Food vitamins and minerals can lead to diseases that can have far-reaching effects on health. For instance, 30% of the world's population either has, or is at risk for developing, iodine deficiency. It is estimated that at least 3 million children are blind due to vitamin A deficiency. Vitamin C deficiency results in scurvy. Calcium, Vitamin D, and phosphorus are inter-related; the consumption of each may affect the absorption of the others. Kwashiorkor and marasmus are childhood disorders caused by lack of dietary protein. Many individuals limit what foods they eat for reasons of morality, or other habit. For instance, vegetarians
Vitamin B12 deficiency anemia its first step, of taking an oral dose of radiolabelled vitamin B, followed by quantitation of the vitamin in the patient's urine over a 24-hour period via measurement of the radioactivity. A second step of the test repeats the regimen and procedure of the first step, with the addition of oral intrinsic factor. A patient with PA presents lower than normal amounts of intrinsic factor; hence, addition of intrinsic factor in the second step results in an increase in vitamin B absorption (over the baseline established in the first). The Schilling test distinguished PA from other forms of B deficiency,