Low carbohydrate diets have been linked to reduced longevity – except for when dieters ditch the steak for plant-based alternatives.
An analysis of data from 15,400 people in the US has found a U-shaped relationship between mortality and carbohydrate intake. The study found that the people who lived longest tended to be those who got around 50 to 55 per cent of their energy intake from carbohydrates. At the age of 50, such people could expect to live a further 33 years.
This is one year longer than people who get 70 per cent or more of their energy from carbs, and four years longer than people get less than 30 per cent of their calories from carbohydrates.
Sara Seidelmann, at Brigham and Women’s Hospital in Boston, and her colleagues wondered if the types of fat and protein people eat on low-carb diets might contribute to reduced longevity.
Diving into the data, they found that when people replaced carbs with meat such as lamb, pork, beef and chicken – typical for low carb dieters in Europe and the US — their mortality increased.
But the opposite was true for those who instead ate plant-based sources of protein and fat such as legumes, vegetables and nuts. “The more you exchange plant-based fats and proteins for carbohydrates, the more the risk lowers,” says Seidelmann.
The team think that the increased mortality of a low carb, high meat diet is due to lower intake of fruit and vegetables, and the harmful effects of animal proteins and fats on the body’s inflammation and oxidative stress systems.
“If you are going to choose a very low carbohydrate diet as a way to lose weight or as an eating pattern, it’s very important that you are mindful to replace carbohydrate with more plant-based food,” says Seidelmann.
As for those who eat a lot of carbs, their death rates may be higher due to metabolic problems associated with eating large amounts of refined carbohydrates, such as white rice and bread.
Lancet Public Health DOI: 10.1016/S2468-2667(18)30135-X
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