Longevity is based on lots of factors, including diet and genetics.
A doctor shared the diet change that has made him "healthier" than a 20-year-old.
Dr David Sinclair, who is a professor of genetics at Harvard Medical School, explained he is experimental and has tried various diets and supplements to improve his health.
Recently, he cut out dairy foods which he believed has drastically improved his health and longevity.
Dr David Sinclair shared diet advice for a longer life
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He said he was eating a lot of cheese and his diet a couple of times a week consisted of a cheeseboard with a couple of glasses of red wine.
The doctor added: "I've looked at my blood biochemistry and I'm actually now younger and healthier than I've ever been [since cutting out dairy]."
The expert explained he had been tracking various factors in his health for around 14 years and had not seen such good results before.
"I can plot various parameters [such as] testosterone, glucose, inflammation, blood type and blood cell composition," he told The Knowledge Project Podcast.
"For most of those markers, I'm better than a 20-year-old for health and I think a lot of that is due to the new diet that I've adopted."
As well as cutting out dairy, Dr Sinclair added he was following a Mediterranean diet.
Eating a balanced diet is best for health and the results of cutting out food groups may vary.
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He claimed cutting out dairy has made him healthier
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However, a recent study carried out at the University of Bergen in Norway suggested reducing dairy is important to extend lifespan.
It found a diet with reduced dairy and eggs, no red or processed meat and no sugar-sweetened beverages could increase longevity.
Dr Sinclair previously shared the supplement he uses every day to stay young.
He said he had noticed nothing but "benefits" when taking NAD.