Bone and nutrition in elderly women: protein, energy, and calcium as main determinants of bone mineral density

Abstract

Objective: Nutrition is an important factor in the prevention and treatment of osteoporosis. Our goal was to examine the relationship between various nutrients and bone mass of several skeletal sites in elderly women, taking into account possible confounding variables. Design/methods: A cross-sectional study in 136 healthy Caucasian, postmenopausal women, free of medications known to affect bone was carried out. Bone mineral density (BMD) and body composition (lean and fat tissue) were measured by dual X-ray absorptiometry using specialized software for different skeletal sites. Parathyroid hormone (PTH) and vitamin D, 25(OH)D, as possible confounders, were determined in serum samples. Dietary intake, including all supplements, was assessed by 3-day dietary record and analyzed using Food Processor 1 . Past physical activity and present walking were examined as well and accounted for as potential confounders. Simple and multiple regression models were created to assess the relationships between nutrients and BMD. To examine the co-linear variables and their possible independent association with bone, subgroup analyses were performed. Results: Showed independent influence of calcium, energy, and protein, examined separately and in multiple regression models on BMD of several skeletal sites. Magnesium, zinc and vitamin C were significantly related to BMD of several skeletal sites in multiple regression models (controlled for age, fat and lean tissue, physical activity and energy intake), each contributing more than 1% of variance. Serum PTH and 25(OH)D did not show significant association with bone mass. Conclusions: Despite the cross-sectional nature of our study we were able to show a significant relationship between BMD and several critical nutrients: energy, protein, calcium, magnesium, zinc and vitamin C. The exact involvement of these nutrients and their clinical significance in bone health need to be further elucidated in humans and conclusions about the effects of a single nutrient on bone mass must be given cautiously, taking into account its interaction and co-linearity with others. Understanding relationships among nutrients, not just limited to calcium and vitamin D, but others that have not been investigated to such extent, is an important step toward identifying preventive measures for bone loss and prevention of osteoporosis.

Predictors of low bone mineral density in the elderly: the role of dietary intake, nutritional status and sarcopenia

“…Energy intake is related to body size, physical activity and weight variations that influence BMD, which is why previous authors found significant relationship between BMD and energy intake (Ilich et al, 2003). No such relationship appears in our study, probably due to the highly variable levels of physical activity thermogenesis in the elderly, and also to differences in body size: among subjects with the same BMI, those who are taller and heavier have a higher energy intake, but they might have the same BMD.…”

“…Understanding the effect of potentially modifiable lifestyle factors on BMD in the elderly is essential to osteoporosis prevention and treatment; among these factors, sarcopenia and nutritional disorders may have a key role (Ilich et al, 2003).…”

“…Nutritional disorders, and malnutrition in particular, are common in elderly people and might be expected to exacerbate the physiological age-related muscle and bone mass decline (Ilich et al, 2003). An appropriate approach to investigating the effect of nutrition on BMD includes estimating energy and protein intake and measuring body mass index (BMI) as an indicator of energy malnutrition and serum albumin to identify protein malnutrition.…”

Is there a role for vitamin C in preventing osteoporosis and fractures? A review of the potential underlying mechanisms and current epidemiological evidence

“…(dietary and supplemental) vitamin C intake has not been linked with BMD in women (83,84,88) ; and 324 both positive and negative associations have been reported in men (74) , although the latter findings previously been shown to be significantly lower in smokers than non-smokers (65) and serum vitamin 327 C levels are lower in smokers independent of dietary intakes (64,65) . Hence, the exclusion of smokers 328 to the study may have led to more consistent findings.…”

“…Although positive associations between dietary 318 vitamin C intake and supplements and bone density have previously been reported, findings have 319 been inconsistent (8,9,74,(83)(84)(85) . (6,8,11,74,84,86,87) , three to seven-day food diaries (9,88) and 24-hour recalls (12,83) . Moreover, total…”