“As we age, our gut function declines in line with all the other functions in our body. There’s a stereotype that old people are concerned with fibre intake and eat dried fruits, and this is because they’re more likely to get constipated,” Medlin explains.

“We also fall into habits with our eating as we age due to long-standing routines with food or because getting to the shops gets trickier, and a more limited diet will have an impact on the diversity of gut bacteria we have.”

Women are particularly likely to suffer changing gut health as a result of menopause, says Medlin. “We have recently learned that as a woman ages, the fall in her oestrogen means the diversity of her gut microbiome also reduces,” she explains.

That change could be one of the factors responsible for the increased risk of heart disease that happens in later life. “The new structure of the gut microbiome in older women is closer to that of men and is also associated with a risk of cardiovascular disease. This certainly isn’t the whole picture but it’s very likely to be a strong contributory factor.”

Longevity tips: is better gut health the key to living longer?