Full-Scale Clinical Data and Reshaped Intestinal Microbiome on a Short-Term Low-Phosphorus Diet among Healthy Adults

During the past few decades, phosphorus intake has dramatically increased along with higher protein intake and overuse of inorganic phosphate additives worldwide. The detrimental effects of overconsumption of phosphorus are well recognized for patients with chronic kidney disease (CKD), and dietary phosphorus restriction was recommended for these patients. However, the effects of dietary phosphorus restriction in healthy people have not been fully studied.

In this open-label crossover study, healthy adult men (n = 12) consumed normal phosphorus diet (NPD, 1,500 mg/d) for five days. After a 10-day washout period, healthy adults took low phosphorus diet (LPD, 500 mg/d) for another five days. On the fifth day of each intervention, blood, urine and saliva samples were collected at ten time points, and fecal specimens were collected for bacterial taxa identification.

We found that 24-h mean levels of serum phosphate (Pi), urinary Pi, serum parathyroid hormone and fibroblast growth factor 23 decreased, while serum calcium (Ca) and 1,25-dihydroxy vitamin D increased significantly under LPD compared with those under NPD. Dietary phosphorus intake did not change salivary Pi, urinary Ca, salivary Ca and magnesium (Mg) metabolism. Compared with NPD, LPD increased the relative abundance of beneficial microbes including Bacteroidetes, Ruminococcaceae and Lachnospiraceae, indicating that multiple bacterial metabolic pathways have been shifted.

Full-scale data of dietary phosphorus restriction on Pi, Ca and Mg metabolism in healthy male adults are provided. More importantly, for the first time, dietary phosphorus restriction was found to reshape the intestinal microbiome, which provides information for benefits of dietary phosphorus restriction in healthy people, and potential clues for treating patients with CKD.