Current consumer and research-related nutritional databases cannot be relied upon to list accurate amounts of phosphorus in beverages and likely foods, according to the latest product review in the Journal of Renal Nutrition (2016;26:e27-e30).
Recent studies have reported inaccuracies in databases, so Caitlin Krekel, MSPH, RD, LDN, and colleagues decided to test them formally test them. For 46 drinks, they compared actual phosphorus measurements from Medallion Laboratories in Minneapolis with listed amounts in databases and calorie-counting sites. Beverages included popular colas, fruit-flavored drinks, coffee drinks, iced teas, lemonades, vitamin-containing waters, and sports drinks, all available at grocery stores.
The researchers found just 28 of the 46 beverages in the Nutrient Data System for Research (NDSR). Of these, listed phosphorus amounts were lower than measured amounts for 78%. Similarly, the USDA Standard Nutrient Reference Database yielded exact matches for just 5 beverages and sometimes underestimated phosphorus content. The Web sites MyFitnessPal and CalorieKing provided no phosphorus information for any of the beverages.
Manufacturers supplied phosphorus amounts for 14 of the beverages that were remarkably similar to measured amounts. When products provided no such information, the investigators calculated phosphorus content based on cation values listed on the nutrition facts labels. These calculations approached actual phosphorus amounts, but they were time-consuming to produce.
Listing phosphorus content on nutrition facts labels is still voluntary. Yet, they may provide the best estimates of dietary phosphorus for providers and patients concerned about hyperphosphatemia.
“Increasing awareness among food manufacturers about the importance of dietary phosphorus restriction in patients with kidney disease may help encourage self reporting of phosphorus content and consequently improve the quality of dietary phosphorus content information available to both researchers and consumers,” Krekel and colleagues concluded.