机体摄取适当的营养素对肿瘤的预防是有帮助的，但我们还不能完全明确不同群体摄取某些个别营养物质对肿瘤预防的确切作用。近来，Arch Intern Med杂志发表的一项研究表明：罹患心血管疾病的人服用B族维生素和Ω3不饱和脂肪酸并不能达到预防肿瘤的目的。
研究人员共招募了2,501名受试者包括514名女性和1,987名男性，男性受试者占受试者总数的79.4%，这些受试者年龄均在45至80岁之间。受试者在参与研究之前的12个月内都曾有缺血性中风、不稳定心绞痛或者急性心肌梗塞等疾病，工作人员参试者随机分组，并从2003年2月开始就随访研究，直至2009年7月结束。
结果发现2.3%的受试者因罹患肿瘤而死亡，7%的受试者包括145名男性和29名女性体内出现的原发性肿瘤，男性受试者罹患肿瘤率为83.3%，罹患肿瘤的死亡率为81%。这些数据证实受试者补充B族维生素、Ω3不饱和脂肪酸与是否罹患肿瘤之间并没有直接的联系。
不仅B族维生素和Ω3不饱和脂肪酸对肿瘤的预防没有明显效果，研究还发现这两种营养物质甚至能增加女性罹患肿瘤的风险。研究人员表示由于参试人数较少，这些数据只是通过初步试验分析得到的，结果的可靠性还有待于进一步证实。（生物谷Bioon.com）
doi:10.1001/archinternmed.2011.1450
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B Vitamin and/or -3 Fatty Acid Supplementation and Cancer
Valentina A. Andreeva, PhD; Mathilde Touvier, PhD; Emmanuelle Kesse-Guyot, PhD; Chantal Julia, MD; Pilar Galan, MD; Serge Hercberg, MD
Background To advance knowledge about the cancer-chemopreventive potential of individual nutrients, we investigated the effects of B vitamin and/or -3 fatty acid supplements on cancer outcomes among survivors of cardiovascular disease.
Methods This was an ancillary study of the Supplementation With Folate, Vitamins B6 and B12 and/or Omega-3 Fatty Acids (SU.FOL.OM3) secondary prevention trial (2003-2009). In all, 2501 individuals aged 45 to 80 years were randomized in a 2 x 2 factorial design to one of the following 4 daily supplementation groups: (1) 5-methyltetrahydrofolate (0.56 mg), pyridoxine hydrochloride (vitamin B6; 3 mg) and cyanocobalamin (vitamin B12; 0.02 mg); (2) eicosapentaenoic and docosahexaenoic acid (600 mg) in a 2:1 ratio; (3) B vitamins and -3 fatty acids; or (4) placebo. Overall and sex-specific hazard ratios (HRs) and 95% CIs regarding the cancer outcomes were estimated with Cox proportional hazards models.
Results After 5 years of supplementation, incident cancer was validated in 7.0% of the sample (145 events in men and 29 in women), and death from cancer occurred in 2.3% of the sample. There was no association between cancer outcomes and supplementation with B vitamins (HR, 1.15 [95% CI, 0.85-1.55]) and/or -3 fatty acids (HR, 1.17 [95% CI, 0.87-1.58]). There was a statistically significant interaction of treatment by sex, with no effect of treatment on cancer risk among men and increased cancer risk among women for -3 fatty acid supplementation (HR, 3.02 [95% CI, 1.33-6.89]).
Conclusion We found no beneficial effects of supplementation with relatively low doses of B vitamins and/or -3 fatty acids on cancer outcomes in individuals with prior cardiovascular disease.
