National food supply may predict lifespan

18th November 2020 | Eativity editors

A new global study from the University of Sydney has looked at how macronutrient supplies in different countries are associated with the risk of death at different ages.

The research was led by Dr Alistair Senior, a researcher in the Charles Perkins Centre and Faculty of Science at the University of Sydney.

“We found that the risk of death in early life is minimised where the supply is relatively high in fats and proteins – around 40 and 16 percent of energy, respectively,” he says.

However, in later life, reducing the supply of energy from fats and substituting it for carbohydrates has the lowest mortality.

“It’s a fascinating story, which reflects at the level of national food supplies the fact that macronutrient requirements change with age,” Dr Senior says. “It’s also likely to be of interest when considering the food security of nations, and how changes in supply might translate to patterns of mortality.”

Japan has one of the world’s highest life expectancies, and a diet rich in fish and plant-based foods.

Why macronutrients matter

Macronutrients are the primary source of energy in the foods we eat, and are categorised into three major groups: proteins, fats and carbohydrates.

The study found the total calorie supply per person associated with minimal mortality is relatively stable (around 3500 calories a day) with age, but the composition of calorie intake in terms of dietary proteins, fats and carbohydrates is not.

Before the age of 50, 40 to 45 percent of energy from each of fat and carbohydrates and 16 percent from protein minimises mortality. However, for later life, lower fat and protein supplies at 22 percent and 11 percent, respectively, and replacing these with carbohydrates is associated with the lowest rate of mortality.

“What was really neat was that we saw a clear shift in the supply that minimised mortality at above age 50, where it looked like a high carb supply becomes important,” Dr Senior says.

The study also found that globally, under-nutrition is evident, even as recently as 2016. But in wealthy countries, the effects of over-nutrition are prominent, where high supplies – particularly from fats and carbs – are predicted to lead to high levels of mortality.

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