The secret to healthy ageing may be a diet low in protein and high in healthy carbs

Nutritional scientist Dr Samantha Solon-Biet from the University of Sydney’s Charles Perkins Centre is challenging ageing research that has convinced us to eat fewer calories. 

Her research suggests that the 2 million plus Australians who go on a diet every year may be better off focusing less on low-carb, high-protein diets, unless their only goal is weight loss. 

Dr Solon-Biet’s results suggest that while adequate protein intake is critical for growth, reproduction and maintaining lean mass, the best formula for healthy ageing could be a diet low in protein and high in healthy carbohydrates. This combination switches off the underlying biological machinery known to promote accelerated ageing, a process conserved across budding yeasts to long-lived mammals. This approach is groundbreaking because it shifts the goalposts from calorie counting to eating the right mixture of ‘macronutrients’ – carbohydrates, protein and fat.

Biggest health challenge

Dr Solon-Biet’s approach to delay disease and ageing through diet addresses our number one health imperative. Ageing is accepted as the biggest risk factor for disease and death, and more than three quarters of elderly Australians have a chronic disease, according to the Australian Institute of Health and Welfare.

Globally, the World Health Organization estimates that chronic diseases such as cardiovascular disease and diabetes account for about 70 percent of deaths.

The research findings paint a clearer picture of the role of a little-known hormone called Fibroblast Growth Factor 21 (FGF21) – a hormone produced primarily in the liver. The research shows that diets high in carbohydrate and low in protein are the best for boosting levels of FGF21 in mice. 

“If our findings in mice also apply to humans it could reduce the burden of disease more significantly than eradicating cancer,” Dr Solon-Biet predicts.

The high-carb element does not mean gorging processed cakes and cookies, however. It’s about eating a smaller proportion of protein and plenty of ‘good carbs’ – vegetables and wholegrains that suppress your appetite and promote a healthy gut environment because they are high in nutrients and fibre.

Her evidence-based research challenges the often flimsy basis for ‘wonder’ diets.

“Around 70 percent of data in popular diet books is not backed by science,” she says.

Global leader in ageing research

The Charles Perkins Centre is already a leading hub for ageing research, thanks partly to Dr Solon-Biet’s work, and nutritional ‘geometry’, led by her own research supervisor and the centre’s Academic Director, Professor Stephen Simpson and Professor David Raubenheimer.

Dr Solon-Biet and Professor Simpson rely on the expertise of University mathematicians to crunch the numbers that support this geometric approach, and interrogate research from every possible angle. On any given day she collaborates with researchers across biochemistry, microbiology, public health, medicine, business and pharmacology. 

Dr Solon-Biet’s landmark 2014 study in metabolic biology journal Cell Metabolism opened many doors and she has also greatly benefited from a University of Sydney SOAR fellowship – a fellowship that supports outstanding early and mid-career researchers.

Her manipulation of macronutrients presents an exciting opportunity to strike back against lifestyle diseases and offer a diet solution that may be more feasible and sustainable for healthy ageing, for the long-term.