Complete proteins and incomplete proteins

Another way to describe the quality of proteins is to say that they're either complete or incomplete. A complete protein is one that contains ample amounts of all essential amino acids; an incomplete protein does not. A protein low in one specific amino acid is called a limiting protein because it can build only as much tissue as the smallest amount of the necessary amino acid. You can improve the protein quality in a food containing incomplete/ limiting proteins by eating it along with one that contains sufficient amounts of the limited amino acids. Matching foods to create complete proteins is called complementarity.

For example, rice is low in the essential amino acid lysine, and beans are low in the essential amino acid methionine. By eating rice with beans, you improve (or complete) the proteins in both. Another example is pasta and cheese. Pasta is low in the essential amino acids lysine and isoleucine; milk products have abundant amounts of these two amino acids. Shaking Parmesan cheese onto pasta creates a higher-quality protein dish. In each case, the foods have complementary amino acids. Other examples of complementary protein dishes are peanut butter with bread, and milk with cereal. Many such combinations are a natural and customary part of the diet in parts of the world where animal proteins are scarce or very expensive. Here are some categories of foods with incomplete proteins:

i Grain foods: Barley, bread, bulgur wheat, cornmeal, kasha, and pancakes i Legumes: Black beans, black-eyed peas, fava beans, kidney beans, lima beans, lentils, peanut butter, peanuts, peas, split peas, and white beans i Nuts and seeds: Almonds, Brazil nuts, cashews, pecans, walnuts, pumpkin seeds, sesame seeds (tahini), and sunflower seeds iBEfl In order for the foods to complement each other, you must eat them together. In other words, rice and beans at one meal, not rice for lunch and beans for dinner. Table 6-2 shows how to combine foods to improve the quality of their proteins.

Table 6-2 How to Combine Foods to Complement Proteins

This Food

Complements This Food


Whole grains

Legumes (beans)

Rice and beans

Dairy products

Whole grains

Cheese sandwich, pasta with cheese, pancakes (wheat and milk/egg batter)

Legumes (beans)

Nuts and/or seeds

Chili soup (beans) with caraway seeds

Dairy products

Legumes (beans)

Chili beans with cheese

Dairy products

Nuts and seeds

Yogurt with chopped nut garnish

The lowdown on gelatin and your fingernails

Everyone knows that gelatin is protein that strengthens fingernails. Too bad everyone's wrong. Gelatin is produced by treating animal bones with acid, a process that destroys the essential amino acid tryptophan. Surprise: Bananas are high in tryptophan. Slicing bananas onto your gelatin increases the quality of the protein. Adding milk makes it even better, but that still may not heal your splitting nails. The fastest way to a cure is a visit to the dermatologist, who can tell you whether the problem is an allergy to nail polish, too much time spent washing dishes, a medical problem such as a fungal infection, or just plain peeling nails. Then the dermatologist may prescribe a different nail polish (or none at all), protective gloves, a fungicide (a drug that wipes out fungi), or a lotion product that strengthens the natural glue that holds the layers of your nails together.

Deciding How Much Protein You Need

The National Academy of Sciences Food and Nutrition Board, which sets the requirements (for example, RDAs) for vitamins and minerals, also sets goals for daily protein consumption. As with other nutrients, the board has different recommendations for different groups of people: young or older, men or women.

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  • doderic
    How to improve quality of incomplete protein?
    3 years ago
  • medhane
    How to improve protein of incomplete proteins?
    3 years ago

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