Isomaltodextrin inhibits kidney enlargement induced by a high-protein diet through its metabolism by gut microbiota

To evaluate the effects of the soluble fiber isomaltodextrin in a protein-biased diet, a 21-day protein diet trial was conducted in rats, with 60% of the calories derived from protein. The results revealed that the high-protein diet alone led to a significant increase in kidney weight. In contrast, the consumption of water with 5% isomaltodextrin dissolved in it, along with a high-protein diet, suppressed this weight gain. To elucidate this mechanism, an analysis of serum urea toxins confirmed that the concentrations of phenyl sulfate were significantly higher with high protein, and significantly lower with isomaltodextrin. The impact of a high-protein diet increased phenol in cecal contents, an increase that was mitigated by isomaltodextrin. This suggests that the inhibitory effect of isomaltodextrin on renal hypertrophy was due to the suppression of urea toxin precursor production by the gut microbiota.