Plain language summary
It is known that calcium and phosphate form amorphous calcium phosphate in the small intestines, which can lead to various beneficial changes in the human gut. Currently it remains unclear whether dietary phosphorous influences serum phosphate concentrations. The aim of this study was to analyse the cytotoxicity and genotoxicity of faecal water and faecal concentrations of short chain fatty acids in 62 healthy subjects. All participants received placebo for two weeks, and afterwards an intervention for eight weeks according to the assigned group of either 1000 mg/d phosphorus, 1000 mg/d phosphorus and 500 mg/d calcium and 1000 mg/d phosphorus and 1000 mg/d calcium. Faecal collection took place after the placebo period and after the eight-week intervention period. This study found that the high phosphorus supplementation did not affect the toxicity of faecal water, nor the faecal fat concentrations, independent of calcium. Based on these results, the authors conclude that this study provides first hints for a potential phosphorus-induced modulation of the gut community.
Abstract
BACKGROUND In recent years, high phosphate intakes were discussed critically. In the small intestine, a part of the ingested phosphate and calcium precipitates to amorphous calcium phosphate (ACP), which in turn can precipitate other intestinal substances, thus leading to a beneficial modulation of the intestinal environment. Therefore, we analysed faecal samples obtained from a human intervention study regarding gut-related parameters. METHODS Sixty-two healthy subjects (men, n = 30; women, n = 32) completed the double-blind, placebo-controlled and parallel designed study (mean age: 29 ± 7 years; mean BMI: 24 ± 3 kg/m2). Supplements were monosodium phosphate and calcium carbonate. During the first 2 weeks, all groups consumed a placebo sherbet powder, and afterwards a sherbet powder for 8 weeks according to the intervention group: P1000/Ca0 (1000 mg/d phosphorus), P1000/Ca500 (1000 mg/d phosphorus and 500 mg/d calcium) and P1000/Ca1000 (1000 mg/d phosphorus and 1000 mg/d calcium). After the placebo period and after 8 weeks of intervention faecal collections took place. We determined in faeces: short-chain fatty acids (SCFA) and fat as well as the composition of the microbiome (subgroup) and cyto- and genotoxicity of faecal water (FW). By questionnaire evaluation we examined tolerability of the used phosphorus supplement. RESULTS Faecal fat concentrations did not change significantly due to the interventions. Concentrations of faecal total SCFA and acetate were significantly higher after 8 weeks of P1000/Ca500 supplementation compared to the P1000/Ca0 supplementation. In men, faecal total SCFA and acetate concentrations were significantly higher after 8 weeks in the P1000/Ca1000 group compared to the P1000/Ca0 one. None of the interventions markedly affected cyto- and genotoxic activity of FW. Men of the P1000/Ca1000 intervention had a significantly different gut microbial community compared to the men of the P1000/Ca0 and P1000/Ca500 ones. The genus Clostridium XVIII was significantly more abundant in men of the P1000/Ca1000 intervention group compared to the other groups. Supplementations did not cause increased intestinal distress. CONCLUSIONS The used high phosphorus diet did not influence cyto- and genotoxicity of FW and the concentrations of faecal fat independent of calcium intake. Our study provides first hints for a potential phosphorus-induced modulation of the gut community and the faecal total SCFA content. TRIAL REGISTRATION The trial is registered at ClinicalTrials.gov as NCT02095392 .
Methodological quality
Allocation concealment
:
Yes
