7.6: Protein-Energy Malnutrition

Protein deficiency rarely occurs alone. Typically, there’s a deficiency of calories and other nutrients as well. Severe protein deficiency is most commonly seen in children living in poverty in developing countries.

As would be expected, a severe protein deficiency affects the synthesis of a wide variety of proteins in the body and has diverse effects. For example, less of a blood protein called albumin is made. As a result, some of the fluid normally held in the blood by albumin flows out of the blood vessels and into the surrounding tissue. This causes the tissue to swell, and a protein deficient child to look “puffy,” especially in the face and belly.

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The diseases of protein-energy malnutrition are also known as marasmus (marasmos is Greek, meaning wasting away) and Kwashiorkor (a local term in Gold Coast, Africa for displaced child). When a nursing mother is malnourished, she makes less milk, but the milk she does make is fairly normal in composition (i.e., the milk isn’t “protein deficient”).

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Protein-deficient children are often small for their age and are prone to infection (antibodies are proteins). If their hair is normally black, it may contain light bands of orange, from insufficient pigment to darken it (the pigment melanin is made from the amino acid tyrosine). Brain growth may also suffer, often starting before birth with a malnourished mother.

Clearly, breastfeeding is of tremendous importance in developing countries where malnutrition and poor sanitation are common. Breast milk is often the only regular source of high-quality protein and other essential nutrients available to an infant. Breast milk also provides calories and some protection against infections. The infants often develop protein-energy malnutrition when they are displaced at the breast by a newborn sibling.

The Need for Energy Comes First

Meeting energy needs is a higher priority for the body than meeting protein needs. If a diet is deficient in calories, the body will “burn” amino acids to meet energy needs rather than use the amino acids to make protein. Thus, when energy needs aren’t met, protein needs are higher because some of the protein is diverted for energy production. Inadequate amounts of calories and protein often go hand in hand in many developing countries—a protein deficiency is made much worse by a calorie deficit.

A dilemma occurs in setting requirements and making recommendations for protein intake in developing countries. Should the recommended protein intake be based on the actual average intake of calories, which is often inadequate, or should it be set lower, based on an assumption of adequate calories? This is an important question, because recommendations for protein intake are used in forming food policies, and are used by individual countries as well as world health organizations in providing aid.

Food rich in protein (e.g., meat, eggs, milk) is much more expensive than food rich in carbohydrate (e.g., rice, corn). Using protein-rich food to provide necessary calories is an inefficient use of available resources. Thus, when resources are limited, the need for inexpensive sources of calories is related to the problem of providing adequate protein.