Human Biochemistry, Volume 2 - Murray R. 1993

Special Topics
Nutrition, Digestion, and Absorption
Biomedical Significance

Severe nutritional deficiency is rare in most developed countries, although a certain degree of such deficiency may occur among the destitute or elderly, in groups with specific nutritional needs (children, pregnant or nursing mothers, the sick and convalescent, alcoholics), and in individuals consuming restricted amounts of food voluntarily or by necessity. In developing countries, Various Forms of severe nutritional deficiency are more widespread, such as Protein deficiency (kwashiorkor), vitamin deficiencies (such as vitamin A leading to xerophthalmia), mineral deficiencies (such as iron deficiency causing anemia), and energy deficiency (starvation). Until recently, overeating was associated solely with obesity, but the concept linking the excessive intake of certain nutrients to The Development of specific diseases—such as atherosclerosis, CORONARY Heart DISEASE, diabetes, breast and colon Cancer, cerebrovascular disease and stroke, and Liver cirrhosis—is now gaining increasingly widespread recognition. Malabsorption of nutrients or defects in the digestive enzyme system also lead to pathological conditions. For example, malabsorption of vitamin B₁₂ and folate causes anemia; malabsorption of calcium, magnesium, and vitamin D leads to tetany and Osteoporosis; and finally, generalized malabsorption syndrome encompasses these as well as other disorders. Lactase deficiency impairs milk tolerance, while defects in the absorption of neutral Amino Acids characterize Hartnup disease.