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Tuesday, February 28, 2012

Low-Fat, High-Carb Diets Reverse Insulin Resistance

Dr. George Lundberg, the former editor-in-chief of JAMA, graciously invited me to coauthor this editorial on how starchy, low-fat diets reverse insulin resistance!

Monday, February 27, 2012

High-Calcium Diets Probably Cause Osteoporosis

At least every 5 years, the U.S. Department of Agriculture and the U.S. Department of Health and Human Services are required by federal law to issue Dietary Guidelines for Americans. According to the law, these guidelines are supposed to be based on the best available science. Yet some of their recommendations don’t seem to have any basis in science at all. In particular, I think that their recommendations about calcium intake will make the problem of osteoporosis worse, not better.

The USDA claims that Americans aren’t getting enough calcium in their diets and that they need to consume more cow’s milk and other dairy products. Yet why should I imagine that human beings need to drink any cow’s milk at all? Every other animal species on the face of the planet gets enough calcium from its food without drinking any milk at all from another species. Only mammals drink milk, and all they get is their mother’s milk during infancy. In fact, most human beings throughout most of the history of our species didn’t consume any dairy products at all. So why should I imagine that adult human beings need the equivalent of 3 glasses of skim milk every day? It makes no sense.

From what I’ve seen, it's really hard to find any cases of anyone who got sick or had any problems with their bones or teeth because of a low-calcium diet. The human body is actually really good at adapting to a low calcium intake. A review of the literature found that there’s no consistent evidence that dairy products help children build stronger bones and teeth. Worse yet, we've known for more than 20 years that a high-protein, high-calcium diet probably causes osteoporosis. In other words, the USDA is making recommendations that aren't based on the best available science. That is a serious violation of federal law. 

Monday, February 20, 2012

Can Too Much Omega 3 Fatty Acid Promote Cancer?

Lately, many people have been claiming that fish is health food. The American Heart Association and the American Diabetes Association urge people to eat fish. Yet if people follow that advice, they’ll still be at risk for heart disease and diabetes and they might increase their risk for cancer. The omega 3 fatty acids in fish oil can end up in the fatty deposits that clog people’s arteries. Like other fats, they promote insulin resistance. Also, eating too much omega 3 fatty acid could promote cancer by suppressing the immune system. 

Weight Problems
Fats are fattening, and all fats seem to be equally fattening. Each gram of fat provides 9 calories. It doesn’t matter whether the fat is saturated, monounsaturated, or polyunsaturated. If you don’t know which kind of fat is which, click here

Switching from type of fat to another won’t help you lose weight. If you want to have less fat in your body, put less fat in your mouth. 

Type 2 Diabetes
Type 2 diabetes is the body’s desperate attempt to avoid further weight gain. The high blood sugar levels in people with type 2 diabetes result from insulin resistance. In other words, their bodies don’t respond normally to the hormone insulin. Scientists have known since the early 20th century that this problem results from a high-fat diet. The same problem occurs in people who are consuming too much fat from eating fish and olive oil.
Clogged Arteries
All three types of fat—saturated, monounsaturated, and polyunsaturated—can lead to atherosclerosis, which is the buildup of crud inside your arteries. Switching from saturated fat to some other kind of fat doesn’t stop the problem. The best way to stop the crud from building up in your arteries is to eat much less fat (usually <10% of calories). Eating less fat and cholesterol is the most important thing you can do to reduce your total cholesterol levels. Once your total cholesterol levels go below 150 mg/dL, your arteries become self-cleaning. 

People who eat fish instead of beef do tend to have fewer heart attacks. However, it’s because the omega 3 fatty acids in fish act as a blood thinner. Most deadly heart attacks start when a pimple of atherosclerosis in one of the heart’s coronary arteries bursts and causes a blood clot. Blood thinners reduce the ability of the blood to form clots. Taking blood thinners reduces a person’s risk of dying of a blood clot in the heart or brain. However, it increases the person’s risk of bleeding to death after a car accident. It also increases the person’s risk of destructive or deadly bleeding into the brain (hemorrhagic stroke).

Most people think of fat as a calorie source, as fuel. However, the body uses some kinds of fats as raw materials for making other kinds of things. The body uses omega 6 and omega 3 fatty acids to make substances that help to regulate the immune system.

Your body needs small amounts of omega 3 and omega 6 fatty acids, which must come from your food. However, eating too much of these essential fatty acids can suppress the immune system. This leaves the body less able to defend itself against viruses, bacteria, parasites, and cancer.

Getting Just Enough Fat
For most people, the best policy is to keep fat intake to a minimum. The trace amounts of fats found in vegetables and unrefined starches easily meet most people’s fat requirements.

Your body can make all of the saturated fat and monounsaturated fat that it needs. You don’t need to get any saturated or monounsaturated fat at all from your food. There are only two kinds of fat that you need to get from your food. One is an omega 6 fatty acid called linoleic acid. The other is an omega 3 fatty acid called alpha-linolenic acid. These fatty acids come from plants. Even the omega 3 fatty acids in fish came originally from the plants at the bottom of the food chain.

To find people who have a real deficiency of the essential fatty acids, you have to look at hospital patients who were fed nothing but sugar intravenously. Even in those cases, the fat deficiency could be solved by rubbing a little bit of vegetable oil on the patient’s skin.

People who eat a diet based on low-fat, unrefined plant foods automatically get enough of both of the essential fatty acids. If you are worried about getting the ideal balance of omega 3 to omega 6 fatty acids, it’s best to keep your overall fat intake low. You may also want to add a spoonful of ground flaxseed to your cereal in the morning. Flaxseed contains a lot of the omega 3 fatty acid alpha-linolenic acid. Flaxseed is also a good source of soluble fiber, as well as phytonutrients that seem to have an anticancer effect.

Friday, February 17, 2012

The USDA’s “My Plate” Makes No Sense

If you’ve ever watched Sesame Street, you may remember the song about categories: “One of these things is not like the others. One of these things just doesn’t belong.” That song ran through my head when I looked at the USDA’s My Plate food group system. One of the foods groups isn’t like the others and just doesn’t belong. Can you guess which one?

If you guessed protein, you’re right! Four of the food groups represent a type of foodstuff, but protein is a nutrient. Why would anyone sort foods this way?

People often have to sort things into categories for various purposes. The categories that you create depend on what goal you are trying to achieve. If you are doing your laundry, you first sort your clothes into three categories. You can wash some things in the washing machine. You have to wash other things in the sink. Still others have to go to the dry cleaner. You probably sort the machine-washable clothes by whether they go in the regular cycle or the delicates cycle. Unless you don’t mind if your whites turn pink, you should also sort your machine-washable clothes by color. In other words, all of the clothes get sorted into a particular category according to how they get washed. Of course, you’d sort your clothes by different criteria when you are deciding what to wear. You might have some outfits that you wear to work or school, others that you might wear to a nightclub, and still others that you might wear while painting or gardening.

In contrast, the My Plate food group system isn’t a good categorization system for any purpose. Four of the groups represent a type of foodstuff: fruit, vegetables, grains, and dairy. The fifth group represents a nutrient: protein. Why do four of the food groups represent foodstuffs but the other one represents a nutrient that is easily supplied by three of the other food groups? It makes no sense. If you think about what goes into the protein group, the category makes even less sense. 

The protein group is the old “meat” group from the Basic Four Food Groups in disguise. It consists of meat, eggs, fish, and legumes (beans and peas). Yet there’s no good reason to put legumes in the same group with meat, fish, and eggs. Meat, eggs, and fish are all animal tissue. Therefore, they all contain fat and cholesterol but no fiber or carbohydrate. In contrast, legumes are plant tissue. They contain zero cholesterol, only trace amounts of fat, but plenty of fiber and carbohydrate. All of those foods do contain a lot of protein, but protein deficiency is simply not something that people really need to worry about. There’s no need to encourage people to eat high-protein foods, so there’s no need for a “protein” group.

I would never put legumes in the same category as meat, fish, and eggs. The reason is simple. People would be better off if they didn’t eat any meat, fish, or eggs at all. Eating even small amounts of those foods increases the risk of death from chronic disease. In contrast, the world’s healthiest populations tend to eat a lot of beans. So maybe the children’s song is right: “Beans, beans, good for your heart….” 

At first glance, the USDA’s My Plate system looks a lot like the Physicians Committee for Responsible Medicine’s Power Plate. However, the Physicians Committee for Responsible Medicine designed the Power Plate to promote human health, not to sell food products. The Power Plate includes only four categories of food: fruit, vegetables, whole grains, and legumes (beans and peas).

The PCRM’s Power Plate doesn’t include a separate category for protein because you can easily get enough protein by eating vegetables, grains, and beans. The Power Plate doesn’t contain meat or dairy foods, because those foods increase the risk of serious health problems, such as obesity, heart disease, autoimmune disease, and cancer. The Power Plate also excludes refined foods, such as olive oil and corn syrup, which merely provide empty calories. 

Wild gorillas meet their nutritional needs by eating practically nothing but vegetables and a little bit of fruit and a few nuts. These foods provide all of the essential nutrients except for vitamin B12 and vitamin D. Vitamin B12 comes from bacteria, and the body makes its own vitamin D when bright sunshine hits the skin.

Gorillas mainly eat leaves. Leaves provide plenty of protein, as a percentage of calories. However, wild gorillas have to spend about 8 hours a day eating, just to get enough calories. If you don’t want to spend all day eating leaves, add some starchy foods to your diet. That means whole grains, legumes, and starchy roots and tubers, such as potatoes and sweet potatoes. These starchy foods will fill you up but will help you stay slim and healthy.