Hope's Edge_ The Next Diet for a Small Planet - Frances Moore Lappe [85]
In addition, the recommended allowances of protein are calculated for healthy people. Ill health and age, as well as genetic differences, could result in greatly differing needs. Genetic differences may play a role not only in our needs but also in our taste for foods (which may or may not be related to needs). In a recent study, adult identical twins were found more similar in their choices of foods, including the protein density of the diet, than were fraternal twins.3
Figure 11. Hypothetical Mixed Plant and Dairy Diet (Just to Prove a Point)
Effects of Stress
Even more surprising, any individual’s need for protein can vary a lot. Physical stress—pain, for example—or psychological stress—even from exam pressure—can push your protein need up by as much as one-third. But remember, most of us eat almost twice the protein our bodies can use, so we can easily get the “extra” protein needed under stress from the protein already in most of our diets.
A World Health Organization report4 discussed these stress conditions: (1) heat: unacclimatized individuals lose nitrogen (a primary component of protein) in heavy sweating; (2) heavy work: athletes and others may need additional protein when they are increasing their muscle mass, although the amount needed is not likely to be large (some studies, though not widely substantiated, suggest an additional 25 percent intake over the totals recommended here if you are building muscle mass); (3) inadequate energy intake: when overall calorie intake is not adequate, some dietary protein is used for energy and thus is not available to meet protein needs; (4) infection: infections, especially acute ones, cause some depletion of body nitrogen due to increased urinary excretion and poor intestinal absorption (as with diarrhea); these losses need to be replaced with additional protein during recovery.
The obvious conclusion is this: we should suspect any diet “expert” who claims that we all would do better on a high-protein or a low-protein diet. Instead of following a recommended allowance blindly, we should become better observers of our own body’s well-being, developing what protein researcher Williams calls “body wisdom.” Part of body wisdom is being aware of how you feel—your energy level, general health, and temperament. (Certain nutritional deficiencies negatively affect appetite and choice of foods, so just feeling “satisfied” is not enough.) Body wisdom also involves being a wise observer of your body’s condition: many types of nutritional deficiencies show up as deterioration in the hair, skin, and nails and in the slow healing of wounds.
Why Do We Need Protein Anyway?
Given protein’s importance to the body, perhaps it is not so surprising that a certain mystique grew up around it. We simply cannot live on fats and carbohydrates alone. Protein makes up about one-half of the nonwater components of our bodies. Just as cellulose provides the structural framework of a tree, protein provides the framework for animals. Skin, hair, nails, cartilage, tendons, muscles, and even the organic framework of bones are made up largely of fibrous proteins. Obviously, protein is needed for growth in children. Adults also need it to replace tissues that are continually breaking down and to build tissues, such as hair and nails, which are continually growing.
But talking about the body’s need for “protein” is unscientific. What the body needs from food are the building blocks of protein—amino acids, specifically the eight that the body cannot manufacture itself, which are called “essential amino acids.” Even more precisely, what the body actually requires are the carbon skeletons of these essential amino