The study, published in Cell Reports, discovered that the action of a gene called FOXO is inhibited in flies given a high sugar diet in early life, causing long-term effects. The FOXO gene is important for longevity in a wide variety of species, including yeast, flies, worms and humans, so the team say the findings may have broad implications.
Even while feeding on a healthy diet, the flies that had previously eaten a high-sugar diet started to die earlier, and on average had 7% shorter lifespans. This was caused by a change in the programming of the flies’ physiology caused by the sugar-rich diet eaten in early adulthood.
To understand how the high sugar diet affected longevity, the scientists analysed the flies at a molecular level. They found the unhealthy diet promoted molecular changes that looked very much like flies with genetically reduced FOXO.
Crucially, further experiments showed that the diet-driven changes to lifespan are dependent on FOXO. This mechanism was also found in another species, a worm called Caenorhabditis elegans, suggesting it is relevant to a variety of animals.
“The fact that transient high sugar accelerates aging 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,” said co-author, Professor David Gems, UCL Institute of Healthy Ageing.
The findings improve our understanding how changes in diet and gene expression affect the speed of aging.