Effects of Excessive Dietary Phosphorus Intake on Bone Health
Purpose of Review
The purpose of this review is to provide an overview of dietary phosphorus, its sources, recommended intakes, and its absorption and metabolism in health and in chronic kidney disease and to discuss recent findings in this area with a focus on the effects of inorganic phosphate additives in bone health.
Recent findings show that increasing dietary phosphorus through inorganic phosphate additives has detrimental effects on bone and mineral metabolism in humans and animals. There is new data supporting an educational intervention to limit phosphate additives in patients with chronic kidney disease to control serum phosphate.
The average intake of phosphorus in the USA is well above the recommended dietary allowance. Inorganic phosphate additives, which are absorbed at a high rate, account for a substantial and likely underestimated portion of this excessive intake. These additives have negative effects on bone metabolism and present a prime opportunity to lower total phosphorus intake in the USA. Further evidence is needed to confirm whether lowering dietary phosphorus intake would have beneficial effects to improve fracture risk.
KeywordsPhosphorus Nutrition Bone Phosphate additives
Papers of particular interest, published recently, have been highlighted as: • Of importance •• Of major importance
- 1.Institute of Medicine. DRI: dietary reference intakes for calcium, phosphorus, magnesium, vitamin D, and fluoride. Washington, DC: National Academy Press; 1997.Google Scholar
- 5.• McClure ST, Chang AR, Selvin E, Rebholz CM, Appel LJ. Dietary sources of phosphorus among adults in the United States: results from NHANES 2001-2014. Nutrients. 2017;9(2):95. Recent NHANES analysis of relative contributions of various dietary sources of phosphorus to total phosphorus intake in the U.S. CrossRefPubMedCentralGoogle Scholar
- 9.Amato D, Maravilla A, Montoya C, Gaja O, Revilla C, Guerra R, et al. Acute effects of soft drink intake on calcium and phosphate metabolism in immature and adult rats. Rev Investig Clin. 1998;50(3):185–9.Google Scholar
- 16.•• Scanni R, von Rotz M, Jehle S, Hulter HN, Krapf R. The human response to acute enteral and parenteral phosphate loads. J Am Soc Nephrol. 2014;25(12):2730–9. This study used nasoduodenal and intravenous infusions of phosphate and urine phosphorus recovery to show that the kidney completely compensates for added phosphate loads by increasing phosphaturia, and that there appears to be no role for the intestine in regulating renal phosphate excretion in response to a phosphate load. CrossRefPubMedPubMedCentralGoogle Scholar
- 17.• St-Jules DE, Jagannathan R, Gutekunst L, Kalantar-Zadeh K, Sevick MA. Examining the proportion of dietary phosphorus from plants, animals, and food additives excreted in urine. J Ren Nutr. 2017;27(2):78–83. A recent review article aimed at describing the bioavailablity of phosphorus from plant, animal, and inorganic phosphate additive sources. The authors examine the proportion of dietary phosphorus consumed in four controlled feeding studies that is excreted in the urine as an indirect measure of intestinal phosphorus absorption. This paper illustrates clearly that there is a difference between “digestibility” (i.e. bioaccessibility) of phosphorus from various sources that has been shown through in vitro digestion studies, and the actual bioavailability (absorption) of phosphorus from these foods. CrossRefPubMedGoogle Scholar
- 54.•• Gutiérrez OM, Luzuriaga-McPherson A, Lin Y, Gilbert LC, Ha S-W, Beck GR Jr. Impact of phosphorus-based food additives on bone and mineral metabolism. J Clin Endocrinol Metab. 2015;100(11):4264–71. This is a controlled feeding study that shows the adverse effects of increasing dietary phosphorus through addition of inorganic phosphate additives on bone metabolism in healthy adults. The authors also present complementary studies in mice that show similar adverse effects on bone and mineral metabolism, including detrimental effects of phosphate additives on bone mineral density and cortical and cancellous bone geometry. CrossRefPubMedPubMedCentralGoogle Scholar
- 59.•• Campos-Obando N, Koek WN, Hooker ER, van der Eerden BC, Pols HA, Hofman A, et al. Serum phosphate is associated with fracture risk: the Rotterdam study and MrOS. J Bone Miner Res. 2017;32(6):1182–93. Serum phosphate levels within the normal range are associated with an increased fracture risk in men and women from the Rotterdam Study and men from MrOS. This was independent of phosphorus intake, but the authors note that phosphate intake accuracy may be limited by assessment methods. Google Scholar
- 67.Kemi VE, Karkkainen MU, Rita HJ, Laaksonen MM, Outila TA, Lamberg-Allardt CJ. Low calcium:phosphorus ratio in habitual diets affects serum parathyroid hormone concentration and calcium metabolism in healthy women with adequate calcium intake. Br J Nutr. 2010;103(4):561–8.CrossRefPubMedGoogle Scholar
- 74.• Nelson SM, Sarabia SR, Christilaw E, Ward EC, Lynch SK, Adams MA, et al. Phosphate-containing prescription medications contribute to the daily phosphate intake in a third of hemodialysis patients. J Ren Nutr. 2017;27(2):91–6. This is an analysis of the phosphorus content of medications used by hemodialysis patients, showing that medications can contribute a meaningful amount of phosphorus to total intake for patients who are often advised to follow a phosphorus-restricted diet. CrossRefPubMedGoogle Scholar
- 75.National Kidney Foundation. K/DOQI clinical practice guidelines for bone metabolism and disease in chronic kidney disease. Am J Kidney Dis. 2003;42(4 Suppl 3):S1–201.Google Scholar
- 77.•• de Fornasari ML, Dos Santos Sens YA. Replacing phosphorus-containing food additives with foods without additives reduces phosphatemia in end-stage renal disease patients: a randomized clinical trial. J Ren Nutr. 2017;27(2):97–105. This is a 3-month randomized controlled trial of an educational intervention to decreased phosphate additive intake in hemodialysis patients that corroborates the work of Sullivan et al. (2009). Patients who received the intervention had significantly improved serum phosphate after three months, with no change in indicators of nutritional status. CrossRefPubMedGoogle Scholar