Martínez María Elena, Giovannucci Edward, Jiang Ruiyun, Henning Susanne M, Jacobs Elizabeth T, Thompson Patricia, Smith-Warner Stephanie A, Alberts David S
Arizona Cancer Center, University of Arizona, Tucson, AZ, USA.
Int J Cancer. 2006 Sep 15;119(6):1440-6. doi: 10.1002/ijc.21978.
In 1996, the US Food and Drug Administration mandated the fortification of grain products with folic acid, a nutrient that has been associated with lower risk of colorectal neoplasia. We assessed the relation of plasma folate and homocysteine and colorectal adenoma recurrence separately in 2 studies: the first involved an intervention of a cereal supplement that contained folic acid, wheat bran fiber (WBF), and the second was conducted primarily during postfortification of the food supply using ursodeoxycholic acid (UDCA). Analyses were stratified for multivitamin use. Results show that plasma folate and homocysteine concentrations were associated with adenoma recurrence among nonusers of multivitamins only. Among nonmultivitamin users, the odds ratio [OR] (95% confidence interval [CI]) for those in the highest versus the lowest folate quartile was 0.65 (0.40-1.06) for the WBF study and 0.56 (0.31-1.02) for the UDCA; likewise, individuals in the highest versus the lowest quartile of homocysteine had higher odds of adenoma recurrence, in both the WBF (OR = 2.25; 95% CI = 1.38-3.66) and UDCA (OR = 1.93; 95% CI = 1.07-3.49) populations. Analyses comparing multivitamin users to different plasma folate concentrations among nonusers show that odds of recurrence for supplement users was lower only when compared to nonusers who had lower concentrations. Our results show that higher plasma folate or lower homocysteine levels are associated with lower odds of recurrence among nonusers of multivitamins in both studies. Our finding, suggesting that multivitamins or supplemental folate only benefit individuals with lower plasma folate concentrations, should be taken into consideration when designing and interpreting results of intervention studies.
1996年，美国食品药品监督管理局规定谷物产品需强化添加叶酸，叶酸是一种与降低结直肠肿瘤发生风险相关的营养素。我们在两项研究中分别评估了血浆叶酸、同型半胱氨酸与结直肠腺瘤复发之间的关系：第一项研究涉及一种含有叶酸、麦麸纤维（WBF）的谷物补充剂干预；第二项研究主要在食品供应强化添加熊去氧胆酸（UDCA）后进行。分析按多种维生素使用情况进行分层。结果显示，仅在不使用多种维生素的人群中，血浆叶酸和同型半胱氨酸浓度与腺瘤复发相关。在不使用多种维生素的人群中，WBF研究中叶酸水平处于最高四分位数与最低四分位数者相比，比值比[OR]（95%置信区间[CI]）为0.65（0.40 - 1.06），UDCA研究中为0.56（0.31 - 1.02）；同样，同型半胱氨酸水平处于最高四分位数与最低四分位数者相比，在WBF（OR = 2.25；95% CI = 1.38 - 3.66）和UDCA（OR = 1.93；95% CI = 1.07 - 3.49）人群中腺瘤复发几率更高。将使用多种维生素者与不使用者中不同血浆叶酸浓度进行比较的分析表明，仅在与血浆叶酸浓度较低的不使用者相比时，补充剂使用者的复发几率较低。我们的结果表明，在两项研究中，较高的血浆叶酸水平或较低的同型半胱氨酸水平与不使用多种维生素者较低的复发几率相关。我们的发现表明多种维生素或补充叶酸仅对血浆叶酸浓度较低的个体有益，在设计和解释干预研究结果时应予以考虑。
