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Homebound, sunlight-deprived elderly people appear to be at risk for vitamin D deficiency. Researchers compared 116 people aged 65 and older who were confined indoors for at least six months to 128 healthy ambulatory elderly not confined. The confined group resided in community dwellings or in a nursing home. Eighty-three percent of the homebound elderly living in the community took in less than the recommended daily allowance for vitamin D compared to 36% of nursing home residents. Fifty-four percent of the community residents had serum levels of 25-OHD below 25 nmol/L, which is below the normal range compared to 38% of nursing home residents. Vitamin D supplementation may be useful in improving vitamin D levels in homebound elderly, who can be at greater risk for bone loss, weakness, and functional impairments., Objective.- To assess the vitamin D status in homebound, community-dwelling elderly persons; sunlight-deprived elderly nursing home residents; and healthy, ambulatory elderly persons. Design. - A cohort analytic study. Participants. - Of 244 subjects at least 65 years old, 116 subjects (85 women and 31 men) had been confined indoors for at least 6 months, either in private dwellings in the community (the Hopkins Elder Housecall Program) or in a teaching nursing home (The Johns Hopkins Geriatrics Center). The 128 control subjects, a healthy ambulatory group, came from the Baltimore Longitudinal Study on Aging. All subjects were free of diseases or medications that might interfere with their vitamin D status. Main Outcome Measures. - Serum levels of 25-hydroxyvitamin D (25-OHD) and 1,25-dihydroxyvitamin D (1,25-[[OH.sub.2]]D) were measured in all subjects. In a subgroup of 80 subjects, serum levels of intact parathyroid hormone (PTH), ionized calcium, and osteocalcin and intake of vitamin D (through 3-day food records) were assessed. A randomly selected cohort of sunlight-deprived subjects also had serum levels of vitamin D binding protein measured. Results. - In sunlight-deprived subjects overall, the mean 25-OHD level was 30 nmol/L (12 ng/mL) (range,

Excess body fat or obesity is known to increase risk of poor vitamin D status in nonathletes but it is not known if this is the case in athletes. Furthermore, the reason for this association is not understood, but is thought to be due to either sequestration of the fat-soluble vitamin within adipose tissue or the effect of volume dilution related to obese individuals' larger body size. Forty two US college athletes (24 men 18 women, 20.7 ± 1.6 years, 85.0 ± 28.7 kg, BMI = 25.7 ± 6.1 kg/m²) provided blood samples during the fall and underwent measurement of body composition via dual energy X-ray absorptiometry. Serum samples were evaluated for 25-hydroxyvitamin D (25(OH)D) concentration to assess vitamin D status using Diasorin 25(OH)D radioiodine assay. Serum 25(OH)D concentration was negatively associated with height (r = -0.45), total body mass (r = -0.57), BMI (r = -0.57), body fat percentage (r = -0.45), fat mass (r = -0.60) and fat-free mass (r = -0.51) (p < .05). These associations did not change after controlling for sex. In a linear regression mixed model, fat mass (coefficient -0.47, p = .01), but not fat-free mass (coefficient -0.18, p = .32) significantly predicted vitamin D status and explained approximately 36% of the variation in serum 25(OH)D concentration. These results suggest that athletes with a large body size and/or excess adiposity may be at higher risk for vitamin D insufficiency and deficiency. In addition, the significant association between serum 25(OH)D concentration and fat mass in the mixed model, which remained after controlling for sex, is in support of vitamin D sequestration rather than volume dilution as an explanation for such association. [ABSTRACT FROM AUTHOR]

Premature infants with very low birth weights frequently suffer from rickets, a bone mineral deficiency. Improvements in the bone mineral content (BMC) and the bone width (BW) of 12 premature (average 31 weeks gestation) very low birth weight infants were compared with 19 normal term infants. All of the infants were given a formula containing no calciferol. The calciferol, normally contained in formula, was given as a separate daily oral supplement. The BMC and the BW were measured at birth and at 8 and 16 weeks of age. Measurements were taken at the junction of the middle and distal thirds of the radius bone in the arm. This area was chosen because it has the least variation in mineral content. At birth, the BMC and the BW were significantly different in the two groups. When measurements were taken again at 16 weeks, no differences were noted between the premature and the normal infants. These results may be attributed to statistical error, or to the intensive hospital care received by these infants. The bone mineralization rate among these premature infants was significantly higher than reported in previous studies. (Consumer Summary produced by Reliance Medical Information, Inc.)

Background: Higher total 25-hydroxyvitamin D [25(OH)D] levels are associated with improved survival among patients with colorectal cancer, but the relationships between circulating vitamin D binding protein (VDBP), and bioavailable or free 25(OH)D, and colorectal cancer survival remain unknown. Methods: We examined the associations between prediagnostic plasma levels of vitamin D-related markers and survival among 603 White participants diagnosed with colorectal cancer from two prospective U.S. cohorts. Plasma VDBP and total 25(OH)D were directly measured, while bioavailable and free 25(OH)D was calculated using a validated formula on the basis of total 25(OH)D, VDBP, and albumin levels. Cox proportional hazards regression was used to estimate HRs for overall and colorectal cancer-specific mortality, with adjustment for other prognostic markers and potential confounders. Results: Higher VDBP levels were associated with improved overall (Ptrend = 0.001) and colorectal cancer-specific survival (Ptrend = 0.02). Compared with patients in the lowest quartile, those in the highest quartile of VDBP had a multivariate HR of 0.58 [95% confidence interval (CI), 0.41-0.80] for overall mortality and 0.58 (95% CI, 0.37-0.91) for colorectal cancer-specific mortality. The results remained similar after further adjustment for total 25(OH)D levels. In contrast, neither bioavailable nor free 25(OH)D levels were associated with overall or colorectal cancer-specific mortality (all Ptrend > 0.15). Conclusions: Prediagnostic circulating concentrations of VDBP were positively associated with survival among patients with colorectal cancer. [ABSTRACT FROM AUTHOR]

To learn more about the optimal dose of vitamin D (critical for the formation of normal bone) for newborn infants, a study was carried out in 27 low-birth-weight, premature infants in good health and in 25 healthy full-term infants. The subjects were randomly assigned to receive one of four vitamin D doses daily and their blood was sampled at regular intervals to determine the concentrations of parathyroid hormone (which helps regulate the movement of calcium into and out of bone), calcium, phosphorus, and other factors. The study continued from birth until the infants reached 16 weeks of age. The four doses were: 10 or 20 micrograms per day (400 or 800 units per day) of vitamin D, or 0.85 or 1.5 micrograms per day of 25-hydroxyvitamin D3 (also called calcidiol; the major circulating form of vitamin D and one of its metabolic precursors). The levels of all substances measured in the four experimental conditions during the study are presented in tabular form. The results indicate, based on blood levels of vitamin D, that 10 micrograms per day, or 400 International Units, are sufficient for premature and full-term well infants. However, while the lower dose of 25-hydroxyvitamin D provided enough vitamin D for the low-birth-weight infants, it was not enough to maintain proper levels in the full-term babies. (Consumer Summary produced by Reliance Medical Information, Inc.)