Health food intake and risk of overall death and cancer incidence in the general population of Amami Islands and mainland of Kagoshima, Japan

OBJECTIVES: Various health foods have been introduced and marketed on television and the internet; however, evidence of their efficacy and effects is often limited to in vitro and in vivo studies. To examine the relationship between health food intake, overall death and cancer incidence risk, we conducted a cohort study on the general population of the Kagoshima Prefecture. METHODS: We recruited 7561 eligible participants (3136 men and 4425 women) from the general populations of Amami islands and mainland Kagoshima Prefecture, Japan. We estimated the hazard ratios and 95% confidence intervals for overall death and cancer incidence using Cox proportional hazard models, adjusting for confounding variables, for the total and nine types of health foods (black vinegar, glucosamine, chlorella, Agaricus, royal jelly, green juice, garlic, blueberry, and turmeric). RESULTS: Black vinegar was the most commonly consumed health food (2.3% in men and 2.6% in women). In the baseline cross-sectional study, positive associations were found between black vinegar and hypertension, garlic and glucose intolerance, and other health foods and dyslipidemia. However, in the prospective study, no significant association was observed between the intake of total and nine-specific health foods and overall deaths and cancer incidence, except for green juice, in which HR for cancer incidence was increased (2.84, 1.15–7.04). CONCLUSIONS: Health foods commonly consumed by the general population of Kagoshima were not significantly associated with the risk of overall death and cancer incidence, except green juice intake. Further study is required to clarify the potential increased risk of cancer with green juice intake.