Combining Lemon and Glycerin may Beneficially Regulate Blood Glucose Levels by Modulating Gut Microbiota in Non-obese Diabetic Mice

Abstract

Both dietary lemon and glycerin have shown beneficial effects in diabetic humans and animals. It was hypothesized that there were potential therapeutic advantages of combining both agents in hyperglycemic and healthy mice. In a 6-month study using mature adult male non-obese diabetic (NOD) mice, oral treatment with either lemon or glycerin alone increased blood glucose levels during the third month glucose tolerance test and decreased the activity of the predicted glycolysis/gluconeogenesis pathways when compared to the vehicle control; however, this was no longer observed when lemon and glycerin were combined. Metabolomic analysis indicated that acetate was increased in the fecal samples after treatment with either glycerin or the combination. A 2-month study was also conducted in both male and female NOD mice and suggested that there were more gut microbiome changes at one month in comparison to six months. In older NOD male mice, treatment with the combination for six months decreased insulin resistance. In both adult male and female C57BL/6 mice, dosing with the combination for two months decreased blood glucose levels, as well as glucose tolerance and insulin resistance. In addition, treatment with the combination decreased body weights, especially in male mice, in all four studies. Overall, these studies suggest that lemon and glycerin in combination may reduce the side effects of individual treatments (e.g., transient hyperglycemia) and have some additional benefits (e.g., weight loss). Microbiome modulation likely contributed to the observed beneficial effects.