Evaluation of phosphorus, calcium, and magnesium content in commercially available foods formulated for healthy cats

Abstract

Background: High dietary phosphorus (P) and low calcium-to-phosphorus ratio (Ca:P) are associated with kidney damage in cats. There are no established guidelines for dietary P maximum for cats.Objectives: To quantify crude protein, P, Ca, and magnesium (Mg) concentrations in cat foods and compare among food formats (dry, canned, raw), primary protein ingredients, protein concentrations (low, moderate, high), grain-free versus grain-containing foods, foods intended for adult maintenance versus all life stages, and cost.Samples: Eighty-two commercial nonprescription cat foods.Methods: Descriptive study. Mineral concentrations were measured using inductively coupled argon plasma-optical emission spectroscopy. Crude protein was measured using the Dumas nitrogen combustion method. Mineral and crude protein concentrations were compared among food categories.Results: Twenty-seven foods contained ≥3.6 g P/1000 kcal metabolizable energy (ME), of which 7 exceeded 4.8 g/1000 kcal ME. Thirteen foods had low Ca:P ratio (≤1.0). The low-protein diet group had no products ≥3.6 g P/1000 kcal ME, which was significantly different compared to the high-protein diet group (52% of products had ≥3.6 g P/1000 kcal ME; P = .01). No significant differences in P content and Ca:P ratio were found among other diet categories. Canned foods had significantly lower Mg compared to dry (P < .001) and raw (P = .007) foods. Declared minimum P and Ca were significantly lower than analyzed concentrations (P = .0005 and P = .003, respectively).Conclusions and Clinical Importance: The high number of foods with high P and low Ca suggest that pet food regulatory reform should be considered.

Towards establishing no observed adverse effect levels (NOAEL) for different sources of dietary phosphorus in feline adult diets: results from a 7-month feeding study

“…Two diets were tested at this level, containing either 4g/1000kcal (4184kJ) or 5g/1000kcal (4184kJ) levels of total P, with Ca:P ratios of 1 and 1.3, respectively. Our aim was to not only investigate the effect of this level of STPP inclusion, but also any potential interactions with higher total P levels observed among commercial dry diets (11) . This enabled two hypotheses to be tested, firstly that a diet formulated to 4g/1000kcal (4184kJ) total P (incorporating 1g P from STPP) and a Ca:P =1 would not cause observable adverse effects; and secondly increasing the total P to 5g/1000kcal (4184kJ), while maintaining STPP contribution at 1g, with a Ca:P of 1.3 would also not cause observable adverse effects and allow more flexibility in dietary formulations using organic raw materials.…”

Evaluation of nutrient content and caloric density in commercially available foods formulated for senior cats

“…15 One-third of the foods for senior cats had phosphorus concentrations ≥3.6 g/1000 kcal ME, similar to the proportion of foods for adult cats exceeding this concentration in a previously reported nutritional analysis of 81 foods. 9 This value is of concern considering that a previous study found an association between high phosphorus intake in cats with CKD before diagnosis compared to a group of control cats, 18 and foods with excessive inorganic phosphorus (>3.6 g/1000 kcal ME of total phosphrus, with ≥1.5 g/1000 kcal ME as inorganic phosphorus) have been shown to promote ultrasonographic renal changes and renolith formation in healthy cats. 19,20 is a rough assessment of insoluble fiber only and does not represent the total content of fiber in the food.…”

“…Values from a subset of adult cat foods (1 lot number per food; n = 59) described in a previous publication were used for comparison. 9…”

“…Samples were shipped on ice overnight to a commercial laboratory (Midwest Laboratory, Omaha, Nebraska) for analysis. Values from a subset of adult cat foods (1 lot number per food; n = 59) described in a previous publication were used for comparison 9 …”

Additives in pet food: are they safe?

“…Excess phosphorus may cause sustained kidney damage and decreased renal function in some cats (Summers et al . 2020) and limiting dietary phosphorus in cats with chronic kidney disease (CKD) appears to help delay CKD progression (Geddes et al . 2016, Liera 2020).…”