Dietary choline, but not L-carnitine, increases circulating lipid and lipoprotein concentrations, without affecting body composition, energy expenditure or respiratory quotient in lean and obese male cats during weight maintenance

Alexandra Rankovic; Shoshana Verton-Shaw; Anna K Shoveller; Marica Bakovic; Gordon Kirby; Adronie Verbrugghe

doi:10.3389/fvets.2023.1198175

Dietary choline, but not L-carnitine, increases circulating lipid and lipoprotein concentrations, without affecting body composition, energy expenditure or respiratory quotient in lean and obese male cats during weight maintenance

Front Vet Sci. 2023 Jul 26:10:1198175. doi: 10.3389/fvets.2023.1198175. eCollection 2023.

Authors

Alexandra Rankovic¹, Shoshana Verton-Shaw², Anna K Shoveller³, Marica Bakovic⁴, Gordon Kirby¹, Adronie Verbrugghe²

Affiliations

¹ Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada.
² Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada.
³ Department of Animal Biosciences, Ontario Agricultural College, University of Guelph, Guelph, ON, Canada.
⁴ Department of Human Health and Nutritional Sciences, College of Biological Sciences, University of Guelph, Guelph, ON, Canada.

Abstract

Introduction: Due to the involvement in one-carbon metabolism and lipid mobilization, choline and L-carnitine supplementation have been recommended to minimize hepatic lipid accumulation and support fat oxidation, respectively. This study investigated the lipotropic benefits of choline or L-carnitine supplementation in lean and obese cats maintaining body weight (BW).

Methods: Lean [n = 9; body condition score (BCS): 4-5/9] and obese (n = 9; BCS: 8-9/9) adult male neutered colony cats were used in a replicated 3 x 3 complete Latin square design. Treatments included choline (378 mg/kg BW^0.67), L-carnitine (200 mg/kg BW) and control (no supplement). Treatments were supplemented to the food for 6 weeks each, with a 2-week washout between treatments. Cats were fed once daily to maintenance energy requirements, and BW and BCS were assessed weekly. Fasted blood collection, indirect calorimetry, and dual-energy X-ray absorptiometry occurred at the end of each treatment period. Serum was analyzed for cholesterol (CHOL), high-density lipoprotein CHOL (HDL-C), triglycerides (TAG), non-esterified fatty acids (NEFA), glucose, creatinine (CREAT), urea, alkaline phosphatase (ALP) and alanine aminotransferase (ALT). Very low-density lipoprotein CHOL (VLDL) and low-density lipoprotein CHOL (LDL-C) were calculated. Data were analyzed using proc GLIMMIX, with group and period as random effects, and treatment, body condition, and their interaction as fixed effects, followed by a Tukey's post-hoc test when significance occurred.

Results: Cats supplemented choline had lower food intake (P = 0.025). Treatment did not change BW, BCS and body composition (P > 0.05). Obese cats had greater ALP, TAG, and VLDL, and lower HDL-C compared to lean cats (P < 0.05). Choline resulted in greater CHOL, HDL-C, LDL-C and ALT (P < 0.05). L-carnitine resulted in lower CREAT (P = 0.010). Following the post-hoc test, differences between treatment means were not present for ALP (P = 0.042). No differences were found for glucose, urea or NEFA (P > 0.05). Obese cats had a lower fed respiratory quotient (RQ), regardless of treatment (P = 0.045). Treatment did not affect fed or fasted RQ and energy expenditure (P > 0.05).

Discussion: Choline appeared to increase circulating lipid and lipoprotein concentrations regardless of body condition, likely through enhanced lipid mobilization and hepatic elimination. Neither dietary choline or L-carnitine altered body composition or energy metabolism in the lean or obese cats, as compared to control.

Keywords: dual-energy x-ray absorptiometry; feline nutrition; indirect calorimetry; methionine; methyl donor; one carbon metabolism; pet obesity.

Grants and funding

Funding for this research was provided by a Natural Sciences and Engineering Research Council (NSERC) Collaborative Research and Development Grant (CRDPJ #472710-16), in partnership with Elmira Pet Products (Elmira, ON, Canada). The choline chloride and L-carnitine supplements were kindly provided by Balchem (New Hampton, NY, United States of America).