Scientists suggest switching meat for plant-based protein and fats is healthier and could even extend life expectancy
A study, published in The Lancet Health, has investigated the association between carbohydrate intake and mortality.
Low carb diets such as the Ketogenic or Atkins have gained massive popularity in recent years thanks in part to endorsement from celebrities – but these diets rely on cutting out carb-heavy foods such as vegetables, bread, sugar, rice and pasta – and instead replacing them with high protein meat, fish and cheese.
The scientists compared low-carb diets rich in animal proteins and fats with those that contained lots of plant-based protein and fat.
Dr Sara Seidelmann, clinical and research fellow in cardiovascular medicine from Brigham and Women’s Hospital in Boston, led the study. Speaking to the BBC, she said:
“Low-carb diets that replace carbohydrates with protein or fat are gaining widespread popularity as a health and weight-loss strategy.
“However, our data suggests that animal-based low carbohydrate diets, which are prevalent in North America and Europe, might be associated with shorter overall lifespan 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.”
The study was conducted in the form of a questionnaire filled out by 15,400 people in the US, following their eating habits since the 1980s. They were asked about the food and drink they consumed along with portion sizes. Scientists were then able to estimate the proportion of calories they got from carbohydrates, fats and protein.
The authors found similar trends in eight other study cohorts involving 430,000 people. They 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.
Lowering carb intake isn’t all bad however – the scientists found that participants in their study who fell in to the moderate carb group had a slightly lower risk of death compared with the high carb group – on average participants from the age of 50 were expected to live another 33 years.
Cutting Out the Good Stuff
The risk comes when these ‘fad’ diets are followed without enough focus on nutrients and their source, warn specialists.
Prof Nita Forouhi is from the Medical Research Council (MRC) nutritional epidemiology unit at the University of Cambridge. The programme leader wasn’t involved in the study but outlined this key point:
“A really important message from this study is that it is not enough to focus on the nutrients, but whether they are derived from animal or plant sources.
“When carbohydrate intake is reduced in the diet, there are benefits when this is replaced with plant-origin fat and protein food sources, but not when replaced with animal-origin sources such as meats.”
Find out more about what is needed for a balanced plant-based diet in our Nutrition in a Nutshell guide.