Dose-response relationship between dietary choline and serum lipid profile, energy expenditure, and respiratory quotient in overweight adult cats fed at maintenance energy requirements

Abstract

Choline is an essential nutrient linked to hepatic lipid metabolism in many animal species, including cats. The current study investigated the serum lipid profiles, serum liver enzymes, respiratory quotients and energy expenditures of overweight cats fed maintenance diets, in response to graded doses of supplemental dietary choline. Overweight (body condition score [BCS]:≥6/9) adult male neutered cats (n=14) were supplemented with five choline chloride doses for three-week periods, in a 5 x 5 Latin square design. Doses were based on individual body weight (BW) and the daily recommended allowance (RA) for choline (63mg/kg BW 0.67) according to the National Research Council. Doses were: control (no additional choline: 1.2 x RA, 77 mg/kg BW 0.67), 2 x RA (126mg/kg BW 0.67), 4 x RA (252mg/kg BW 0.67), 6 x RA (378mg/kg BW 0.67), and 8 x RA (504mg/kg BW 0.67). Choline was top-dressed over the commercial extruded cat food (3620mg choline/kg diet), fed once a day at maintenance energy requirements (130kcal/kgBW 0.4). Body weight and BCS were assessed weekly. Fasted blood samples were taken and indirect calorimetry was performed at the end of each three-week period. Serum was analyzed for cholesterol, high-density lipoprotein cholesterol (HDL-C), triglycerides, non-esterified fatty acids, glucose, creatinine, blood urea nitrogen (BUN), alkaline phosphatase (ALP) and alanine aminotransferase. Very low-density lipoprotein cholesterol (VLDL) and low-density lipoprotein cholesterol were calculated. Data was analyzed via SAS using proc GLIMMIX, with group and period as the random effects, and treatment as the fixed effect. Statistical significance was considered at P < 0.05. Body weight and BCS did not change (P > 0.05). Serum cholesterol, HDL-C, triglycerides, and VLDL increased with 6 x RA (P < 0.05). Serum ALP decreased with 8 x RA (P = 0.004). Choline at 4 x and 6 x RA decreased serum BUN (P = 0.006). Fed or fasted respiratory quotient and energy expenditure did not differ among dietary choline doses (P > 0.05). These results suggest that dietary choline supplementation at 6 x RA may increase hepatic fat mobilization through increased lipoprotein transport, and beneficially support hepatic health in overweight cats. Future studies that combine these results with existing knowledge of feline weight loss and hepatic lipidosis are warranted.

Serum metabolomic analysis of the dose-response effect of dietary choline in overweight male cats fed at maintenance energy requirements

“…This data parallels previous increases in serum PC and LPC in growing kittens supplemented with additional dietary choline [48]. As previously hypothesized, the increase in PC with choline at 6 x NRC RA was likely responsible for the higher serum lipid and lipoprotein concentrations previously reported in these same overweight cats [47]. The increased serum lipid and lipoprotein profiles suggested increased hepatic lipid mobilization.…”

“…However, before choline supplementation can be assessed as a possible nutritional intervention for obese cats undergoing weight loss, an adequate dose must be determined. Previous research by Verbrugghe et al [46] and Rankovic et al [47] found that choline at 5 x NRC RA in obese cats and choline at 6 x NRC RA in overweight cats, respectively, appeared to improve hepatic lipid mobilization as increased serum TAG, cholesterol (CHOL), high-density lipoprotein cholesterol (HDL-C) and VLDL were observed in both studies. In-depth analyses of choline-related metabolic pathways were however not performed in these studies.…”

“…As a result, the observed increases in ornithine-derived metabolites may be indicative of increased urea cycle activity with choline supplementation. However, this seems unlikely due to the lower concentrations of serum blood urea nitrogen with choline at 6 and 8 x NRC RA in these cats [ 47 ].…”

“…The University of Guelph Animal Care Committee (AUP#4118) approved all procedures following provincial and national animal care and use guidelines [ 47 ].…”

“…Four weeks before the start, and throughout the trial, cats were fed a commercial extruded diet (Nutram Total Grain-Free ® Chicken and Turkey Recipe, Elmira Pet Products, Elmira, ON, Canada), formulated for adult maintenance according to the Association of American Feed Control Officials (AAFCO). Nutrient analyses of the diet, including proximate analysis, vitamins, minerals and amino acids, were previously described by Rankovic et al [ 47 ]. The diet contained 3901 mg choline/kg diet dry matter basis (DMB), as determined by the enzymatic colorimetric method, described by the Association of Official Analytical Chemists (AOAC 999.14) [ 51 ].…”