Chapter 15: Fat-Soluble Vitamins
- Page ID
- 58112
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- 15.1: Fat-Soluble Vitamins
- Like the water-soluble vitamins, the fat-soluble vitamins are chemical substances needed by the body in tiny amounts, which must be supplied from outside sources. But unlike the water-soluble vitamins, they can be stored in large amounts, especially in the liver. So dietary excesses—much smaller excesses than in the case of the water-soluble vitamins—can become toxic.
- 15.2: Vitamin A
- Many of the earliest insights into nutritional deficiency concerned the fat-soluble vitamins. Among the first recorded references to the relationship between vitamin A-rich foods and night blindness are found in writings which are some 3,500 years old. Eber’s Papyrus, an Egyptian document from about 1500 B.C., defines the phenomenon of night blindness and suggests a cure of feeding patients the roasted livers of oxen or roosters (livers of virtually all animals are rich sources of vitamin A.)
- 15.3: Vitamin D
- Like vitamin A, vitamin D has a long history. Rickets, the most striking sign of D deficiency, was recognized at least 2,500 years ago. And centuries ago the deficiency disease was understood to be curable or preventable by eating certain foods—which eventually were found to be potent sources of vitamin D.
- 15.4: Vitamin E
- Symptoms of Vitamin E deficiency haven’t been seen in healthy populations, even in those whose diets have little vitamin E. Deficiencies have only been seen in unusual circumstances. It can occur, for example, in cases of cystic fibrosis because of the fat malabsorption associated with the disease. Vitamin E supplements are routinely given to such at-risk groups.
- 15.5: Vitamin K
- Vitamin K can be made by bacteria living in the digestive tract. This protects us from deficiencies—unless the bacteria are somehow destroyed or disease interferes with the absorption of K into the blood.