Study finds older adults consume too much phosphorus, too little calcium

November 24, 2015

A new study has found that high intake of dietary phosphorus, relative to calcium intake, is associated with a lower calcium to phosphorus ratio overall. When this ratio skews low for calcium and high for phosphorus, it potentially has adverse health effects including arterial calcification, bone loss and death.

Dr. John Anderson

Kathy Roggenkamp

Reuben Adatorwovor

The three co-authors of the study, all from the UNC Gillings School of Global Public Health, are Reuben Adatorwovor, graduate student of biostatistics, Kathy Roggenkamp, MA, research instructor of biostatistics, and John Anderson, PhD, adjunct professor of nutrition.

The full article is titled, “Intakes of Calcium and Phosphorus and Calculated Calcium-to-Phosphorus Ratios of Older Adults: NHANES 2005–2006 Data,” and was published online Nov. 19 by Nutrients.

Previous research has shown that a substantial percentage of older adults (more than 50 years old), who have a higher risk of fractures than younger adults, typically have low intakes of dietary calcium that are dominated by higher intakes of dietary phosphorus from both natural sources and phosphorus chemicals added to foods. This pattern leads to lower calcium to phosphorus ratios than are desirable.

In order to examine calcium and phosphorus intakes and the resulting ratios (by mass) across gender and older adult age groups, the researchers analyzed the National Health and Nutrition Examination Survey from 2005 to 2006. Calcium intakes were calculated from both foods and supplements, whereas phosphorus intakes were calculated from food composition values, including phosphate chemicals, as the amounts of phosphorus additives in processed foods are not available.

Average older adult intakes were lower for calcium and higher for phosphorus than the amounts suggested by current Recommended Dietary Allowances (RDAs).

As both low calcium intakes and high phosphorus intakes contribute to non-ideal ratios, the researchers suggest older adults shift consumption patterns to more closely match intakes recommended by the RDAs.

Whether calcium to phosphorus ratios that are lower than recommended contribute to increased risk of bone loss, arterial calcification and all-cause mortality cannot be inferred from the data in this study. It is clear, however, that the amounts of chemical phosphorus added to products by the food industry should be monitored.

“We appeal to the general public and food processing companies regarding the excessive use of phosphorus additives in processed foods,” says co-author Adatorwovor. “We hope the finding that too much phosphorus in our diets may have adverse health effects will be an incentive to reverse the widespread use of phosphorus additives.”