How Much Protein Is Necessary?

Americans are constantly told that protein is important in the diet. But how much do we really need?

Scientists have been working on this question for a long time. The best they can do is to give us a working formula, and warn us that every individual is unique. Your biological individuality must be your guide.

 

The working formula they have devised is based on your body weight. On average, they calculate that your body requires .9 grams of protein per kilogram (2.2 pounds) of body weight. A 150-pound woman would need about 61 grams a day, a 200-pound man about 81 grams. However, new evidence shows that because men have more lean muscle tissue and less fat than women, that woman should figure into this calculation of .9 gram the percentage of her lean tissue and fat tissue and the amount of exercise.

This formula is not new: it was proposed in 1935 by a League of Nations commission, and it has been reaffirmed several times since then.

Unfortunately, you are very likely to have been taught now-discredited earlier theories. Were you ever told that people who do hard physical labor need more protein than the rest of us? (This would base the formula on the level of activity rather than on body weight.) They generally don’t need more calories and a modest increase in protein. The idea that they do goes back to an 1881 study of German laborers who were found to eat an average of 118 grams daily. The researchers assumed that figure to be correct for anyone doing that kind of work.

Several researchers who endorse the .9 gram per kilogram of bodyweight assume that half the protein comes from complete animal sources.16 This does not mean they are telling you that you must eat meat to get enough protein. Complete animal sources include eggs, milk, cheese, and other dairy products. It may not be a bad idea to choose a lacto-ovo-vegetarian diet over a purely vegetarian one.

This is probably unnecessarily overcautious. It doesn’t take into account the possibility of combining incomplete proteins to complement each other and add up to complete protein. A handful of mixed nuts and seeds, or a helping of stir-fried tofu flavored with Japanese miso and served over buckwheat noodles, or that breakfast of whole-grain cereal topped with seeds, nuts, and milk, certainly supply one meal’s worth of high-quality protein. And they do not contain the high levels of fat or chemical residues found in meat.

Any formula, however, is only a starting point. You must modify it to consider your biological individuality. Some of the most important items to consider besides your weight are your age; the makeup of the amino acids in your body (biochemical tests can be performed to measure your nitrogen balance or the level of urea in your blood plasma); and special circumstances. These include pregnancy, growth, age, illness, and general stress levels. And your diet also should be examined to determine total calorie intake, major sources of protein, etc.

Biological Individuality and Special Protein Needs

Adults normally use their protein resources to maintain a proper balance between the breakdown and buildup of bodily tissues. In certain special circumstances, the protein is needed for other functions as well, and more must be consumed to maintain health.

Infants and children need extra protein for physical growth. Some nutritionists tell us that protein should account for a higher percentage of total calories for children than for adults.17 The League of Nations commission quoted earlier gave separate formulas for children and adolescents.

grams of protein per kilogram of body weight

Ages

3.5

1-3

3

3- 5

2.5

5- 15

2

15_17

155

17-21

Since these formulas are based on an adult ratio of .9 gram per kilogram of body weight,18 the recommendations may be slightly too high. They also suggest eating part of this protein in animal form, which is known to be unnecessary.19 In any case, it is likely that the high protein diet most Americans eat more than suffices to supply enough protein for the young. You would do better to concentrate on seeing that their protein comes from the right sources.

Pregnant women and lactating mothers are the other major group who need extra protein. High-quality protein intake is required during pregnancy to promote the normal development of the fetus and during lactation to guarantee full production of the mother’s milk. The Food and Nutrition Board of the National Research Council recommends that pregnant women increase their protein intake (based on 1.5 g/ kg for normal adults) by 35 percent. Lactating women should increase it even moreby 70 percent. Other authorities recommend simply increasing total protein intake by 10 grams during pregnancy and 20 grams during lactation. This can easily be accomplished with snacks like cheese sandwiches on whole-grain bread, handfuls of nuts and seeds, an extra baked potato with sunflower or sesame seeds, etc. You still don’t require animal flesh.

Conditions of physical/emotional stress such as illness or a difficult work situation also create temporarily elevated protein needs, and care should be taken to meet them.

One way to achieve the increase is to eat high-quality protein snacks, such as seeds and nuts. If you’re working long hours at a stressful job, keep a large bowl of your favorites sitting by your desk. Cashews, walnuts, almonds, peanuts, sunflower seeds, and soybeans can all be used in this way. At meals, be sure to have a protein drink (dozens of formulas are available at your health food store or health section of your supermarket). Also, you can vary grains and legume dishes with different types of cheeses or with eggs.

As you grow older, your body may not use the protein you eat as efficiently, so you may need to eat more from different sources, although older people generally require less protein. Unfortunately, the expense of most high-quality protein foods makes elderly people decrease their intake too much. They buy too many starchy foods and ignore the cheap protein sources such as grains, legumes, seeds, sprouts, tofu products, eggs, and milk. If they reduce their total calories, good protein is often the first thing to go.

O f course, you can’t account for variables that change from hour to hour. Not only do your body’s needs vary, but the content of your diet also doesn’t remain constant every day. Nor does protein account for a steady percentage of your total calories. You eat at different times; you cook and prepare your food in different ways; you metabolize food at different rates at different times of the day, and the protein content of each food varies depending on how you prepare it. No two slices of cheese are exactly identical. The same slice would be digested and metabolized differently at lunchtime and suppertime, and its nutrition will be affected by whether you toast it, grill it, or use it in an eggplant casserole. All these factors affect the question of how much usable protein you get from your food.

How Do You Know If You’re Getting Enough Protein?

You can obtain biochemical tests measuring nitrogen and urea levels in the urine and blood plasma. However, first, take a look at the visible portion of your body yourself. Remember, the structure of all your cells depends on protein. What does your hair look like? Is it healthy and shiny, or limp and dull? What about your fingernails and toenails? Are they hard and smooth, or do they chip and flake? Is your skin healthy-looking? Your hair, nails, and skin all rely on protein to maintain their structural soundness and visual appearance. If they look unhealthy, you may not be getting enough protein. Also, minor, superficial injuries such as scrapes and bruises should heal at a prompt, nor* mal rate. If your appearance is below par, you should analyze your diet.

A chart listing the protein content of common foods in grams of usable protein can help you to carry out your own simple nutritional analysis. Give some thought to how you might increase your protein intake. The key to getting adequate protein is to vary and balance your sources. The simplest method (avoiding meat and fish) is to supplement nuts, seeds, grains, legumes, and sprouts with complete proteins such as eggs and dairy products.

As long as you get about one-third of your total protein from complete sources and average about 25 grams per meal, you should be certain of obtaining all you need. If you’re ill, or still growing, about one-half to two-thirds of your protein should come from complete sources. Minimal amounts of the right protein are much more important than larger amounts of the wrong ones.

Summary

Your weight is the main factor determining how much protein you need since protein is so intrinsic to your body’s structure. In general, no matter how much or how little exercise they get, adults require .9 grams of protein for every kilogram (2.2 pounds) of body weight. (To find out how many grams of protein you need, divide your weight in pounds by 2.2, then multiply by .9.) Vegans should perhaps get a bit more to compensate for imperfectly complemented incomplete proteins.

Young children need more protein relative to their body weight, but this adds up to less than adults require in total. Children ages 1 to 3 need 3.5 grams per kilogram. (A twenty-five-pound, fast-growing toddler would need about 40 grams of protein, compared to the 60 grams needed by his or her 150-pound mother.) Adolescents, again, have increased needs (2 g/kg for 15- to 17-year-olds, 1.5 g/kg for 17- to 21-year-olds).

Pregnant women need 35 percent more protein than usual. People under stress should also increase their protein intake. Although older people generally need less protein, sometimes as you age your body uses protein less efficiently. For this reason, women over fifty-five are advised to increase their intake of high-quality protein foods.

We are each biologically unique, and our need for protein changes at different times and in different circumstances. If your hair is healthy and shiny, your fingernails and toenails hard and smooth, your skin healthy-looking, and if bruises heal promptly, you are probably getting enough protein. If not, you should analyze your diet and perhaps consider having your urine and blood plasma analyzed for nitrogen and urea levels.

 

 

 

 

 

 

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