Consumption of a low glycaemic index diet in late life extends lifespan of Balb/c mice with differential effects on DNA damage.

BACKGROUND: Caloric restriction is known to extend the lifespan of all organisms in which it has been tested. Consequently, current research is investigating the role of various foods to improve health and lifespan. The role of various diets has received less attention however, and in some cases may have more capacity to improve health and longevity than specific foods alone. We examined the benefits to longevity of a low glycaemic index (GI) diet in aged Balb/c mice and examined markers of oxidative stress and subsequent effects on telomere dynamics. RESULTS: In an aged population of mice, a low GI diet extended average lifespan by 12%, improved glucose tolerance and had impressive effects on amelioration of oxidative damage to DNA in white blood cells. Telomere length in quadriceps muscle showed no improvement in the dieted group, nor was telomerase reactivated. CONCLUSION: The beneficial effects of a low GI diet are evident from the current study and although the impact to telomere dynamics late in life is minimal, we expect that earlier intervention with a low GI diet would provide significant improvement in health and longevity with associated effects to telomere homeostasis.

Fructose containing sugars modulate mRNA of lipogenic genes ACC and FAS and protein levels of transcription factors ChREBP and SREBP1c with no effect on body weight or liver fat.

The aim of this study was to determine the effects of high-glucose, high-fructose and high-sucrose diets on weight gain, liver lipid metabolism and gene expression of proteins involved with hepatic fat metabolism. Rats were fed a diet containing either 60% glucose, 60% fructose, 60% sucrose, or a standard chow for 28 days. Results indicated that high-fructose and high-sucrose diets were associated with higher mRNA levels of gene transcripts involved with fat synthesis; ACC, FAS and ChREBP, with no change in SREBP-1C mRNA. The protein level of ChREBP and SREBP1c was similar in liver homogenates from all groups, but were higher in nuclear fractions from the liver of high-fructose and high-sucrose fed rats. The mRNA level of gene transcripts involved with fat oxidation was the same in all three diets, whilst a high-fructose diet was associated with greater amount of mRNA of the fat transporter CD36. Despite the changes in mRNA of lipogenic proteins, the body weight of animals from each group was the same and the livers from rats fed high-fructose and high-sucrose diets did not contain more fat than control diet livers. In conclusion, changing the composition of the principal monosaccharide in the diet to a fructose containing sugar elicits changes in the level of hepatic mRNA of lipogenic and fat transport proteins and protein levels of their transcriptional regulators; however this is not associated with any changes in body weight or liver fat content.

The effect of cocoa supplementation on hepatic steatosis, reactive oxygen species and LFABP in a rat model of NASH.

BACKGROUND: Non alcoholic steatohepatitis is hypothesised to develop via a mechanism involving fat accumulation and oxidative stress. The current study aimed to investigate if an increase in oxidative stress was associated with changes in the expression of liver fatty acid binding protein in a rat model of non alcoholic steatohepatitis and whether cocoa supplementation attenuated those changes. METHODS: Female Sprague Dawley rats were fed a high fat control diet, a high fat methionine choline deficient diet, or one of four 12.5% cocoa supplementation regimes in combination with the high fat methionine choline deficient diet. RESULTS: Liver fatty acid binding protein mRNA and protein levels were reduced in the liver of animals with fatty liver disease when compared to controls. Increased hepatic fat content was accompanied by higher levels of oxidative stress in animals with fatty liver disease when compared to controls. An inverse association was found between the levels of hepatic liver fatty acid binding protein and the level of hepatic oxidative stress in fatty liver disease. Elevated NADPH oxidase protein levels were detected in the liver of animals with increased severity in inflammation and fibrosis. Cocoa supplementation was associated with partial attenuation of these pathological changes, although the severity of liver disease induced by the methionine choline deficient diet prevented complete reversal of any disease associated changes. Red blood cell glutathione was increased by cocoa supplementation, whereas liver glutathione was reduced by cocoa compared to methionine choline deficient diet fed animals. CONCLUSION: These findings suggest a potential role for liver fatty acid binding protein and NADPH oxidase in the development of non alcoholic steatohepatitis. Furthermore, cocoa supplementation may have be of therapeutic benefit in less sever forms of NASH.