Abstract
BackgroundWe recently demonstrated that feeding a natural CLAt10,c12-enriched butter to lean female rats resulted in small, but significant increases in fasting glucose and insulin concentrations, and impaired insulin tolerance. Our goal was to extend these findings by utilizing the diabetes-prone female fatty Zucker rat. Rats were fed custom diets containing 45 % kcal of fat derived from control and CLAt10,c12-enriched butter for 8 weeks.MethodsCLA t10,c12-enriched butter was prepared from milk collected from cows fed a high fermentable carbohydrate diet to create subacute rumen acidosis (SARA); control (non-SARA) butter was collected from cows fed a low grain diet. Female fatty Zucker rats (10 weeks old) were randomly assigned to one of four diet treatments: i) low fat (10 % kcal), ii) 45 % kcal lard, iii) 45 % kcal SARA butter, or iv) 45 % kcal non-SARA butter. A low fat fed lean Zucker group was used as a control group. After 8 weeks, i) glucose and insulin tolerance tests, ii) insulin signaling in muscle, adipose and liver, and iii) metabolic caging measurements were performed.ResultsGlucose and insulin tolerance were significantly impaired in all fatty Zucker groups, but to the greatest extent in the LARD and SARA conditions. Insulin signaling (AKT phosphorylation) was impaired in muscle, visceral (perigonadal) adipose tissue and liver in fatty Zucker rats, but was generally similar across dietary groups. Physical activity, oxygen consumption, food intake and weight gain were also similar amongst the various fatty Zucker groups.ConclusionsIncreasing the consumption of a food naturally enriched with CLAt10,c12 significantly worsens glucose and insulin tolerance in a diabetes-prone rodent model. This outcome is not explained by changes in tissue insulin signaling, physical activity, energy expenditure, food intake or body mass.
Highlights
We recently demonstrated that feeding a natural CLAt10,c12-enriched butter to lean female rats resulted in small, but significant increases in fasting glucose and insulin concentrations, and impaired insulin tolerance
Our findings indicated that feeding the CLAt10,c12-enriched butter resulted in small, but significant increases in fasting glucose and insulin concentrations, as well as impaired insulin tolerance [13]
After our study was published, there was another report showing that feeding butter enriched in the CLAc9,t11 isomer to lean rats prevented the hyperinsulinemia induced by a high fat diet; interestingly, there was no effect on oral glucose tolerance in this study [14]
Summary
We recently demonstrated that feeding a natural CLAt10,c12-enriched butter to lean female rats resulted in small, but significant increases in fasting glucose and insulin concentrations, and impaired insulin tolerance. Almost no studies have examined the metabolic consequences of consuming a food source in which the CLA isomer content has been naturally altered i.e. not merely adding CLA isomer in the chemical form to a food To this end, we recently examined the impact of feeding a CLAt10,c12-enriched butter (60 % of total kcal) to lean, healthy female rats. After our study was published, there was another report showing that feeding butter enriched in the CLAc9,t11 isomer to lean rats prevented the hyperinsulinemia induced by a high fat diet; interestingly, there was no effect on oral glucose tolerance in this study [14] These two studies demonstrate a potential, albeit relatively small, effect of consuming natural food sources with altered CLA isomer content on indices of insulin sensitivity
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have