Increasing dietary nitrate has no effect on cancellous bone loss or fecal microbiome in ovariectomized rats. Issue 5 (30th March 2017)

• Record Type: Journal Article
• Authors: Conley, Melissa N.; Roberts, Cooper; Sharpton, Thomas J.; Iwaniec, Urszula T.; Hord, Norman G.
• Is Part Of: Molecular nutrition & food research. Volume 61:Issue 5(2017)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-03-30
• Subjects: Dietary nitrate -- Nitric oxide -- Osteoporosis -- Postmenopause -- Vegetables; Food -- Biotechnology -- Periodicals; Food -- Microbiology -- Periodicals; Nutrition -- Periodicals; Food -- Toxicology -- Periodicals; Nutrition -- Periodicals; Food Microbiology -- Periodicals; Food Technology -- Periodicals; Molecular Biology -- Periodicals; 664.0705
• DOI: 10.1002/mnfr.201600372
• Languages: English
• ISSNs: 1613-4125

Abstract

Abstract : Nitrate‐rich foods may be positively associated with bone health. A rat model of ovarian hormone deficiency‐induced bone loss was employed to assess the role of dietary nitrate on indices of bone health and gut microbiome. While ovarian hormone deficiency‐induced bone loss and changes in the fecal microbiome, dietary nitrate did not slow bone turnover, loss, or alter fecal microbiome composition in this model. Abstract : Scope: Studies suggest diets rich in fruit and vegetables reduce bone loss, although the specific compounds responsible are unknown. Substrates for endogenous nitric oxide (NO) production, including organic nitrates and dietary nitrate, may support NO production in age‐related conditions, including osteoporosis. We investigated the capability of dietary nitrate to improve NO bioavailability, reduce bone turnover and loss. Methods and results: Six‐month‐old Sprague Dawley rats [30 ovariectomized (OVX) and 10 sham‐operated (sham)] were randomized into three groups: (i) vehicle (water) control, (ii) low‐dose nitrate (LDN, 0.1 mmol nitrate/kg bw/day), or (iii) high‐dose nitrate (HDN, 1.0 mmol nitrate/kg bw/day) for three weeks. The sham received vehicle. Serum bone turnover markers; bone mass, mineral density, and quality; histomorphometric parameters; and fecal microbiome were examined. Three weeks of LDN or HDN improved NO bioavailability in a dose‐dependent manner. OVX resulted in cancellous bone loss, increased bone turnover, and fecal microbiome changes. OVX increased relative abundances of Firmicutes and decreased Bacteroideceae and Alcaligenaceae. Nitrate did not affect the skeleton or fecal microbiome. Conclusion: These data indicate that OVX affects the fecal microbiome and that the gut microbiome is associated with bone mass. Three weeks of nitrate supplementation does not slow bone loss or alter the fecal microbiome in OVX.