Bone, aging mineralization, vitamin

Although most fragility fractures in women occur after age 50, certain groups of premenopausal women are at high risk for osteoporosis. The NOF recommends measuring bone mineral density in premenopausal women with risk factors in addition to sex and race, in whom treatment would be considered.1 Premenopausal women at risk for osteoporosis should follow all nonpharmacologic recommendations for exercise and adequate calcium and vitamin D intake. Currently, no good data... 

Martini and Wood (2002) tested the bioavailability of 3 different sources of Ca in 12 healthy elderly subjects (9 women and 3 men of mean SEM age 70 3 and 76 6 years, respectively) in a 6-week crossover trial conducted in a Human Study Unit. Each Ca source supplied 1000 mg Ca/day and was ingested for 1 week with meals (as 500 mg Ca 2x/day), thus contributing to a high-Ca intake (1300 mg Ca/day). A low-Ca intake (300 mg Ca/day strictly from the basal diet) was adhered to for 1 week in-between each treatment. The Ca sources included skim milk, CCM-fortified OJ, and a dietary supplement of CaCOa. Assessment parameters were indirect measures predicted to reflect the relative bioavailability of Ca postprandially via an acute PTH suppression test (hourly for 4h). Longer-term responses to Ca supplementation were assessed via a number of urinary and serum hormone, mineral, and bone resorption biomarkers (i.e., vitamin D, Ca, phosphorus, and collagen t) e 1 N-telopeptide cross-links). 

Ca not only works in conjunction with vitamin D to enhance bone health, its effects on bone maintenance have been surmised to be enhanced in postmenopausal women by the presence of other minerals. A 2-year double-blind, placebo-controlled trial evaluated the effect of supplementary Ca (1000 mg elemental Ca/day as CCM) on lumbar spine bone loss in the presence and absence of a combination of trace minerals integral to bone maintenance (i.e., copper, 2.5 mg/day manganese, 5.0 mg/day zinc, 15.0mg/day). Participants included 59 healthy postmenopausal women of mean age ( SD) 66 + 7 years who were on average 18.1 8.9-year postmenopausal (Strause et al, 1994). At baseline, the mean Ca... 

Protein, calcium, vitamins A and D needed to prevent the loss of bone minerals that frequently occurs with increasing age... 

Bones joint pains, thickening of the long bones, hypercalcemia, and calcification of soft tissues, but with reduced bone mineral density. High intakes of vitamin A are associated with an increased rate of loss of bone mineral density with age, and some studies have shown that intakes above 1,500 /xg per day are associated with increased incidence of osteoporosis and hip fracture, although other studies have not shown any relationship between vitamin A intake and osteoporosis (Institute of Medicine, 2001). At high levels of intake, vitamin A both stimulates bone... 

Immunoreactive parathyroid hormone concentrations may be increased by anticonvulsants, while bone mineral content is reduced. Hypocalcemia and osteopenia can occur, despite normal serum concentrations of active vitamin D metabolites, suggesting that they may be independent of drug effects on vitamin D metabolism. Bone biopsies have shown increased osteoid but normal calcification front formation, accelerated rate of mineralization, and reduced mineralization lag time, suggesting increased skeletal turnover rather than osteomalacia (96). The risk of age-related fractures in drug-treated epileptic patients is not greatly increased (97). 

In adults receiving long-term parenteral nutrition, despite its anabolic effects on other tissues, there is no improvement in bone density. Infants treated with parenteral nutrition from birth also develop low bone density for age, suggesting that parenteral nutrition treatment in some way contributes to the osteopenia (5). A 17% long-term increase in spinal bone mineral content has been shown in patients who have received parenteral nutrition solntions without vitamin D. However, this rise was nearly balanced by a 15% fall in hip bone mineral content (115). In a Danish study of bone mineral content in adults receiving home parenteral nutrition for short bowel syndrome, despite the fact that all were on free oral intake as a supplement to the parenteral nutrition, 47% had mandibular osteoporosis while 33% had osteoporosis in the forearm and radiographic changes of osteoporotic fractures in the vertebral column. Dental and periodontal tissues were normal (116). 

Eastell R, Yergey AL, Vierira NE, Cedel SL, Kumar R, Riggs BL. Interrelationship among vitamin D metabolism, true calcium absorption, parathyroid function, and age in women evidence of an age-related intestinal resistance to 1,25-dEiydroxyvitamin D action. J Bone Miner Res 1991 6 125-32. 

In a retrospective audit of 105 patients (38 men and 67 women, over 18 years of age) in a tertiary care center in India, 56 % had at least one documented intervention related to osteoporosis prevention (calcium, vitamin D, bisphosphonates, or a bone mineral density study) [17. Only three patients received bisphosphonates for osteoporosis prophylaxis. There was poor pretherapeutic risk assessment, absence of instructions regarding preventive measures, inappropriate investigation for the presence of osteoporosis, and unacceptable failure to use bone protective agents. 

Calcium Adequate calcium intake is required to maintain bone mineral density and reduce the risk of osteoporosis in the elderly. In addition to the reduced absorption of calcium by elderly people that results from age-related changes in vitamin D metabolism, the elderly also show a reduced ability to increase the efficiency of calcium absorption as an adaptive response to low-calcium diets. Also, as noted earlier, the low-acid conditions resulting from atrophic gastritis can reduce calcium absorption. Dietary calcium reacts with hydrochloric acid in the stomach to form soluble calcium chloride, which is absorbed in the small intestine. In the United States, the recommended calcium intake is 1200mg/day for men and women older than age 70. Many elderly people may benefit from calcium supplements. 

There was strong evidence-based literature that demonstrated a decrease in the circulating concentration of 25(OH)D, and an increase in the PTH level correlated with an increased risk of skeletal fractures in both the hip and spine in this age group. Studies in both men and women supplemented with 10-25 pgday of vitamin D demonstrated reduced bone resorption, increased bone mineral content, and a decrease in vertebral and nonverte-bral fractures. Therefore, because this age group is even less likely to receive an adequate amount of exposure to sunlight than adults aged 50-70 years and because they have a reduced capacity to produce vitamin D in their skin, it was recommended... 

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