Du 2021（Nutrition and Cancer, 13 项研究，3095 例）：高辣摄入胃癌 OR 2.28 (95% 1.76-2.96)Pabalan 2014（10 项研究）：更明确是 U 型 —— 低摄入 OR 0.55（风险更低），中高摄入 OR 1.94（升高）；在韩国人群里，高摄入的风险更高 为什么会打架
三个原因值得记住，它们是读所有营养研究的通用工具：
1. 研究设计不同：前瞻队列（先问饮食，再等结局）vs 病例对照（先找到病人，再回忆饮食）。后者天生有回忆偏倚——得了胃癌的人回想我以前是不是吃太辣了，答案会被病情本身带偏。 2. 剂量不同：韩国、墨西哥某些人群的辣椒摄入量，远超中国队列里每周吃几天辣的口径。低摄入保护、高摄入有害的 U 型，本身就意味着吃多少比吃不吃重要。 3. 人群不同：基因、腌制食品、幽门螺杆菌感染率、盐摄入——这些在不同人群里差别巨大，都会跟着辣一起被算进去。
Caterina, M. J., Schumacher, M. A., Tominaga, M., Rosen, T. A., Levine, J. D., & Julius, D. (1997). The capsaicin receptor: a heat-activated ion channel in the pain pathway. Nature, 389(6653), 816-824. Expression cloning of TRPV1: a non-selective cation channel on nociceptive sensory neurons, activated by capsaicin and by noxious heat above ~43 C. 10.1038/39807
The Nobel Assembly at Karolinska Institutet. (2021). The Nobel Prize in Physiology or Medicine 2021: Discoveries of receptors for temperature and touch. Awarded to David Julius and Ardem Patapoutian; Julius used capsaicin to identify TRPV1 as the heat-sensing ion channel. www.nobelprize.org/prizes/medicine/2021/press-release
U.S. Department of Agriculture, Agricultural Research Service. (2019). FoodData Central: Peppers, hot chili, red and green, raw. Raw red chili ~40 kcal/100 g and ~144 mg vitamin C/100 g; realistic culinary portions are only a few grams, so per-100 g nutrient density greatly overstates actual intake. fdc.nal.usda.gov
Nolden, A. A., Lenart, G., & Hayes, J. E. (2019). Putting out the fire - efficacy of common beverages in reducing oral burn from capsaicin. Physiology & Behavior, 208, 112557. Seven beverages compared; milk beat water, but skim and whole milk never differed, challenging the lipophilic-partitioning hypothesis and implicating casein over fat. 10.1016/j.physbeh.2019.05.018
Nolden, A. A., Lenart, G., Spielman, A. I., & Hayes, J. E. (2024). Inducible desensitization to capsaicin with repeated low-dose exposure in human volunteers. Physiology & Behavior, 275, 114447. Capsaicin rinse twice daily for 14 days cut burn ~24% with cross-desensitization; TRPV1 mRNA did not decrease, so the mechanism remains unresolved. 10.1016/j.physbeh.2023.114447
Anand, P., & Bley, K. (2011). Topical capsaicin for pain management: therapeutic potential and mechanisms of action of the new high-concentration capsaicin 8% patch. British Journal of Anaesthesia, 107(4), 490-502. Sustained high-concentration capsaicin defunctionalizes nociceptors via TRPV1 overactivation, with reversible retraction of epidermal nerve fibers. 10.1093/bja/aer260
Derry, S., Rice, A. S. C., Cole, P., Tan, T., & Moore, R. A. (2017). Topical capsaicin (high concentration) for chronic neuropathic pain in adults. Cochrane Database of Systematic Reviews, 1, CD007393. Eight RCTs, 2488 participants; results were judged susceptible to publication bias and only a weak second-line recommendation was given. 10.1002/14651858.CD007393.pub4
Ludy, M. J., Moore, G. E., & Mattes, R. D. (2012). The effects of capsaicin and capsiate on energy balance: critical review and meta-analyses of studies in humans. Chemical Senses, 37(2), 103-121. No overall significant effect on energy expenditure (SMD 0.11, 95% CI -0.06 to 0.29); a rise appeared only at doses at or above 135 mg. Authors estimate a hedonically acceptable dose yields ~10 kcal/day. 10.1093/chemse/bjr100
Whiting, S., Derbyshire, E. J., & Tiwari, B. (2014). Could capsaicinoids help to support weight management? A systematic review and meta-analysis of energy intake data. Appetite, 73, 183-188. Capsaicinoids before a meal reduced ad libitum intake at that meal by 309.9 kJ (74.0 kcal); authors urge caution given high between-study variability. 10.1016/j.appet.2013.11.005
Graham, D. Y., Smith, J. L., & Opekun, A. R. (1988). Spicy food and the stomach: evaluation by videoendoscopy. JAMA, 260(23), 3473-3475. Twelve volunteers; a spicy Mexican meal with 30 g jalapeno caused virtually no gastric mucosal damage, whereas a bland meal plus 1950 mg aspirin produced multiple erosions. jamanetwork.com/journals/jama/fullarticle/375639
Rodriguez-Stanley, S., Collings, K. L., Robinson, M., Owen, W., & Miner, P. B. (2000). The effects of capsaicin on reflux, gastric emptying and dyspepsia. Alimentary Pharmacology & Therapeutics, 14(1), 129-134. In 11 heartburn sufferers, capsaicin left esophageal/gastric pH profiles unchanged but significantly shortened time to peak heartburn (120 vs 247 min), indicating sensitization of sensory neurons rather than increased acid. 10.1046/j.1365-2036.2000.00682.x
Lv, J., Qi, L., Yu, C., Yang, L., Guo, Y., Chen, Y., et al. (2015). Consumption of spicy foods and total and cause specific mortality: population based cohort study. BMJ, 351, h3942. China Kadoorie Biobank; 487,375 adults, median 7.2 years follow-up, 20,224 deaths. Versus under 1 day/week, adjusted HR for total mortality was 0.86 (95% CI 0.82-0.90) at 6-7 days/week. Baseline table shows frequent eaters were 82.1% vs 47.8% rural and smoked and drank more. Authors state causal inference is not possible. 10.1136/bmj.h3942
Ofori-Asenso, R., Mohsenpour, M. A., Nouri, M., Faghih, S., Liew, D., & Mazidi, M. (2021). Association of spicy chilli food consumption with cardiovascular and all-cause mortality: a meta-analysis of prospective cohort studies. Angiology, 72(7), 625-632. Four cohorts, 564,748 adults; regular chilli consumers had ~12% lower all-cause mortality (pooled 0.88, 95% CI 0.86-0.90). Observational - not causal. 10.1177/0003319721995666