Low inflammatory activity in Japanese adults is associated with foods and lifestyle practices common in Japan. Drinking green tea, eating seafood, and consuming vegetables are linked to lower C-reactive and Interleukin-6 (IL-6) proteins. More frequent bathing is also associated with lower IL-6, a new study reports in the journal Brain, Behavior, and Immunity.
Both C-reactive protein (CRP) and Interleukin-6 (IL-6), the important biomarkers of inflammation have been shown to be associated with the pathogenesis of infectious disease. In addition, increased levels of CRP and IL-6 have been shown to be associated with other medical conditions.
For example, CRP can increase the risk of developing coronary artery disease. Likewise, IL-6 is linked with the inflammatory process in diseases like diabetes, cardiovascular disease, depression, cancer, and arthritis. More strikingly, recent research has shown that increased levels of both CRP and IL-6 are found in severe COVID-19 cases.
Many theories have emerged to answer questions like why more people have not died from COVID-19 in Japan. Is it because of their superior immunity, lower BMI, genetic susceptibility, or something else? Levels of inflammatory proteins including CRP and IL-6 have shown to be low in Japanese when compared with European and American populations.
A recent study, published in the journal Brain, Behavior, and Immunity shows that there are cultural and lifestyle links including ‘drinking tea, eating seafood, consuming vegetables, and partaking in relaxing baths regularly’ with the lower values of the two inflammatory proteins. The study, however, did not link lower COVID-19 casualties among the Japanese population with their lifestyle practices.
In the study, the researchers randomly selected 382 participants, mean age was 55.5 years (+/-14.1 years, 31-80 years of age), mean BMI 22.6. Physical exercise, smoking status, and alcohol consumption in addition to some disease conditions such as hypertension, heart disease, body mass index (BMI), and HA1c values were used as covariates that may influence the level of the proteins.
Participants were rated based on their engagement in several different behavioral activities such as consumption of tea, seafood, vegetable consumption, and taking relaxing baths. Researchers collected blood samples from all participants during their visit to a medical facility near the University of Tokyo. All serum specimens were then transported in freezing condition to the USA for CRP and IL-6 analysis.
To test the association between lifestyle variables (Japanese Diet or Bathing) and inflammatory activity, the authors have used hierarchical multiple regression methods using each lifestyle variable as a predictor and each inflammatory measure as the outcome in separate analyses.
They found that ‘consuming a Japanese diet was associated with significantly lower CRP and IL-6 levels’ and ‘more frequent bathing was associated with lower IL-6’.
The study, however, did not rule out the involvement of some heritable factors underlying the lower levels of these two pro-inflammatory proteins besides the association of lower adiposity, lower the BMI level lower is the value of inflammatory proteins.
Coe, C. L., Y. Miyamoto, et al. (2020). “Cultural and life style practices associated with low inflammatory physiology in Japanese adults.” Brain, Behavior, and Immunity 90: 385-392.