LAUSR

BACKGROUND & AIMS A Western-style diet, which is high in fat and sugar, can cause significant dyslipidemia and non-alcoholic fatty liver disease; the diet has an especially strong effect in women, regardless of total calorie intake. Dietary supplementation with beneficial microbes might reduce the detrimental effects of a Western-style diet. We assessed the effects of Lactococcus lactis subsp. cremoris on weight gain, liver fat, serum cholesterol, and insulin resistance in female mice on a high-fat, high-carbohydrate diet. METHODS Female C57BL/6 mice were fed either a high-fat, high-carbohydrate (Western-style) diet that contained 40% fat, (mostly milk fat) and 43% carbohydrate (mostly sucrose) or calorie-matched per gram control diet. The diets of mice were supplemented with 1x 109 CFU of L lactis subsp. cremoris ATCC 19257 or Lactobacillus rhamnosus GG ATCC 53103 (control bacteria), 3 times per week for 16 weeks. Body weights were measured, and fecal, blood, and liver tissues were collected and analyzed. Livers were analyzed for fat accumulation and inflammation and blood samples were analyzed for cholesterol and glucose levels. Mice were housed within CLAMS-HC monitoring systems and respiratory exchange ratio and activity measured. Hepatic lipid profiles of L lactis subsp. cremoris-supplemented mice were characterized by lipidomic mass spectrometry analysis. RESULTS Mice fed L lactis subsp. cremoris while on the Western-style diet gained less weight, developed less hepatic steatosis and inflammation, and had a lower mean serum level of cholesterol and body mass index than mice fed the control bacteria. Mice fed the L lactis subsp. cremoris had increased glucose intolerance while on the Western-style diet, compared to mice fed control bacteria, and had alterations in hepatic lipids, including oxylipins. CONCLUSIONS Dietary supplementation with L lactis subsp. cremoris in female mice on a high-fat, high-carbohydrate (Western-style) diet caused them to gain less weight, develop less liver fat an inflammation, reduce serum cholesterol levels, and increase glucose tolerance, compared with mice on the same diet fed control bacteria. L lactis subsp. cremoris is safe for oral ingestion and might be developed for persons with metabolic and liver disorders caused by a Western-style diet.