Dietary Betaine and Fatty Acids Change Circulating Single-Carbon Metabolites and Fatty Acids in the Dog

SIMPLE SUMMARY: The dog successfully consumes a wide range of dietary polyunsaturated fatty acids (PUFAs), while specific changes in fatty acid intakes have relatively unknown subsequent effects on circulating concentrations of those fatty acids and their metabolites. Similarly, single-carbon metabolism in the dog is known to be an essential part of their metabolism. However, the subsequent effects of increasing betaine (a single-carbon donor) are relatively unknown as to their effects on circulating concentrations of metabolites and fatty acids. Changing dietary fatty acids increased circulating concentrations of those dietary fatty acids and this response (the subsequent increase in circulating concentration to a daily fatty acid intake) was increased for EPA with dietary betaine. Dietary betaine also reduced a number of xenobiotics, an effect which shows a positive influence on gut microbiota. ABSTRACT: In order to evaluate the interaction of betaine and n-3 PUFA in foods consumed by the dog, six extruded dry foods were formulated. The control food had no specific source of added betaine or n-3 fatty acids, while the test foods were supplemented with betaine, flax or fish oil in a 2 × 3 factorial design (no added n-3 source, added flax, added menhaden fish oil, and all with or without added betaine). Forty eight adult dogs were used in this study. All dogs were assigned to one of the six dietary treatments and consumed that food for the length of the 60-day study. Blood was analyzed for metabolomics (plasma), fatty acids and selected health-related analytes (serum) at the beginning and the end of the study. Added dietary betaine increased single-carbon metabolites (betaine, dimethyl glycine, methionine and N-methylalanine), decreased xenobiotics (stachydrine, N-acetyl-S-allyl-L-cysteine, 4-vinylguaiacol sulfate, pyrraline, 3-indoleglyoxylic acid, N-methylpipecolate and ectoine) and enhanced the production of eicosapentaenoic acid (EPA). Dietary betaine also decreased the concentration of circulating carnitine and a number of carnitine-containing moieties. The addition of the n-3 fatty acids alpha-linolenic, EPA and docosahexaenoic acid (DHA) increased their respective circulating concentrations as well as those of many subsequent moieties containing these fatty acids. The addition of alpha-linolenic acid increased the concentration of EPA when expressed as a ratio of EPA consumed.