This preliminary study found no significant differences in the effect of various combinations of beverages on hydration status of healthy adult males. Advising people to disregard caffeinated beverages as part of the daily fluid intake is not substantiated by the results of this study. The across-treatment weight loss observed, when combined with data on fluid-disease relationships, suggests that optimal fluid intake may be higher than common recommendations. Further research is needed to confirm these results and to explore optimal fluid intake for healthy individuals.

Limited research in young adults and immature animals suggests a detrimental effect of tobacco on bone during growth. This study investigated the effects of nicotine, the major alkaloid component of tobacco, on calciotropic hormone concentrations and bone status in growing female rats. One-month-old animals received either saline (n = 10), nicotine at 3.0 mg/kg/day (n = 10), or nicotine at 4.5 mg/kg/day (n = 10) administered subcutaneously via osmotic minipumps for either 2 or 3 months. Sera, femora, tibiae, and lumbar vertebrae (3-5) were collected at necropsy. The concentrations of serum calcium, phosphorus, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, parathyroid hormone, calcitonin, and insulin-like growth factor-I were determined. Bone variables evaluated included mineral content and density (vertebrae and femora), cancellous and cortical histomorphometry (tibiae), and bone strength (vertebrae and femora). Statistically significant differences in serum mineral and hormone concentrations were not associated with nicotine dose or exposure time. No significant nicotine treatment effects were detected for bone mineral content and density, bone histomorphometry, or bone strength. We conclude that nicotine treatment for 2 or 3 months at serum concentrations in the upper range of those found in smokers has no detrimental effect on bone mass, volume, or strength in the growing rat.

This study investigated the effects of nicotine, the chemical responsible for tobacco addiction, on bone and on serum mineral and calcitropic hormone levels in adult, female rats to help resolve a current controversy regarding the impact of nicotine on bone health. Seven-month-old rats received either saline (n = 12), low-dose nicotine (4.5 mg/kg/day, n = 2), or high-dose nicotine (6.0 mg/kg/day, n = 12) administered subcutaneously via osmotic minipumps for 3 months. Blood, femora, tibiae, and lumbar vertebrae (3-5) were collected at necropsy for determination of serum mineral and hormonal concentrations, bone density (femora and vertebrae), bone turnover (tibiae), and bone strength (femora). The presence of nicotine in serum (111 +/- 7 and 137 +/- 10 ng/ml for the low- and high-dose nicotine groups, respectively) confirmed successful delivery of the drug via osmotic minipumps. Nicotine-induced treatment differences were not detected in serum calcium, 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D. However, serum phosphorus and parathyroid hormone (PTH) were higher in rats treated with high-dose nicotine, and serum calcitonin was lower in rats treated with both high- and low-dose nicotine than in control rats. Nicotine treatment had no effect on tibial cancellous or cortical bone turnover or femoral bone mineral content (BMC) and density (BMD). Femoral ultimate load and vertebral BMC were lower in rats treated with high-dose nicotine than in control rats. We conclude that nicotine at serum concentrations 2.5-fold greater than the average in smokers has limited detrimental effects on bone in normal, healthy female rats.

This study determined the effects of nicotine on serum concentrations of several calciotropic hormones, and bone formation and resorption end-points in 7 month old, adult female rats. Animals were administered either saline (n= 9/group), low dose nicotine at 3.0 mg/kg/day (n=lO/group) or high dose nicotine at 4.5 mg/kg/day (n=ll/group) by subcutaneous osmotic minipurnps. At the end of a three months treatment period, serum concentrations of calcium, phosphorus, parathyroid hormone, calcitonin, 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D were determined. Femora, tibiae, and lumbar vertebrae (3-5) were collected and bone parameters evaluated included mineral density and content (femora and vertebrae), strength (femora and vertebrae) and histomorphometry (tibiae). Animals given nicotine had significantly lower levels of 25-hydroxyvitamin D than controls [20.821.4 nglml for the low dose group and 20.7?1.0 ng/ ml for the high dose group versus 27.621.3 ng/ml for the control group (mean?S.E.M.), P

Inclusion of plain drinking water compared to exclusion of plain drinking water in the diet did not affect the markers of hydration used in this study.