Dietary l-carnitine supplementation improves bone mineral density by suppressing bone turnover in aged ovariectomized rats

Phytomedicine. 2008 Aug;15(8):595-601. doi: 10.1016/j.phymed.2008.02.026. Epub 2008 Jun 9.


Postmenopausal bone loss is a major public health concern. Although drug therapies are available, women are interested in alternative/adjunct therapies to slow down the bone loss associated with ovarian hormone deficiency. The purpose of this study was to determine whether dietary supplementation of l-carnitine can influence bone density and slow the rate of bone turnover in an aging ovariectomized rat model. Eighteen-month-old Fisher-344 female rats were ovariectomized and assigned to two groups: (1) a control group in which rats were fed ad libitum a carnitine-free (-CN) diet (AIN-93M) and (2) another fed the same diet but supplemented with l-carnitine (+CN). At the end of 8 weeks of feeding, animals were sacrificed and bone specimens were collected for measuring bone mineral content (BMC) and density (BMD) using dual energy X-ray absorptiometry. Femoral microarchitectural properties were assessed by microcomputed tomography. Femoral mRNA levels of selected bone matrix proteins were determined by northern blot analysis. Data showed that tibial BMD was significantly higher in the rat fed the +CN diet than those fed the -CN (control) diet. Dietary carnitine significantly decreased the mRNA level of tartrate-resistant acid phosphatase (TRAP), an indicator of bone resorption by 72.8%, and decreased the mRNA abundance of alkaline phosphatase (ALP) and collagen type-1 (COL), measures of bone formation by 63.6% and 61.2%, respectively. The findings suggest that carnitine supplementation slows bone loss and improves bone microstructural properties by decreasing bone turnover.

MeSH terms

  • Acid Phosphatase / genetics
  • Acid Phosphatase / metabolism
  • Aging / physiology*
  • Alkaline Phosphatase / genetics
  • Alkaline Phosphatase / metabolism
  • Animals
  • Bone Density / drug effects*
  • Carnitine / pharmacology*
  • Collagen Type I / genetics
  • Collagen Type I / metabolism
  • Dietary Supplements*
  • Eating
  • Female
  • Femur / drug effects
  • Femur / physiology
  • Isoenzymes / genetics
  • Isoenzymes / metabolism
  • Lumbar Vertebrae / drug effects
  • Lumbar Vertebrae / physiology
  • Osteoporosis / prevention & control
  • Ovariectomy*
  • Phytotherapy
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Rats
  • Rats, Inbred F344
  • Tartrate-Resistant Acid Phosphatase
  • Tibia / drug effects
  • Tibia / physiology
  • Vitamin B Complex / pharmacology
  • Weight Gain


  • Collagen Type I
  • Isoenzymes
  • RNA, Messenger
  • Vitamin B Complex
  • Alkaline Phosphatase
  • Acid Phosphatase
  • Tartrate-Resistant Acid Phosphatase
  • Carnitine