Folate intake and the risk of colorectal cancer in a Korean population
J Kim1, D H Kim2, B H Lee3, S H Kang4, H J Lee5, S Y Lim1, Y K Suh2 and Y O Ahn6
1Cancer Epidemiology Branch, National Cancer Research Institute, National Cancer Center, Goyang, South Korea
2Department of Social and Preventive Medicine, Hallym University College of Medicine, Chunchon, Kangwon-do, South Korea
3Department of General Surgery, Hallym University Sacred Heart Hospital, Anyang, South Korea
4Department of Statistics, Seoul National University, Seoul, South Korea
5Department of Social and Preventive Medicine, Inha University College of Medicine, Incheon, South Korea
6Department of Preventive Medicine, Seoul, Seoul National University College of Medicine, Seoul, South Korea
Background: Folate, a water-soluble B vitamin and one of the major micronutrients in vegetables, is known as an essential factor for the de novo biosynthesis of purines and thymidylate, and it plays an important role in DNA synthesis and replication. Thus, folate deficiency results in ineffective DNA synthesis, and has been shown to induce the initiation and progression of colorectal cancer (CRC). Recently, the incidence of CRC in Korea has increased markedly in both men and women; this trend may be related to the adoption of a more 'westernized' lifestyle, including dietary habits.
Objective: A hospital-based case–control study was conducted to examine the relationship between folate intake and the risk of CRC within a Korean population.
Methods: A total of 596 cases and 509 controls, aged 30-79 years, were recruited from two university hospitals. Site- and sex-specific odds ratios (ORs) were estimated using logistic regression models.
Results: Cases were more frequently found to have a family history of CRC among first-degree relatives, to consume more alcohol, to be more likely current smokers and less likely to participate in vigorous physical activity than the controls. In the overall data for men and women combined, multivariate ORs (95% confidence interval (CI), P for trend) comparing the highest vs the lowest quartile of dietary folate intake were: 0.47 (0.32–0.69, <0.001) for CRC, 0.42 (0.26–0.69, <0.001) for colon cancer and 0.48 (0.28–0.81, 0.007) for rectal cancer. An inverse association was also found in women with dietary folate intake: 0.36 (0.20–0.64, <0.001) for CRC, 0.34 (0.16–0.70, 0.001) for colon cancer and 0.30 (0.12–0.74, 0.026) for rectal cancer, but not in men. In addition, the total folate intake of women was strongly associated with a reduced risk of rectal cancer (OR, 0.38; 95% CI, 0.17–0.88; P for trend=0.04).
Conclusion: We found a statistically significant relationship between higher dietary folate intake and reduced risk of CRC, colon cancer and rectal cancer in women. A significant association is indicated between higher total folate intake and reduced risk of rectal cancer in women.
NOTE Excellent source of Folate - Green beans, leek, parsnip, cabbage, beetroot, green peas, spinach, capsicum, cauliflower, chick peas, oranges, orange juice, peanuts, oats, wholegrain bread. Good source of Folate - Wheat germ, cos lettuce, banana, avocado, carrot, parsley, tomato, strawberry, canned salmon, hazelnuts, cashews, walnuts, almonds. Liver is also rich in folic acid, but it is not recommended for pregnant women because it is also very rich in vitamin A. Too much vitamin A can be harmful to your unborn child