关于硒元素（Selenium，Se）的生物学效应，研究得最多的恐怕是其抗癌作用，但学术界对此历来就存有争议^[1-15]。

     尽管如此，人们还是相信摄硒能够降低癌症风险。许多食物中都富含硒，如巴西坚果（brazil nuts，如下图）。然而，最近的一项随机控制临床试验（RCCT，randomized controlled clinical trials）研究表明，硒对非黑素类的皮肤癌、前列腺癌都无防范作用。研究结果发表在Cochrane Database Syst. Rev（2011年，第5期，DOI: 10.1002/14651858.CD005195）上。主持这项研究的是来自德国柏林THR学院（Institute for Transdisciplinary Health Research）的Gabriele Dennert 教授。

     该研究组搜索了摄硒效应的临床研究文献，发现了49项预期的观察研究（observational studies）和6项随机控制临床试验。其中，观察研究表明，高硒摄入可以防范癌症，但RCCT研究却表明无此明显作用。另外还有迹象表明，如果摄硒时程过长，会造成有害效应。  

1. Russo MW, Murray SC, Wurzelmann JI, Woosley JT, Sandler RS (1997). "Plasma selenium levels and the risk of colorectal adenomas". Nutrition and Cancer 28 (2): 125–9. doi:10.1080/01635589709514563. PMID 9290116.
2. Knekt P, Marniemi J, Teppo L, Heliövaara M, Aromaa A (15 November 1998). "Is low selenium status a risk factor for lung cancer?". American Journal of Epidemiology 148 (10): 975–82. PMID 9829869. http://aje.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=9829869. 
3. Young KJ, Lee PN (1999). "Intervention studies on cancer". European Journal of Cancer Prevention 8 (2): 91–103. doi:10.1097/00008469-199904000-00003. PMID 10335455. 
4. Burguera JL, Burguera M, Gallignani M, Alarcón OM, Burguera JA (1990). "Blood serum selenium in the province of Mérida, Venezuela, related to sex, cancer incidence and soil selenium content" (Free full text). Journal of Trace Elements and Electrolytes in Health and Disease 4 (2): 73–7. PMID 2136228. 
5. Clark LC, Combs GF, Turnbull BW, et al. (1996). "Effects of selenium supplementation for cancer prevention in patients with carcinoma of the skin. A randomized controlled trial. Nutritional Prevention of Cancer Study Group". JAMA 276 (24): 1957–63. doi:10.1001/jama.276.24.1957. PMID 8971064. 
6. Lippman SM, Klein EA, Goodman PJ, et al. (2009). "Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the Selenium and Vitamin E Cancer Prevention Trial (SELECT)" (Free full text). JAMA 301 (1): 39–51. doi:10.1001/jama.2008.864. PMID 19066370. 
7. "Chemoprevention Database". http://www.inra.fr/reseau-nacre/sci-memb/corpet/indexan.html. Retrieved 2009-05-05. 
8. Garland M, Morris JS, Stampfer MJ, et al. (1995). "Prospective study of toenail selenium levels and cancer among women". Journal of the National Cancer Institute 87 (7): 497–505. doi:10.1093/jnci/87.7.497. PMID 7707436. 
9. Hercberg S, Galan P, Preziosi P, et al. (1998). "Background and rationale behind the SU.VI.MAX Study, a prevention trial using nutritional doses of a combination of antioxidant vitamins and minerals to reduce cardiovascular diseases and cancers. Supplementation en Vitamines et Minéraux Antioxydants Study" (Free full text). International Journal for Vitamin and Nutrition Research 68 (1): 3–20. PMID 9503043. http://www.nlm.nih.gov/medlineplus/antioxidants.html. 
10. Hercberg S, Galan P, Preziosi P, et al. (2004). "The SU.VI.MAX Study: a randomized, placebo-controlled trial of the health effects of antioxidant vitamins and minerals" (Free full text). Archives of Internal Medicine 164 (21): 2335–42. doi:10.1001/archinte.164.21.2335. PMID 15557412. 
11. "Selenium and Chemotherapy - Nutrition Health". http://nutrition-health.info/index.php/Selenium_and_Chemotherapeutic_Drugs. 
12. "Selenium Cancer". http://nutrition-health.info/index.php/Selenium_Cancer_1. 
13. Nilsonne G, Sun X, Nyström C, et al. (2006). "Selenite induces apoptosis in sarcomatoid malignant mesothelioma cells through oxidative stress". Free Radical Biology & Medicine 41 (6): 874–85. doi:10.1016/j.freeradbiomed.2006.04.031. PMID 16934670. 
14. Tsavachidou D, McDonnell TJ, Wen S, et al. (2009). "Selenium and vitamin E: cell type- and intervention-specific tissue effects in prostate cancer". Journal of the National Cancer Institute 101 (5): 306–20. doi:10.1093/jnci/djn512. PMC 2734116. PMID 19244175. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2734116. 
15. Klein EA (2009). "Selenium and vitamin E: interesting biology and dashed hope". Journal of the National Cancer Institute 101 (5): 283–5. doi:10.1093/jnci/djp009. PMID 19244172.