The Use of Vitamins and Minerals in Skeletal Health

American Association of Clinical Endocrinologists and the American College of Endocrinology Position Statement

Daniel L. Hurley, MD, FACE; Neil Binkley, MD, FACE; Pauline M. Camacho, MD, FACE; Dima L. Diab, MD, FACE, FACP, CCD; Kurt A. Kennel, MD, FACE; Alan Malabanan, MD, FACE, CCD; Vin Tangpricha, MD, PhD, FACE

Disclosures

Endocr Pract. 2018;24(10):915-924. 

In This Article

Macronutrients and Isoflavones

Protein is a major nutrient essential for collagen synthesis in bone.[86] Current IOM guidelines for dietary protein are 0.8 g/kg,[87] although maintenance of muscle mass and bone strength was not an endpoint for these RDA requirements. A meta-analysis of cross-sectional studies suggests either no association or a small positive association between protein intake and BMD.[88] Several studies found inconclusive evidence linking dietary protein intake with fracture risk.[89] The prospective Iowa Women's Health Study reported a decreased relative risk of hip fracture across increasing quartiles of animal protein intake, compared to vegetable protein, in postmenopausal women.[90] The prospective 5-year Canadian Multicentre Osteoporosis study showed that low protein intakes (<12% of total calories) were associated with almost double the risk of fragility fracture in postmenopausal women and men aged ≥50 years compared to higher (≥15% of total calories) protein consumption.[91] The protein source was a determinant of BMD but not fracture risk, whereby greater dairy protein intake was associated with higher BMD compared to plant-based protein. It has been hypothesized that a high-protein (i.e., acid-based) diet is associated with hypercalciuria from bone resorption. However, a recent review concluded that the dietary acid hypothesis is not supported by current evidence.[92] In addition, a protein and calcium interaction has been identified, suggesting increased dietary protein is associated with decreased fracture incidence with calcium intakes >800 mg/day, whereas the effect appears reversed during lower calcium intake.[93] The balance of evidence suggests that adequate protein intake is an important modifiable risk factor associated with reduced risk of fragility fracture.

Flavonoids are lipid-soluble polyphenols widely distributed in plants and may act as chemical messengers and anti-oxidants. Isoflavones are "natural" or "phytoestrogens" (e.g., bioactive compounds that bind to the estrogen receptor) found in various plants and foods, most notably soybeans. Tea flavonoids have been suggested to protect against bone loss, but epidemiologic studies have shown mixed results of habitual tea consumption on BMD and fracture risk, and the results from clinical trials are limited.[94] There has been increasing interest in whether isoflavones can promote bone health and ameliorate bone loss,[95] but studies are conflicting regarding a positive BMD effect.[96] There is little support for the use of isoflavone supplements in Western countries due to inconclusive evidence that these compounds improve BMD or decrease fracture risk.[97–99]

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