Exposure to a sugar rich diet in early life causes permanent gene expression changes in fruit flies - resulting in a reduced lifespan
Sugar intake is correlated with many poorer health outcomes, but we're still attempting to understand the complex biological changes that such a diet can cause. Researchers at UCL and Monash University have now tested the effect of a more transient exposure to a sugar dense diet on flies, by comparing the lifespans of female flies fed a healthy diet containing 5% sugar to those fed 8 times that level. Both were fed these diets for a 3 week period before transitioning onto a 'healthy' diet for the remainder of their lives.
Massive sugar exposure may have long term consequences
The researchers found that even after flies were fed a healthy diet, those that went through a 3 week gluttony period died around 7% earlier on average. This particular species of fly has an average lifespan of 90 days. Curious as to what was causing this rise in mortality rates, the researchers looked closer at gene expression in the affected flies.
They found that those flies exhibited molecular changes very similar to those found in flies with depleted expression of a gene called FOXO. They then confirmed that the long term influence of dietary changes was as a result of inactivation of the FOXO gene. FOXO is an important gene that has been linked to aging and longevity in a range of studies. It's involved with a huge range of functions from apoptosis, DNA repair and metabolism to oxidative stress resistance
"The fact that transient high sugar accelerates ageing in both species and by the same mechanism is pretty shocking. It is yet more evidence of how much we have to fear from excess sugar in the diet"
Does this relate to humans?
While a similar mechanism is known to exist in the organism C. elegans, while humans possess similar genes their function is not fully understood. The transient sugar period in this work would actually translate to around 20 years of massive sugar consumption in humans, so it's possible in people residual effects following poor dietary habits are perhaps more reversible. Humans are also relatively long lived and therefore may be more flexible in response to energy intake.
"The burden of age-related ill health is being exacerbated by poor diets and we know these can cause long-term, detrimental effects by programming our physiology. Our finding helps understand how bad diets can impact on animal lifespan. The dietary intervention we used is extreme - similar to feeding a human only cake for two decades - but the mechanism we uncovered may also be mediating long-term effects of diet in humans and this is an important idea to explore in the future"
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