Eating a diet which is low in carbohydrates could knock years off lifespan, a 25 year study suggests.
Food plans which replace carbs with protein and fat, such as the Ketogenic or Atkins, have gained popularity in recent years, and are often endorsed by celebrities such as Gwyneth Paltrow and Kim Kardashian
But new research which has followed 15,400 people since the 1980s found those with low carb diets died an average of four years earlier than those who had moderate intakes.
Even people who had high intakes were better off than those who drastically cut out carbohydrates.
“Low-carb diets that replace carbohydrates with protein or fat are gaining widespread popularity as a health and weight loss strategy,” said study leader Dr Sara Seidelmann, Clinical and Research Fellow in Cardiovascular Medicine from Brigham and Women’s Hospital, Boston.
“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.
“Instead, if 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.”
For the study, researchers followed 15,428 adults aged 45-64 years from 1987, monitoring their diets and health outcomes for more than two decades.
The researchers found that from age 50, the average life expectancy was 83 years for those with moderate carbohydrate intake (50 - 55 per cent of daily calories) which was four years longer than those with very low carbohydrate consumption (less than 40 per cent of calories) who lived an average of 79 years. Those with a high carb intake (greater than 70 per cent of daily calories), lived until an average age of 82.
Researchers also found that replacing carbohydrates with protein and fat from animal sources was associated with a higher risk of mortality than moderate carbohydrate intake.
In contrast, replacing carbohydrates with plant-based foods was linked to a lower risk of mortality.
The authors found similar trends in eight other study cohorts involving 430,000 people and speculate that Western-type diets that heavily restrict carbohydrates often lead to greater consumption of animal proteins and fats which may drive inflammation, biological ageing and oxidative stress.
Commenting on the study Catherine Collins, an NHS dietitian, said: “No aspect of nutrition is so hotly contended on social media than the carb versus fat debate, despite the long term evidence on health benefits firmly supporting the higher carb argument.
“Yet supporters of the cult of Low Carb High Fat (LCHF) eating, itself based on a lifestyle choice and the flimsiest of evidence supporting benefit, will no doubt disagree with this newest research on the subject.
“Such a stance is at odds with advice from WHO and government health bodies globally – including the UK’s Public Health England – that recommend a carb intake to provide around half our daily calorie needs.”
Prof Nita Forouhi, MRC Epidemiology Unit, University of Cambridge, added: “This finding is spot-on in line with the Public Health England dietary guidelines in the UK.
“Current guidelines have been criticised by those who favour low-carb diets, largely based on short term studies for weight loss or metabolic control in diabetes, but it is vital to consider long-term effects and to examine mortality, as this study did.”
The research was published in The Lancet Public Health.