Most of the previous studies on diet and colorectal cancer were based on diets consumed during the 1990s.

We used Cox-regression models to estimate adjusted hazard ratios for colorectal cancer by dietary factors in the UK Biobank study. Men and women aged 40–69 years at recruitment (2006–10) reported their diet on a short food-frequency questionnaire (n = 475 581). Dietary intakes were re-measured in a large sub-sample (n = 175 402) who completed an online 24-hour dietary assessment during follow-up. Trends in risk across the baseline categories were calculated by assigning re-measured intakes to allow for measurement error and changes in intake over time.

During an average of 5.7 years of follow-up, 2609 cases of colorectal cancer occurred. Participants who reported consuming an average of 76 g/day of red and processed meat compared with 21 g/day had a 20% [95% confidence interval (CI): 4–37] higher risk of colorectal cancer. Participants in the highest fifth of intake of fibre from bread and breakfast cereals had a 14% (95% CI: 2–24) lower risk of colorectal cancer. Alcohol was associated with an 8% (95% CI: 4–12) higher risk per 10 g/day higher intake. Fish, poultry, cheese, fruit, vegetables, tea and coffee were not associated with colorectal-cancer risk.

Consumption of red and processed meat at an average level of 76 g/d that meets the current UK government recommendation (≤90 g/day) was associated with an increased risk of colorectal cancer. Alcohol was also associated with an increased risk of colorectal cancer, whereas fibre from bread and breakfast cereals was associated with a reduced risk.

• Previous studies have found an increased risk of colorectal cancer in those with high intakes of red and processed meat. Most previous studies collected information on dietary intakes during the 1990s or earlier and patterns in meat consumption have since changed.

• In addition, few studies have used re-measured intakes to reduce the impact of measurement error, and to quantify the amount of red and processed meat that is associated with an increased risk. Measurement error generally biases the associations towards the null value; the associations observed in previous studies that did not re-measure intakes may be underestimated.

• Our study found that people who were consuming red and processed meat four or more times per week, had a 20% increased risk of colorectal cancer compared with those who were consuming red and processed meat less than twice a week.

Acknowledgements

This research has been conducted using the UK Biobank Resource under Application Number 3037. K.E.B. and T.J.K. conceived of the research. K.E.B. analysed the dataset and wrote the first draft of the manuscript. N.M. contributed code for the analysis. K.E.B., N.M. and T.J.K. interpreted the results, revised the draft paper, and read and approved the final manuscript. UK Biobank is an open-access resource. Bona fide researchers can apply to use the UK Biobank dataset by registering and applying at http://ukbiobank.ac.uk/register-apply/.

Conflict of interest: Dr Bradbury’s spouse is a brewer at Steam Brewing Company, Auckland, New Zealand. Drs Key and Murphy have no competing interests to declare.

References