Positive Health Online

Abstract

KIRK and colleagues, Bastyr University, Bellevue, Washington USA developed a dietary assessment instrument to measure soy food consumption and isoflavone intake and to test this instrument for reliability.

Background

Methodology

A soy food frequency questionnaire, administered twice to participants, separated by a 2-week interval, was tested for reproducibility of estimates of soy food consumption and isoflavone (genistein and daidzein) intake. The recruits to the study were a convenience sample of 51 faculty, staff and students from a naturopathic university.

Results

Correlation coefficients comparing mean soy food servings per month between the two administrations of the questionnaire ranged from 0.50 for soy yogurt to 0.89 for tempeh. Correlation coefficients between the 2 questionnaire administrations for genistein and daidzein intake were the same: 0.89. The mean intake of genistein and daidzein was 7 +/- 10 and 4 +/- 6 mg/day, respectively. 95% of the total genistein and daidzein intake was contributed by 15 foods: tofu, soy yoghurt, tempeh, soy milk, low-fat tofu, soy flour, miso, soy protein isolate, low-fat soy milk, veggie soy burger, textured vegetable protein, miso soup, cooked soybeans, soy hot dogs, and natto (fermented soy beans) .

Conclusion

The soy food frequency questionnaire developed for this study provided highly reproducible estimates of soy food consumption and isoflavone intake and may be a useful tool to study the associations between isoflavone exposure and risks for chronic diseases.

References

Kirk P et al. Development of a soy food frequency questionnaire to estimate isoflavone consumption in US adults. Journal of the American Dietetic Association 99(5): 558-63. May 1999.