Diet and colorectal cancer in UK Biobank: a prospective study

Abstract

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

Methods: 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.

Results: 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.

Conclusions: 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.

Keywords: Diet; UK Biobank; colorectal cancer; processed meat; prospective study; red meat.

Figure 1.

Hazard ratios (95% CIs) for the associations between animal foods and colorectal cancer in UK Biobank. Participants are categorized according to their intake at recruitment. Mean intake in each category is from the web-based 24-hour dietary assessments. Trend per increment uses the re-measured intakes from the web-based 24-hour dietary assessments. Models were stratified by age (<45, 45–, 50–, 55–, 60–, ≥65 years), sex, geographical region (10 regions) and socio-economic status (in fifths, based on the Townsend deprivation index¹⁴) and adjusted for education (College or University degree, vocational qualifications, optional national exams at ages 17–18 years, national exams at age 16 years, none of the above, unknown), smoking status (never, past, current <10 cigarettes per day, current 10–14 cigarettes per day, current 15–19 cigarettes per day, current 20+ cigarettes per day, unknown), waist circumference (sex-specific fifths, unknown), height (sex-specific fifths, unknown), physical activity [low: <10 excess metabolic equivalent (MET)-hours per week, moderate: 10–49.9 excess MET-hours per week, high: ≥50 excess MET-hours per week, unknown¹⁵], alcohol intake (<1, 1–7, 8–15, ≥16 g/day, unknown) (except for analyses where alcohol was the main exposure), family history of colorectal cancer (mother, father or sibling having had colorectal cancer, no family history, unknown), aspirin or ibuprofen use (regular use, not regular use, unknown), use of vitamin D supplements (regular use, not regular use, unknown), use of folate supplements (regular use, not regular use, unknown) and in women only: parity (0, 1–2, ≥3 live births, unknown), menopause (pre-menopausal, post-menopausal, unsure because of hysterectomy, unsure because of other reason, unknown), oral contraceptive agent (OCA) use (never, ever, unknown) and HRT use (never, ever, unknown).

Figure 2.

Hazard ratios (95% CIs) for the associations between plant foods, fibre, and alcohol and colorectal cancer in UK Biobank. Participants are categorized according to their intake at recruitment. Mean intake in each category is from the web-based 24-hour dietary assessments. Trend per increment uses the re-measured intakes from the web-based 24-hour dietary assessments. Models were stratified by age (<45, 45–, 50–, 55–, 60–, ≥65 years), sex, geographical region (10 regions) and socio-economic status (in fifths, based on the Townsend deprivation index¹⁴) and adjusted for education (College or University degree, vocational qualifications, optional national exams at ages 17–18 years, national exams at age 16 years, none of the above, unknown), smoking status (never, past, current <10 cigarettes per day, current 10–14 cigarettes per day, current 15–19 cigarettes per day, current 20+ cigarettes per day, unknown), waist circumference (sex-specific fifths, unknown), height (sex-specific fifths, unknown), physical activity [low: <10 excess metabolic equivalent (MET)-hours per week, moderate: 10–49.9 excess MET-hours per week, high: ≥50 excess MET-hours per week, unknown¹⁵], alcohol intake (<1, 1–7, 8–15, ≥16 g/day, unknown) (except for analyses where alcohol was the main exposure), family history of colorectal cancer (mother, father or sibling having had colorectal cancer, no family history, unknown), aspirin or ibuprofen use (regular use, not regular use, unknown), use of vitamin D supplements (regular use, not regular use, unknown), use of folate supplements (regular use, not regular use, unknown) and in women only: parity (0, 1–2, ≥3 live births, unknown), menopause (pre-menopausal, post-menopausal, unsure because of hysterectomy, unsure because of other reason, unknown), oral contraceptive agent (OCA) use (never, ever, unknown) and HRT use (never, ever, unknown).