Poster Presentation 29th Australian and New Zealand Bone and Mineral Society Annual Scientific Meeting 2019

Increasing green leafy vegetables containing vitamin K1 reduces the total and the undercarboxylated fraction of osteocalcin: a 4-week randomised control trial (#116)

Marc Sim 1 2 , Joshua Lewis 1 3 4 , Richard L Prince 5 6 , Itamar Levinger 7 8 , Claire Palmer 9 , Nicola Bondonno 1 4 , Elizabeth Byrnes 10 , Amanda Devine 1 , Carl Schultz 4 11 , Kevin Croft 9 , Jonathan Hodgson 1 4 , Lauren Blekkenhorst 1 4
  1. School of Medical & Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
  2. Medical School, Royal Perth Hospital Unit, The University Western Australia, Perth, Western Australia, Australia
  3. Centre for Kidney Research, Children's Hospital at Westmead, The University of Sydney, Sydney, New South Wales, Australia
  4. Medical School, Royal Perth Hospital Unit, The University Western Australia, Perth, Western Australia, Australia
  5. Medical School, Sir Charles Gardner Unit, The University Western Australia, Perth, Western Australia, Australia
  6. Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia
  7. Institute for Health and Sport, Victoria University, Melbourne, Victoria, Australia
  8. Australian Institute for Musculoskeletal Science (AIMSS), University of Melbourne and Western Health, Melbourne, Victoria, Australia
  9. School of Biomedical Science, The University Western Australia, Nedlands, Western Australia, Australia
  10. Department of Clinical Biochemistry, PathWest Laboratory Medicine, Queen Elizabeth II Medical Centre, Perth, Western Australia, Australia
  11. Department of Cardiology, Royal Perth Hospital, Perth, Western Australia, Australia

Aim:  Increased vitamin K may reduce or reverse age-related bone loss. Although green leafy vegetables are a rich source of vitamin K1, their effects on human bone remain unclear. Total osteocalcin (tOC) is a recognised marker of bone turnover and the ratio of undercarboxylated osteocalcin (ucOC)/tOC is a measure of vitamin K status. Thus we evaluated the effect of consuming green leafy vegetables for 4 weeks on tOC, ucOC and the ratio of ucOC:tOC.

Methods: Osteocalcin forms were measured by sandwich-electrochemiluminescence immunoassay in serum pre- and post-intervention from a crossover randomised controlled trial examining the effects of increasing dietary nitrate (through green leafy vegetables) on blood pressure. Thirty older individuals (mean age 61.8 ± 9.9 years, 66% male) were randomised to a controlled crossover trial design with 4-week treatment periods separated by 4-week washout periods. The 3 experimental phases included: (i) increased consumption of green leafy vegetables (GLV; 200 g/d containing 371.5 ± 63.5 µg/d of vitamin K1); (ii) increased consumption of vegetables, not green and leafy (N-GLV; 200 g/d containing 3.3 ± 0.3 µg/d of vitamin K1); and (iii) control (CON), no increase in vegetable intake.

Results: Pre-intervention tOC, ucOC and ucOC:tOC levels were similar (P>0.05) between phases. Over the month of GLV, tOC, ucOC and ucOC:tOC levels were significantly lower compared to pre-intervention (P≤0.001). Compared to CON, post-intervention tOC, ucOC and ucOC:tOC levels were ~14%, 31% and 19% lower in GLV (P<0.05). No changes were observed in N-GLV and CON (P>0.05).

Conclusion: Four weeks of increased vitamin K1-rich green leafy vegetable intake reduced tOC, a bone turnover marker. Second, as expected the ucO;tOC ratio fell more as a result of increasing vitamin K-dependent carboxylation. These data support our previous work on the beneficial influence of vegetables on fracture reduction (1), possibly through dietary vitamin K1 containing foods.

  1. (1) Blekkenhorst LC, Hodgson JM, Lewis JR, Devine A, Woodman RJ, Lim WH, Wong G, Zhu K, Bondonno CP, Ward NC, Prince RL (2017) Vegetable and fruit intake and fracture-related hospitalisations: a prospective study of older women. Nutrients 9:E511