In September 2017, the book Dietary Phosphorous – Health, Nutrition, and Regulatory Aspects was published by CRC Press. Authors Mona Calvo and Jaime Uribarri review dietary intake levels of phosphorus and discuss health endpoints associated with phosphorus consumption. The authors argue that current intakes of phosphorus are higher than human physiological requirements, and assert higher serum phosphorus concentrations are shown to be significantly associated with a higher incidence of morbidity and mortality in North America and Europe.
Phosphorus is an essential nutrient that is required for human health. Published dietary reference intakes for phosphorus include estimates of average requirements and recommended dietary allowances. However, not all authoritative bodies have provided tolerable upper intake levels for dietary phosphorus due to inadequate scientific evidence.
Phosphates are common food additives used to leaven cakes, cookies, pancakes, waffles, and donuts; to maintain the structure and hydration of meat, poultry, and seafood products; to improve fluidity of evaporated milk; flavor or add minerals to beverages; and to maintain the structure of canned fruit and vegetable products. Often there are no alternatives that can be used in the same small quantities to accomplish these functions in foods. In addition, some food-additive phosphates contain other minerals, such as calcium, potassium, and magnesium, which are consumed by some populations in quantities below what is recommended. Therefore, consumption of these phosphates help assist with intake of such nutrients.
In addition to reviewing intake levels, the book authors discuss health endpoints associated with phosphorous intake that go beyond physiologic requirements such as progression of chronic kidney disease (CKD), mineral bone disease and calcification of soft tissue, cardiovascular disease, mortality, anemia, and cancer (strictly in-vitro studies). The authors suggest phosphorus intake is associated with each of these conditions, and present different levels of evidence for each endpoint. While phosphorus intake has been associated with certain endpoints in specific sub-populations, including those predisposed to such conditions, in 2017 an extensive research review identified only two primary research publications that focused on data specific to a direct association between a food-additive phosphate and clinical outcomes in the general population. Otherwise, the investigator in the review found that any associations between phosphorus intake and health endpoints are inconclusive.
The outcome of the 2017 research review is consistent with the National Academy of Medicine as well as the European Food Safety Authority’s (EFSA) 2015 Scientific Opinion on dietary reference values for phosphorus, which stated “available data were not sufficient to establish a Tolerable Upper Intake Level (UL) for phosphorus.” Thus, future research on upper level intake is needed as the causality of any association between dietary phosphorous and clinical outcomes identified in studies could not be determined.
Difficulties in determining dietary phosphorus intake and, in particular, the intake of food-additive phosphate include: the inherent limitations of widely used dietary ascertainment methods, such as 24-hour dietary recalls and food frequency questionnaires (FFQs); likely inaccuracies in nutrient composition tables, as well as inherent difficulties in determining the quantity of phosphorus intake.
Though there is inadequate evidence currently available regarding dietary phosphorous intake, concerns related to health outcomes remain. Any policy or regulatory actions taken should be based in high quality evidence and align with recommendations made by authorities such as EFSA and the National Academy of Medicine.