According to a recent study in the journal BMJ, the Japanese are one of the the longest-living populations in the world. Women there, for instance, have a life expectancy of 87 years. Although many factors likely feed into this longevity, such as universal health insurance and socioeconomic factors, the question of the role of diet and its potential impact on health is always intriguing.
Led by Dr.Kayo Kurotani of the National Centre for Global Health and Medicine, Tokyo, a group of researchers investigated whether eating a healthy diet was associated with a decrease in total and cause-specific mortality. Although numerous studies have supported this association, according to the authors, few have involved Asian populations.
The standard used was the Japanese Food Guide Spinning Top, which makes recommendations that are similar to the U.S. Food Guide.
The scientists performed a prospective, large population-based study of the diets of Japanese adults aged 40-69 from five Japanese public health center areas. At the study's initiation, participants filled out questionnaires about their health and lifestyles (including smoking, drinking and diets), and repeated these surveys both five and 10 years later. For the current investigation, the researchers used the data from the five-year follow up as the baseline, since it contained a more extensive list of foods than the initial survey had. Overall, the mean followup time was 15 years.
The investigators created an adherence score for the food guide — the higher the score, the better the adherence. The scores ranged from 0 to 80. Included in the study were about about 37,000 men and 43,000 women.
For the second survey, the average score was 53. Those with higher scores tended to be older and female. They were also less likely to smoke or drink alcohol every week.
In accounting for all causes of death, higher food guide scores (and thus better diets) were associated with a 15 percent lower risk of all-cause death. This was also true for some cause-specific mortality — cardiovascular disease and cerebrovascular disease (e.g. strokes) and there were mixed results about the decreased risk of death from cancer. It was significant for men, but not for women.
"Our findings, together with previous reports," the authors concluded, "suggest that a dietary pattern of high intake of vegetables and fruits and adequate intake of fish and meat can significantly decrease the risk of mortality from cardiovascular disease in East Asian populations, particularly from cerebrovascular disease."
While this study supports much of what we have seen in studies of other populations, it's important to address the inevitable weakness that all dietary intake data are self-reported, something that is unavoidable.
It's also interesting to note that these authors did not single out meat as a negative item, but instead that a balanced consumption of all foods seems to be associated with greater longevity.