Vitamin adolescence

Pure selenium deficiency, without concurrent vitamin E deficiency, is not generally seen except in animals on experimental diets (113). In China, selenium deficiency in humans has been associated with Keshan disease, a cardiomyopathy seen in children and in women of child-bearing ages, and Kashin-Beck disease, an endemic osteoarthritis in adolescents (113). 

In the vitamin D deficiency disease rickets, the bones of children are undermineralized as a result of poor absorption of calcium. Similar problems occur in adolescents who are deficient during their growth spurt. Osteomalacia in adults results from demineralization of bone in women who have little exposure to sunlight, often after several pregnancies. Although vitamin D is essential for prevention and treatment of osteomalacia in the elderly, there is little evidence that it is beneficial in treating osteoporosis. 

Amenorrhea in the adolescent population is of great importance because this is the time in the female life cycle when peak bone mass is achieved. The cause of amenorrhea and appropriate treatment must be identified promptly in this population because hypoestrogenism contributes negatively to bone development. Estrogen replacement, typically via an OC, is important. In addition, ensuring that the patient is receiving adequate amounts of calcium and vitamin D is imperative. 

The balance between excess and insufficient zinc is important. Zinc deficiency occurs in many species of plants and animals, with severe adverse effects on all stages of growth, development, reproduction, and survival. In humans, zinc deficiency is associated with delayed sexual maturation in adolescent males poor growth in children impaired growth of hair, skin, and bones disrupted Vitamin A metabolism and abnormal taste acuity, hormone metabolism, and immune function. Severe zinc deficiency effects in mammals are usually prevented by diets containing >30 mg Zn/kg DW ration. Zinc deficiency effects are reported in aquatic organisms at nominal concentrations between 0.65 and 6.5 pg Zn/L of medium, and in piscine diets at <15 mg Zn/kg FW ration. Avian diets should contain >25 mg Zn/kg DW ration for prevention of zinc deficiency effects, and <178 mg Zn/kg DW for prevention of marginal sublethal effects. 

The US daily allowances-The US daily allowances for vitamin K have not been officially established, but have been estimated to be 10 to 20 meg for infants, 15 to 100 meg for children and adolescents, and 70 to 140 meg for adults. Usually, dietary vitamin K will satisfy these requirements, except during the first 5 to 8 days of the neonatal period. 

Donelly, B. 1. (1996). Vitamin A and respiratory syncytial virus infection. Arch. Pediatr. Adolesc. Med. 150, 882-892. 

Abrams, S. A., Griffin, 1. J., Hawthorne, K. M., Gunn, S. K., Gundberg, C. M., and Carpenter, T. O. (2005b). Relationships among Vitamin D Levels, parathyroid hormone, and calcium absorption in young adolescents. J. Clin. Endocrinol. Metab. 90,5576-5581. 

McDuffie JR, Calls KA, Booth SL, Uwaifo GI, Yanovski JA. Effects of orlistat on fat-soluble vitamins in obese adolescents. Pharmacotherapy 2002 22(7) 814-22. 

Pettifor JM Rickets and vitamin D deficiency in children and adolescents. Endocrinol Metab Clin North Am 2005 34 537. [PMID 16085158]... 

Willett AM. Vitamin D status and its relationship with parathyroid hormone and bone mineral status in older adolescents. Proc Nutr Soc. 2005 64 193-203. 

On the other hand, milk is not only an essential food for infants, but for children and adults as well. Children need sufficient nutrients and energy to meet the demands of growth and development. Demands for nutrients such as protein, Ca, Fe, and Zn are relatively high, and teenagers require quite large amounts of B vitamins - thiamine, riboflavin and niacin. In addition, approximately 45 percent of the adult skeleton is laid down during adolescence. 

The average diet in the United States is considered to supply between 5 and 15 xg/ day. In foods, the vitamin is bound to proteins via peptide linkages but can be readily absorbed in the intestinal tract. The RDA is 3 xg for adults and adolescents. 

Malnutrition (low dietary intake of calcium and vitamins K and C) is associated with lower peak bone mass during adolescence. 

Numerous reports of elevated concentrations of lipid [57,58], protein [57,58] and DNA [54] oxidation products in CF patients have now been published. Importantly, oxidative stress is not present in all CF patients at all times. Oxidative stress, like the recurring infections, is probably cyclic. Importantly, antioxidant status tends to decrease with age in CF [58], hence older CF patients are particularly susceptible to renewed cycles of pulmonary inflammation. It is tempting to speculate that it is this oxidant/antioxidant imbalance that is responsible, in part, for their decline in lung function with advancing age. The reason for the fall in antioxidant status in CF is not clear, however decreased compliance in taking vitamin supplements may play a role. Alternatively, it is conceivable those repeated cycles of pulmonary inflammation, and associated oxidative stress, also contributes to the decline in antioxidant status. Whatever the exact cause, it is probable that the worsening antioxidant status of the CF adolescent contributes to their deteriorating clinical circumstances. 

However, potential therapeutic interventions require randomized prospective studies. Variables that might be addressed in such trials include the impact of monotherapy and polytherapy on the attainment of peak bone mass in adolescence and adulthood bone health in women characterization of the impact of limitations in physical activity on bone density in patients with epilepsy who have cerebral palsy or those with developmental disabilities or mental retardation the effects of newer antiepileptic drugs on bone metabolism standardization of the workup for bone disease in patients with epilepsy and the effectiveness of the current recommendations for supplementation with calcium and vitamin D. 

The findings of these and other studies have led the Food and Nutrition Board of the U.S. Institute of Medicine to recommend a tolerable upper intake level of3000 tg/day of preformed vitamin A for men of 19 years and older, with lower levels for women of child-bearing age, infants, children, and adolescents. Carotenemia results from a chronic excessive intake of carotene-rich foods, principally carrots. This condition, in which yellowing of skin is observed, is benign, because the excess carotene is deposited rather than converted to vitamin A. 

Osteoblasts, odontoblasts, and cementoblasts need vitamin C to make collagen, vitamin D for uptake of calcium into the body (Chap. 10), and vitamins A and K to synthesize and secrete the active form of osteocalcin. Vitamins C and D are the most important during childhood and adolescence to make adequate amounts of type I collagen and supply a net increase in calcium to the body. Ameloblasts, like other cells of ectodermal origin, require vitamin A to differentiate and secrete their proteins, but none of the other vitamins. Calcification of enamel appears independent of the increase in blood calcium level mediated by vitamin D. 

Lewis S, Broadfield E, Fogarty A, Britton J The relationship of respiratory symptoms and lung function with intakes of apples and tomatoes. Am J Respir Crit Care Med 2001 163 A40. Occhiuto JS, Saldiva SM, Dockery DW, Speizer FE Dietary vitamin C and pulmonary function in adolescents. Am J Respir Crit Care Med 2001 163 A40. 

Osteoporosis can be prevented or reduced by regular exercise and adequate dietary intake of calcium and vitamin D throughout life but especially in adolescence. 

Calcium The utility of supplemental calcium to protect bone has been the subject of considerable debate. While the impact of supplementation in adolescents, young adults, or early postmenopausal women is argued, some studies do suggest that supplemental calcium in the elderly, typically in combination with vitamin D, suppresses bone turnover, improves bone mineral density, and decreases the incidence of fractures. Typical dosing has been in the range of 1000 mg/day in adolescents and young adults and 1500 mg/day in the elderly. Calcium supplements are most often taken with meals to improve absorption. 

Although the RDA or AI for each vitamin varies with age and sex, the difference is usually not very large once adolescence is reached. For example, the RDA for... 

The phenylalanine- and tyrosine-free infant drink mix XPHEN TYR Tyrosidon, and the phenylalanine-, tyrosine-and methionine-free infant drink mix XPTM Tyrosidon are suitable for infants, children, adolescents and adults but, unhke other proprietary preparations suitable for the management of tyrosinemia, they are carbohydrate, vitamin and mineral free, which need to be added to the diet. This may allow more appropriate age-specific supplementation, including iodine. 

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