingest it.

Type 2 diabetes is characterized by "defects in both insulin secretion and insulin action," and saturated fat appears to impair both. Researchers showed saturated fat ingestion reduces insulin sensitivity within hours. The subjects were non-diabetics, so their pancreases should have been able to boost insulin secretion to match the drop in sensitivity. But no, "insulin secretion failed to compensate for insulin resistance in subjects who ingested [the saturated fat]." This implies saturated fat impaired beta cell function as well, again just within hours after going into our mouth. "[I]ncreased consumption of [saturated fats] has a powerful short- and long-term effect on insulin action," contributing to the dysfunction and death of pancreatic beta cells in diabetes.

Saturated fat isn't just toxic to the pancreas. The fats found predominantly in meat and dairy--chicken and cheese are the two main sources in the American diet--are considered nearly "universally toxic." In contrast, the fats found in olives, nuts, and avocados are not. Saturated fat has been found to be particularly toxic to liver cells, contributing to the formation of fatty liver disease. If you expose human liver cells to plant fat, though, nothing happens. If you expose our liver cells to animal fat, a third of them die. This may explain why higher intake of saturated fat and cholesterol are associated with non-alcoholic fatty liver disease.

By cutting down on saturated fat consumption, we may be able to help interrupt these processes. Decreasing saturated fat intake can help bring down the need for all that excess insulin. So either being fat or eating saturated fat can both cause excess insulin in the blood. The effect of reducing dietary saturated fat intake on insulin levels is substantial, regardless of how much belly fat we have. It's not just that by eating fat we may be more likely to store it as fat. Saturated fats, independently of any role they have in making us fat, "may contribute to the development of insulin resistance and its clinical consequences." After controlling for weight, alcohol, smoking, exercise, and family history, diabetes incidence was significantly associated with the proportion of saturated fat in our blood.

So what causes diabetes? The consumption of too many calories rich in saturated fats. Just like everyone who smokes doesn't develop lung cancer, everyone who eats a lot of saturated fat doesn't develop diabetes--there is a genetic component. But just like smoking can be said to cause lung cancer, high-calorie diets rich in saturated fats are currently considered the cause of type 2 diabetes.

I have a lot of videos on diabetes, including:

Preventing the disease:

And treating it:

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

Solving a Colon Cancer Mystery

Solving-a-Colon-Cancer-Mystery.jpeg

Colorectal cancer is the second leading cause of cancer death in the United States, after lung cancer. The rates of lung cancer around the world vary by a factor of 10. If there was nothing we could do to prevent lung cancer--if it just happened at random--we'd assume that the rates everywhere would be about the same. But since there's such a huge variation in rates, it seems like there's probably some external cause. Indeed, we now know smoking is responsible for 90% of lung cancer cases. If we don't want to die of the number-one cancer killer, we can throw 90% of our risk out the window just by not smoking.

There's an even bigger variation around the world for colon cancer. As discussed in Solving a Colon Cancer Mystery, it appears colon cancer doesn't just happen, something makes it happen. If our lungs can get filled with carcinogens from smoke, maybe our colons are getting filled with carcinogens from food. Researchers from the University of Pittsburgh and the University of Limpopo sought to answer the question, "Why do African Americans get more colon cancer than native Africans?" Why study Africans? Because colon cancer is extremely rare in native African populations, more than 50 times lower than rates of Americans, white or black.

It's the fiber, right? The first to describe the low rates of colon cancer in native Africans, Dr. Denis Burkitt ascribed it to their staple diet traditionally high in whole grains and, consequently, high in fiber content. We seem to get a 10% reduction in risk for every 10 grams of fiber we eat a day. If it's a 1% drop for each gram, and native Africans are eating upwards of 100 grams a day, it could explain why colon cancer is so rare in sub-Saharan Africa.

Wait a second. The modern African diet is highly processed and low in fiber, yet there has been no dramatic increase in colon cancer incidence. Their diet today has such a low fiber content because most populations now depend on commercially produced refined cornmeal. We're not just talking low fiber intake, we're talking United States of America low, down around half the recommended daily allowance. Yet colon disease in Africa is still about 50 times less common than in the United States.

Maybe it's because native Africans are thinner and exercise more? No, they're not, and no, they don't. If anything, their physical activity levels may now be even lower than Americans'. So if they're sedentary like us and eating mostly refined carbs, few whole plant foods, and little fiber like us, why do they have 50 times less colon cancer than we do? There is one difference. The diet of both African Americans and Caucasian Americans is rich in meat, whereas the native Africans' diet is so low in meat and saturated fat they have total cholesterol levels averaging 139 mg/dL, compared to over 200 mg/dL in the United States.

They may not get a lot of fiber anymore, but they continue to minimize meat and animal fat consumption, which supports other evidence indicating the most powerful determinants of colon cancer risk may be meat and animal fat intake levels. So why do Americans get more colon cancer than Africans? Maybe the rarity of colon cancer in Africans is not the fiber, but their low animal product consumption.

Although opinions diverge as to whether cholesterol, animal fat, or animal protein is most responsible for the increased colon cancer risk, given that all three have been proven to have carcinogenic properties, it may not really matter which component is worse, as a diet laden in one is usually laden in the others.

I've previously suggested phytates may play a critical role as well (Phytates for the Prevention of Cancer). Resistant starch may be another player. Since native Africans cool down their corn porridge, some of the starch can crystallize and effectively turn into fiber. (This is the same reason pasta salad and potato salad better feed our gut bacteria than starchy dishes served hot.) I touch on it briefly in Bowel Wars: Hydrogen Sulfide vs. Butyrate. Resistant starch may also help explain Beans and the Second Meal Effect. And for even more, see Resistant Starch & Colon Cancer and Getting Starch to Take the Path of Most Resistance.

Fiber may just be a marker for healthier eating since it's only found concentrated in unprocessed plant foods. So the apparent protection afforded by high fiber diets may derive from whole food plant-based nutrition rather than the fiber itself (so fiber supplements would not be expected to provide the same protection). Here are some videos that found protective associations with higher fiber diets:

What might be in animal products that can raise cancer risk? Here's a smattering:

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: Department of Foreign Affairs and Trade / Flickr. This image has been modified.

Original Link

Solving a Colon Cancer Mystery

Solving-a-Colon-Cancer-Mystery.jpeg

Colorectal cancer is the second leading cause of cancer death in the United States, after lung cancer. The rates of lung cancer around the world vary by a factor of 10. If there was nothing we could do to prevent lung cancer--if it just happened at random--we'd assume that the rates everywhere would be about the same. But since there's such a huge variation in rates, it seems like there's probably some external cause. Indeed, we now know smoking is responsible for 90% of lung cancer cases. If we don't want to die of the number-one cancer killer, we can throw 90% of our risk out the window just by not smoking.

There's an even bigger variation around the world for colon cancer. As discussed in Solving a Colon Cancer Mystery, it appears colon cancer doesn't just happen, something makes it happen. If our lungs can get filled with carcinogens from smoke, maybe our colons are getting filled with carcinogens from food. Researchers from the University of Pittsburgh and the University of Limpopo sought to answer the question, "Why do African Americans get more colon cancer than native Africans?" Why study Africans? Because colon cancer is extremely rare in native African populations, more than 50 times lower than rates of Americans, white or black.

It's the fiber, right? The first to describe the low rates of colon cancer in native Africans, Dr. Denis Burkitt ascribed it to their staple diet traditionally high in whole grains and, consequently, high in fiber content. We seem to get a 10% reduction in risk for every 10 grams of fiber we eat a day. If it's a 1% drop for each gram, and native Africans are eating upwards of 100 grams a day, it could explain why colon cancer is so rare in sub-Saharan Africa.

Wait a second. The modern African diet is highly processed and low in fiber, yet there has been no dramatic increase in colon cancer incidence. Their diet today has such a low fiber content because most populations now depend on commercially produced refined cornmeal. We're not just talking low fiber intake, we're talking United States of America low, down around half the recommended daily allowance. Yet colon disease in Africa is still about 50 times less common than in the United States.

Maybe it's because native Africans are thinner and exercise more? No, they're not, and no, they don't. If anything, their physical activity levels may now be even lower than Americans'. So if they're sedentary like us and eating mostly refined carbs, few whole plant foods, and little fiber like us, why do they have 50 times less colon cancer than we do? There is one difference. The diet of both African Americans and Caucasian Americans is rich in meat, whereas the native Africans' diet is so low in meat and saturated fat they have total cholesterol levels averaging 139 mg/dL, compared to over 200 mg/dL in the United States.

They may not get a lot of fiber anymore, but they continue to minimize meat and animal fat consumption, which supports other evidence indicating the most powerful determinants of colon cancer risk may be meat and animal fat intake levels. So why do Americans get more colon cancer than Africans? Maybe the rarity of colon cancer in Africans is not the fiber, but their low animal product consumption.

Although opinions diverge as to whether cholesterol, animal fat, or animal protein is most responsible for the increased colon cancer risk, given that all three have been proven to have carcinogenic properties, it may not really matter which component is worse, as a diet laden in one is usually laden in the others.

I've previously suggested phytates may play a critical role as well (Phytates for the Prevention of Cancer). Resistant starch may be another player. Since native Africans cool down their corn porridge, some of the starch can crystallize and effectively turn into fiber. (This is the same reason pasta salad and potato salad better feed our gut bacteria than starchy dishes served hot.) I touch on it briefly in Bowel Wars: Hydrogen Sulfide vs. Butyrate. Resistant starch may also help explain Beans and the Second Meal Effect. And for even more, see Resistant Starch & Colon Cancer and Getting Starch to Take the Path of Most Resistance.

Fiber may just be a marker for healthier eating since it's only found concentrated in unprocessed plant foods. So the apparent protection afforded by high fiber diets may derive from whole food plant-based nutrition rather than the fiber itself (so fiber supplements would not be expected to provide the same protection). Here are some videos that found protective associations with higher fiber diets:

What might be in animal products that can raise cancer risk? Here's a smattering:

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: Department of Foreign Affairs and Trade / Flickr. This image has been modified.

Original Link

Plant versus Animal Iron

Plant versus Animal Iron.jpeg

It is commonly thought that those who eat plant-based diets may be more prone to iron deficiency, but it turns out that they're no more likely to suffer from iron deficiency anemia than anybody else. This may be because not only do those eating meat-free diets tend to get more fiber, magnesium, and vitamins like A, C, and E, but they also get more iron.

The iron found predominantly in plants is non-heme iron, which isn't absorbed as well as the heme iron found in blood and muscle, but this may be a good thing. As seen in my video, The Safety of Heme vs. Non-Heme Iron, avoidance of heme iron may be one of the key elements of plant-based protection against metabolic syndrome, and may also be beneficial in lowering the risk from other chronic diseases such as heart disease.

The data linking coronary heart disease and the intake of iron, in general, has been mixed. This inconsistency of evidence may be because of where the iron comes from. The majority of total dietary iron is non-heme iron, coming mostly from plants. So, total iron intake is associated with lower heart disease risk, but iron intake from meat is associated with significantly higher risk for heart disease. This is thought to be because iron can act as a pro-oxidant, contributing to the development of atherosclerosis by oxidizing cholesterol with free radicals. The risk has been quantified as a 27% increase in coronary heart disease risk for every 1 milligram of heme iron consumed daily.

The same has been found for stroke risk. The studies on iron intake and stroke have had conflicting results, but that may be because they had never separated out heme iron from non-heme iron... until now. Researchers found that the intake of meat (heme) iron, but not plant (non-heme) iron, was associated with an increased risk of stroke.

The researchers also found that higher intake of heme iron--but not total or plant (non-heme) iron--was significantly associated with greater risk for type 2 diabetes. There may be a 16% increase in risk for type 2 diabetes for every 1 milligram of heme iron consumed daily.

The same has also been found for cancer, with up to 12% increased risk for every milligram of daily heme iron exposure. In fact, we can actually tell how much meat someone is eating by looking at their tumors. To characterize the mechanisms underlying meat-related lung cancer development, researchers asked lung cancer patients how much meat they ate and examined the gene expression patterns in their tumors. They identified a signature pattern of heme-related gene expression. Although they looked specifically at lung cancer, they expect these meat-related gene expression changes may occur in other cancers as well.

We do need to get enough iron, but only about 3% of premenopausal white women have iron deficiency anemia these days. However, the rates are worse in African and Mexican Americans. Taking into account our leading killers--heart disease, cancer, and diabetes--the healthiest source of iron appears to be non-heme iron, found naturally in abundance in whole grains, beans, split peas, chickpeas, lentils, dark green leafy vegetables, dried fruits, nuts, and seeds.

But how much money can be made on beans, though? The processed food industry came up with a blood-based crisp bread, made out of rye flour and blood from cattle and pigs, which is one of the most concentrated sources of heme iron, about two-thirds more than blood from chickens. If blood-based crackers don't sound particularly appetizing, you can always snack on cow blood cookies. And there are always blood-filled biscuits, whose filling has been described as "a dark-colored, chocolate flavored paste with a very pleasant taste." (It's dark-colored because spray-dried pig blood can have a darkening effect on the food product's color.) The worry is not the color or taste, it's the heme iron, which, because of its potential cancer risk, is not considered safe to add to foods intended for the general population.

Previously, I've touched on the double-edged iron sword in Risk Associated With Iron Supplements and Phytates for the Prevention of Cancer. It may also help answer Why Was Heart Disease Rare in the Mediterranean?

Those eating plant-based diets get more of most nutrients since whole plant foods are so nutrient dense. See Nutrient-Dense Approach to Weight Management.

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

Original Link

Plant versus Animal Iron

Plant versus Animal Iron.jpeg

It is commonly thought that those who eat plant-based diets may be more prone to iron deficiency, but it turns out that they're no more likely to suffer from iron deficiency anemia than anybody else. This may be because not only do those eating meat-free diets tend to get more fiber, magnesium, and vitamins like A, C, and E, but they also get more iron.

The iron found predominantly in plants is non-heme iron, which isn't absorbed as well as the heme iron found in blood and muscle, but this may be a good thing. As seen in my video, The Safety of Heme vs. Non-Heme Iron, avoidance of heme iron may be one of the key elements of plant-based protection against metabolic syndrome, and may also be beneficial in lowering the risk from other chronic diseases such as heart disease.

The data linking coronary heart disease and the intake of iron, in general, has been mixed. This inconsistency of evidence may be because of where the iron comes from. The majority of total dietary iron is non-heme iron, coming mostly from plants. So, total iron intake is associated with lower heart disease risk, but iron intake from meat is associated with significantly higher risk for heart disease. This is thought to be because iron can act as a pro-oxidant, contributing to the development of atherosclerosis by oxidizing cholesterol with free radicals. The risk has been quantified as a 27% increase in coronary heart disease risk for every 1 milligram of heme iron consumed daily.

The same has been found for stroke risk. The studies on iron intake and stroke have had conflicting results, but that may be because they had never separated out heme iron from non-heme iron... until now. Researchers found that the intake of meat (heme) iron, but not plant (non-heme) iron, was associated with an increased risk of stroke.

The researchers also found that higher intake of heme iron--but not total or plant (non-heme) iron--was significantly associated with greater risk for type 2 diabetes. There may be a 16% increase in risk for type 2 diabetes for every 1 milligram of heme iron consumed daily.

The same has also been found for cancer, with up to 12% increased risk for every milligram of daily heme iron exposure. In fact, we can actually tell how much meat someone is eating by looking at their tumors. To characterize the mechanisms underlying meat-related lung cancer development, researchers asked lung cancer patients how much meat they ate and examined the gene expression patterns in their tumors. They identified a signature pattern of heme-related gene expression. Although they looked specifically at lung cancer, they expect these meat-related gene expression changes may occur in other cancers as well.

We do need to get enough iron, but only about 3% of premenopausal white women have iron deficiency anemia these days. However, the rates are worse in African and Mexican Americans. Taking into account our leading killers--heart disease, cancer, and diabetes--the healthiest source of iron appears to be non-heme iron, found naturally in abundance in whole grains, beans, split peas, chickpeas, lentils, dark green leafy vegetables, dried fruits, nuts, and seeds.

But how much money can be made on beans, though? The processed food industry came up with a blood-based crisp bread, made out of rye flour and blood from cattle and pigs, which is one of the most concentrated sources of heme iron, about two-thirds more than blood from chickens. If blood-based crackers don't sound particularly appetizing, you can always snack on cow blood cookies. And there are always blood-filled biscuits, whose filling has been described as "a dark-colored, chocolate flavored paste with a very pleasant taste." (It's dark-colored because spray-dried pig blood can have a darkening effect on the food product's color.) The worry is not the color or taste, it's the heme iron, which, because of its potential cancer risk, is not considered safe to add to foods intended for the general population.

Previously, I've touched on the double-edged iron sword in Risk Associated With Iron Supplements and Phytates for the Prevention of Cancer. It may also help answer Why Was Heart Disease Rare in the Mediterranean?

Those eating plant-based diets get more of most nutrients since whole plant foods are so nutrient dense. See Nutrient-Dense Approach to Weight Management.

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

Original Link

How Much Water Should We Drink Every Day?

How Much Water Should We Drink Every Day?.jpeg

More than 2000 years ago Hippocrates (460-377 BCE) said, "If we could give every individual the right amount of nourishment and exercise, not too little and not too much, we would have found the safest way to health." What does that mean when it comes to water? Water has been described as a neglected, unappreciated, and under-researched subject, and further complicating the issue, a lot of the papers extolling the need for proper hydration are funded by the bottled water industry.

It turns out the often quoted "drink at least eight glasses of water a day" dictum has little underpinning scientific evidence . Where did that idea come from? The recommendation was traced to a 1921 paper, in which the author measured his own pee and sweat and determined we lose about 3% of our body weight in water a day, or about 8 cups (see How Many Glasses of Water Should We Drink in a Day?). Consequently, for the longest time, water requirement guidelines for humanity were based on just one person.

There is evidence that not drinking enough may be associated with falls and fractures, heat stroke, heart disease, lung disorders, kidney disease, kidney stones, bladder and colon cancer, urinary tract infections, constipation, dry mouth, cavities, decreased immune function and cataract formation. The problem with many of these studies is that low water intake is associated with several unhealthy behaviors, such as low fruit and vegetable intake, more fast-food, less shopping at farmers markets. And who drinks lots of water? People who exercise a lot. No wonder they tend to have lower disease rates!

Only large and expensive randomized trials could settle these questions definitively. Given that water cannot be patented, such trials seem unlikely; who's going to pay for them? We're left with studies that find an association between disease and low water intake. But are people sick because they drink less, or are they drinking less because they're sick? There have been a few large prospective studies in which fluid intake is measured before disease develops. For example, a Harvard study of 48,000 men found that the risk of bladder cancer decreased by 7% for every extra daily cup of fluid we drink. Therefore, a high intake of water--like 8 cups a day--may reduce the risk of bladder cancer by about 50%, potentially saving thousands of lives.

The accompanying editorial commented that strategies to prevent the most prevalent cancers in the West are remarkably straightforward in principle. To prevent lung cancer, quit smoking; to prevent breast cancer, maintain your ideal body weight and exercise; and to prevent skin cancer, stay out of the sun. Now comes this seemingly simple way to reduce the risk of bladder cancer: drink more fluids.

Probably the best evidence we have for a cut off of water intake comes from the Adventist Health Study, in which 20,000 men and women were studied. About one-half were vegetarian, so they were also getting extra water by eating more fruits and vegetables. Those drinking 5 or more glasses of water a day had about half the risk of dying from heart disease compared to those who drank 2 or fewer glasses a day. Like the Harvard study, this protection was found after controlling for other factors such as diet and exercise. These data suggest that it was the water itself that was decreasing risk, perhaps by lowering blood viscosity (blood thickness).

Based on all the best evidence to date, authorities from Europe, the U.S. Institute of Medicine, and the World Health Organization recommend between 2.0 and 2.7 liters (8 to 11 cups) of water a day for women, and 2.5 to 3.7 liters (10 to 15 cups) a day for men. This includes water from all sources, not just beverages. We get about a liter from food and the water our body makes. So this translates into a recommendation for women to drink 4 to 7 cups of water a day and men 6 to 11 cups, assuming only moderate physical activity at moderate ambient temperatures.

We can also get water from all the other drinks we consume, including caffeinated drinks, with the exception of stronger alcoholic drinks like wines and spirits. Beer can leave you with more water than you started with, but wine actively dehydrates you. However, in the cancer and heart disease studies I mentioned above, the benefits were only found with increased water consumption, not other beverages.

I've previously touched on the cognitive benefits of proper hydration here: Does a Drink Of Water Make Children Smarter?

Surprised tea is hydrating? See my video Is Caffeinated Tea Dehydrating?

Surprised that the 8-a-day rested on such flimsy evidence? Unfortunately, so much of what we do in medicine has shaky underpinnings. That's the impetus behind the idea of evidence-based medicine (what a concept!). Ironically, this new movement may itself undermine some of the most effective treatments. See Evidence-Based Medicine or Evidence-Biased?

How else can we reduce our risk of bladder cancer? See Raw Broccoli and Bladder Cancer Survival.

What kind of water? I recommend tap water, which tends to be preferable from a chemical and microbial contamination standpoint. What about buying one of those fancy alkalizing machines? See Alkaline Water: a Scam?

It's so nice to have data on such a fundamental question. We have much to thank the Adventists for. You will see their studies cropping up frequently. See, for example, Plant-Based Diets and Diabetes, The Okinawa Diet: Living to 100, and Evidence-Based Eating.

In health,

Michael Greger, M.D.

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

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

Original Link

How Much Water Should We Drink Every Day?

How Much Water Should We Drink Every Day?.jpeg

More than 2000 years ago Hippocrates (460-377 BCE) said, "If we could give every individual the right amount of nourishment and exercise, not too little and not too much, we would have found the safest way to health." What does that mean when it comes to water? Water has been described as a neglected, unappreciated, and under-researched subject, and further complicating the issue, a lot of the papers extolling the need for proper hydration are funded by the bottled water industry.

It turns out the often quoted "drink at least eight glasses of water a day" dictum has little underpinning scientific evidence . Where did that idea come from? The recommendation was traced to a 1921 paper, in which the author measured his own pee and sweat and determined we lose about 3% of our body weight in water a day, or about 8 cups (see How Many Glasses of Water Should We Drink in a Day?). Consequently, for the longest time, water requirement guidelines for humanity were based on just one person.

There is evidence that not drinking enough may be associated with falls and fractures, heat stroke, heart disease, lung disorders, kidney disease, kidney stones, bladder and colon cancer, urinary tract infections, constipation, dry mouth, cavities, decreased immune function and cataract formation. The problem with many of these studies is that low water intake is associated with several unhealthy behaviors, such as low fruit and vegetable intake, more fast-food, less shopping at farmers markets. And who drinks lots of water? People who exercise a lot. No wonder they tend to have lower disease rates!

Only large and expensive randomized trials could settle these questions definitively. Given that water cannot be patented, such trials seem unlikely; who's going to pay for them? We're left with studies that find an association between disease and low water intake. But are people sick because they drink less, or are they drinking less because they're sick? There have been a few large prospective studies in which fluid intake is measured before disease develops. For example, a Harvard study of 48,000 men found that the risk of bladder cancer decreased by 7% for every extra daily cup of fluid we drink. Therefore, a high intake of water--like 8 cups a day--may reduce the risk of bladder cancer by about 50%, potentially saving thousands of lives.

The accompanying editorial commented that strategies to prevent the most prevalent cancers in the West are remarkably straightforward in principle. To prevent lung cancer, quit smoking; to prevent breast cancer, maintain your ideal body weight and exercise; and to prevent skin cancer, stay out of the sun. Now comes this seemingly simple way to reduce the risk of bladder cancer: drink more fluids.

Probably the best evidence we have for a cut off of water intake comes from the Adventist Health Study, in which 20,000 men and women were studied. About one-half were vegetarian, so they were also getting extra water by eating more fruits and vegetables. Those drinking 5 or more glasses of water a day had about half the risk of dying from heart disease compared to those who drank 2 or fewer glasses a day. Like the Harvard study, this protection was found after controlling for other factors such as diet and exercise. These data suggest that it was the water itself that was decreasing risk, perhaps by lowering blood viscosity (blood thickness).

Based on all the best evidence to date, authorities from Europe, the U.S. Institute of Medicine, and the World Health Organization recommend between 2.0 and 2.7 liters (8 to 11 cups) of water a day for women, and 2.5 to 3.7 liters (10 to 15 cups) a day for men. This includes water from all sources, not just beverages. We get about a liter from food and the water our body makes. So this translates into a recommendation for women to drink 4 to 7 cups of water a day and men 6 to 11 cups, assuming only moderate physical activity at moderate ambient temperatures.

We can also get water from all the other drinks we consume, including caffeinated drinks, with the exception of stronger alcoholic drinks like wines and spirits. Beer can leave you with more water than you started with, but wine actively dehydrates you. However, in the cancer and heart disease studies I mentioned above, the benefits were only found with increased water consumption, not other beverages.

I've previously touched on the cognitive benefits of proper hydration here: Does a Drink Of Water Make Children Smarter?

Surprised tea is hydrating? See my video Is Caffeinated Tea Dehydrating?

Surprised that the 8-a-day rested on such flimsy evidence? Unfortunately, so much of what we do in medicine has shaky underpinnings. That's the impetus behind the idea of evidence-based medicine (what a concept!). Ironically, this new movement may itself undermine some of the most effective treatments. See Evidence-Based Medicine or Evidence-Biased?

How else can we reduce our risk of bladder cancer? See Raw Broccoli and Bladder Cancer Survival.

What kind of water? I recommend tap water, which tends to be preferable from a chemical and microbial contamination standpoint. What about buying one of those fancy alkalizing machines? See Alkaline Water: a Scam?

It's so nice to have data on such a fundamental question. We have much to thank the Adventists for. You will see their studies cropping up frequently. See, for example, Plant-Based Diets and Diabetes, The Okinawa Diet: Living to 100, and Evidence-Based Eating.

In health,

Michael Greger, M.D.

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

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

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Which Dietary Factors Affect Breast Cancer Most?

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One of my favorite cancer-specific charities, the American Institute for Cancer Research, lauds the China Study and the documentary Forks Over Knives, with which they share the same bottom-line message: The healthiest diets are those that revolve around whole plant foods.

They then translate that advice into their Ten Recommendations for Cancer Prevention, featured in my video Which Dietary Factors Affect Breast Cancer Most? We now have evidence that those who follow such advice are actually protected against cancer. Breast cancer risk was reduced by 60% in women who met at least five recommendations compared with those who met none. The most important dietary advice was to be as lean as possible within the normal range of body weight, eat mostly foods of plant origin, and limit alcoholic drinks.

What about other cancers? Greater adherence to the AICR dietary guidelines was also associated with significantly less endometrial, colorectal, lung, kidney, stomach, oral, liver, and esophageal cancer. In other words, adherence to dietary recommendations for cancer prevention may lower the risk of developing most types of cancer. The drop in bladder cancer did not reach statistical significance, but a larger follow-up study following 469,000 people for 11 years (the largest to date) found that just a 3% increase in the consumption of animal protein calories was associated with a 15% higher risk of bladder cancer, whereas just a 2% increase in plant protein was associated with a 23% lower risk.

AICR recommendation number ten is that cancer survivors should follow the recommendations for cancer prevention. The same diet that can help prevent cancer in the first place can be used to help save our life after diagnosis. Adherence to the guidelines for cancer prevention was found to be associated with lower mortality among older female cancer survivors, or breast cancer and other cancers in general.

A cancer diagnosis is considered a teachable moment to get people eating and living healthier. Oncologists revel at the growth in the number of cancer survivors in this country, now ten million strong and growing. It's great that those with cancer are living longer, but even better to prevent it in the first place so we can all live longer. Not only does adherence to the guidelines lower cancer risk, but extends our lifespan because the guidelines are also significantly associated with a lower hazard of dying from heart disease and respiratory disease, suggesting that following the recommendations could "significantly increase longevity."

Just like eating to prevent cancer helps to prevent heart disease, eating to protect our heart helps prevent cancer. It sounds self-evident, but adherence to a healthy lifestyle is therefore associated with a lower risk of mortality overall. And the more healthy behaviors we have, the longer we get to live. Such factors included not smoking, walking every day, or eating green leafy vegetables almost daily.

To help differentiate the effects of diet from other lifestyle behaviors like smoking and drinking on cancer incidence, Adventists were recently compared to Baptists. Both discourage alcohol and tobacco, but the Adventists go further, encouraging a reduction of meat. In general, the Adventists had lower cancer hazard rates than the Baptists, and within Adventist populations, the vegetarians did even better, and those eating the most plants, did the best.

Why do plant-based diets appear to lower the risk of cancer? A number of fascinating mechanisms:

Specific to breast cancer:

Though plant-based beverages may be harmful: Breast Cancer and Alcohol: How Much Is Safe?

In terms of foods associated with breast cancer survival, see:

In health,
Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live, year-in-review presentations--2013: Uprooting the Leading Causes of Death, More Than an Apple a Day, 2014: From Table to Able: Combating Disabling Diseases with Food, 2015: Food as Medicine: Preventing and Treating the Most Dreaded Diseases with Diet, and my latest, 2016: How Not To Die: The Role of Diet in Preventing, Arresting, and Reversing Our Top 15 Killers.

Image Credit: MesserWoland

Image Credit: [Lev Kropotov] © 123RF.com

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How Big Food Twists the Science

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

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

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

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

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

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

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

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

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

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

Here are some examples:

In health,
Michael Greger, M.D.

PS: If you haven't yet, you can subscribe to my free videos here and watch my live, year-in-review presentations--2013: Uprooting the Leading Causes of Death, More Than an Apple a Day, 2014: From Table to Able: Combating Disabling Diseases with Food, 2015: Food as Medicine: Preventing and Treating the Most Dreaded Diseases with Diet, and my latest, 2016: How Not To Die: The Role of Diet in Preventing, Arresting, and Reversing Our Top 15 Killers.

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