“Mediterranean-style diets are good for you but only once you’ve eaten that way for a long time.”

IN FACT: A study released earlier this year found it only takes a year of eating like they do in the Mediterranean to boost types of gut bacteria linked to healthy ageing, while reducing levels of bacteria associated with disease-causing inflammation at the same time.

TO MAKE IT WORK: Stick to a predominantly plant-based diet, rich in wholegrains, legumes, nuts, and fruit and vegetables. If you do eat meat, include fish and chicken twice a week, but limit red meat to just a few times a month. Also replace butter with olive oil and salt with herbs and spices.