Not all carbohydrates are bad: Higher intake of starch reduces mortality in Japanese men
According to researchers from Japan, there was no significant association between any type of carbohydrates and mortality for Japanese women.
They presented their findings in the British Journal of Nutrition, examining the association of different types of carbohydrates, including starch, and total sugar, on mortality in a population-based cohort.
Methodology
The study recruited 29,079 residents who were aged 35 years and above, from the Takayama Study in Japan, in 1992.
Diet was assessed by a validated food-frequency questionnaire at baseline.
Estimations of the intake of individual types of carbohydrates (starch, glucose, fructose, sucrose, maltose, and lactose) were based on the Japanese Standard Tables of Food Composition (2015).
Carbohydrate intake (quartile medians) was expressed as a percentage of energy.
Mortality was ascertained during 16 years of follow-up.
Starch and mortality
Researchers explained their findings, “We found that a higher intake of starch was associated with a decreased risk of total mortality, whereas a higher intake of total sugar intake was associated with increased risk of total mortality in men.”
Intake of starch was significantly inversely associated with total mortality for the highest quartile versus lowest quartile (p<0.001) in men.
Similarly, comparing the highest versus lowest quartile, total sugar intake was significantly positively associated with total mortality in men (p<0.001).
According to the study, the main dietary sources of starch were rice and other cereals, while total sugar intake were mostly sweetened beverages in Japan.
In women, there was no significant association between carbohydrate types and total mortality, suggesting that the high intake of starch and low intake of sugars may favour longevity of Japanese men only.
The researchers also observed most studies on carbohydrate and total mortality studied sugar, and not starch.
They referenced one other study known, the NIH-AARP Diet and Health Study, which examined sugar intake. It found high intake of total sugars was significantly associated with an increased risk of total mortality in men and women.
Additional studies
The researchers reported a limitation in their study, “Our questionnaire was designed to measure an individual's relative intakes of nutrients or foods rather than absolute values.
Although we presented the mean values for dietary intakes, some of them may be overestimated by our questionnaire,” they said.
However, they said the new findings on different types of carbohydrates - starches and sugars, have different associations with total mortality in men.
And since studies on the intake of different types of carbohydrates and long-term mortality were sparse, the researchers suggested additional studies in different populations.
Source: British Journal of Nutrition
https://doi.org/10.1017/S0007114519001661
“Intake of starch and sugars and total and cause-specific mortality in a Japanese community: The Takayama Study”
Authors: Chisato Nagata, et al.
