Researchers from the University of Tokyo conducted the first study to quantify the consumption of highly processed foods and examine its relationship with diet quality among Japanese children and adolescents. Highly processed foods (HPFs) accounted for over a quarter of total energy intake among young people. Consumption was negatively associated with the intake of healthy foods, such as fruits, vegetables and legumes, and positively associated with the consumption of confectionery.
It is well known that poor quality diets are considered major risk factors for many health problems and even for non-communicable diseases such as type 2 diabetes. Therefore, researchers are trying to understand factors related to diet quality as a way to improve people’s health improve. Research on HPFs is rapidly increasing, highlighting their potential impact on public health. However, few studies have been conducted in Japan, and none have focused on children and adolescents, due to difficulties in assessing them.
“Our previous research on HPF consumption among adults in Japan found that higher consumption was negatively associated with diet quality. This important finding prompted us to investigate whether similar associations exist among younger generations,” says Assistant -professor Nana Shinozaki from the School of Public Health. “My team and I conducted a cross-sectional study, assessing many people over a short period of time rather than fewer people over a long period of time, to understand the link between HPF consumption and overall diet quality among Japanese children and adolescents. found that higher HPF consumption is associated with poorer diet quality in 1,318 participants aged 3-17 years.
This probably doesn’t come as a surprise to many, but it’s important to note that this is the first time hard data has been collected on this specific demographic group, and that fact could help improve public health. One of the problems with diet research is that many of these issues do not have a precise definition. For this reason, Shinozaki and her team chose an existing food classification framework developed by researchers at the University of North Carolina at Chapel Hill (UNCCH) in the US to classify the foods participants consumed, and the Healthy Eating Index-2020 and the Nutrient – Rich Food Index 9.3 to evaluate the quality of their diet. According to the UNCCH classification, HPFs are defined as “multi-ingredient, industrially formulated mixtures that have been processed in such a way that they are no longer recognizable as their original plant/animal source.”
“The biggest challenge was collecting detailed dietary data, which is essential for identifying which foods are HPFs, on eight days over the course of a year from a large sample of approximately 1,300 individuals,” says Shinozaki. “This process of assessment by researchers and assessments by participants or parents was very burdensome for both participants and researchers due to the need for accurate and consistent recording of dietary intake. Our study could not have been accomplished without the support of dietitians in the study. Japan, which played a crucial role in supporting participants and collecting data.”
What may surprise some readers is that the cliché that the Japanese national diet is the model for healthy eating is a bit inaccurate and outdated.
“Professor Kentaro Murakami (of the University of Tokyo) recently found that in a nationally representative sample of Japanese adults, the average total score of the Healthy Eating Index-2015, a widely accepted diet quality index, was comparable to that of average Americans. This finding suggests that The Japanese diet might not be as healthy as expected,” said Shinozaki. “Wherever you are, on an individual level, increasing the consumption of whole or minimally processed foods, especially fresh fruits and vegetables, would be beneficial public awareness campaigns, policies and regulations, or food availability and market changes Promoting the reduction of HPFs could be beneficial. Our findings support ongoing efforts to develop dietary guidelines and public health strategies aimed at reducing the prevalence of diet-related diseases .”
