High phosphorus intake and gut-related parameters – results of a randomized placebo-controlled human intervention study

Abstract

BackgroundIn 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.MethodsSixty-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.ResultsFaecal 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.ConclusionsThe 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 registrationThe trial is registered at ClinicalTrials.gov as NCT02095392.Electronic supplementary materialThe online version of this article (10.1186/s12937-018-0331-4) contains supplementary material, which is available to authorized users.

Calcium and Phosphate Metabolism, Blood Lipids and Intestinal Sterols in Human Intervention Studies Using Different Sources of Phosphate as Supplements—Pooled Results and Literature Search

“…The genotoxicity and cytotoxicity of faecal water remained unchanged after supplementation with phosphate alone in one study [ 13 ].…”

“…Cats et al (1993) also showed that there was no change in the cytolytic activity of faecal water following calcium phosphate supplementation [ 28 ]. Trautvetter et al (2018) showed that there were no changes in the genotoxic potential or the cytotoxicity of faecal water following phosphate supplementation [ 13 ]. All these authors supposed that the formation of calcium phosphate complexes and the co-precipitation of bile acids or other intestinal substances may be responsible for a rather decreased toxicity.…”

“…In the small intestine, dietary calcium and phosphate are able to form calcium-phosphate complexes (amorphous calcium phosphate, ACP), which can precipitate nutritional ingredients and intestinal substances such as bile acids and fatty acids [ 10 ]. Consequently, several physiological changes may occur in the human gut, such as modulation of the composition of faecal bile acids and gut microbiota [ 11 , 12 , 13 ]. Increased excretion of bile acids can result in an interruption of the enterohepatic circulation.…”

“…The question therefore arises whether a higher amount of phosphorus leads to similar results. Trautvetter et al (2018) showed that microbiota and faecal short-chain fatty acids (SCFA) were modulated by phosphate supplementation [ 13 ]; however, it was also shown that calcium metabolism was impaired by a high-phosphate diet [ 20 ]. Such effects of phosphate supplementation are of particular interest, since the phosphorus intake of Western societies is far above the recommendation, not least due to the usage of phosphate additives in food production [ 6 , 21 ].…”

Role of Dietary Micronutrients on Gut Microbial Dysbiosis and Modulation in Inflammatory Bowel Disease

“…[ 202 ] High Ca diets also impacted microbial fermentation, Ca phosphate increased proximal colon butyrate concentrations in rats, [ 203 ] while the supplementation of Ca carbonate within a human intervention trial significantly increased total fecal SCFA and acetate. [ 204 ]…”