Journal Article

High-fat diets provoke phosphorus absorption from the small intestine in rats

Ito, Mikiko, Masuda, Masashi, Nakamatsu, Yurino, Kawamoto, Keisuke, Tanaka, Sarasa, Nakao-Muraoka, Mari, Niida, Yuki, Sakuma, Masae, Arai, Hidekazu, Taketani, Yutaka

2020

Overview

•A high-fat diet increases the apparent absorption rate of phosphorus.•A high-fat diet increases type-IIb sodium-phosphate cotransporter and type-III sodium-phosphate cotransporter expression in the duodenum.•Dietary fat might be an important factor in the control of serum phosphorus levels. The ratio of dietary carbohydrate to fat may affect phosphorus metabolism because both calcium and phosphorus are regulated by similar metabolic mechanisms, and a high-fat diet (HFD) induces deleterious effects on the absorption of dietary calcium. We hypothesized that an HFD induces an increase in phosphorus absorption. The aim of this study was to evaluate the effects of differences in the quantity and quality of dietary fat on phosphorus metabolism over the short- and long-term. Eighteen 8-wk-old Sprague–Dawley male rats were fed an isocaloric diet containing varied ratios of carbohydrates to fat energy and sources of fat (control diet, HFD, and high- saturated fat diet [HF-SFA]). At 3 d and 7 wk after the allocation and initiation of the test diets, feces and urine were collected and used for phosphorus and calcium measurement. The fecal phosphorous concentration (F-Pi) was lower in the HF-SFA group than in the other two groups; however, the urine phosphorus concentration (U-Pi) was significantly higher in the HF-SFA group than the other two groups when the rats were fed over the short- (P < 0.01) and long -term (P < 0.01 versus control, P < 0.05 versus HFD group). There were no significant differences in type-IIa sodium-phosphate cotransporter (NaPi-2 a) and type-IIc sodium-phosphate cotransporter (NaPi-2 c) mRNA expression, which are renal phosphate transport-related genes; however, the expression of type-IIb sodium-phosphate cotransporter (NaPi-2 b) and type-III sodium-phosphate cotransporter (Pit-1) mRNA in the duodenum was higher in the HFD and HF-SFA groups than in the control group (P < 0.05), although there were no significant differences in these in the jejunum. The present results indicated that an HFD, particularly HF-SFA, increases intestinal phosphate absorption compared with control.

• Publisher: Elsevier Inc,Elsevier Limited
• Subject: Absorption / Animals / Calcium / Calcium (dietary) / Calcium - metabolism / Calcium absorption / Carbohydrates / Diet / Diet, High-Fat / dietary calcium / dietary carbohydrate / Dietary fat / Dietary Fats - pharmacology / Duodenum / Duodenum - metabolism / energy / experimental diets / Fat metabolism / Feces / Feces - chemistry / Food / Gene expression / genes / High fat diet / Intestinal Absorption - drug effects / Intestine / Intestine, Small - metabolism / Jejunum / Laboratory animals / Male / males / messenger RNA / Metabolism / Phosphate / Phosphates / Phosphorus / Phosphorus - metabolism / Pit1 protein / Polymerase chain reaction / Ratios / Rats / Rats, Sprague-Dawley / Saturated fat / saturated fats / Serum phosphorus levels / Small intestine / Sodium / sodium phosphate / Sodium-Phosphate Cotransporter Proteins, Type IIb - metabolism / Sodium-Phosphate Cotransporter Proteins, Type III - metabolism / symporters / Urine