The impact of low-protein high-carbohydrate diets on aging and lifespan

Abstract

Most research on nutritional effects on aging has focussed on the impact of manipulating single dietary factors such as total calorie intake or each of the macronutrients individually. More recent studies using a nutritional geometric approach called the Geometric Framework have facilitated an understanding of how aging is influenced across a landscape of diets that vary orthogonally in macronutrient and total energy content. Such studies have been performed using ad libitum feeding regimes, thus taking into account compensatory feeding responses that are inevitable in a non-constrained environment. Geometric Framework studies on insects and mice have revealed that diets low in protein and high in carbohydrates generate longest lifespans in ad libitum-fed animals while low total energy intake (caloric restriction by dietary dilution) has minimal effect. These conclusions are supported indirectly by observational studies in humans and a heterogeneous group of other types of interventional studies in insects and rodents. Due to compensatory feeding for protein dilution, low-protein, high-carbohydrate diets are often associated with increased food intake and body fat, a phenomenon called protein leverage. This could potentially be mitigated by supplementing these diets with interventions that influence body weight through physical activity and ambient temperature.

Keywords: Ageing; Aging; CPC diet; Caloric restriction; Dietary carbohydrate; Dietary protein; Geometric Framework.

Fig. 1

Published response surfaces for lifespan versus dietary macronutrients. In each figure, the x axis represents a measure of protein (dietary or intake; protein, casein or yeast) and the y axis represents a measure of carbohydrates (dietary or intake; carbohydrate or sucrose). The response surfaces vary from red which is the longest lifespan to blue which is the shortest lifespan. The red line represents the nutritional rail or PC ratio associated with the longest lifespan while the blue line represents that with the shortest lifespan. a–h from [, –27, 30, 31] and i is a surface of simulated data parameterised from the results presented by Slonaker et al. in 1931 [55, 129]

Fig. 2

Physical activity and cold environmental temperature might reverse the weight gain associated with LPHC diets and act synergistically to increase lifespan. These effects might be mediated via countering effects of LPHC diets on mitochondrial uncoupling