How Much Water Should We Drink Every Day?

How Much Water Should We Drink Every Day?.jpeg

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

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

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

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

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

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

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

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

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

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

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

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

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

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

In health,

Michael Greger, M.D.

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

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

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How Much Water Should We Drink Every Day?

How Much Water Should We Drink Every Day?.jpeg

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

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

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

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

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

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

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

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

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

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

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

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

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

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

In health,

Michael Greger, M.D.

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

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

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Fast Food Restaurants in Children’s Hospitals

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The food industry spends billions on advertising. Promotion costs for individual candy bars can run in the tens of millions. McDonald's alone spends a billion dollars on advertising every year. Such figures dwarf the National Cancer Institute's million dollar annual investment promoting fruit and vegetable consumption or the 1.5 million spent on cholesterol education. That McBillion goes a long way.

Children's food preferences are being molded by McDonald's even before they learn to tie their shoelaces. By the early age of three to five years, preschoolers preferred the taste of foods and drinks if they thought they were from McDonald's. This was true even for carrots--baby carrots placed in a bag with McDonald's logo reportedly tasted better. And if they get sick, children can continue to eat McDonald's in the hospital.

Nearly 1 in 3 children's hospitals have a fast food restaurant inside, leading parents to have more positive perceptions of the healthiness of McDonald's food (See Hospitals Selling Sickness). They can also just buy the naming rights altogether: The Ronald McDonald Children's Hospital, for example. In teaching hospitals, though, Krispy Kreme tops the list. Hospitals may wish to revisit the idea of serving high-calorie fast food in the very place where they also care for the most seriously ill.

This is reminiscent of the fight against tobacco back in the 1980's when public health advocates made radical suggestions, such as not selling cigarettes in hospitals. By working to make our hospitals ultimately smoke-free, we become part of a global campaign to completely eliminate the tobacco scourge. The task is difficult, but so was eradicating smallpox. Maybe it's time to stop selling sickness in hospitals.

For more on health entities appeasing the junk food industry, see my video Collaboration With the New Vectors of Disease. Even the Academy of Nutrition and Dietetics, the registered dietitian organization, has quite the shady history which I document near the end of my 2014 annual review presentation From Table to Able.

Even cynical me was surprised by my profession's hostility towards nutrition. 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: davef3138 / Flickr

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What To Do if You Suspect Gluten Problems

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Symptoms of gluten sensitivity include irritable bowel type symptoms such as bloating, abdominal pain, and changes in bowel habits, as well as systemic manifestations such as brain fog, headache, fatigue, depression, joint and muscle aches, numbness in the extremities, skin rash, or anemia. I previously discussed why people who suspect they might be gluten sensitive should not go on a gluten-free diet. But if that's true, what should they do?

The first thing is a formal evaluation for celiac disease, which currently involves blood tests and a small intestinal biopsy. If the evaluation is positive, then a gluten-free diet is necessary. If it's negative, it's best to try a healthier diet with more fruits, vegetables, whole grains and beans while avoiding processed junk. In the past, a gluten-free diet had many benefits over the traditional American diet because it required increasing fruit and vegetable intake--so no wonder people felt better eating gluten-free: no more unhealthy bread products, no more fast food restaurants. Now, there is just as much gluten-free junk out there.

If a healthy diet doesn't help, then the next step is to try ruling out other causes of chronic gastrointestinal distress. In a study of 84 people who claim gluten causes them adverse reactions (they're referred to in the literature as"PWAWGs," People Who Avoid Wheat and/or Gluten), highlighted in my video, How to Diagnose Gluten Intolerance, about a third didn't appear to have gluten sensitivity at all. Instead, they either had an overgrowth of bacteria in their small intestine, were fructose or lactose intolerant, or had a neuromuscular disorder like gastroparesis or pelvic floor dysfunction. Only if those are also ruled out, would I suggest people suffering from chronic suspicious symptoms try a gluten-free diet. If symptoms improve, stick with it and maybe re-challenge with gluten periodically.

Unlike the treatment for celiac disease, a gluten-free diet for gluten sensitivity is ideal not only to prevent serious complications from an autoimmune reaction, but to resolve symptoms and try to improve a patient's quality of life. However, a gluten-free diet itself can also reduce quality of life, so it's a matter of trying to continually strike the balance. For example, gluten-free foods can be expensive, averaging about triple the cost. Most people would benefit from buying an extra bunch of kale or blueberries instead.

No current data suggests that that general population should maintain a gluten-free lifestyle, but for those with celiac disease, a wheat allergy, or a sensitivity diagnosis, gluten-free diets can be a lifesaver.

For more on gluten, check out Is Gluten Sensitivity Real? and Gluten-Free Diets: Separating the Wheat from the Chat.

Some food strategies that may help with irritable bowel symptoms are covered in a few of my previous videos, such as Kiwifruit for Irritable Bowel Syndrome and Cayenne Pepper for Irritable Bowel Syndrome and Chronic Indigestion.

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: Jeremy Segrott/ Flickr

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How Learning to Cook Can Save Your Life

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The eating habits of modern Americans have been described as, "eating breakfast in their cars, lunch at their desks and chicken from a bucket." Within the last few decades, Americans are eating out more and more, and cooking fewer meals at home, which are typically healthier. Home-cooled meals tend to contain less saturated fat, cholesterol, and sodium, and more fiber. Therefore, the benefits to preparing healthy food at home may include the prevention of chronic disease. Just because food is prepared at home doesn't mean it's healthy, though. Microwaving a frozen pizza isn't exactly home cooking.

One of the problems is many people no longer know how to cook. For example, one study reported that 25% of the men in the study had absolutely no cooking skills whatsoever. Another study in the UK compared the nutritional content of meals created by television chefs to TV dinners, and both were then compared to the nutritional guidelines published by the World Health Organization. The researchers looked at a hundred of each, and not a single one complied with the nutrition standards. And the TV chef recipes were even less healthy than the TV dinners!

Many people don't know how to make healthy food taste good. This is not a new problem; an editorial in the Journal of the American Medical Association bemoaned the same issue back in 1913. In the United States, "vegetables are frequently boiled in a way which deprives them of their characteristic odor and their toothsomeness. 'Villainous and idiotic' are the only adjectives that can describe our methods of cooking vegetables."

Researchers in Taiwan recently found that in a group of elderly Taiwanese people, those who cooked their own food were not only healthier, but also lived longer. In a ten year study, highlighted in my video, Cooking to Live Longer, those who cooked most frequently had only 59% of the mortality risk. This took into account the exercise people got grocery shopping, physical function, and chewing ability. So why did they live longer? Those that cooked typically ate a more nutritious diet with a higher consumption of vegetables.

The effect on mortality was much more evident in women than in men. It turns out that "men were, with doubtful justification, more positive about the nutritional value of convenience foods compared with women." Women who cooked made better food choices in general.

As one author noted in the book Something from the Oven, over the last century:

"we began the long process of turning over to the food industry many of the decisions about what we eat...Today our staggering rates of obesity and diabetes are testimony to the faith we put in corporations to feed us well. But the food industry is a business, not a parent; it doesn't care what we eat as long as we're willing to pay for it. Home cooking these days has far more than sentimental value; it's a survival skill."

With the onslaught of health information out there, access to simple, healthy recipes has never been easier. While cooking at home requires more effort, energy, and cleaning, the results, health aside, are often more rewarding. Learning to cook is a simple art, and with the right amount of patience and delicious ingredients, it can help us take back control of our own lives.

Check out your local public library for cookbooks--I've been amazed at the selection in all of the cities I've lived. Or for those for which books are just so 20th century, the online Rouxbe Cooking School holds healthy cooking classes.

More on fast food:

Some other unsavory bits about the food industry:

I think this is the only other mention of celebrity chefs I have:
Paula Deen: diabetes drug spokesperson

-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.

Picture by Moyan Brenn on Flickr

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Coca-Cola Stopped Sponsoring the Academy of Nutrition and Dietetics

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The American Dietetic Association (ADA) is the world's largest association of nutrition professionals. They claim to be devoted to "improving the nation's health." They promote a series of Nutrition Fact Sheets. Who writes them? Industry sources pay $20,000 per fact sheet to the ADA and explicitly take part in writing the documents. The ADA then promotes them through its journal and on its website.

Some of these fact sheets are "What's a Mom to Do: Healthy Eating Tips for Families" sponsored by Wendy's; "Lamb: The Essence of Nutrient Rich Flavor," sponsored by the Tri-Lamb Group; "Cocoa and Chocolate: Sweet News" sponsored by the Hershey Center for Health and Nutrition; "Eggs: A Good Choice for Moms-to-Be" sponsored by the American Egg Board's Egg Nutrition Center; "Adult Beverage Consumption: Making Responsible Drinking Choices" in connection with the Distilled Spirits Council; and "The Benefits of Chewing Gum" sponsored by the Wrigley Science Institute. For visuals, see Academy of Nutrition and Dietetics Conflicts of Interest.

Did you know there was a Wrigley Science Institute?

In 2008, the ADA announced that the Coca-Cola Company had become an "ADA Partner" through its corporate relations sponsorship program. The ADA "provides partners a national platform via ADA events and programs with prominent access to key influencers, thought leaders and decision makers in the nutrition marketplace." The ADA's press release also pointed out that "the Coca-Cola Company will share their research findings with ADA members in forums such as professional meetings and scientific publications." For example, did you know there are "No Harmful Effects of Different Coca-Cola Beverages on Rat Testicles?" Was that even a concern? Thou doth protest too much methinks...

When the American Academy of Pediatrics was called out on their proud new corporate relationship with Coke to support patient education on healthy eating, an executive vice-president of the Academy tried to quell protest by explaining that this alliance was not without precedent. The American Academy of Pediatrics has had relationships with Pepsi and McDonald's for some time. This is reminiscent of similar types of relationships in the past, like doctors promoting cigarette smoking.

The fact that the Academy of Pediatrics was also collaborating with Pepsi and McDonald's didn't seem to placate the critics. So the executive continued, noting that the American Dietetic Association has made a policy statement that "There are no good or bad foods." Indeed, that's the ADA's official position, "classification of specific foods as good or bad is overly simplistic."

One commentator asks, "Is this what [family doctors] have been reduced to...? To justify an unholy financial alliance we hide behind what others say and do and deny that there are actually unhealthy, 'bad' foods. I wonder how much money the ADA receives from the Coca-Cola Company and other food and beverage companies to have come up with this counter-intuitive 'no good or bad foods' philosophy?"

In 2012, the American Dietetic Association changed their name to the Academy of Nutrition and Dietetics. Did their policies change at all? A landmark report from one of my favorite industry watchdogs, Michele Simon, found that they continue to take millions of dollars in corporate sponsorship money every year from meat, processed junk, dairy, soda, and candy bar companies, and in return offer official educational seminars to teach dietitians what to say to their clients. So when you hear the title "registered dietitian," this is the group they're forced to be registered through. Thankfully there are also Dietitians for Professional Integrity.

After giving millions of dollars to the Academy of Nutrition and Dietetics, Coca Cola has apparently withdrawn sponsorship. It's not enought o disclose conflicts of interest; we should strive to eliminate them in medical and nutrition research.

For more on the corrosive effect of money and politics in nutrition, see:

There are lots of evidence-based dietitians, such as Brenda Davis, Jeff Novick, and Julieanna Hever--not to mention our very own Joseph Gonzales!

-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: Piotr Drabik / Flickr

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What Do Eggs Do To Our Arteries?

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In reaction to the study that found a similar exponential increase in artery clogging plaque in both smokers and egg eaters, one critic countered that eggs have beneficial effects on vascular endothelium, the inner lining of our arteries, citing a 2005 study on egg consumption and endothelial function, funded by the American Egg Board (highlighted in my video, Eggs and Arterial Function).

The study was done on a group of men and women eating the standard American diet, were overweight, had "normal" cholesterol, (which is to say extremely high cholesterol--LDL levels twice as high as could be considered optimal). As the authors of a paper published in the Journal of the American College of Cardiology note, it's often not appreciated "that the average blood cholesterol level in the United States, the so-called normal level, was actually too high," accelerating heart disease and "putting a large fraction of the so-called normal population at a higher risk" for coronary heart disease, our number one killer.

If we threw a lit match into a flaming pool of gasoline and saw no real difference in the height of the flames, we can't conclude that throwing lit matches into gasoline is not a fire hazard. But that is exactly what the Egg Board study concluded. When the addition of eggs didn't make the arterial function worse than it already was, they concluded that "short-term egg consumption does not adversely affect endothelial function in healthy adults."

The egg board paid for a follow-up study using folks who were even worse off, with a mean total cholesterol of 244. They reported that egg consumption had no effect on endothelial function... as compared to sausage and cheese. Yet instead of sounding the alarm that eating eggs is as bad for arterial function as a McDonald's Sausage McMuffin (!), the researchers concluded that egg consumption was found to be non-detrimental to endothelial function and cholesterol levels. The subjects started out with life-threatening cholesterol, and ended up with life-threatening cholesterol.

Why don't endothelial function and cholesterol levels get even worse? Because there's a plateau effect. We can basically max out on our cholesterol absorption. After a certain level of intake, it's just another match to the fire. If we're already consuming the standard American diet averaging 400mg of cholesterol daily, even adding two jumbo eggs to our diet may not have a sizeable impact. But to people trying to eat healthy, those two eggs could shoot their cholesterol up 20 points.

However, a fat-free, cholesterol-free egg substitute was found to be beneficial. That is, not eating eggs lowers cholesterol levels and improves endothelial function--and that's what these people needed. Their arteries were already hurting, they needed something to bring the fire down, not more matches. The subjects were apparently eating so unhealthy that adding eggs couldn't make things much worse, but eating oatmeal instead of eggs made things better, helping to quench the fire. So even the Egg Board-funded studies said that not eating eggs is better for our arteries, yet these are the same studies that pro-egg folks cite to claim beneficial vascular effects.

More on the reaction to the Eggs vs. Cigarettes in Atherosclerosis study in my video, Debunking Egg Industry Myths, as well as further discussion of the effects of the cholesterol in eggs on the cholesterol levels in the blood of egg consumers. More on that in:

I previously featured a food that actually does benefit vascular function. See Walnuts and Artery Function. Though the nut industry did try a similar tactic, see my video Nuts and Bolts of Cholesterol Lowering. The beef, soda, and dairy industries may also be guilty of experimental manipulation. See BOLD Indeed: Beef Lowers Cholesterol and Food Industry "Funding Effect".

In health,
Michael Greger, M.D.

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

Image Credit: Pietro Bellini / Flickr

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What’s Driving America’s Obesity Problem?

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Currently, nearly two-thirds of Americans are overweight. By 2030 it is estimated more than half our population may be clinically obese. Childhood obesity has tripled, and most children will grow up to be overweight as well. The United States may be in the midst of raising the first generation since our nation's founding that will have a shorter predicted life span than that of the previous generation.

The food industry blames inactivity. We just need to move more, they say. But what is the role of exercise in the treatment of obesity?

"There is considerable debate in the medical literature today about whether physical activity has any role whatsoever in the epidemic of obesity that has swept the globe since the 1980s." The increase in calories per person is more than sufficient to explain the U.S. epidemic of obesity. In fact, if anything, the level of physical activity over the last few decades has actually gone up in both Europe and North America.

This has important policy implications. We still need to exercise more, but the priorities for reversing the obesity epidemic should focus on the overconsumption of calories (See How Much Exercise to Sustain Weight Loss?). American children are currently eating about an extra 350 calories (equal to about a can of soda and small fries), and adults are eating about an extra 500 calories (equal to about a Big Mac). We'd have to walk two hours a day, seven days a week to burn off those calories. So exercise can prevent weight gain, but the amount required to prevent weight gain may be closer to twice the current recommendations. It's more effective to stick to foods rich in nutrients but poor in calories: see my video Calculate Your Healthy Eating Score. It's cheaper too, see Best Nutrition Bang For Your Buck.

Public health advocates have been experimenting with including this kind of information. One study found that fast food menus labeled with calories and the number of miles to walk to burn those calories appeared the most effective in influencing the selection of lower calorie meals.

Exercise alone may have a small effect, and that small effect can make a big difference on a population scale. A 1% decrease in BMI nationwide might prevent millions of cases of diabetes and heart disease and thousands of cases of cancer. But why don't we lose more weight from exercise? It may be because we're just not doing it enough. "The small magnitude of weight loss observed from the majority of exercise interventions may be primarily due to low doses of prescribed exercise."

People tend to overestimate how many calories are burned by physical activity. For example, there's this myth that a bout of sexual activity burns a few hundred calories. So may think, "Hey, I could get a side of fries with that." But if we actually hook people up and measure energy expenditure during the act (and the study subjects don't get too tangled up with all the wires and hoses) it may be only close to the metabolic equivalent of calisthenics. Given that the average bout of sexual activity only lasts about six minutes, a young man might expend approximately 21 calories during sexual intercourse. Due to baseline metabolic needs, he would have spent roughly one third of that just lying around watching TV, so the incremental benefit is plausibly on the order of 14 calories. So maybe he could have one fry with that.

I previously touched on this in my video Diet or Exercise, What's More Important For Weight Loss?

Don't get me wrong--exercise is wonderful! Check out, for example:

-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: Glamhag / Flickr

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What is Actually in Chicken Nuggets?

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In a scathing expose of the USDA's new meat inspection program, the Washington Post quoted a representative from the meat inspectors union, who said:

"pig processing lines may be moving too quickly to catch tainted meat... Tremendous amounts of fecal matter remain on the carcasses. Not small bits, but chunks."

What about the other white meat?

In the video, Autopsy of Chicken Nuggets, you can see an infographic the Physician's Committee for Responsible Medicine created to highlight what they consider to be the five worst contaminants in chicken products. In their investigation of retail chicken products in ten U.S. cities, they found fecal contamination in about half the chicken they bought at the store. But with all the focus on what's in chicken products, we may have lost sight on what may be missing--such as actual chicken.

Researchers from the University of Mississippi Medical Center and the Baptist Medical Center recently published an "autopsy" of chicken nuggets in the American Journal of Medicine. The purpose was to determine the contents of chicken nuggets from two national food chains. Because chicken nuggets are popular among children, the researchers thought that parents should know more about what they may be feeding to their kids.

The nugget from the first restaurant was composed of approximately 50% skeletal muscle, with the remainder composed primarily of fat, blood vessels and nerves, and generous quantities of skin or gut lining and associated supportive tissue. The nugget from the second restaurant was composed of approximately 40% skeletal muscle with lots of other tissues, including bone.

"I was floored," said the lead investigator. "I had read what other reports have said is in them and I didn't believe it. I was astonished actually seeing it under the microscope." I profile some of those other pathology reports in my videos What's in a Burger? and What Is Really in Hot Dogs?

The researchers concluded that since actual chicken meat was not the predominant component of either nugget, the term "chicken" nugget was really a misnomer.

If we're going to eat something chicken-ish that isn't chicken meat, why not truly boneless chicken: Chicken vs. Veggie Chicken.

More on fecal contamination of chicken in Fecal Bacteria Survey, of fish in Fecal Contamination of Sushi, and of pork in Yersinia in Pork. How can that be legal? See Salmonella in Chicken & Turkey: Deadly But Not Illegal.

More on the preservatives in chicken in Phosphate Additives in Meat Purge and Cola and antibiotic contamination in Drug Residues in Meat.

Estrogenic Cooked Meat Carcinogens also build up in poultry in particular, something the Physicians Committee also tested for previously: Fast Food Tested for Carcinogens.

-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: Jacob Enos / Flickr

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Where are Phosphate Additives Found?

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In my videos Phosphate Additives in Meat Purge and Cola and Phosphate Additives in Chicken, I talked about the danger of phosphate and phosphate additives, and how phosphates are often added to chicken and turkey to help preserve the meat. But how often is poultry injected with phosphates? The vast majority of chicken products (more than 90%) were found to contain these additives. However, most packages did not list the additives on their label.

Sometimes they call the phosphate additives "flavorings" or "broth," and sometimes the labels don't say anything at all. In the video, How to Avoid Phosphate Additives, you can see the different ways phosphate additives have been listed (if they are listed at all) on ingredient labels. I'd recommend minimizing one's intake of anything with the four letters: "phos". These additives are also used in junk foods and fast food. Some products have phosphorus and aluminum additives. We see this a lot in processed cheeses. One grilled cheese sandwich may exceed the World Health Organization's provisional tolerable daily intake of aluminum by 428%. (I've previously touched on the aluminum in cheese in Aluminum in Vaccines vs. Food). More concerning, though, are the levels of lead in some venison (Filled Full of Lead) and mercury in tuna (The Effect of Canned Tuna on Future Wages).

The food industry no longer has to list phosphorus content on the nutrition facts label. There have been calls from the public health community to mandate that phosphorus content of foods be included back on the nutrition facts label, but I'm not holding my breath.

All these studies bring home the same strong message, "phosphorus-containing additives are present in most meat products and significantly increase the phosphorus content. Moreover, the lack of this information in the Nutrition Facts labels and even in nutrition databases prevents patients and dietitians from accurately estimating the phosphorus content of their food and their daily intake."

-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 thanks to Sylvar / Flickr

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