Choose Healthier Sources of Protein

WE KNOW FAR LESS ABOUT protein in healthy diets and the role it plays in the onset of disease than we do about fats and carbohydrates. Not because protein is unimportant—quite the contrary, it’s very important—but because it has been studied far less intensively than the other main components of food in relation to long-term health and disease. Much of the focus to date has been on the minimum amount of protein that children need for healthy development and that adults need to keep from slowly breaking down their own tissues. Far less attention has been paid to other important questions, like how much protein is best or if it matters whether your protein comes from animal or vegetable sources or whether a high-protein diet is better for losing or controlling weight than a low-fat, high-carbohydrate diet. Intriguing research on soy and weight loss strategies has kindled new interest in protein that is yielding better information.As we wait for the full answer, eating more protein from fish, chicken, and vegetable sources like beans and nuts and getting less from red meat and dairy products is fourth on the list of healthy eating strategies.

In this article from the Food Properties section, we take a look at all the necessary information about this topic. Stay with 4teenweightloss .



Your hair and skin are mostly protein. Ditto your muscles, the oxygen-carrying hemoglobin in your blood, and the multitude of enzymes that keep you alive and active. In fact, your body is home to at least ten thousand different proteins. On the molecular level, proteins are long, intricate chains fashioned from just twenty or so basic building blocks called amino acids. Because our bodies are constantly making new proteins and because we don’t store amino acids as we do fats, we need a near daily supply of protein.
Some dietary proteins are complete, meaning they contain all the amino acids needed to make new protein. Others are incomplete, lacking one or more essential amino acids—ones we can’t make from scratch or convert from other amino acids. Meat, poultry, fish, eggs, and dairy products tend to be good sources of complete proteins, while vegetable protein is often incomplete. That’s why vegetarians need to eat combinations that complement each other, such as rice and beans, peanut butter and bread, tofu and brown rice.


The latest dietary guidelines from the Institute of Medicine set the recommended daily allowance (RDA) for protein at 0.8 grams per kilogram of body weight, or just over 7 grams per 20 pounds. Translated to real body weights, that would mean 50 grams of protein a day for a 140-pound person and almost 65 grams for a 180-pound person. You can hit this goal almost without thinking, given the abundance of protein-containing foods. (See the table below.) For example, a cup of yogurt at lunch and a serving of chicken plus rice and beans for dinner adds up to about 60 grams of protein. Because it is so easy for us to get protein, it’s uncommon for healthy adults in this country to have a protein deficiency.
Aside from the minimum amount of protein needed to keep the body running, there’s little guidance on the ideal amount of dietary protein or the healthiest proportion of calories contributed by protein. Country-to-country comparisons of protein intake and health aren’t much help because diets around the world tend to have similar amounts of protein. In the average American diet, which we tend to think of as meat-centered, about 15 percent of calories come from protein. In the largely vegetarian, rice- based diets that are common throughout Asia, about 12 percent of calories come from protein. (Rice, which we think of as a carbohydrate, is about 8 percent protein.) Other types of human studies haven’t paid that much attention to protein. And diet fads further confuse the issue, with competing claims for high-protein, low- carbohydrate diets and low-protein, high-carbohydrate diets.Until there’s a good reason to change, getting 7–8 grams of protein per twenty pounds of body weight is a good guide for most people.



Protein in general has been linked at one time or another with a variety of chronic diseases. Protein intake probably isn’t intimately related to the development of cancer, though it may influence the role of heart disease, diabetes in children, obesity, and gastrointestinal disorders. Specific proteins in food, the air, and elsewhere are responsible for a variety of allergies, though we don’t discuss that topic in detail here.

Choose Healthier Sources of Protein

• Protein and cancer. There’s no good evidence that eating a little or a lot of protein influences the risk of cancer in humans. You may have heard about low cancer rates in Japan, where the average diet contains a bit less protein, and certainly less animal protein, than the average American diet. In reality, total cancer rates in traditional Japan are about the same as they are here, though the types of cancers that are the most common in each country are different. Several prospective studies have suggested that diets higher in methionine, one of the building blocks of protein, may help reduce risks of colon and possibly breast cancer. Just how much methionine provides maximal benefit remains to be determined. A report from the Nurses’ Health Study suggests that among women who have been diagnosed with breast cancer, those who eat more protein (and thus less carbohydrates) may live longer than those with lower-protein, higher-carbohydrate diets. But this work clearly needs to be confirmed by other research.
• Protein and heart disease. Cutting back on carbohydrates and replacing those calories with protein lowers the levels of triglycerides, which would be good for heart disease and also boosts HDL, the protective form of cholesterol. (The same things happen when you replace carbohydrates with monounsaturated or polyunsaturated fat, so it may well be that levels of blood fats are actually responding to less carbohydrate rather than to more protein or more fat.)


So far, the Nurses’ Health Study is the only large prospective study to have examined the link between dietary protein and cardiovascular disease. Over the course of fourteen years, we asked more than eighty thousand initially healthy women about what they ate. The group of women who ate the most protein, accounting for about a quarter of daily calories, were 25 percent less likely to have had a heart attack or to have died of heart disease than the women who ate the least protein, about 15 percent of calories. It didn’t seem to matter if the protein came from animals or vegetables, and the apparent protective effect applied equally to women on low-fat and high-fat diets. While this needs to be confirmed, it offers strong reassurance that even eating a lot of protein doesn’t harm the heart.
• Protein and diabetes. The amount of protein in the diet doesn’t seem to have an effect on the development of type
2 (adult-onset) diabetes. One or more specific proteins found in cow’s milk may—and I stress the may—play a role in the development of type 1 diabetes in children, one reason cow’s milk isn’t recommended for infants.
• Protein and other chronic diseases. The medical literature is full of reports linking allergic responses to specific protein sources with conditions ranging from arthritis and breathing problems to chronic digestive disorders. Eggs, fish, milk, peanuts, tree nuts, and soybeans are known to cause allergic reactions in some people. A startling and well-documented report published in the New England Journal of Medicine, for example, showed that something in cow’s milk causes an allergic response leading to severe chronic constipation in some young children. In a group of sixty-five toddlers with chronic constipation, two weeks’ worth of soy milk in place of cow’s milk cleared up the problem in two-thirds of the children. A return to cow’s milk led to the return of constipation. What’s more, the “responders” were also more likely to have had constant runny noses, bronchospasm, and skin inflammation when drinking cow’s milk. This may be a sentinel report pointing the way to other links between specific proteins and chronic disease.


The debate over which type of protein is better rumbles on two levels: personal health and environmental health.
• Personal health: In terms of your health, there isn’t enough evidence to argue that one type of protein is better for you than another. Worldwide surveys of protein consumption and heart disease death rates hint that the more animal protein in the diet, the more heart disease, and the more vegetable protein, the less heart disease. But different dietary and lifestyle habits from country to country—things like consumption of saturated fat or smoking rates or amount of physical activity—make these surveys difficult to interpret. The only large prospective study of protein and heart disease showed that eating more animal or vegetable protein was linked with a lower risk of heart disease.


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