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General Nutrition and Diet Facts

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Dietary Proteins

 

Protein is in every living cell in the body. Our bodies need protein from the foods we eat to build and maintain bones, muscles and skin. We can get proteins in our diet from meat, dairy products, nuts and certain grains and beans. Proteins from meat and other animal products are complete proteins.
This means they supply all of the amino acids the body cannot make on its own. Plant proteins are incomplete. You must combine them to get all of the amino acids your body needs.

What is Protein?

Take away the water and about 75 percent of your weight is protein. This chemical family is found throughout the body. It's in muscle, bone, skin, hair, and virtually every other body part or tissue. It makes up the enzymes that power many chemical reactions and the hemoglobin that carries oxygen in your blood. At least 10,000 different proteins make you what you are and keep you that way.
Twenty or so basic building blocks, called amino acids, provide the raw material for all proteins. Following genetic instructions, the body strings together amino acids. Some genes call for short chains, others are blueprints for long chains that fold, origami-like, into intricate, three-dimensional structures.
Because the body doesn't store amino acids, as it does fats or carbohydrates, it needs a daily supply of amino acids to make new protein.
It is important to get enough dietary protein. You need to eat protein every day, as said earlier your body doesn't store it the way it stores fats or carbohydrates. The average person needs 50 to 65 grams of protein each day. This is the amount in four ounces of meat and a cup of cottage cheese.
Surprisingly little is known about protein and health. We know that adults need a minimum of 1 gram of protein for every kilogram of body weight per day to keep from slowly breaking down their own tissues. That's about 9 grams of protein for every 20 pounds. Beyond that, there's relatively little solid information on the ideal amount of protein in the diet, a healthy target for calories contributed by protein, or the best kinds of protein.
Protein malnutrition leads to the condition known as kwashiorkor. Lack of protein can cause growth failure, loss of muscle mass, decreased immunity, weakening of the heart and respiratory system, and death.
Getting the minimum daily requirement of protein is easy. Cereal with milk for breakfast, a peanut butter and jelly sandwich for lunch, and a piece of fish with a side of beans for dinner adds up to about 70 grams of protein, plenty for the average adult.

Too much of protein :

Digesting it releases acids that the body usually neutralizes with calcium and other buffering agents in the blood. Eating lots of protein, such as the amounts recommended in the so-called low-carb or no-carb diets, takes lots of calcium. Some of this may be pulled from bone. Following a high-protein diet for a few weeks probably won't have much effect on bone strength. Doing it for a long time, though, could weaken bone.

All proteins are not same :

Some of the protein you eat contains all the amino acids needed to build new proteins. This kind is called complete protein. Animal sources of protein tend to be complete. Other protein sources lack one or more amino acids that the body can't make from scratch or create by modifying another amino acid. Called incomplete proteins, these usually come from fruits, vegetables, grains, and nuts.
Vegetarians need to be aware of this. To get all the amino acids needed to make new protein - and thus to keep the body's systems in good shape - people who don't eat meat, fish, poultry, eggs, or dairy products should eat a variety of protein-containing foods each day.

Protein and chronic disease

The most solid connection between proteins and health has to do with allergies. Proteins in food and the environment are responsible for these overreactions of the immune system to what should be harmless proteins. Beyond that, relatively little evidence has been gathered regarding the effect of protein on the development of chronic diseases.
Cardiovascular disease: Many studies has investigated the association between dietary protein and heart disease or stroke. From those studies, it was found that women who ate the most protein (about 110 grams per day) 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 68 grams per day) over a 14-year period. Whether the protein came from animals or vegetables or whether it was part of low-fat or higher-fat diets didn't seem to matter. These results offer reassurance that eating a lot of protein doesn't harm the heart. In fact, it is possible that eating more protein while cutting back on easily digested carbohydrates may be benefit the heart.
Diabetes: Although proteins found in cow's milk have been implicated in the development of type 1 diabetes (formerly called juvenile or insulin-dependent diabetes), ongoing research has yielded inconsistent results. Later in life, the amount of protein in the diet doesn't seem to adversely affect the development of type 2 (adult-onset) diabetes, although research in this area is ongoing.
Cancer: There's no good evidence that eating a little protein or a lot of it influences cancer risk.

Soy : Better protein source

One protein source that has been getting a lot of attention is soybeans. Regular eating soy-based foods lowers cholesterol, chills hot flashes, prevents breast and prostate cancer, aids weight loss, and wards off osteoporosis. Some of these benefits have been attributed a unique characteristic of soybeans-their high concentrations of isoflavones, a type of plant-made estrogen (phytoestrogen).
As is so often the case, some of the claims made for soy were based on preliminary evidence, while others go far beyond the available evidence.
Heart disease: A meta-analysis of 38 controlled clinical trials showed that eating approximately 50 grams of soy protein a day in place of animal protein reduced total cholesterol levels by 9.3 percent, LDL cholesterol by 12.9 percent, and triglycerides by 10.5 percent. Such reductions, if sustained over time, could have meant a 20 percent reduction in the risk of heart attack, stroke, or other forms of cardiovascular disease. According to a comprehensive update of soy research, eating 50 grams of soy lowers LDL only about 3%. Keep in mind that 50 grams of soy protein is more than half the average person's daily protein requirement. It's the equivalent of 1 pounds of tofu or eight 8-ounce glasses of soymilk a day.
Even though soy protein itself has little direct effect on cholesterol, soy foods are good for the heart and blood vessels because they usually replace less healthful choices, like red meat, and because they deliver plenty of polyunsaturated fat, fiber, vitamins, and minerals, and are low in saturated fat.
Hot flashes: Soy has also been investigated as a treatment for hot flashes and other problems that often accompany menopause. Soybeans are rich in phytoestrogens. In some tissues, these substances mimic the action of estrogen. So they could cool hot flashes by giving a woman an estrogen-like boost during a time of dwindling estrogen levels.
Breast cancer: Phytoestrogens don't always mimic estrogens. In some tissues they actually block the action of estrogen. If such estrogen-blocking action occurs in the breast, then eating soy could, in theory, reduce the risk of breast cancer because estrogen stimulates the growth and multiplication of breast and breast cancer cells. But studies so far haven't provided a clear answer, with some showing a benefit and others showing no association between soy consumption and breast cancer. In fact, a handful of unsettling reports suggest that concentrated supplements of soy proteins may stimulate the growth of breast cancer cells. Large prospective studies now underway should offer better information regarding soy and breast cancer risk.
Other cancers: Although substances in soy could conceivably protect against endometrial, ovarian, colorectal, prostate, and other cancers, there is no good evidence for this.
Memory and thinking ability: A few studies have raised the possibility that eating soy could help prevent the age-related loss of memory or decline in cognitive function. Two recent trials have yielded contradictory results in this area, with one showing a benefit for soy and another showing no benefit.
Finally, there's no evidence that pills containing isoflavones extracted from soybeans offer benefits, and some studies raise concerns about harmful side effects.

Recommendations for Protein Intake:

Get a good mix of proteins. Almost any reasonable diet will give you enough protein each day. Eating a variety of foods will ensure that you get all of the amino acids you need.
Pay attention to the protein package. You rarely eat straight protein. Some comes packaged with lots of unhealthy fat, like when you eat marbled beef or drink whole milk. If you eat meat, steer yourself toward the leanest cuts. If you like dairy products, skim or low-fat versions are healthier choices. Beans, soy, nuts, and whole grains offer protein without much saturated fat and with plenty of healthful fiber and micronutrients.
Balance carbohydrates and protein. Cutting back on highly processed carbohydrates and increasing protein improves levels of blood triglycerides and HDL, and so may reduce your chances of having a heart attack, stroke, or other form of cardiovascular disease. It may also make you feel full longer, and stave off hunger pangs. Too much protein, though, could weaken bones.
Eat soy in moderation. Soybeans, tofu, and other soy-based foods are an excellent alternative to red meat. But don't go overboard. Two to four servings a week is a good target. And stay away from supplements that contain concentrated soy protein or soy extracts, such as isoflavones. Larger amounts of soy may soothe hot flashes and other menopause-associated problems, but the evidence for this is weak.

Dietary Sources of Protein

Food Serving Weight in grams Protein grams % Daily Value
  Hamburger, extra lean   6 ounces   170   48.6   97
  Chicken, roasted   6 ounces   170   42.5   85
  Fish   6 ounces   170   41.2   82
  Tuna, water packed   6 ounces   170   40.1   80
  Beefsteak, broiled   6 ounces   170   38.6   77
  Cottage cheese   1 cup   225   28.1   56
  Cheese pizza   2 slices   128   15.4   31
  Yogurt, low fat    8 ounces    227   11.9    24
  Tofu   1/2 cup   126   10.1   20
  Lentils, cooked    1/2 cup   99   9   18
  Skim milk   1 cup   245   8.4   17
  Split peas, cooked    1/2 cup   98   8.1   16
  Whole milk    1 cup   244   8   16
  Lentil soup    1 cup   242    7.8   16
  Kidney beans, cooked   1/2 cup    87    7.6    15
  Cheddar cheese    1 ounce    28    7.1    14
  Macaroni, cooked    1 cup   140   6.8   14
  Soymilk    1 cup   245   6.7   13
  Egg   1 large    50    6.3    13
  Whole wheat bread    2 slices    56   5.4   11
  White bread    2 slices   60   4.9   10
  Rice, cooked    1 cup    158    4.3    9
  Broccoli, cooked    5 inch piece    140   4.2   8
  Baked potato   2x5 inches    156   3   6
  Corn, cooked    1 ear    77    2.6    5
Nuts :

Many people think of nuts as just another junk food snack. In reality, nuts are excellent sources of protein and other healthful nutrients.
One surprising finding from nutrition research is that people who regularly eat nuts are less likely to have heart attacks or die from heart disease than those who rarely eat them. Several of the largest studies have shown a consistent 30 percent to 50 percent lower risk of myocardial infarction, sudden cardiac death, or cardiovascular disease associated with eating nuts several times a week. Eating a diet that includes one ounce of nuts daily can reduce your risk of heart disease.
There are several ways that nuts could have such an effect. The unsaturated fats they contain help lower LDL (bad) cholesterol and raise HDL (good) cholesterol. One group of unsaturated fat found in walnuts, the omega-3 fatty acids, appears to prevent the development of erratic heart rhythms. Omega-3 fatty acids (which are also found in fatty fish such as salmon and bluefish) may also prevent blood clots, much as aspirin does. Nuts are rich in arginine, an amino acid needed to make a molecule called nitric oxide that relaxes constricted blood vessels and eases blood flow. They also contain vitamin E, folic acid, potassium, fiber, and other healthful nutrients.

 


 
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