Influence of Folic Acid Restriction on Alkaline Phosphatase Activity in Ovariectomized Rats on a High-Fat Diet

Abstract

  In the present study, we examined the impact of folic acid restriction on alkaline phosphatase (ALP) activity in ovariectomized (OVX) rats on a high-fat diet. Thirteen-week-old female Sprague-Dawley rats were subjected to either OVX (n = 44) or sham-operation (n = 11). One week after the surgery, OVX rats were further divided into 4 categories based on the diet: normal diet (OXV-Cont.), folic acid-restricted normal diet (OVX-FR), high-fat diet (OVX-H), and folic acid-restricted high-fat diet (OVX-HFR). On day 28, there was no significant difference in serum ALP level among the 4 OVX groups. The serum folic acid level was significantly lower by folic acid restriction (p < 0.001). On the other hand, the serum homocysteine concentration was higher in the OVX-HFR group than in the OVX-Cont. group (p < 0.01). Analysis of a multiple comparison test demonstrated that femoral ALP activity was lower in the OVX-HFR group than in the OVX-H group (p < 0.001), suggesting an association between high-fat diet and folic acid restriction. Collectively, we demonstrated that folic acid restriction reduces femoral ALP activity in OVX rats on a high-fat diet. As femoral ALP activity is a marker of osteogenesis, our study suggests that folic acid restriction increases the risk of osteoporosis in individuals on a high-fat diet.