title: Increasing dietary nitrate has no effect on cancellous bone loss or fecal microbiome in ovariectomized rats.
abstract: 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.
  
  
  
  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.
  
  
  
  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.
authors.affiliation: School of Biological and Population Health Sciences, College of Public Health and Human Sciences, Oregon State University, Corvallis, OR, USA.|Center for Healthy Aging Research, Oregon State University, Corvallis, OR, USA.
authors.forename: Melissa N
authors.initials: MN
authors.lastname: Conley
authors.affiliation: School of Biological and Population Health Sciences, College of Public Health and Human Sciences, Oregon State University, Corvallis, OR, USA.
authors.forename: Cooper
authors.initials: C
authors.lastname: Roberts
authors.affiliation: Center for Healthy Aging Research, Oregon State University, Corvallis, OR, USA.|Departments of Microbiology and Statistics, College of Science, Oregon State University, Corvallis, OR, USA.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Sharpton
authors.affiliation: Center for Healthy Aging Research, Oregon State University, Corvallis, OR, USA.|Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, USA.
authors.forename: Urszula T
authors.initials: UT
authors.lastname: Iwaniec
authors.affiliation: School of Biological and Population Health Sciences, College of Public Health and Human Sciences, Oregon State University, Corvallis, OR, USA.|Center for Healthy Aging Research, Oregon State University, Corvallis, OR, USA.
authors.forename: Norman G
authors.initials: NG
authors.lastname: Hord
mesh_terms: D015502:Absorptiometry, Photon; D042401:Alcaligenaceae / Q000302:isolation & purification; D000818:Animals; D001438:Bacteroidaceae / Q000302:isolation & purification; D015415:Biomarkers / Q000097:blood; D015519:Bone Density / Q000187:drug effects; D001862:Bone Resorption / Q000517:prevention & control*; D000071556:Cancellous Bone / Q000187:drug effects* / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005243:Feces / Q000382:microbiology*; D005260:Female; D000068536:Bacillota / Q000302:isolation & purification; D000069196:Gastrointestinal Microbiome / Q000187:drug effects*; D009566:Nitrates / Q000097:blood / Q000494:pharmacology*; D009569:Nitric Oxide / Q000097:blood; D015675:Osteocalcin / Q000097:blood; D010024:Osteoporosis / Q000517:prevention & control; D010052:Ovariectomy; D051381:Rats; D017207:Rats, Sprague-Dawley; D017422:Sequence Analysis, DNA
chemical_list: D015415:Biomarkers; D004269:DNA, Bacterial; D009566:Nitrates; D015675:Osteocalcin; D009569:Nitric Oxide
keywords: Dietary nitrate; Nitric oxide; Osteoporosis; Postmenopause; Vegetables