TABLE 1.
Characteristics of included studies.
| References Country |
Type of cancer | Type of study | Sample size | Diet/Serum | Nutrient type | Adjustment for covariates. | NOS score |
| Roswall et al. (27) Denmark | Colon and rectal cancer | Cohort study | 56,332/748 | Diet | β-carotene | Education, alcohol consumption, consumption of red and processed meat, smoking status | 7 |
| Murtaugh et al. (23) United States | Rectal cancer | Case-control study | 952/1,205 | Diet | Lycopene, β-carotene, lutein | Age, body mass index, physical activity, energy intake, dietary fiber, dietary calcium, and smoking status | 7 |
| Williams et al. (53) United States | Colorectal cancer | Case-control study | 945/959 | Diet | β-carotene | Age, gender, education, smoking status, BMI, physical activity, family history, history of alcohol use | 6 |
| Park et al. (26) United States | Colon and rectal cancer | Cohort study | 191,004/2,378 | Diet | Lycopene, α-carotene, β-carotene, carotenoids, β-cryptoxanthin, Lutein | Gender, age, family history of colorectal cancer, history of intestinal polyps, number of pack-years smoked, body mass index | 8 |
| Slattery et al. (54) United States | Colon cancer | Case-control study | 1,993/2,410 | Diet | Lycopene, α-carotene, β-carotene, β-cryptoxanthin, Lutein, zeaxanthin | Age, gender, smoking, alcohol consumption, BMI and long term strenuous physical activity | 7 |
| Leenders et al. (22) Europe | Colon and rectal cancer | Case-control study | 1,399/1,399 | Diet | Lycopene, α-carotene, β-carotene, carotenoids, retinol | Smoking, alcohol consumption, BMI, physical activity, consumption level | 7 |
| Terry et al. (55) Canada | Colon and rectal cancer | Cohort study | 56,837/5,681 | Diet | Lycopene, α-carotene, β-carotene, carotenoids | Smoking status, relative body mass (body mass index), total fat intake, energy, alcohol, and folic acid, or menopausal status | 7 |
| Nkondjock and Ghadirian (56) Canada | Colon cancer | Case-control study | 402/688 | Diet | Lycopene, α-carotene, β-carotene, carotenoids, lutein/zeaxanthin, β-cryptoxanthin | Age, history of CC in first-degree relatives, marital status, gender, physical activity, fiber and folate consumption, and total energy intake | 7 |
| Wang et al. (57) Japan | Colon and rectal cancer | Case-control study | 816/815 | Diet | Lycopene, carotenoids | Age, residence, family history of colorectal cancer, smoking, alcohol consumption, BMI, type of work, physical activity | 6 |
| Negri et al. (58) Italy | Colorectal cancer | Case-control study | 1,953/4,154 | Diet | Lycopene, carotenoids, retinol | Sociodemographic characteristics, smoking, physical activity, anthropometric measurements at different ages, family history of cancer | 7 |
| Levi et al. (59) Switzerland | Colorectal cancer | Case-control study | 223/491 | Diet | Carotenoids, retinol | Age, sex, education, smoking, alcohol, body mass index, physical activity, and total energy and fiber intake | 7 |
| Lu et al. (60) China | Colorectal cancer | Case-control study | 845/845 | Diet | Lycopene, α-carotene, β-carotene, carotenoids, lutein/zeaxanthin, β-cryptoxanthin | Education, marital status, occupation, income, family history of cancer, smoking status, passive smoking, alcohol consumption, occupational activities, family and leisure activities, BMI | 7 |
| Paiva et al. (61) Portugal | Colorectal cancer | Case-control study | 100/211 | Diet | Carotenoids | Age, sex, marital status, work physical activity, family history of cancer, body mass index, fiber, carotene, vitamin C, and total energy | 7 |
| Rosato et al. (24) Switzerland | Colorectal cancer | Case-control study | 329/1,361 | Diet | β-carotene | Age, gender, family history, alcohol use, education, physical activity | 6 |
| Key et al. (62) United Kingdom | Colorectal cancer | Case-control study | 565/1,951 | Diet | β-carotene | Height, weight, energy intake, alcohol intake, dietary fiber, smoking, alcohol | |
| consumption, physical activity, education, social class | 7 | ||||||
| Cook et al. (63) United States | Colon and rectal cancer | Cohort study | 22,071/267 | Diet | β-carotene | Age, education, marital status, occupation, income, family history of cancer, smoking status, passive smoking, alcohol consumption, occupational activity, BMI | 7 |
| Wakai et al. (64) Japan | Colon and rectal cancer | Case-control study | 507/2,535 | Diet | Carotenoids, retinol | Sex, age, family history, smoking, alcohol use, physical activity, energy intake | 7 |
| Shin et al. (25) China | Colon and rectal cancer | Cohort study | 73,314/283 | Diet | Carotenoids, retinol | Age, menopausal status, education, smoking, alcohol consumption, physical activity, family history of colorectal cancer, use of vitamin supplements, and total energy intake | 8 |
| Kabat et al. (65) United States | Colorectal cancer | Cohort study | 5,477/88 | Serum | Lycopene,α-carotene, β-carotene, Lutein + Zeaxanthin,β-Cryptoxanthin, Retinol | Age, body mass index, waist circumference, alcohol intake, physical activity, family history of colorectal cancer, ethnicity | 8 |
| Huang et al. (28) China | Colorectal cancer | Case-control study | 538/564 | Serum | Lycopene, α-carotene, β-carotene, lutein/zeaxanthin, β-cryptoxanthin | Living conditions, educational level, occupation, income, study, alcohol consumption, family history of colorectal cancer, physical activity | 7 |
| Luo et al. (66) China | Colon and rectal cancer | Case-control study | 535/552 | Serum | Retinol | Age, sex, residence, educational level, marital status, income, family and leisure activities, passive smoking, alcohol consumption, adult height, and BMI | 6 |
| Malila et al. (67) Finland | Colorectal cancer | Cohort study | 26,951/184 | Serum | Retinol, β-carotene | Age, body mass index (BMI), number of cigarettes smoked per day, occupational and leisure time physical activity, serum cholesterol concentration, alcohol intake | 8 |