Recent data published by the World Health Organization (WHO) shows that Japan outperforms the G7 countries when it comes to life expectancy.
And while there is no single explanation, diet is believed to play a prominent role. Research published in the BMJ strengthens this relationship.
The study found that a higher intake of fermented soy products, such as miso and natto – staples of the Japanese diet – was associated with a lower risk of death.
In Asian countries, especially Japan, several types of soy products are widely consumed, such as natto (fermented soybeans with Bacillus subtilis), miso (fermented soybeans with Aspergillus oryzae), and tofu (soybean curd).
Researchers have yet to establish a link between soy products, especially fermented soy products, and specific health effects.
A team of researchers in Japan set out to investigate the relationship between several types of soy products and death from any cause, such as cancer, total cardiovascular disease and respiratory disease.
The researchers based their findings on 42,750 men and 50,165 women, between the ages of 45 and 74, who were participating in a study conducted in 11 areas of public health centers in Japan.
The researchers found that a higher intake of fermented soybeans (natto and miso) was associated with a significant decrease (10%) in all-cause mortality risk, but total soy product intake was not associated with all-cause of death.
Men and women who ate natto were less likely to die of cardiovascular disease than others, but there was no association between soy intake and cancer-related deaths.
These results persisted even after more adjustments were made to vegetable intake, which was higher among those consuming higher amounts of soy.
The researchers noted that fermented soy products are rich in fiber, potassium and more bioactive ingredients than their non-fermented counterparts, which may help explain their associations.
However, this is an observational study, so the cause cannot be identified, and researchers cannot rule out the possibility that some of the observed risks are due to other, non-measurable factors.
They concluded: “In this large pilot study conducted in Japan with a high rate of soybean consumption, no significant association was found between total soy product intake and all causes of death. Conversely, higher intake of fermented soy products (natto and miso) was associated with a decrease. Risk of death. “
Mounting evidence suggests that fermented soy products are linked to health benefits, researchers wrote in a linked editorial.
They concluded that more studies are still required, “to improve our understanding of the health effects of fermented soybeans, and possibly to inform the development of healthier and more palatable products. These efforts must be collaborative, including not only researchers, but also policy-makers and the food industry.”
What is included in a typical Japanese diet?
The typical Japanese diet features plant-based foods and fish, as well as a modest Western diet, such as meat, milk, and dairy products that may be associated with longevity in Japan.