BIOLOGY Volume 1 - A Guide to General Biology - 2004

8. HETEROTROPHIC NUTRITION

8.9. Malnutrition

8.9.4. Protein Deficiency: Kwashiorkor and Marasmus

Protein deficiency can arise in two ways. First, the diet may provide sufficient energy yet lack adequate protein. This is common in certain regions of Africa where the staple foods are maize (corn), yams, or cassava—crops that are rich in starch and therefore energy, but deficient in protein. Maize flour lacks the essential amino acid Tryptophan, which is required for Protein Synthesis. In areas where wheat is cultivated, protein deficiency is rare.

The second cause of protein deficiency is a low dietary energy intake. In such situations, the body's own Proteins are broken down as an energy source, as discussed above.

Kwashiorkor

In both cases of protein deficiency, a condition known as kwashiorkor may develop. This disorder was first described in Ghana in 1935, and its name derives from a term meaning "the disease of the child who is displaced from the breast when a younger sibling is born." Transitioning a child from a milk-based diet to one rich in starch leads to protein deficiency.

The characteristic appearance of a child suffering from kwashiorkor is shown in Fig. 8.30, A. The symptoms of this condition include:

1) Hair becomes thin, brittle, sparse, easily dislodged, and frequently loses its pigmentation;

2) the Salivary Glands are affected, becoming greatly enlarged and giving the face a characteristic "moon-faced" appearance;

3) the abdomen becomes distended due to the accumulation of gas in the Small Intestine, caused by overgrowth of Bacteria;

4) edema develops As a result of fluid accumulation in body Tissues, being particularly noticeable in the feet and lower legs (later spreading to the arms). This Swelling is caused by a reduced plasma protein concentration, which increases the Blood Water potential and drives fluid from the bloodstream into the interstitial tissues, thereby causing edema;

5) Muscle wasting, low body weight, and stunted growth; mental development is also delayed;

6) patchy Skin pigmentation disorders occur; the skin becomes coarse; wound healing is impaired; jaundice may develop;

7) interest in the surrounding environment fades, accompanied by irritable apathy;

8) fatty Liver; biochemical changes lead to fat accumulation in the liver, severely impairing its function;

9) vitamin deficiency disorders manifest with their characteristic symptoms, particularly deficiencies in Vitamins A and D;

10) lowered resistance to infections.

Kwashiorkor is frequently fatal.

Class="center">

Fig. 8.30. A. A child with kwashiorkor exhibits sparse hair and characteristic skin lesions associated with the condition. B. A child displaying symptoms of both marasmus and kwashiorkor.

Marasmus (General Wasting)

Another well-known condition caused by malnutrition is marasmus (general wasting). It was initially believed that this condition resulted purely from a low-calorie diet, though the Etiology may be more complex (see Structure/133.html">Discussion below). A child suffering from marasmus is shown in Fig. 8.30, B, and can be compared with a child suffering from kwashiorkor. The signs and symptoms of marasmus include:

1) shrunken and withered facial features giving an aged appearance, with sunken eyes;

2) muscular dystrophy, causing the arms and legs to become thin; low body fat content.

3) hair is not affected;

4) no edema;

5) very low weight; by some estimates, a child may lose more than 60% of the body mass typical for their age;

6) reduced resistance to infections;

7) vitamin deficiency diseases, as seen in kwashiorkor.

As our understanding of malnutrition continues to grow, the distinction between marasmus and kwashiorkor is becoming increasingly blurred. Within the same family, some children may develop marasmus while others develop kwashiorkor, despite consuming the same diet; occasionally, a child may develop marasmus following kwashiorkor. The child shown in Fig. 8.30, B exhibits both the slender limbs characteristic of marasmus and the distended abdomen typical of kwashiorkor. Currently, both conditions are considered to be consequences of malnutrition, or protein-energy malnutrition. In both cases, growth retardation and a reduced resistance to infections are invariably observed.