身体里可能发生的事是这样的：腌肉带进来的亚硝酸盐，在胃里、在加热时、也在肠道里（血红素铁会推动这一步）和胺类反应，生成能往 DNA 上挂小基团的 N-亚硝基化合物；没被吸收的血红素铁一路走到大肠，在那里催化氧化，产物损伤肠壁细胞。两条线都落在大肠。这是解释加工肉与结直肠癌关联的主要机制，多数环节来自动物实验和实验室测量，后面讲它怎样增加癌症风险的一章细说。
Bouvard, V., Loomis, D., Guyton, K. Z., Grosse, Y., Ghissassi, F. E., Benbrahim-Tallaa, L., et al. (2015). Carcinogenicity of consumption of red and processed meat. Lancet Oncology, 16(16), 1599-1600. IARC classifies processed meat as Group 1 carcinogen, red meat as Group 2A. 10.1016/S1470-2045(15)00444-1
World Health Organization. (2012). Guideline: Sodium intake for adults and children. World Health Organization. Recommends a reduction to less than 2 g/day of sodium (5 g/day of salt) in adults - a strong recommendation. For children, the recommended maximum adult level of 2 g/day sodium should be adjusted downward based on the energy requirements of children relative to those of adults. www.who.int/publications/i/item/9789241504836
Chinese Nutrition Society. (2022). Dietary Guidelines for Chinese Residents (2022). Core recommendation three: eat vegetables at every meal, with at least 300 g of fresh vegetables per day of which dark-coloured vegetables should make up half; eat fruit every day, 200-350 g of fresh fruit per day, and fruit juice does not substitute for whole fruit. The accompanying Balanced Diet Pagoda gives a vegetable range of 300-500 g/day at the 1600-2400 kcal energy levels. Core recommendation five (less salt and oil, limit sugar and alcohol), verified verbatim 2026-08-21: adults should take no more than 5 g of salt per day; cooking oil 25-30 g per day; added sugar no more than 50 g per day and preferably under 25 g; and for adults who drink, no more than 15 g of alcohol per day. Other core figures on the same official page: at least 300 g of fresh vegetables daily with dark-coloured vegetables making up half, 200-350 g of fresh fruit daily with juice not substituting for whole fruit, the equivalent of over 300 mL of liquid milk, 200-300 g of cereals, and 120-200 g of animal-protein foods. The same official page also says: on average 12 kinds of food a day and 25 or more a week. It carries no saturated-fat percentage-of-energy line (read 2026-09-24). www.sport.gov.cn/n20001280/n20001265/n20066978/c24291669/content.html
Norat, T., Bingham, S., Ferrari, P., Slimani, N., Jenab, M., Mazuir, M., et al. (2005). Meat, fish, and colorectal cancer risk: the European Prospective Investigation into Cancer and Nutrition (EPIC). Journal of the National Cancer Institute, 97(12), 906-916. 10.1093/jnci/dji164
World Cancer Research Fund / American Institute for Cancer Research. (2018). Diet, Nutrition, Physical Activity and Cancer: a Global Perspective (Third Expert Report). WCRF/AICR. Ten evidence-based Cancer Prevention Recommendations: maintain a healthy weight, be physically active, eat wholegrains/vegetables/fruit/beans, limit fast foods and ultra-processed foods, limit red and processed meat, limit sugar-sweetened drinks, limit alcohol, and do not rely on supplements for cancer prevention. The meat recommendation reads: eat no more than moderate amounts of red meat and little, if any, processed meat. For red meat it gives a quantity - no more than about three portions a week, equivalent to about 350-500 g (12-18 oz) COOKED weight. For processed meat it deliberately gives NO gram figure, only the wording consume very little, if any. Evidence grading for colorectal cancer: processed meat is graded convincing, red meat probable. www.wcrf.org/diet-activity-and-cancer
World Health Organization / International Agency for Research on Cancer. (2015). Cancer: Carcinogenicity of the consumption of red meat and processed meat (Q&A accompanying IARC Monographs Volume 114). Classifications: processed meat Group 1, carcinogenic to humans; red meat Group 2A, probably carcinogenic to humans. Quantitative estimate, verbatim: an analysis of data from 10 studies estimated that every 50 gram portion of processed meat eaten daily increases the risk of colorectal cancer by about 18 percent. Two statements that bound how the classification may be used, both verbatim: IARC is a research organization that evaluates the evidence available on the causes of cancer but does not make health recommendations as such; and, on whether an intake threshold exists, the data available for evaluation did not permit a conclusion about whether a safe level exists. Cite this record - not the Group 1 / 2A classification alone - whenever the site states the 50 g / 18 percent figure or explains why IARC issues no gram limit. Red meat, verbatim: if the association of red meat and colorectal cancer were proven to be causal, data from the same studies suggest that the risk of colorectal cancer could increase by 17% for every 100 gram portion of red meat eaten daily (Q&A page, re-read 2026-09-25). www.who.int/news-room/questions-and-answers/item/cancer-carcinogenicity-of-the-consumption-of-red-meat-and-processed-meat
Zhong, V. W., Van Horn, L., Greenland, P., Carnethon, M. R., Ning, H., Wilkins, J. T., et al. (2020). Associations of processed meat, unprocessed red meat, poultry, or fish intake with cardiovascular disease and all-cause mortality. JAMA Internal Medicine, 180(4), 503-512. 6 US cohorts, 29,682 adults, median 19.0 years. Per 2 servings a week: incident CVD HR 1.07 for processed meat, 1.03 unprocessed red meat, 1.04 poultry, 1.00 fish (non-significant); all-cause death 1.03 processed, 1.03 unprocessed red meat, 0.99 poultry and 0.99 fish (both non-significant). Observational (abstract, PMID 32011623). 10.1001/jamainternmed.2019.6969