If you give elderly mice a low-glycaemic diet for the rest of their life they live 12 percent longer than mice given standard food. Researchers at Deakin University in Australia write about this in Longevity & Healthspan. Their animal study suggests that a low-glycemic diet delays aging at the molecular level.
Eating a low-glycaemic diet means that your blood sugar level doesn’t rise too high. This is easy to do by avoiding easily absorbed carbohydrates such as sugar, sweets and glucose. You can find detailed tables with information on the glycaemic index of all kinds of food on the web.
The Australian researchers gave middle-aged lab mice aged 20 weeks food with a glycaemic index of 27 for the rest of their life. A control group was given standard feed with a glycaemic index of 70. To give you an idea: bread, noodles and croissants have a glycaemic index of about 70; apples, wholemeal pasta and quinoa have a glycaemic index of just over 30.
The mice on the glycaemic diet lived 12 percent longer, as the figure below shows.
When the mice were 24 months old the ones that were on the low-glycaemic diet [squares] reacted better when given glucose than the animals in the control group [triangles].
The researchers found less DNA with abasic sites in the cells of the elderly mice in the low-glycaemic group [triangles] than in the cells of the control group [squares]. Abasic sites are where the DNA has molecular damage. These increase as a result of aging.
The researchers also found less 8-OH-2-dG-DNA in the low-glycaemic group. This is also damaged DNA, and this kind of damage also increases with aging.
A classic way of measuring molecular aging is to measure the length of the telomeres in the DNA. The shorter they are, the further the aging process has progressed. The low-glycaemic diet had no statistically significant effect on telomere length however.
“The relevance of the findings to humans would still needs to be tested”, the researcher write. “However it is possible to speculate that consumption of a low glycaemic index diet late in life still has beneficial health effects and it may extend lifespan, although the effect may not be as dramatic as an intervention earlier in life. The extension of life may not represent a significant number of years lived but rather an improved quality of life or healthspan.”
Consumption of a low glycaemic index diet in late life extends lifespan of Balb/c mice with differential effects on DNA damage.
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.
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.
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.
PMID: 24472560 [PubMed] PMCID: PMC3922916