JAMA：水果蔬菜并非多多益善
生物谷报道：“伊人天上来，复归天上去。”风华绝代“林妹妹”因乳腺癌憾别人间。乳腺癌是全球妇女的头号癌症杀手，每年导致50万人死亡。之前的研究结果显示，某些食物特别是含有抗氧化剂的食物能够显著降低乳腺癌的发病率。抗氧化剂能够预防DNA损伤造成的突变，因此有降低癌发率的功效。近年来，医师一直希望证实，增加含抗氧化剂丰富的水果和蔬菜的摄入量，能够降低妇女罹患乳腺癌的风险。
一项最新研究结果显示，日食五份以上的水果和蔬菜——美国食品与药品管理局（FDA）推荐的数量，没有额外的抗乳腺癌的作用。然而，摄入五份的水果和蔬菜似乎仍有抗乳腺癌作用。
乳腺癌是全球妇女的头号癌症杀手，每年导致50万人死亡。之前的研究结果显示，某些食物特别是含有抗氧化剂的食物能够显著降低乳腺癌的发病率。抗氧化剂能够预防DNA损伤造成的突变，因此有降低癌发率的功效。近年来，医师一直希望证实，增加含抗氧化剂丰富的水果和蔬菜的摄入量，能够降低妇女罹患乳腺癌的风险。
加州大学圣地牙哥分校John Pierce与其同事对3000名之前接受过早期乳腺癌（early-stage breast cancer）治疗的妇女的健康情况进行跟踪调查。其中半数的妇女收到传单，上面推荐FDA认可的日食五份水果和蔬菜的治疗方法，另半数妇女收到的传单上不仅包括上述建议的数量，还包括吃额外数量的水果、蔬菜以及吃膳食纤维和低脂食物。
7年后，研究人员将两组的复发率和新发生的乳腺癌的比例进行对比，所得结果相似。两种治疗策略的结果相似，说明附加食物没有带来附加效果。尽管过多的水果和蔬菜不会降低患病风险，Pierce强调他们小组之前的研究结果显示，吃至少是所推荐的数量再加上有规律的身体操练确实有效，“不需要过量。”详细内容刊登于本周Journal of the American Medical Association杂志。
这份报告并不是坚不可摧的，哈佛大学流行病学家JoAnn Manson认为研究人员还需要实际跟踪收到这些传单的人群：他们不一定“照方办事”。然而，哈佛大学影响学家和流行病学家Meir Stampfer虽然额外的食物对防癌无效，但也可以帮助妇女延年益寿，也许是降低了心血管病的发病率。
注：虽然此类研究技术含量不高，但的确关乎百姓幸福安康，国内有没有相似的研究呢，或者说相似研究在国内有无赞助单位呢？
原始出处:
Journal of the American Medical Association
Vol. 298 No. 3, July 18, 2007
Influence of a Diet Very High in Vegetables, Fruit, and Fiber and Low in Fat on Prognosis Following Treatment for Breast Cancer
The Women's Healthy Eating and Living (WHEL) Randomized Trial
John P. Pierce, PhD; Loki Natarajan, PhD; Bette J. Caan, DrPh; Barbara A. Parker, MD; E. Robert Greenberg, MD; Shirley W. Flatt, MS; Cheryl L. Rock, PhD, RD; Sheila Kealey, MPH; Wael K. Al-Delaimy, MD, PhD; Wayne A. Bardwell, PhD; Robert W. Carlson, MD; Jennifer A. Emond, MS; Susan Faerber, BA; Ellen B. Gold, PhD; Richard A. Hajek, PhD; Kathryn Hollenbach, PhD; Lovell A. Jones, PhD; Njeri Karanja, PhD; Lisa Madlensky, PhD; James Marshall, PhD; Vicky A. Newman, MS, RD; Cheryl Ritenbaugh, PhD, MPH; Cynthia A. Thomson, PhD; Linda Wasserman, MD, PhD; Marcia L. Stefanick, PhD
JAMA. 2007;298:289-298.
Context Evidence is lacking that a dietary pattern high in vegetables, fruit, and fiber and low in total fat can influence breast cancer recurrence or survival.
Objective To assess whether a major increase in vegetable, fruit, and fiber intake and a decrease in dietary fat intake reduces the risk of recurrent and new primary breast cancer and all-cause mortality among women with previously treated early stage breast cancer.
Design, Setting, and Participants Multi-institutional randomized controlled trial of dietary change in 3088 women previously treated for early stage breast cancer who were 18 to 70 years old at diagnosis. Women were enrolled between 1995 and 2000 and followed up through June 1, 2006.
Intervention The intervention group (n = 1537) was randomly assigned to receive a telephone counseling program supplemented with cooking classes and newsletters that promoted daily targets of 5 vegetable servings plus 16 oz of vegetable juice; 3 fruit servings; 30 g of fiber; and 15% to 20% of energy intake from fat. The comparison group (n = 1551) was provided with print materials describing the "5-A-Day" dietary guidelines.
Main Outcome Measures Invasive breast cancer event (recurrence or new primary) or death from any cause.
Results From comparable dietary patterns at baseline, a conservative imputation analysis showed that the intervention group achieved and maintained the following statistically significant differences vs the comparison group through 4 years: servings of vegetables, +65%; fruit, +25%; fiber, +30%, and energy intake from fat, –13%. Plasma carotenoid concentrations validated changes in fruit and vegetable intake. Throughout the study, women in both groups received similar clinical care. Over the mean 7.3-year follow-up, 256 women in the intervention group (16.7%) vs 262 in the comparison group (16.9%) experienced an invasive breast cancer event (adjusted hazard ratio, 0.96; 95% confidence interval, 0.80-1.14; P = .63), and 155 intervention group women (10.1%) vs 160 comparison group women (10.3%) died (adjusted hazard ratio, 0.91; 95% confidence interval, 0.72-1.15; P = .43). No significant interactions were observed between diet group and baseline demographics, characteristics of the original tumor, baseline dietary pattern, or breast cancer treatment.
Conclusion Among survivors of early stage breast cancer, adoption of a diet that was very high in vegetables, fruit, and fiber and low in fat did not reduce additional breast cancer events or mortality during a 7.3-year follow-up period.
Trial Registration clinicaltrials.gov Identifier: NCT00003787
Author Affiliations: Moores UCSD Cancer Center, University of California, San Diego, La Jolla (Drs Pierce, Natarajan, Parker, Rock, Al-Delaimy, Bardwell, Hollenbach, Madlensky, and Wasserman and Mss Flatt, Kealey, Faerber, and Newman); Kaiser Permanente Northern California, Division of Research, Oakland (Dr Caan); Fred Hutchinson Cancer Research Center, Seattle, Washington (Dr Greenberg); Stanford Comprehensive Cancer Center (Dr Carlson) and Stanford Prevention Research Center (Dr Stefanick), Stanford University, Stanford, California; Department of Family and Preventive Medicine, Division of Biostatistics, University of California, San Diego (Ms Emond); Department of Public Health Sciences, University of California, Davis (Dr Gold); M. D. Anderson Cancer Center, University of Texas, Houston (Drs Hajek and Jones); Center for Health Research, Portland, Oregon (Dr Karanja); Roswell Park Cancer Institute, Buffalo, NY (Dr Marshall); and Department of Family and Community Medicine (Dr Ritenbaugh) and Arizona Cancer Center, Department of Nutritional Sciences (Dr Thomson), University of Arizona, Tucson.
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