Cross-cultural associations:

Average starch intake and 50-year coronary heart disease mortality rates in 16 cohorts

In the 1960s, foods were prepared at home and had more fiber than ultra-processed foods produced nowadays. The average intake of starch was correlated (R=0.74) with the average consumption of bread, cereals, legumes and potatoes. The average intake of starch varied from 10 % of energy in the US to more than 50 % of energy in Japan. The average intake of starch was inversely related ecologically to 50-year CHD mortality rates among the 16 cohorts (R = -0.71).

Average starch intake and 50-year CHD death rates

Average starch intake and 50-year CHD death rates
US: US railroad; EF: East Finland; WF: West Finland, ZU: Zutphen, the Netherlands; CR: Crevalcore, Italy; MO: Montegiorgio, Italy; RR: Rome railroad, Italy; DA:Dalmatia, Croatia; SL: Slavonia, Croatia; VK: Velika Krsna, Serbia; ZR: Zrenjanin, Serbia; BE: Belgrade, Serbia; KT: Crete, Greece; CO: Corfu, Greece; TA: Tanushimaru, Japan; UB: Ushibuka, Japan

Interpretation

These results suggest that plant foods rich in starch and fiber, may protect against CHD mortality. Unprocessed plant foods contain the carbohydrate starches amylose and amylopectin and non-starch polysaccharides (total dietary fiber). In contrast, ultra-processed foods contain amylose and amylopectin but without fiber. Starch is inversely related to CHD mortality ecologically. Controlled dietary experiments support replacement of added sugars by starch to reduce LDL-cholesterol level, an established causal risk factor of CHD.

References

More cohort findings with 25 or 50-year follow-up in the 16 cohorts

The original cross-cultural associations from the 1960s were later repeated using 25 and 50-year CHD mortality data for serum cholesterol and saturated fat intake and extended with associations on flavonoids and dietary patterns.

25-year follow-up study findings

50-year follow-up study findings

Are these cross-cultural associations causal?

Ecological or cross-cultural associations are frequently viewed as the lowest level of evidence about causality. However, to demean ecological associations is to fail to recognize the powerful indication they provide about the population burden of disease. They can be useful for prevention when correlations among populations are congruent with sound clinical evidence, with significant correlations at the level of individuals within populations, and with known mechanisms.

Read more about cross-cultural findings

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