Calcium and phosphorus are indispensable for bone health and tooth formation. The levels of these minerals in the blood are controlled by two hormones, vitamin D and parathormone (parathyroid hormone), which is secreted by small glands called the parathyroid glands.
According to a recent study published in the Nutrition Journal, high intake of phosphorus through diet does not result in high blood phosphate levels in healthy individuals. These individuals should, however, make sure that their calcium intake is adequate.
‘People taking high levels of phosphorus must include calcium supplements.’
AdvertisementPhosphorus is mainly obtained from protein-rich foods. Junk and processed foods, and carbonated drinks contain inorganic phosphorus, which is completely absorbed and could acutely raise phosphorus levels in the blood. Their increasing use has raised concerns about their possible adverse effects on regular junk food consumers, many of whom are children.
Though the recommended intake of phosphorus for an adult is 700 mg / day, people end up taking in around double the amount. Excess phosphates are excreted by the kidneys. Therefore, a high intake of phosphates could be particularly dangerous in a patient with chronic kidney disease (CKD). High phosphate levels have been associated with cardiovascular events in individuals with or without kidney disease.
Researchers investigated the possible effects of intake of excess phosphorus on several metabolic parameters with or without calcium supplementation. The 66 healthy individuals included in the study were administered 1g of phosphorus with or without calcium (500 mg or 1g per day) added to sherbet powder for a period of 8 weeks. The final analysis was conducted on data obtained from 62 individuals.
The researchers found that:
- Excess intake of phosphorus did not affect the fasting levels of phosphate in the blood. The phosphate levels in the urine and the feces increased in all the groups, indicating that it was being excreted by the body.
- Calcium excretion in the urine decreased in individuals taking only phosphorus and nocalcium. It is important to supplement adequate amounts of calcium to those on a high phosphorus diet.
- High phosphorus and calcium intake may cause imbalances in iron and magnesium metabolism. Serum magnesium levels did not change significantly in the subjects, though renal excretion decreased in those who were not given calcium. Plasma levels of iron and ferritin were not affected. Plasma transferrin levels increased in the group administered phosphorus with 500 mg of calcium. Ferritin and transferrin bind to iron and control the levels of free iron in the blood.
- Vitamin D levels increased in all the groups irrespective of whether the patient received calcium or not along with the phosphorus. The levels of parathyroid hormone did not change significantly in any group.
- Bones in our body undergo a continuous process of repair called bone remodeling. In this process, damaged bone is removed by certain cells through bone resorption, and is replaced by new bone. The levels of markers of bone formation, osteocalcin and bone specific alkaline phosphatase (BAP), as well as of bone resorption (CTX) decreased in the groups receiving phosphate plus calcium. But the changes were not significant enough to indicate a relevant effect of the intervention on bone remodeling.
- Another parameter that was measured was the fibroblast growth factor 23 (FGF23). FGF23 tries to maintain normal blood phosphate levels by decreasing its absorption from the intestine and increasing its excretion via the urine. Increase in FGF23 levels have been associated with cardiovascular disease. In this study, a temporary rise in FGF23 levels were noted at 4 weeks of treatment, which did not persist at 8 weeks.
Reference:Trautvetter U, Jahreis G, Kiehntopf M, Glei M. Consequences of a high phosphorus intake on mineral metabolism and bone remodeling in dependence of calcium intake in healthy subjects - a randomized placebo-controlled human intervention study. Nutrition Journal 2016; 15:7. DOI: 10.1186/s12937-016-0125-5