Macronutrient availability in national food supply may indicate age-specific mortality trends

17 Nov 2020 --- The availability of proteins, carbohydrates and fats in a country’s food supply correlates with national mortality patterns, according to a new global study.

The research also found that optimal protein supply on a national level lessens after age 50.

Researchers from the University of Sydney, Australia, compared age-specific mortality (ASM) and national macronutrient supply data, using 1,879 life tables from 103 countries. 

It is the most extensive analysis to date of corresponding national macronutrient supplies, survival statistics and economic data, flag the study’s authors. 

The correlation between mortality and macronutrients
The researchers tested energy intake and the balance of macronutrients at a macro-level, between the national macronutrient supplies and their patterns of age-specific mortality. 

The study found the total calorie supply per person associated with minimal mortality is relatively stable (around 3500 kcal per capita per day) with age. 

Optimal levels of carbohydrates increase from 40 to 65 percent in older individuals, according to a study that analyzed food supply as it relates to morality.However, the composition of calorie intake in terms of dietary proteins, fats and carbohydrates is not age-stable.

“We found that the risk of death in early life is minimized where the supply is relatively high in fats and proteins, around 40 and 16 percent of energy, respectively,” says Dr. Alistair Senior, research lead and a researcher in the Charles Perkins Centre and Faculty of Science at the University of Sydney.  

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

After the age of 50, optimal levels of carbohydrates increase from 40 to 65 percent in older individuals. For the same age group, the optimal level of protein decreases from 16 to 11 percent. 

“We saw a clear shift in the supply that minimized mortality at above age 50, where it looked like a high carbohydrate supply becomes important,” says Senior. 

The study also found that undernutrition is evident globally, even as recently as 2016. 

However, in wealthy countries, the effects of overnutrition are prominent, where high supplies, particularly from fats and carbohydrates, are predicted to lead to high levels of mortality.

National supply as diet indicators
The study’s authors found that macronutrient supplies are strong predictors of age-specific mortality even after correction for time and economic factors.

“It was intriguing to see that the pattern of reduced rates of mortality in mid- to later-life with an increase in the ratio of carbohydrate-to-protein in the diet reflected studies in the laboratory on the biology of aging,” according to co-author Professor Stephen Simpson, who is the director of the Charles Perkins Centre. 

Team member Professor David Raubenheimer, who is also nutrition theme leader at the Charles Perkins Centre affirms: “While food supply data are not a direct indicator of diets, they provide a good measure of differences in national food environments.”

“This attests to the power of food environments to influence diets and health,” he adds. 

Governments are increasingly addressing the food supply and its environments to mitigate the effects of chronic illness. This is seen in marketing restrictions to protect vulnerable groups from unhealthy foods. Taxes and levies to reduce sugar or sodium, such as those in the UK, are taking off worldwide. 

More to be discovered
Senior suggests that while the survey shows good indications, there are some limitations, which his team will be looking at going forward. 

“It’s important to note though that this is not a guide to what an individual should be eating – we looked at the supply that a country is providing at a per capita level,” he continues. 

“This theoretically sets the upper limit to what people are eating, but there is a whole range of factors that translate a country’s food supply into what ends up actually being consumed.”

Edited by Missy Green