The Study
Are popular books about diet and health written based on scientific evidence? A comparison of citations between the USA and Japan
This study didn't check if the diet advice in books is right or wrong—it just counted how often authors wrote down where they got their info. It found that American books tend to cite more sources than Japanese ones, but that doesn't mean one is better or more accurate.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
Scientists checked 200 popular diet books from the U.S. and Japan to see if they cited real science, like research studies.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 539 / 100
Quality score
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — this means most Japanese diet books are less likely to be based on solid science, even if they sound expert.
- 2In the U.S., 49 out of 100 books cited high-quality research reviews; in Japan, only 9 did.
- 397% of U.S.
- 4books gave clear source details; only 64% of Japanese books did.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Public Health Nutrition
Year
2023
Authors
F. Oono, Riho Adachi, Akinori Yaegashi, M. Kishino, Risa Ogata, A. Kinugawa, Ayari Tsumura, Mizuki Suga, Moe Matsumoto, Tomoya Takaoka, Yuya Kakutani, K. Murakami, Satoshi Sasaki
Related Content
Claims (5)
Popular diet and health books in Japan are much less likely to cite high-quality scientific reviews of human studies than similar books in the USA, where nearly half include such evidence.
American diet books almost always give full details about where their information comes from, while Japanese diet books often omit key details like author names or publication dates, making it harder to verify their claims.
Even when written by doctors, Japanese diet books rarely cite high-quality scientific reviews, unlike American ones, which suggests that factors like language or training may limit access to scientific evidence in Japan.
Authors with medical degrees are more likely to include references in their diet books than authors without medical training, in both the USA and Japan.
In the health and nutrition book market, books that accurately cite scientific sources are less popular than books that lack scientific rigor.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.