Diet plays an important part in longevity and a doctor shared sugar should be avoided where possible.
Eating excessive amounts of sugar can speed up the signs of ageing and promote life-limiting diseases, the expert explained.
While what you eat is not the only contributor to a long life, a bad diet can increase the risk of illness.
Dr David Sinclair named it the "big killer" and Britons should avoid it where possible.
Sugar can promote life-threatening illnesses
PA
He said: "The big killer is sugar. Glucose, particularly fructose, is also pernicious.
"If you give animals lots of glucose and especially fructose, they will get fatty liver disease or diabetes."
He added the effects glucose has on the body could "ultimately lower your longevity".
The doctor explained "your defences against diseases and ageing are going to be working at a minimum" if eating a lot of sugar throughout the day.
Instead, he advised people keep their glucose levels "low and consistent".
A study published in the National Library of Medicine echoed this advice.
It said illnesses such as obesity, type-2 diabetes, insulin resistance, hyperinsulinemia, hypertriglyceridemia, and hypertension are brought on by the excessive consumption of sugars including fructose and sucrose.
It concluded consuming lower doses of fructose can extend the lifespan of participants.
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Dr David Sinclair shared advice
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Dr Sinclair added "eating less often" is also a good starting place for longevity.
The period of not eating is "so important for boosting the body's defences against ageing", he explained on his podcast Lifespan with Dr David Sinclair.
Intermittent fasting is where dieters eat all their daily calories within a set time frame and fast for the remaining hours of the day.
A study published in the University of Utah's Department of Nutrition and Integrative Physiology suggested it may help people to live longer.
