牛奶中关键营养成分能降低癌症风险
根据发表在最新的《美国临床营养学杂志》（American Journal of Clinical Nutrition）上的文章结果显示，牛奶中的关键营养物，包括维生素D以及钙除了保持骨骼强壮外，还可以降低妇女患上癌症的风险达到60%。
此项为期4年的临床研究分析了超过1000名年龄超过55岁的女性，她们被分成3组，1）每天摄入1400-1500毫克钙和1100 IU维生素D，2）只摄入1400-1500毫克钙，3）摄入安慰剂。结果发现，第一组患上癌症的风险降低了60%，第二组降低了47%。
50名妇女在4年研究中患上了癌症，包括乳腺癌、肠癌、肺癌等。研究人员排除了13位在第一年就被诊断出癌症的妇女后，钙和维生素D的保护作用变得更加明显，同时服用钙和维生素D的妇女患上癌症的风险降低了77%。
大约有1050万美国人患有癌症，科学家一直在寻找防止或延缓癌症发生的方法。文章主要作者Joan Lappe表示：“这是首次证明增加维生素D摄入能降低整个癌症风险，这对公众健康有着重要意义。多食用富含维生素D的食物，例如牛奶，就可以降低患上癌症的几率。”
牛奶是美国人食物中主要的钙及维生素D来源。事实上，根据美国政府的报告显示，国民中超过70%的钙来自食物中的牛奶和奶制品。最近的数个相关研究也证实了这一结果，它们表明钙和维生素D可以降低更年期妇女乳腺癌和老年妇女肠癌的风险。这表明每日3份低脂牛奶或脱脂牛奶是有益的，这能每天大约提供900毫克钙以及300 IU维生素D。
原文：
Boosting key milk nutrients may protect against cancer
Key milk nutrients, calcium and vitamin D, may do more than just help keep your bones strong. Increasing intake of calcium and vitamin D could reduce the risk for cancer in women by at least 60 percent, according to a new study published in the American Journal of Clinical Nutrition.
The four-year clinical trial included more than one thousand women over the age of 55 in one of three supplement groups: 1) calcium (1400-1500mg) plus vitamin D (1100 IU vitamin D) 2) calcium only (1400-1500 mg) or 3) a placebo. The researchers found that the risk of developing cancer was 60 percent lower for those who took calcium and vitamin D and 47 percent lower for those taking calcium alone, compared to the placebo.
Fifty women developed nonskin cancer through the course of the four-year study, including breast, colon, lung and other cancers. When researchers excluded the 13 cancers diagnosed during first year of the study, determining these cancers were likely present at the study onset, the protective effect of calcium and vitamin D was even greater, with a 77 percent lower risk for cancer for those taking calcium plus vitamin D compared to the placebo.
With an estimated 10.5 million Americans living with cancer, researchers on a quest for new means to prevent or delay the occurrence of this deadly disease are encouraged by these findings.
“This is the first clinical trial to show that boosting vitamin D status can affect the overall risk for cancer – a proposition that has tremendous public health potential,” said lead author Dr Joan Lappe, a nutrition researcher from Creighton University in Omaha. “By choosing vitamin-D rich foods like milk and taking a supplement Americans can help improve their vitamin D levels and potentially impact their cancer risk.”
Milk is the primary source of calcium and an excellent source of vitamin D in the American diet. In fact, government reports indicate that more than 70 percent of the calcium in our nation’s food supply comes from milk and milk products. Additionally, milk is one of the few food sources of vitamin D, which is fast emerging as a “super nutrient.”
Several recent studies have reported similar conclusions, suggesting that calcium and vitamin D may reduce the risk for breast cancer in premenopausal women and colon cancer in older women. Together, these findings give Americans even more reason to meet the recommended three servings of lowfat or fat-free milk each day, providing 900 mg of calcium and 300 IU of vitamin D daily.
