High prevalence of food intolerances among US internet users.

OBJECTIVE

Food intolerances are commonly reported and are predicted to have gastrointestinal health implications. We aimed to quantify the prevalence of food intolerances among US adults and identify culprit foods through a brief web-based survey.

DESIGN

We invited participation in an online cross-sectional survey involving a single questionnaire. Data were summarised using percentages or medians and interquartile range. Participant characteristics by self-reported food intolerance were compared using the Wilcoxon rank sum test and Pearson's χ2 test. Adjusted analyses were performed using multivariable logistic regression.

SETTING

The survey was internet-based via Amazon's mechanical Turk, a crowdsourcing website for the completion of requester directed tasks.

PARTICIPANTS

Adults who were US-based internet users were invited at ages 18-80.

RESULTS

We collected 2133 survey responses (ages 18-79 years). The rate of food intolerance was 24·8 % (95 % CI 23·0, 26·6) in US adults. Younger (P < 0·01), female (P = 0·05) and Asian, African American or multiple race individuals (P < 0·01) predominated. Lactose intolerance was most common. Frequency of a non-lactose food intolerance was 18·1 % (95 % CI 16·5, 19·8). When categorised broadly, grains, fruit, lactose, fish, vegetables, alcohol and nuts were most troublesome for individuals in that order.

CONCLUSIONS

Self-reported food intolerance is common in US internet users. The effect of food on gastrointestinal symptoms and avoidant behaviours deserves further attention.