Dietary ratio of (n-6)/(n-3) polyunsaturated fatty acids alters the fatty acid composition of bone compartments and biomarkers of bone formation in rats

J Nutr. 2000 Sep;130(9):2274-84. doi: 10.1093/jn/130.9.2274.


The effects of dietary polyunsaturated fatty acids (PUFA) on ex vivo bone prostaglandin E(2) (PGE(2)) production and bone formation rate were evaluated in rats. Weanling male Sprague-Dawley rats were fed AIN-93G diet containing 70 g/kg of added fat for 42 d. The dietary lipid treatments were formulated with safflower oil and menhaden oil to provide the following ratios of (n-6)/(n-3) fatty acids: 23.8 (SMI), 9.8 (SMII), 2.6 (SMIII), and 1.2 (SMIV). Ex vivo PGE(2) production in liver homogenates and bone organ cultures (right femur and tibia) were significantly lower in rats fed diets with a lower dietary ratio of (n-6)/(n-3) fatty acids than in those fed diets with a higher dietary ratio. Regression analysis revealed a significant positive correlation between bone PGE(2) and the ratio of arachidonic acid (AA)/eicosapentaenoic acid (EPA), but significant negative correlations between bone formation rate and either the ratio of AA/EPA or PGE(2) in bone. Activities of serum alkaline phosphatase isoenzymes, including the bone-specific isoenzyme (BALP), were greater in rats fed a diet high in (n-3) or a low ratio of (n-6)/(n-3), further supporting the positive action of (n-3) fatty acids on bone formation. These results demonstrated that the dietary ratio of (n-6)/(n-3) modulates bone PGE(2) production and the activity of serum BALP in growing rats.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Biomarkers
  • Body Weight / drug effects
  • Bone and Bones / metabolism*
  • Diet
  • Dietary Fats / administration & dosage
  • Dietary Fats / pharmacology*
  • Dinoprostone / biosynthesis*
  • Fatty Acids, Omega-3 / administration & dosage
  • Fatty Acids, Omega-3 / pharmacology*
  • Fatty Acids, Omega-6
  • Fatty Acids, Unsaturated / administration & dosage
  • Fatty Acids, Unsaturated / pharmacology*
  • Fish Oils / administration & dosage
  • Fish Oils / pharmacology
  • Liver / drug effects
  • Liver / metabolism
  • Male
  • Osteocalcin / blood
  • Rats
  • Rats, Sprague-Dawley
  • Safflower Oil / administration & dosage
  • Safflower Oil / pharmacology


  • Biomarkers
  • Dietary Fats
  • Fatty Acids, Omega-3
  • Fatty Acids, Omega-6
  • Fatty Acids, Unsaturated
  • Fish Oils
  • Osteocalcin
  • Menhaden oil
  • Safflower Oil
  • Dinoprostone