Putting yeast cells on a diet helps them stay youthful in old age
06 September 2022
Do the foods we eat affect how we age in later life? Researchers at the Babraham Institute, UK, have discovered that a change in diet without restricting calories reduced signs of ageing in yeast cells. This research could provide answers for healthy ageing research in humans.
The scientific community is engaged in a long-running debate about what causes ageing and eventual death. Some people live long, healthy lives and then die within a short period of ill health. Meanwhile, others have an incredibly lengthy period of age-related illness before they die. Research in this area aims to increase the proportion of life spent in good health, without necessarily increasing lifespan.
“You don't really want the lifespan to change too much, but you'd really rather not have all the pathology that goes with ageing,” said Dr Jon Houseley, Group Leader of the Babraham Institute’s epigenetics programme. “So what we're trying to do is find out whether there are ways you can change your diet that puts you into that healthy ageing path rather than the unhealthy ageing path.”
Scientists have known for a while that caloric restriction encourages better health in old age and may even extend lifespan. However, as anybody who has tried and failed to stick to a diet can attest, calorie restriction is difficult to maintain for long periods. “It’s absolutely horrible and you spend your whole life hungry,” Dr Houseley explained. Moreover, studies in mice have shown that the health benefits can quickly disappear once a normal diet is resumed.
Dr Houseley’s group aim to find out whether more subtle dietary changes can have a similar impact on healthy ageing.
The team grew yeast cells in a culture and replaced their usual diet of glucose with a different type of sugar called galactose, but kept the same caloric value. They found that the usual signs of cellular ageing, such as dysregulation of gene regulation, were suppressed – even though the yeast did not live any longer.
“Their lifespan seems to be pretty similar, but these well characterised changes, which look like some sort of pathology, really don’t seem to happen,” said Dr Houseley. “They don’t seem to undergo anything like the normal level of gene expression dysregulation.” This shows that age-related pathologies are not an intrinsic part of growing older and can be lessened by dietary adjustments.
However, these dietary changes only promoted healthy ageing when implemented in young yeast cells. Diet appeared to make no difference in older yeast, suggesting that ageing trajectories are defined at a young age.
So what does this mean for us? Although humans and yeast appear to be worlds apart, both are eukaryotic organisms which share many basic biological processes. There is evidence that the process of ageing is caused by similar genetic and cellular changes across the tree of life, from yeast to rodents – and possibly also humans.
Although humans should not attempt to live off a diet of galactose, which is toxic in high doses, we can take away some general lessons. Firstly, dietary changes from an early age can have long-lasting effects. And secondly, it is possible to promote healthy ageing through more subtle changes in diet rather than strict calorie restriction.
“Ageing is not a simple, inevitable process,” said Dr Houseley, “Actually, it might be something where we can control whether you have a healthy or an unhealthy ageing process. It’s not just going to be luck. It’s not necessarily just going to be genetics. Actually, there are ways that we can get in and control it.”
Dr Jon Houseley will present these findings at the Microbiology Society’s Focused Meeting, British Yeast Group 2022: From Genomes to Cells. His talk, titled ‘Dietary change without restriction promotes constitutive healthy ageing in budding yeast’ will take place at 12:30 BST on Friday 9 September 2022.
