Bone turnover, calcium homeostasis, and vitamin D status in Danish vegans

Eur J Clin Nutr. 2018 Jul;72(7):1046-1054. doi: 10.1038/s41430-017-0081-y. Epub 2018 Jan 23.

Abstract

Background/objectives: A vegan diet has been associated with increased bone fracture risk, but the physiology linking nutritional exposure to bone metabolism has only been partially elucidated. This study investigated whether a vegan diet is associated with increased bone turnover and altered calcium homeostasis due to insufficient intake of calcium and vitamin D.

Subjects/methods: Fractionated and total 25-hydroxyvitamin D (25(OH)-D), parathyroid hormone (PTH), calcium, and four bone turnover markers (osteocalcin, N-terminal propeptide of type I procollagen (PINP), bone-specific alkaline phosphatase (BAP), and C-terminal telopeptide of type I collagen (CTX)) were measured in serum from 78 vegans and 77 omnivores.

Results: When adjusting for seasonality and constitutional covariates (age, sex, and body fat percentage) vegans had higher concentrations of PINP (32 [95% CI: 7, 64]%, P = 0.01) and BAP (58 [95% CI: 27, 97]%, P < 0.001) compared to omnivores, whereas CTX (30 [95% CI: -1, 72]%, P = 0.06) and osteocalcin (21.8 [95% CI: -9.3, 63.7]%, P = 0.2) concentrations did not differ between the two groups. Vegans had higher serum PTH concentration (38 [95% CI: 19, 60]%; P < 0.001) and lower 25(OH)-D serum concentration (-33 [95% CI: -45, -19]%; P < 0.001), but similar serum calcium concentration (-1 [95% CI: -3, 1]%, P = 0.18 compared to omnivores.

Conclusions: Vegans have higher levels of circulating bone turnover markers compared to omnivores, which may in the long-term lead to poorer bone health. Differences in dietary habits including intake of vitamin D and calcium may, at least partly, explain the observed differences.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Alkaline Phosphatase / blood
  • Bone Remodeling / physiology*
  • Bone and Bones*
  • Calcium / administration & dosage
  • Calcium / blood*
  • Calcium, Dietary / administration & dosage
  • Calcium, Dietary / blood
  • Collagen Type I / blood
  • Denmark
  • Diet, Vegan*
  • Feeding Behavior*
  • Female
  • Humans
  • Male
  • Nutritional Status*
  • Osteocalcin / blood
  • Parathyroid Hormone / blood
  • Peptide Fragments / blood
  • Peptides / blood
  • Procollagen / blood
  • Vegans
  • Vitamin D / administration & dosage
  • Vitamin D / analogs & derivatives
  • Vitamin D / blood*
  • Young Adult

Substances

  • Calcium, Dietary
  • Collagen Type I
  • Parathyroid Hormone
  • Peptide Fragments
  • Peptides
  • Procollagen
  • collagen type I trimeric cross-linked peptide
  • procollagen Type I N-terminal peptide
  • Osteocalcin
  • Vitamin D
  • 25-hydroxyvitamin D
  • Alkaline Phosphatase
  • Calcium