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

How to Cook Broccoli

NF-Feb9 Second Strategy to Cooking Broccoli.jpeg

When I used to teach medical students at Tufts, I gave a lecture about this amazing new therapeutic called "iloccor-B." I'd talk about all the new science, all the things it could do, its excellent safety profile. Just as they were all scrambling to buy stock in the company and prescribe it to all their patients, I'd do the big reveal. Apologizing for my "dyslexia," I would admit that I'd got it backwards. All this time I had been talking about broccoli.

The main active ingredient in broccoli is thought to be sulforaphane, which may protect our brains, protect our eyesight, protect our bodies against free radicals, boost our detoxification enzymes, and help prevent and treat cancer.

In my videos The Best Detox and Sometimes the Enzyme Myth is the Truth, I talked about how the formation of sulforaphane is like a chemical flare reaction, requiring the mixing of a precursor compound with an enzyme, which is destroyed by cooking. This may explain why we get dramatic suppression of cancer cell growth from raw broccoli, cauliflower and Brussels sprouts, but hardly anything from boiled, microwaved or steamed (except for microwaved broccoli, which actually retains some cancer fighting abilities). But who wants to eat raw Brussels sprouts?

There is a strategy to get the benefits of raw in cooked form. In raw broccoli, the sulforaphane precursor, called glucoraphanin, mixes with the enzyme (myrosinase) when you chew or chop it. If given enough time--such as when sitting in your upper stomach waiting to get digested--sulforaphane is born. The precursor and sulforaphane are resistant to heat and therefore cooking, but the enzyme is destroyed. No enzyme = no sulforaphane.

That's why I described the "hack and hold" technique--if we chop the broccoli, Brussels sprouts, kale, collards, or cauliflower first and then wait 40 minutes, we can cook them all we want. The sulforaphane is already made; the enzyme has already done its job, so we don't need it anymore.

When most people make broccoli soup, for example, they're doing it wrong. Most people cook the broccoli first, then blend it. We now know it should be done the exact opposite way. Blend it first, wait, and then cook it.

What if we're using frozen broccoli, though? In my video, Second Strategy to Cooking Broccoli, you can see the amount of sulforaphane in someone's body after they eat broccoli soup made from fresh broccoli versus from frozen broccoli. The difference is dramatic. Commercially produced frozen broccoli lacks the ability to form sulforaphane because vegetables are blanched (flash-cooked) before they're frozen for the very purpose of deactivating enzymes. This prolongs shelf life in the frozen foods section, but the myrosinase is dead by the time you take it out of your freezer. It doesn't matter how much you chop it, or how long you wait, no sulforaphane is going to be made. This may be why fresh kale suppresses cancer cell growth up to ten times more than frozen.

The frozen broccoli is still packed with the precursor--remember that's heat resistant--and we could get lots of sulforaphane out of the frozen broccoli by adding some outside enzyme. Where do we get myrosinase enzyme from? Researchers just buy theirs from a chemical company. But we can just walk into any grocery store.

All cruciferous vegetables have this myrosinase. Mustard greens, a cruciferous vegetable, grow out of little mustard seeds, which we can buy ground up in the spice aisle as mustard powder. If we sprinkled some mustard powder on our cooked frozen broccoli, would it start churning out sulforaphane? We didn't know...until now.

Boiling broccoli prevents the formation of any significant levels of sulforaphane due to inactivation of the enzyme. However, researchers from the University of Reading found that the addition of powdered mustard seeds to the heat processed broccoli significantly increased the formation of sulforaphane. In the video I mentioned earlier, Second Strategy to Cooking Broccoli, you can see the amount of sulforaphane in boiled broccoli versus the amount after half a teaspoon or a teaspoon of mustard powder is added. Both a half teaspoon and a full teaspoon increase sulforaphane by the same amount, suggesting that we could use even use less mustard powder for the same effect. Therefore, although domestic cooking leads to the deactivation of myrosinase and stops sulforaphane formation, the addition of powdered mustard seeds to cooked cabbage-family vegetables provides a natural source of the enzyme such that it's practically like eating them raw.

So, if we forget to chop our greens in the morning for the day, or are using frozen, we can just sprinkle some mustard powder on top at the dinner table and we're all set. Daikon radish, horseradish, or wasabi--all cruciferous vegetables packed with the enzyme--work as well. Just a quarter teaspoon of Daikon radish root for seven cups of broccoli worked--just a tiny pinch can do it. Or you can add a small amount of fresh greens to your cooked greens, because the fresh greens have myrosinase enzyme that can go to work on the cooked greens.

I love kitchen chemistry--it totally revolutionized my daily greens prep. One of the first things I used to do in the morning is chop my greens for the day, so when lunch and supper rolls around they'd be good to go. But now with the mustard powder plan, I don't have to pre-chop.

This helps explain the results I presented in Raw Broccoli and Bladder Cancer Survival.

OK, but what's so great about this sulforaphane stuff? For a taste, 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 Uprooting the Leading Causes of Death, More Than an Apple a Day, From Table to Able, and Food as Medicine.

Image Credit: Jessica Spengler / Flickr

Original Link

Bile Binding Beets

NF-Jan21 Which Vegetable Binds Bile Best.001.jpeg

In my video Breast Cancer and Constipation, I discussed how fruits and veggies bind carcinogenic bile acids in our gut. Since bile acids are absorbed back into our systems, they may increase our risk of not only colon cancer but also other cancers as well. In light of this, researchers publishing in the journal, Nutrition Research, concluded that to "lower the risk of diet and lifestyle-related premature degenerative diseases and to advance human nutrition research, relative bile acid-binding potential of foods and fractions need to be evaluated."

They found that some vegetables bind bile acids better than others. We know that those eating more plant-based diets are at a lower risk of heart disease and cancer. This could partly be because of phytonutrients in plants that act as antioxidants and potent stimulators of natural detoxifying enzymes in our bodies. Veggies can also lower cholesterol and detoxify harmful metabolites, functions that can be predicted by their ability to bind bile acids.

A group of USDA researchers studying this topic discovered three important things. First, they found an over five-fold variability in bile acid binding among various vegetables that had similar fiber content, suggesting that bile acid binding is not just related to total dietary fiber content (as previously thought), but instead some combination of unique phytonutrients yet to be determined.

Second, they discovered that steaming significantly improves the bile acid binding of collards, kale, mustard greens, broccoli, peppers, cabbage, beets, eggplant, asparagus, carrots, green beans, and cauliflower, suggesting that in this way steaming vegetables may be more healthful than those consumed raw.

Finally, they ranked multiple vegetables for bile binding ability. Which vegetables kicked the most bile butt? (in my video, Which Vegetable Binds Bile Best?, you can see a visual comparison of bile binding ability.) Turnips turned up last. Then came cabbage, cauliflower, bell peppers, spinach, asparagus and green beans. Mustard greens and broccoli were better. Eggplant, carrots and Brussels sprouts basically tie for the #5 slot. Then collards at #4. Kale got the bronze, okra the silver, and beets the gold. Kale, surprisingly, got beet.

The researchers concluded that inclusion of all these vegetables in our daily diets should be encouraged. When consumed regularly, they concluded, these vegetables may lower the risk of premature degenerative diseases and improve public health.

More raw versus cooked comparisons in

Beets also have a number of other remarkable properties. Check out my video series on Doping with Beet Juice as well as Hearts Shouldn't Skip a Beet, and Whole Beets vs. Juice for Improving Athletic Performance.

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 Uprooting the Leading Causes of Death, More Than an Apple a Day, From Table to Able, and Food as Medicine.

Image Credit: Robert Couse-Baker / Flickr

Original Link

Why Deep Fried Foods May Cause Cancer

NF-Jul21 Cancer Risk from French fries.jpg

In the latest study on dietary patterns and breast cancer risk among women, healthier eating was associated with eliminating three-quarters of the odds of breast cancer, whereas less healthy eating was associated with up to nearly eight times the odds. Included in the unhealthy eating pattern was the consumption of deep-fried foods, which have previously been linked to breast cancer, pancreatic cancer, lung cancer, oral and throat cancers, esophageal cancer, and cancer of the voicebox. No deep fried foods? What's a Southern belle to do? Instead of deep fried foods, how about the traditional Southern diet, characterized by high intakes of cooked greens, beans, legumes, cabbage, sweet potatoes and cornbread, which may reduce the risk of invasive breast cancer significantly.

What about the consumption of deep-fried foods and risk of prostate cancer? Researchers at the Fred Hutchinson Cancer Research Center and the University of Washington found that eating French fries, fried chicken, fried fish, and doughnuts was associated with about a third greater odds of prostate cancer. After stratifying for tumor aggressiveness, they found slightly stronger associations with more aggressive disease, suggesting that regular intake of deep-fried foods may contribute to the progression of prostate cancer as well.

What in deep fried foods is so bad for us? Just heating oil that hot can generate potentially carcinogenic compounds, and then known carcinogens such as heterocyclic amines and polycyclic aromatic hydrocarbons form when the muscles of chickens and fish are cooked at that temperature. Deep-fried plants, on the other hand, can form acrylamide.

I did a video about acrylamide back in 2008, suggesting it's a probable human carcinogen (See Acrylamide in French Fries). Since then, studies have suggested pregnant women may want to cut back on French fries to protect the growth of their baby's body and brain. Based on a study (highlighted in my video, Cancer Risk from French Fries) feeding people a little bag of potato chips every day for a month, it now seems acrylamide may also cause inflammation as well, which could explain its purported role in cancer progression.

Acrylamide intake has been associated with endometrial cancer, ovarian cancer, lung cancer, kidney cancer, and esophageal cancer. How much cancer risk are we talking about? Taiwanese researchers examined lifetime cancer risk and French fry consumption. The researchers picked on French fries because they comprise by far the greatest percentage contribution of acrylamide to the diets of children. They estimated that, at most, one or two boys and girls out of every ten thousand would develop cancer eating French fries that they would otherwise not have developed if they hadn't eaten French fries. So it's not as bad as eating something like fried fish, or fried chicken, but how much is that saying?

The level of cancer risk in both boys and girls associated with French fries depends on how long and hot they're fried. In Europe, the food industry swore that they'd self-regulate and control fry times to decrease acrylamide levels, but we've yet to see any subsequent change in acrylamide levels in French fries.

Researchers continue to urge that the cooking temperature should be as low as possible and the cooking time should be as short as possible, "while still maintaining a tasty quality" of course. We wouldn't want to reduce cancer risk too much--they might not taste as good!

Blanching the potatoes first reduces acrylamide formation, but potato chip companies complain that, not only would it muck with the flavor, but it would reduce the nutritional properties by leaching away some of the vitamin C. But if we're relying on potato chips to get our vitamin C, acrylamide is probably the least of our worries.

More on heterocyclic amines:

There are some things we can do to counteract the effects of these carcinogens, though:

I touch on polycyclic aromatic hydrocarbons in Meat Fumes: Dietary Secondhand Smoke and Is Liquid Smoke Flavoring Carcinogenic?
Certain fats may play a role in breast cancer survival as well: Breast Cancer Survival, Butterfat, and Chicken and Breast Cancer Survival and Trans Fat.

-Michael Greger, M.D.

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

Image Credit: Kim Love / Flickr

Original Link

Living Longer by Reducing Leucine Intake

NF-June16 How What We Eat (And Don't Eat) Impacts How We Age.jpg

Many studies have shown that calorie restriction, without malnutrition, can increase lifespan and lower the risk of age-related diseases, such as cancer.

However, for many people, calorie restriction clearly has its drawbacks. In the classic Minnesota Starvation Study, many of the volunteers suffered a preoccupation with food, constant hunger, binge eating, and lots of emotional and psychological issues. Even researchers who study caloric restriction rarely practice it. There's got to be a better way to suppress the aging engine enzyme, TOR (see Why Do We Age? for more on TOR).

That's why researchers were so excited about rapamycin, a drug that inhibits TOR, thinking it could be caloric restriction in a pill. But like any drug, it a long list of potentially serious side effects. There's got to be a better way.

The breakthrough came when scientists discovered that the benefits of dietary restriction may be coming not from restricting calories, but from restricting protein intake (See my video Caloric Restriction vs. Animal Protein Restriction). If we look at the first comprehensive, comparative meta-analysis of dietary restriction, "the proportion of protein intake was more important for life extension than the degree of caloric restriction." In fact, just "reducing protein without any changes in calorie level have been shown to have similar effects as caloric restriction."

That's good news. Protein restriction is much less difficult to maintain than dietary restriction, and it may even be more powerful because it suppresses both TOR and IGF-1, the two pathways thought responsible for the dramatic longevity and health benefits of caloric restriction.

Some proteins are worse than others. One amino acid in particular, leucine, appears to exert the greatest effect on TOR. In fact, just cutting down on leucine may be nearly as effective as cutting down on all protein. Where is leucine found? Predominantly animal foods: eggs, dairy, and meat (including chicken and fish). Plant foods, such as fruits, vegetables, grains, and beans, have much less.

"In general, lower leucine levels are only reached by restriction of animal proteins." To reach the leucine intake provided by dairy or meat, we'd have to eat nine pounds of cabbage--about four big heads--or 100 apples. These calculations exemplify the extreme differences in leucine amounts provided by a conventional diet in comparison to a plant-based diet. The functional role of leucine in regulating TOR activity may help explain the extraordinary results reported in the Cornell-Oxford-China Study, "since quasi-vegan diets of modest protein content tend to be relatively low in leucine."

This may also help explain the longevity of populations like the Okinawa Japanese, who have about half our mortality rate. The traditional Okinawan diet is only about 10% protein, and practically no cholesterol, because they ate almost exclusively plants. Less than one percent of their diet was fish, meat, eggs, and dairy - the equivalent of one serving of meat a month and one egg every two months. Their longevity is surpassed only by vegetarian Adventists in California, who have perhaps the highest life expectancy of any formally studied population in history.

This reminds of the study I profiled in The Benefits of Caloric Restriction Without the Actual Restricting.

Methionine is another amino acid that may be associated with aging. See Methionine Restriction as a Life Extension Strategy to find out which foods to avoid in that case. Both leucine and methionine content may be additional reasons why Plant Protein is Preferable.

Other reasons why those eating plant-based diets may live longer:

This all may help explain the results of Harvard's Meat and Mortality Studies.

-Michael Greger, M.D.

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

Image Credit: hslo / Flickr

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Currant Treatment for Glaucoma

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In my video, Dietary Prevention for Age-Related Macular Degeneration, I discussed how eating goji berries with nuts and seeds can help build up yellow plant pigments such as lutein and zeaxanthin in our eyes to help fight age-related macular degeneration.

But once we've preserved the pigment in our retinal pigment epithelial cells, we need to keep them alive. This may be where anthocyanin phytonutrients come in. Anthocyanins (from the Greek anthos, meaning flower, and kyanos, meaning blue) are natural plant pigments that make pansies look purple and turn green cabbage into purple cabbage, yellow corn into purple corn, brown rice to purple rice, white potatoes to blue potatoes, orange carrots to purple carrots, and keeps blueberries blue and blackberries black.

As we age, our critical retinal pigment epithelium (RPE) layer starts to break down. However, we may be able to decelerate that aging with blueberries. In the study I profile in my video, Dietary Treatment of Glaucoma, human RPE cells bathed in blueberry anthocyanins had fewer free radicals and a lower proportion of aged cells, suggesting that blueberries and other red, blue, and purple pigmented fruits and vegetables may help prevent age-related macular degeneration. Blueberries may be especially important for blue eyes, as can be seen in my video Greens vs. Glaucoma.

Preventing disease is nice, but what if we already have a disease like glaucoma, an incurable eye disease in which our optic nerve (which connects our eyes to our brain) starts deteriorating, and we start losing our visual fields?

A few years ago, Japanese researchers showed they could apparently halt the progression of glaucoma with black currants. They gave people black currants for six months and found that black currants significantly boosted the blood flow to their optic nerve. The results suggest that black currants might be a safe and valuable option, but because the study was not double-blind and there was no control group, I didn't report on it when it was initially published. But now we've got just such a study. Glaucoma patients were split into two groups--half got black currants; the other half didn't.

The study measured the deterioration of the patients' visual fields in both groups in the two years leading up to the study. Despite taking the best glaucoma drugs on the market, the subjects' visual fields deteriorated. Then the study starts. The berry-free control group continued to worsen, but the berries appeared to stop the disease in its tracks after both one and two years. And since there's no downside to berries (only good side-effects), in my professional opinion everyone with glaucoma should be eating berries every day.

For more on the latest science on preventing and treating vision loss, check out Greens vs. Glaucoma, where I detailed the best foods to help prevent glaucoma. My previous treatment of glaucoma can be found here: Prevent Glaucoma and See 27 Miles Farther.

I've mentioned anthocyanins before in:

They may be why purple potatoes (Anti-Inflammatory Effects of Purple Potatoes) and purple cabbage (Superfood Bargains) may be preferable. Anthocyanins are the pigments in red and purple cabbage that allow for the kitchen chemistry in Testing Your Diet with Pee & Purple Cabbage.

More on currants in Enhanced Athletic Recovery Without Undermining Adaptation.

-Michael Greger, M.D.

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

Image Credit: Rachel / Flickr

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Our Immune System Uses Plants To Activate Gut Protection

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It might seem that our skin is the first line of defense between our insides and the outside world, but our greatest interface with our environment is actually through the lining of our intestines, which covers thousands of square feet. And all that separates our gut from the outer world is a single layer of cells, 50 millionth of a meter thick - less than the thickness of a sheet of paper.

Compare that to our skin. In the video, The Broccoli Receptor: Our First Line of Defense, you can see a layer of skin, dozens of protective cells thick, to keep the outside world outside of our bodies. Why don't we have multiple layers in our gut wall? Because we need to absorb stuff from food into our body. It's a good idea for our skin to be waterproof, so we don't start leaking, but the lining of our gut has to allow for the absorption of fluids and nutrients.

With such a thin, fragile layer between our sterile core and outer chaos, we better have quite a defense system in place. Indeed, that's where "intraepithelial lymphocytes" come in.

Intraepithelial lymphocytes serve two functions: they condition and repair that thin barrier, and they provide a front-line defense against intestinal pathogens. These critical cells are covered with Ah receptors. Ah receptors are like locks, and for decades researchers have been searching for a natural key to fit in these locks to activate those receptors and sustain our immunity. We recently discovered a key: broccoli.

Cruciferous vegetables--broccoli, kale, cauliflower, cabbage, Brussels sprouts--contain a phytonutrient that is transformed by our stomach acid into the key that fits into the Ah receptor, stimulating our intraepithelial lymphocytes. In other words, broccoli leads to the activation of our immune foot soldiers.

In an editorial about Ah receptors and diet, researcher Lora V. Hooper from the Howard Hughes Medical Institute noted, "From childhood we learn that vegetables are good for us, and most of us eat our veggies without giving much thought to the evidence behind this accepted wisdom or to the mechanisms underlying the purported health-boosting properties of a vegetable-rich diet." But now we know that "specific dietary compounds found at high levels in cruciferous vegetables such as broccoli, cauliflower, and cabbage are essential for sustaining intestinal immune function." Green vegetables are in fact required to maintain a large population of those protective intraepithelial lymphocytes.

Maybe that's why vegetable intake is associated with lower risk of inflammatory bowel diseases such as ulcerative colitis, whereas the more meaty Western diet is associated with higher risk of inflammatory bowel diseases. This may be because the activating receptors on our intestinal immune cells are basically sensors of plant-derived phytochemicals.

This raises a broader question: Why did our immune system evolve this requirement for broccoli and other plant foods? Well, when do we need to boost our intestinal defenses the most? When we eat! That's when we may be ingesting pathogens. Linking heightened intestinal immune activation to food intake could serve to bolster immunity precisely when it is needed. At the same time, this would allow energy to be conserved in times of food scarcity, since maintaining these defenses takes considerable amounts of energy. Why remain at red alert 24 hours a day when we eat only a couple of times a day? We evolved for millions of years eating mostly weeds--wild plants, dark green leafy vegetables (or as they were known back then, leaves). By using veggies as a signal to upkeep our immune system, our bodies may be bolstering our immune defenses when we most need them. Thus, the old recommendation to "eat your veggies" has a strong molecular basis. (Did we really evolve eating that many plant foods? See my video Paleolithic Lessons).

This discovery has been all exciting for the drug companies who are looking into Ah receptor active pharmaceuticals. "However," as one research team at Cambridge concluded, "rather than developing additional anti-inflammatory drugs, changing diets which are currently highly processed and low in vegetable content, may be a more cost effective way towards health and well-being."

As remarkable as this story is, it is just the tip of the cruciferous iceberg! See, for example:

How else can we protect our immune function? Exercise (Preserving Immune Function In Athletes With Nutritional Yeast) and sleep (Sleep & Immunity)!

Given the variety and flexibility of most mammalian diets, a specific dependence on cruciferous vegetables for optimal intestinal immune function would seem overly restrictive, no? I address that in my video, Counteracting the Effects of Dioxins

-Michael Greger, M.D.

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

Images thank to Nomadic Lass / Flickr.

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