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

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.

Original Link

Organic versus Conventional: Which has More Nutrients?

Organic versus Conventional - Which has More Nutrients?.jpeg

Are organic foods safer and healthier than conventional alternatives? Those are two separate questions. Some consumers are interested in getting more nutrients; others are more concerned about getting fewer pesticides. Let's do nutrition first.

As seen in my video, Are Organic Foods More Nutritious?, hundreds of studies have been reviewed and researchers didn't find significant differences for most of the traditional nutrients like vitamins and minerals. They concluded that despite the widespread perception that organically produced foods are more nutritious, they didn't find robust evidence to support that perception. They did, however, find higher levels of phenolic phytonutrients in organic.

These so-called "secondary metabolites" of plants are thought to be behind many of the benefits ascribed to eating fruits and vegetables. Organic fruits and vegetables had between 19 and 69% more of a variety of these antioxidant compounds. The theory was that these phytonutrients are created by the plant for its own protection. For example, broccoli releases the bitter compounds like sulforaphane when the plant is chewed to ward off those who might eat it. Bugs take one bite and say, "Ew, this tastes like broccoli!" But pesticide-laden plants are bitten less by bugs and so may be churning out fewer of these compounds. Plants raised organically, on the other hand, are in a fight for their lives and may necessarily have to produce more protection. That was the theory anyway, but we don't have good evidence to back it up. The more likely reason has to do with the fertilizer; plants given high dose synthetic nitrogen fertilizers may divert more resources to growth rather than defense.

These antioxidants may protect the plant, but what about us? More antioxidant phytonutrients are found in organic vegetables and so yes, they displayed more antioxidant activity, but also more antimutagenic activity. Researchers exposed bacteria to a variety of mutagenic chemicals like benzopyrene, the polycyclic aromatic hydrocarbon found in barbecued meat, or IQ, the heterocyclic amine found in grilled/broiled/fried meats (as well as cigarette smoke), and there were fewer DNA mutations in the petri dishes where they added organic vegetables compared to the petri dishes where they added conventional vegetables.

Preventing DNA damage in bacteria is one thing, but what about effects on actual human cells? Organic strawberries may taste better, and have higher antioxidant activity and more phenolic phytonutrients, but what happens when you stack them up head-to-head against human cancer cells? Extracts from organically grown strawberries suppressed the growth of colon cancer cells and breast cancer cells significantly better than extracts from conventional strawberries. Now this was dripping strawberries onto cancer cells growing in a petri dish, but as I showed in Strawberries versus Esophageal Cancer, there are real life circumstances in which strawberries come into direct contact with cancerous and precancerous lesions, and so presumably organic strawberries would work even better, but they haven't yet been tested in clinical trials.

Although in vitro studies show higher antioxidant and antimutagenic activity as well as better inhibition of cancer cell proliferation, clinical studies on the impact of eating organic on human disease simply haven't been done. Based on antioxidant phytonutrient levels, organic produce may be considered 20 to 40% healthier, the equivalent of adding one or two serving's worth to a five-a-day regimen. But organic produce may be 40% more expensive, so for the same money you could just buy the extra servings worth of conventional produce. From a purely nutrients-per-dollar standpoint, it's not clear that organic foods are any better. But people often buy organic foods to avoid chemicals, not because they are more nutritious. For more on the best available science comparing the nutritional content, pesticide risk, heavy metal toxicity, and food poisoning risk of organic versus conventionally raised foods )including practical tips for making your own DIY fruit and veggie wash), see:

I imagine that the reaction to this series will be similar to that for the one I did on GMO foods, riling up critics on both sides of the debate:

More on the nutritional implications of stressed-out plants here:

Production method aside, in vitro, Which Fruit Fights Cancer Better?

In health,

Michael Greger, M.D.

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

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

Original Link

Organic versus Conventional: Which has More Nutrients?

Organic versus Conventional - Which has More Nutrients?.jpeg

Are organic foods safer and healthier than conventional alternatives? Those are two separate questions. Some consumers are interested in getting more nutrients; others are more concerned about getting fewer pesticides. Let's do nutrition first.

As seen in my video, Are Organic Foods More Nutritious?, hundreds of studies have been reviewed and researchers didn't find significant differences for most of the traditional nutrients like vitamins and minerals. They concluded that despite the widespread perception that organically produced foods are more nutritious, they didn't find robust evidence to support that perception. They did, however, find higher levels of phenolic phytonutrients in organic.

These so-called "secondary metabolites" of plants are thought to be behind many of the benefits ascribed to eating fruits and vegetables. Organic fruits and vegetables had between 19 and 69% more of a variety of these antioxidant compounds. The theory was that these phytonutrients are created by the plant for its own protection. For example, broccoli releases the bitter compounds like sulforaphane when the plant is chewed to ward off those who might eat it. Bugs take one bite and say, "Ew, this tastes like broccoli!" But pesticide-laden plants are bitten less by bugs and so may be churning out fewer of these compounds. Plants raised organically, on the other hand, are in a fight for their lives and may necessarily have to produce more protection. That was the theory anyway, but we don't have good evidence to back it up. The more likely reason has to do with the fertilizer; plants given high dose synthetic nitrogen fertilizers may divert more resources to growth rather than defense.

These antioxidants may protect the plant, but what about us? More antioxidant phytonutrients are found in organic vegetables and so yes, they displayed more antioxidant activity, but also more antimutagenic activity. Researchers exposed bacteria to a variety of mutagenic chemicals like benzopyrene, the polycyclic aromatic hydrocarbon found in barbecued meat, or IQ, the heterocyclic amine found in grilled/broiled/fried meats (as well as cigarette smoke), and there were fewer DNA mutations in the petri dishes where they added organic vegetables compared to the petri dishes where they added conventional vegetables.

Preventing DNA damage in bacteria is one thing, but what about effects on actual human cells? Organic strawberries may taste better, and have higher antioxidant activity and more phenolic phytonutrients, but what happens when you stack them up head-to-head against human cancer cells? Extracts from organically grown strawberries suppressed the growth of colon cancer cells and breast cancer cells significantly better than extracts from conventional strawberries. Now this was dripping strawberries onto cancer cells growing in a petri dish, but as I showed in Strawberries versus Esophageal Cancer, there are real life circumstances in which strawberries come into direct contact with cancerous and precancerous lesions, and so presumably organic strawberries would work even better, but they haven't yet been tested in clinical trials.

Although in vitro studies show higher antioxidant and antimutagenic activity as well as better inhibition of cancer cell proliferation, clinical studies on the impact of eating organic on human disease simply haven't been done. Based on antioxidant phytonutrient levels, organic produce may be considered 20 to 40% healthier, the equivalent of adding one or two serving's worth to a five-a-day regimen. But organic produce may be 40% more expensive, so for the same money you could just buy the extra servings worth of conventional produce. From a purely nutrients-per-dollar standpoint, it's not clear that organic foods are any better. But people often buy organic foods to avoid chemicals, not because they are more nutritious. For more on the best available science comparing the nutritional content, pesticide risk, heavy metal toxicity, and food poisoning risk of organic versus conventionally raised foods )including practical tips for making your own DIY fruit and veggie wash), see:

I imagine that the reaction to this series will be similar to that for the one I did on GMO foods, riling up critics on both sides of the debate:

More on the nutritional implications of stressed-out plants here:

Production method aside, in vitro, Which Fruit Fights Cancer Better?

In health,

Michael Greger, M.D.

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

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

Original Link

What Animal Protein Does in Your Colon

What Animal Protein Does in Your Colon.jpeg

There's a take-off of the industry slogan, "Beef: It's What's For Dinner" - "Beef: It's What's Rotting in Your Colon." I saw this on a shirt once with some friends and I was such the party pooper--no pun intended--explaining to everyone that meat is fully digested in the small intestine, and never makes it down into the colon. It's no fun hanging out with biology geeks.

But I was wrong!

It's been estimated that with a typical Western diet, up to 12 grams of protein can escape digestion, and when it reaches the colon, it can be turned into toxic substances like ammonia. This degradation of undigested protein in the colon is called putrefaction, so a little meat can actually end up putrefying in our colon. The problem is that some of the by-products of this putrefaction process can be toxic.

It's generally accepted that carbohydrate fermentation--the fiber and resistant starches that reach our colon--results in beneficial effects because of the generation of short-chain fatty acids like butyrate, whereas protein fermentation is considered detrimental. Protein fermentation mainly occurs in the lower end of colon and results in the production of potentially toxic metabolites. That may be why colorectal cancer and ulcerative colitis tends to happen lower down--because that's where the protein is putrefying.

Probably the simplest strategy to reduce the potential harm of protein fermentation is to reduce dietary protein intake. But the accumulation of these toxic byproducts of protein metabolism may be attenuated by the fermentation of undigested plant matter. In my video, Bowel Wars: Hydrogen Sulfide vs. Butyrate, you can see a study out of Australia showed that if you give people foods containing resistant starch you can block the accumulation of potentially harmful byproducts of protein metabolism. Resistant starch is resistant to small intestine digestion and so it makes it down to our colon where it can feed our good bacteria. Resistant starch is found in cooked beans, split peas, chickpeas, lentils, raw oatmeal, and cooled cooked pasta (like macaroni salad). Apparently, the more starch that ends up in the colon, the less ammonia that is produced.

Of course, there's protein in plants too. The difference is that animal proteins tend to have more sulfur-containing amino acids like methionine, which can be turned into hydrogen sulfide in our colon. Hydrogen sulfide is the rotten egg gas that may play a role in the development of the inflammatory bowel disease, ulcerative colitis (see Preventing Ulcerative Colitis with Diet).

The toxic effects of hydrogen sulfide appear to be a result of blocking the ability of the cells lining our colon from utilizing butyrate, which is what our good bacteria make from the fiber and resistant starch we eat. It's like this constant battle in our colon between the bad metabolites of protein, hydrogen sulfide, and the good metabolites of carbohydrates, butyrate. Using human colon samples, researchers were able to show that the adverse effects of sulfide could be reversed by butyrate. So we can either cut down on meat, eat more plants, or both.

There are two ways hydrogen sulfide can be produced, though. It's mainly present in our large intestine as a result of the breakdown of sulfur-containing proteins, but the rotten egg gas can also be generated from inorganic sulfur preservatives like sulfites and sulfur dioxide.

Sulfur dioxide is used as a preservative in dried fruit, and sulfites are added to wines. We can avoid sulfur additives by reading labels or by just choosing organic, since they're forbidden from organic fruits and beverages by law.

More than 35 years ago, studies started implicating sulfur dioxide preservatives in the exacerbation of asthma. This so-called "sulfite-sensitivity" seems to affect only about 1 in 2,000 people, so I recommended those with asthma avoid it, but otherwise I considered the preservative harmless. I am now not so sure, and advise people to avoid it when possible.

Cabbage family vegetables naturally have some sulfur compounds, but thankfully, after following more than a hundred thousand women for over 25 years, researchers concluded cruciferous vegetables were not associated with elevated colitis risk.

Because of animal protein and processed food intake, the standard American diet may contain five or six times more sulfur than a diet centered around unprocessed plant foods. This may help explain the rarity of inflammatory bowel disease among those eating traditional whole food, plant-based diets.

How could companies just add things like sulfur dioxide to foods without adequate safety testing? See Who Determines if Food Additives are Safe? For other additives that may be a problem, see Titanium Dioxide & Inflammatory Bowel Disease and Is Carrageenan Safe?

More on this epic fermentation battle in our gut in Stool pH and Colon Cancer.

Does the sulfur-containing amino acid methionine sound familiar? You may remember it from such hits as Starving Cancer with Methionine Restriction and Methionine Restriction as a Life Extension Strategy.

These short-chain fatty acids released by our good bacteria when we eat fiber and resistant starches are what may be behind the second meal effect: Beans and the Second Meal Effect.

I mentioned ulcerative colitis. What about the other inflammatory bowel disease Crohn's? See Preventing Crohn's Disease With Diet and Dietary Treatment of Crohn's Disease.

In health,

Michael Greger, M.D.

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

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

Original Link

What Animal Protein Does in Your Colon

What Animal Protein Does in Your Colon.jpeg

There's a take-off of the industry slogan, "Beef: It's What's For Dinner" - "Beef: It's What's Rotting in Your Colon." I saw this on a shirt once with some friends and I was such the party pooper--no pun intended--explaining to everyone that meat is fully digested in the small intestine, and never makes it down into the colon. It's no fun hanging out with biology geeks.

But I was wrong!

It's been estimated that with a typical Western diet, up to 12 grams of protein can escape digestion, and when it reaches the colon, it can be turned into toxic substances like ammonia. This degradation of undigested protein in the colon is called putrefaction, so a little meat can actually end up putrefying in our colon. The problem is that some of the by-products of this putrefaction process can be toxic.

It's generally accepted that carbohydrate fermentation--the fiber and resistant starches that reach our colon--results in beneficial effects because of the generation of short-chain fatty acids like butyrate, whereas protein fermentation is considered detrimental. Protein fermentation mainly occurs in the lower end of colon and results in the production of potentially toxic metabolites. That may be why colorectal cancer and ulcerative colitis tends to happen lower down--because that's where the protein is putrefying.

Probably the simplest strategy to reduce the potential harm of protein fermentation is to reduce dietary protein intake. But the accumulation of these toxic byproducts of protein metabolism may be attenuated by the fermentation of undigested plant matter. In my video, Bowel Wars: Hydrogen Sulfide vs. Butyrate, you can see a study out of Australia showed that if you give people foods containing resistant starch you can block the accumulation of potentially harmful byproducts of protein metabolism. Resistant starch is resistant to small intestine digestion and so it makes it down to our colon where it can feed our good bacteria. Resistant starch is found in cooked beans, split peas, chickpeas, lentils, raw oatmeal, and cooled cooked pasta (like macaroni salad). Apparently, the more starch that ends up in the colon, the less ammonia that is produced.

Of course, there's protein in plants too. The difference is that animal proteins tend to have more sulfur-containing amino acids like methionine, which can be turned into hydrogen sulfide in our colon. Hydrogen sulfide is the rotten egg gas that may play a role in the development of the inflammatory bowel disease, ulcerative colitis (see Preventing Ulcerative Colitis with Diet).

The toxic effects of hydrogen sulfide appear to be a result of blocking the ability of the cells lining our colon from utilizing butyrate, which is what our good bacteria make from the fiber and resistant starch we eat. It's like this constant battle in our colon between the bad metabolites of protein, hydrogen sulfide, and the good metabolites of carbohydrates, butyrate. Using human colon samples, researchers were able to show that the adverse effects of sulfide could be reversed by butyrate. So we can either cut down on meat, eat more plants, or both.

There are two ways hydrogen sulfide can be produced, though. It's mainly present in our large intestine as a result of the breakdown of sulfur-containing proteins, but the rotten egg gas can also be generated from inorganic sulfur preservatives like sulfites and sulfur dioxide.

Sulfur dioxide is used as a preservative in dried fruit, and sulfites are added to wines. We can avoid sulfur additives by reading labels or by just choosing organic, since they're forbidden from organic fruits and beverages by law.

More than 35 years ago, studies started implicating sulfur dioxide preservatives in the exacerbation of asthma. This so-called "sulfite-sensitivity" seems to affect only about 1 in 2,000 people, so I recommended those with asthma avoid it, but otherwise I considered the preservative harmless. I am now not so sure, and advise people to avoid it when possible.

Cabbage family vegetables naturally have some sulfur compounds, but thankfully, after following more than a hundred thousand women for over 25 years, researchers concluded cruciferous vegetables were not associated with elevated colitis risk.

Because of animal protein and processed food intake, the standard American diet may contain five or six times more sulfur than a diet centered around unprocessed plant foods. This may help explain the rarity of inflammatory bowel disease among those eating traditional whole food, plant-based diets.

How could companies just add things like sulfur dioxide to foods without adequate safety testing? See Who Determines if Food Additives are Safe? For other additives that may be a problem, see Titanium Dioxide & Inflammatory Bowel Disease and Is Carrageenan Safe?

More on this epic fermentation battle in our gut in Stool pH and Colon Cancer.

Does the sulfur-containing amino acid methionine sound familiar? You may remember it from such hits as Starving Cancer with Methionine Restriction and Methionine Restriction as a Life Extension Strategy.

These short-chain fatty acids released by our good bacteria when we eat fiber and resistant starches are what may be behind the second meal effect: Beans and the Second Meal Effect.

I mentioned ulcerative colitis. What about the other inflammatory bowel disease Crohn's? See Preventing Crohn's Disease With Diet and Dietary Treatment of Crohn's Disease.

In health,

Michael Greger, M.D.

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

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

Original Link

Striving for Alkaline Pee and Acidic Poo

Stool pH and Colon Cancer.jpg

More than 30 years ago, an idea was put forward that high colonic pH promoted colorectal cancer. A high colonic pH may promote the creation of carcinogens from bile acids, a process that is inhibited once you get below a pH of about 6.5. This is supported by data which shows those at higher risk for colon cancer may have a higher stool pH, and those at lower risk have a low pH. There was a dramatic difference between the two groups, with most of the high risk group over pH 8, and most of the low risk group under pH 6 (see Stool pH and Colon Cancer).

This may help explain the 50-fold lower rates of colon cancer in Africa compared to America. The bacteria we have in our gut depends on what we eat. If we eat lots of fiber, then we preferentially feed the fiber eating bacteria, which give us back all sorts of health promoting substances like short-chain fatty acids that have anti-inflammatory and anti-cancer properties. More of these organic acids were found in the stools of native Africans than African Americans. More acids, so lower pH. Whereas putrefactive bacteria, eating animal protein, are able to increase stool pH by producing alkaline metabolites like ammonia.

The pH of the stools of white versus black children in Africa was compared. Children were chosen because you can more readily sample their stools, particularly the rural black schoolchildren who were eating such high fiber diets--whole grains, legumes, nuts, vegetables, fruits, and wild greens--that 90% of them could produce a stool on demand. Stuffed from head to tail with plants, they could give you a stool sample at any time, just as easy as getting a urine sample. It was hard to even get access to the white kids, though, who were reluctant to participate in such investigations, even though they were given waxed cartons fitted with lids while all the black kids got was a plate and a square of paper towel.

The researchers found significantly lower fecal pH in those eating the traditional, rural plant-based diets compared to those eating the traditional Western diet, who were eating far fewer whole plant foods than the black children. But, remove some of those whole plant foods, like switch their corn for white bread for just a few days and their stool pH goes up, and add whole plant foods like an extra five to seven servings of fruit every day, and their stool pH goes down even further and gets more acidic. It makes sense because when you ferment fruits, veggies, and grains, they turn sour, like vinegar, sauerkraut, or sourdough, because good bacteria like lactobacillus produce organic acids like lactic acid. Those who eat a lot of plants have more of those good bugs. So, using the purple cabbage test highlighted in my video, Testing Your Diet with Pee & Purple Cabbage, we want blue pee, but pink poo.

If you compare the fecal samples of those eating vegetarian or vegan to those eating standard diets, plant-based diets appear to shift the makeup of the bacteria in our gut, resulting in a significantly lower stool pH, and the more plant-based, the lower the pH dropped. It's like a positive feedback loop: fiber-eating bacteria produce the acids to create the pH at which fiber-eating bacteria thrive while suppressing the group of less beneficial bugs.

It might taken even as little as two weeks to bring stool pH down on a plant-based diet. In a study published in the British Journal of Cancer, a dozen volunteers carefully selected for their trustworthiness and randomized to sequentially go on regular, vegetarian, or vegan diets and two weeks in, a significant drop in fecal pH was achieved eating completely plant-based.

But there are differing qualities of plant-based diets. For example, the two groups followed in the study I mentioned earlier had dramatically different stool pH, yet both groups were vegetarian. The high risk group was eating mostly refined grains, very little fiber, whereas the low risk group was eating whole grains and beans, packed with fiber for our fiber-friendly flora to munch on.

Just as a "reduction of high serum cholesterol contributes to the avoidance of coronary heart disease," a fall in the fecal pH value may contribute to the avoidance of bowel cancer and through the same means, eating more whole plant foods.

More on colon cancer prevention in:

In health,

Michael Greger, M.D.

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

Image Credit: Kitti Sukhonthanit © 123RF.com. This image has been modified.

Original Link

Striving for Alkaline Pee and Acidic Poo

Stool pH and Colon Cancer.jpg

More than 30 years ago, an idea was put forward that high colonic pH promoted colorectal cancer. A high colonic pH may promote the creation of carcinogens from bile acids, a process that is inhibited once you get below a pH of about 6.5. This is supported by data which shows those at higher risk for colon cancer may have a higher stool pH, and those at lower risk have a low pH. There was a dramatic difference between the two groups, with most of the high risk group over pH 8, and most of the low risk group under pH 6 (see Stool pH and Colon Cancer).

This may help explain the 50-fold lower rates of colon cancer in Africa compared to America. The bacteria we have in our gut depends on what we eat. If we eat lots of fiber, then we preferentially feed the fiber eating bacteria, which give us back all sorts of health promoting substances like short-chain fatty acids that have anti-inflammatory and anti-cancer properties. More of these organic acids were found in the stools of native Africans than African Americans. More acids, so lower pH. Whereas putrefactive bacteria, eating animal protein, are able to increase stool pH by producing alkaline metabolites like ammonia.

The pH of the stools of white versus black children in Africa was compared. Children were chosen because you can more readily sample their stools, particularly the rural black schoolchildren who were eating such high fiber diets--whole grains, legumes, nuts, vegetables, fruits, and wild greens--that 90% of them could produce a stool on demand. Stuffed from head to tail with plants, they could give you a stool sample at any time, just as easy as getting a urine sample. It was hard to even get access to the white kids, though, who were reluctant to participate in such investigations, even though they were given waxed cartons fitted with lids while all the black kids got was a plate and a square of paper towel.

The researchers found significantly lower fecal pH in those eating the traditional, rural plant-based diets compared to those eating the traditional Western diet, who were eating far fewer whole plant foods than the black children. But, remove some of those whole plant foods, like switch their corn for white bread for just a few days and their stool pH goes up, and add whole plant foods like an extra five to seven servings of fruit every day, and their stool pH goes down even further and gets more acidic. It makes sense because when you ferment fruits, veggies, and grains, they turn sour, like vinegar, sauerkraut, or sourdough, because good bacteria like lactobacillus produce organic acids like lactic acid. Those who eat a lot of plants have more of those good bugs. So, using the purple cabbage test highlighted in my video, Testing Your Diet with Pee & Purple Cabbage, we want blue pee, but pink poo.

If you compare the fecal samples of those eating vegetarian or vegan to those eating standard diets, plant-based diets appear to shift the makeup of the bacteria in our gut, resulting in a significantly lower stool pH, and the more plant-based, the lower the pH dropped. It's like a positive feedback loop: fiber-eating bacteria produce the acids to create the pH at which fiber-eating bacteria thrive while suppressing the group of less beneficial bugs.

It might taken even as little as two weeks to bring stool pH down on a plant-based diet. In a study published in the British Journal of Cancer, a dozen volunteers carefully selected for their trustworthiness and randomized to sequentially go on regular, vegetarian, or vegan diets and two weeks in, a significant drop in fecal pH was achieved eating completely plant-based.

But there are differing qualities of plant-based diets. For example, the two groups followed in the study I mentioned earlier had dramatically different stool pH, yet both groups were vegetarian. The high risk group was eating mostly refined grains, very little fiber, whereas the low risk group was eating whole grains and beans, packed with fiber for our fiber-friendly flora to munch on.

Just as a "reduction of high serum cholesterol contributes to the avoidance of coronary heart disease," a fall in the fecal pH value may contribute to the avoidance of bowel cancer and through the same means, eating more whole plant foods.

More on colon cancer prevention in:

In health,

Michael Greger, M.D.

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

Image Credit: Kitti Sukhonthanit © 123RF.com. This image has been modified.

Original Link