Less protein 'key to longer life'
Cutting down on protein and upping consumption of carbohydrates may be the key to living a longer, healthier life, new research suggests.
In tests on mice, changing the mix of protein and carbs produced the same benefits as reducing calorie consumption by 40%.
Previous research has shown that strict calorie restriction can improve metabolism and extend lifespan across a wide range of species. But such a drastic strategy would be challenging for most people and may harm health.
Eating smaller amounts of high quality protein and a lot of healthy carbohydrates might prove more practical for humans, scientists believe.
Good sources of protein include eggs, milk, white meat and soya. Consuming healthy carbohydrates means choosing foods such as fresh fruits and vegetables, whole grains and pulses, and avoiding refined sugar, white bread and pastries.
Researcher Dr Stephen Simpson, from the University of Sydney in Australia, said: "We've shown that when compared head-to-head, mice got the same benefits from a low protein, high carbohydrate diet as a 40% caloric restriction diet.
"Except for the fanatical few, no one can maintain a 40% caloric reduction in the long-term, and doing so can risk loss of bone mass, libido and fertility."
The mice were observed for eight weeks as they ate a range of diets with different protein and carbohydrate ratios in conditions where food was restricted or provided at all times.
Low protein/high carbohydrate (LPHC) diets when food was always available delivered the same benefits as calorie restriction in terms of insulin activity, blood sugar and cholesterol levels, the scientists found.
Even though mice on LPHC diets ate more - increasing their food and energy intake by 25% to 30% - their metabolism was higher than that of calorie-restricted mice and they did not gain extra weight.
Calorie restriction did not provide any additional benefits for LPHC mice.
If the findings - published in the journal Cell Reports - apply to humans, adjusting protein and carbohydrate intake could lead to healthier ageing, said the researchers.
Dr Simpson added: "It still holds true that reducing food intake and body weight improves metabolic health and reduces the risk of diseases like Type 2 diabetes, obesity, and fatty liver disease.
"However, according to these mouse data and emerging human research, it appears that including modest intakes of high-quality protein and plenty of healthy carbohydrates in the diet will be beneficial for health as we age."