番茄可降低乳腺癌风险

在12月18日的Journal of Clinical Endocrinology & Metabolism杂志上发表的一项研究表明，采用富含番茄的饮食，可以提高具有乳腺癌风险的绝经后妇女的血清脂联素浓度，尤其是身体质量指数较低的妇女，可保护其免受乳腺癌的危害。

　　

生物通报道：根据12月18日在Journal of Clinical Endocrinology & Metabolism杂志上发表的一项研究表明，采用番茄丰富的饮食，可保护绝经后妇女免受乳腺癌的危害。

在绝经后妇女中，乳腺癌的风险增加，因为她们的身体质量指数上升。但是仍然缺乏实用的预防方法来降低乳腺癌风险。关于类胡萝卜素和大豆异黄酮对绝经后妇女循环脂肪因子影响的调查研究还很少。本项研究发现，富含番茄的饮食，对在脂肪和糖代谢调节中发挥作用的激素水平，具有积极的影响。

本研究的第一作者、美国罗格斯大学流行病学助理教授Adana Llanos博士说：“我们的研究结果表明，大量食用番茄和以番茄为原料的食品，即使在很短的时间内，也具有非常明显的优势。”当Llanos还是俄亥俄州立大学综合癌症中心Electra Paskett教授的博士后时，完成了这项研究工作。她说：“水果和番茄富含必需的营养素、维生素、矿物质和植物化学物（例如番茄红素），食用它们，具有显著的益处。基于这项数据，我们认为，定期食用至少每日推荐分量的水果和蔬菜，能够促进高危人群的乳腺癌预防。”

这项纵向交叉研究，在一组70岁绝经后妇女中，分别检测了富含番茄和大豆的饮食对她们的影响。连续10周，这些妇女每天食用番茄红素含量至少为25毫克的番茄产品。在另外一个单独的10周周期中，受试者每天至少食用40克的大豆蛋白。在每个测试周期开始之前，她们分别都被要求在两周时间内放弃吃番茄和大豆制品。

当受试者遵循富含番茄的饮食时，她们的脂联素——参与糖和脂肪水平调节的一种激素——水平上升了9%。具有较低身体质量指数的女性，这种效果略强。

Llanos说：“这项研究证明了预防肥胖的重要性。采用富含番茄的饮食，对体重保持健康的女性的激素水平，具有较大的影响。”

大豆饮食与受试者脂联素水平的下降有关。研究人员最初推理，包含大量大豆的饮食，可能是亚洲女性具有比美国女性更低的乳腺癌发病率的部分原因，但是Llanos说，任何有利的影响，都局限于特定的种族。（生物通：王英）

生物通推荐原文摘要：
Effects of Tomato and Soy on Serum Adipokine Concentrations in Postmenopausal Women at Increased Breast Cancer Risk: A Cross-Over Dietary Intervention Trial
Abstract
Context: Breast cancer risk among postmenopausal women increases as body mass index increases. Practical preventive methods to reduce risk of breast cancer are lacking. Few studies have investigated the effects of carotenoids and isoflavones on circulating adipokines in postmenopausal women.

Objective: The aim was to examine the effects of lycopene- and isoflavone-rich diets on serum adipokines.

Design: This was a 26-week, two-arm, longitudinal crossover trial.

Setting: Participants were recruited from clinics at The Ohio State University Comprehensive Cancer Center.

Participants: Seventy postmenopausal women at increased breast cancer risk participated in the study. The mean age and body mass index of participants was 57.2 years and 30.0 kg/m2, respectively; the study was comprised of 81.4% whites.

Interventions: The interventions included 10 weeks of consumption of a tomato-based diet (≥25 mg lycopene daily) and 10 weeks of consumption of a soy-based diet (≥40 g of soy protein daily), with a 2-week washout in between.

Main Outcome Measures: Changes in serum adiponectin, leptin, and the adiponectin to leptin ratio were examined for each intervention through linear mixed models, with ratio estimates corresponding to postintervention adipokine concentrations relative to preintervention concentrations.

Results: After the tomato intervention, among all women, adiponectin concentration increased (ratio 1.09, 95% confidence interval (CI) 1.00–1.18), with a stronger effect observed among nonobese women (ratio 1.13, 95% CI 1.02–1.25). After the soy intervention, adiponectin decreased overall (ratio 0.91, 95% CI 0.84–0.97), with a larger reduction observed among nonobese women (ratio 0.89, 95% CI 0.81–0.98). Overall, no significant changes in leptin or the adiponectin to leptin ratio were observed after either intervention.

Conclusions: Increasing dietary consumption of tomato-based foods may beneficially increase serum adiponectin concentrations among postmenopausal women at increased breast cancer risk, especially those who are not obese. Additional studies are essential to confirm these effects and to elucidate the specific mechanisms that may make phytonutrients found in tomatoes practical as breast cancer chemopreventive agents.