Eating carbohydrates in moderation may lower the risk of mortality, a study claims.
The study of over 15,400 people in the US found that diets both low (40 per cent energy) and high (70 per cent energy) in carbohydrates were linked with an increase in mortality.
Moderate consumers of carbohydrates (50-55 per cent of energy) had the lowest risk of mortality, said researchers from the Brigham and Women's Hospital in the US.
The finding, published in The Lancet Public Health journal, was confirmed in a meta-analysis of studies on carbohydrate intake including more than 432,000 people from over 20 countries.
The study suggests that not all low-carbohydrate diets appear equal - eating more animal-based proteins and fats from foods like beef, lamb, pork, chicken and cheese instead of carbohydrate was associated with a greater risk of mortality.
Alternatively, eating more plant-based proteins and fats from foods such as vegetables, legumes, and nuts was linked to lower mortality.
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"We need to look really carefully at what are the healthy compounds in diets that provide protection," said Sara Seidelmann from Brigham and Women's Hospital.
"Low-carb diets that replace carbohydrates with protein or fat are gaining widespread popularity as a health and weight loss strategy," said Seidelmann.
"However, our data suggests that animal-based low carbohydrate diets, which are prevalent in North America and Europe, might be associated with shorter overall life span and should be discouraged." she said.
Researchers said if, instead, one chooses to follow a low carbohydrate diet, then exchanging carbohydrates for more plant-based fats and proteins might actually promote healthy ageing in the long term.
The researchers assessed the association between overall carbohydrate intake and all cause-mortality after adjusting for age, sex, race, total energy intake, education, exercise, income level, smoking, and diabetes.
During a median follow-up of 25 years, 6,283 people died.
Results showed a U-shape association between overall carbohydrate intake and life expectancy, with low and high intake of carbohydrates associated with a higher risk of mortality compared with moderate intake.
The researchers estimated that from age 50, the average life expectancy was an additional 33 years for those with moderate carbohydrate intake.
This was four years longer than those with very low carbohydrate consumption (29 years), and one year longer compared to those with high carbohydrate consumption (32 years).
However, the researchers highlight that since diets were only measured at the start of the trial and six years later, dietary patterns could change over 25 years, which might make the reported effect of carbohydrate consumption on lifespan less certain.