New Horizons: Dietary protein, ageing and the Okinawan ratio

Abstract

Nutrition has profound effects on ageing and lifespan. Caloric restriction is the major nutritional intervention that historically has been shown to influence lifespan and/or healthspan in many animal models. Studies have suggested that a reduction in protein intake can also increase lifespan, albeit not as dramatically as caloric restriction. More recent research based on nutritional geometry has attempted to define the effects of nutrition on ageing over a broad landscape of dietary macronutrients and energy content. Such studies in insects and mice indicate that animals with ad libitum access to low-protein, high-carbohydrate diets have longest lifespans. Remarkably, the optimum content and ratio of dietary protein to carbohydrates for ageing in experimental animals are almost identical to those in the traditional diets of the long-lived people on the island of Okinawa.

Protein Leverage: Theoretical Foundations and Ten Points of Clarification

“…The typical range for percent protein in the human diet is from 10% to 25%, with 15% to 20% being most common . It is therefore unsurprising that PL has been detected on diets with 10% but not 5% of energy from protein.…”

“…This might be the reason that some traditional low‐protein diets, such as the Mediterranean and Okinawan diets, are not associated at a population level with energy overconsumption and obesity . Along with these diets’ low protein to carbohydrate ratio, this might also explain why these diets are associated with slowed rates of aging and long life‐spans . In restricting compensatory intake for protein, the high‐fiber content of these diets is likely to limit not only nonprotein energy and total energy intake (via restricting PL) but also protein intakes, and, as discussed in the next section, dietary protein restriction is emerging as an important causal factor in studies of the effects of diet on late‐life health and lifespan .…”

Calorie restriction in rodents: Caveats to consider

“…We have already covered in the previous sections some of the differential physiological responses that distinguish CR from protein restriction (PR) and other aspects of diet composition. The impact of various feeding regimens were recently extensively reviewed (Le Couteur et al, 2016a; Le Couteur et al, 2016b; Masoro, 2005, 2006; Solon-Biet et al, 2015; Speakman and Mitchell, 2011; Speakman et al, 2016). The role of optimal dietary composition for promoting lifespan extension in ad libitum or CR condition remains unknown.…”

“…However, most of the early reports in this field have suggested that manipulations of the macro and micro-nutrient composition do not have a major impact on survival (Iwasaki et al, 1988; Yu et al, 1985; Yu et al, 1982). To counter this earlier argument, a few recent studies have provided highly systematic manipulation of protein content in mouse studies (Le Couteur et al, 2016a; Le Couteur et al, 2016b; Simpson et al, 2015). For example, a 40% PR diet, while maintaining a very similar calorie intake, recapitulated the CR effects on mitochondrial ROS production and oxidative damage in rats (Ayala et al, 2007; Sanz et al, 2004).…”

Diet quality and its implications on the cardio-metabolic, physical and general health of older men: the Concord Health and Ageing in Men Project (CHAMP)

“…Ethnicity has also been identified as a predictor of successful ageing (4,5) . For example, people who consume diets associated with particular cultures, such as the Mediterranean and Okinawan diets, appear to have improved health outcomes and longevity (6,7) . On the negative side, older individuals tend to have suboptimal diets (8)(9)(10)(11) .…”