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常用的食物添加剂可增加患肺癌以及使肺癌发生扩散的风险
美国科学日报(ScienceDaily), 2008年12月30日, ---动物模型的新研究表明, 含无机磷酸盐高的食物可能会加快肺癌肿瘤的增长, 并且可能促进有患肺癌倾向人群的发病。在许多加工食品中含有高无机磷酸盐,例如肉类、奶酪、饮料和烤制食品。
该研究同时表明,调节饮食中的无机磷酸盐可能在肺癌的治疗中起重要作用。该研究是由汉城国立大学的Myung-Haing Cho博士及其同事在小鼠模型上进行的,结果最先发表在美国胸科学会出版的"美国呼吸和紧急护理医学学报"1月期刊上。
Cho博士说,“我们的研究表明,增加无机磷酸盐的摄取量后,会强烈刺激肺癌在小鼠身上的生长;同时表明,调节饮食中的无机磷酸盐含量,可能对肺癌的治疗以及预防起着非常重要的作用”。
肺癌是全球癌症致死的首要原因,而且还是诊断中最常见的一种实性肿瘤。非小细胞肺癌(NSCLC)占各种肺癌的75%以上,其中14%的非小细胞肺癌患者总的平均生存率为35年。较早的研究表明,大约90%的非小细胞肺癌与肺组织中的某种信号通道的激化有关。该研究表明,高浓度的无机磷酸盐可能刺激上述通道。
“肺癌是一种肺组织中的细胞增殖失控的疾病,肺组织中信号通道的断裂可以使正常的细胞发生恶变”,Cho博士说。 仅少量的通道反常现象就可能使正常的细胞发生恶变,这些通道是根据养分吸收率来调节的,因此,导致细胞增殖和增长。
“磷酸盐是生物机体的一种必需的营养素,可以激活某些信号。该研究表明,摄取高浓度的无机磷酸盐后,可能由于改变了这些(信号)通道而大大刺激了肺癌的生长”。
该研究对肺癌模型小鼠进行了四周的研究,随机分配给它们含0.5%或1.0%磷酸盐的饮食,这一含量大致相当于现代人饮食中的含量。四周后,对其肺组织进行了分析,以测定无机磷酸盐对肿瘤的影响。
“我们的研究结果清楚地表明,无机磷酸盐含量较高的饮食引起肿瘤增大,并且刺激了肿瘤的增长”,Cho博士说。
Cho博士指出, 虽然中等含量的磷酸盐在生物机体中起着重要的作用,但食品添加剂会使磷酸盐的含量迅速增加,大大超过日常饮食中的平均含量。许多食品中通过加入磷酸盐来保持水分以及改善食品的结构。
“在九十年代,含磷的食品添加剂估计在一般成人日常膳食中每天占470毫克。但现在许多加工食品中更频繁地加入磷酸盐,其中包括肉类、奶酪、饮料和焙烤食品。因此,根据个人的食物选择,磷的摄取量可能每天增加了1000毫克”。
“虽然规定0.5%接近于正常值,但如今的一般饮食中,实际上接近于1%,甚至实际上可能超过了1%。因此,按照今天的标准,0.5%的摄取量实际上属于低磷酸盐饮食。”
Cho博士说未来将研究饮食中无机磷酸盐的“安全”含量,并且推荐一般人可以容易做到的方法。
他说,“这一研究结果说明对饮食中无机磷酸盐含量的调节有助于肺癌的治疗,我们的最终目标是收集充分的信息来精确评估磷酸盐的危险性”。
美国胸科学会的前会长John Heffner博士说,这方面的动物研究涉及宿主的许多因素和环境之间复杂的相互作用,这种相互作用影响着人类中癌症的发生。 “我们知道,肺癌病人中只有一部分是吸烟的,但其它的原因还不清楚。而现在,这一研究为对人类病例进行对照研究提供了一种理论,以确定饮食中的磷酸盐对促发癌症的作用”。
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Common Food Additive Found To Increase Risk And Speed Spread Of Lung Cancer
http://www.sciencedaily.com/releases/2008/12/081229080851.htm
ScienceDaily (Dec. 30, 2008) — New research in an animal model suggests that a diet high in inorganic phosphates, which are found in a variety of processed foods including meats, cheeses, beverages, and bakery products, might speed growth of lung cancer tumors and may even contribute to the development of those tumors in individuals predisposed to the disease.
The study also suggests that dietary regulation of inorganic phosphates may play an important role in lung cancer treatment. The research, using a mouse model, was conducted by Myung-Haing Cho, D.V.M., Ph.D., and his colleagues at Seoul National University, appears in the first issue for January of the American Journal of Respiratory and Critical Care Medicine, published by the American Thoracic Society.
"Our study indicates that increased intake of inorganic phosphates strongly stimulates lung cancer development in mice, and suggests that dietary regulation of inorganic phosphates may be critical for lung cancer treatment as well as prevention," said Dr. Cho.
Lung cancer is the number one cause of cancer deaths in the world and is also the most frequently diagnosed solid tumor. Non–small cell lung cancer (NSCLC) constitutes over 75 percent of lung cancers and has an average overall 35-year survival rate of 14 percent. Earlier studies have indicated that approximately 90 percent of NSCLC cases were associated with activation of certain signaling pathways in lung tissue. This study revealed that high levels of inorganic phosphates can stimulate those same pathways.
"Lung cancer is a disease of uncontrolled cell proliferation in lung tissue, and disruption of signaling pathways in those tissues can confer a normal cell with malignant properties," Dr. Cho explained. "Deregulation of only a small set of pathways can confer a normal cell with malignant properties, and these pathways are regulated in response to nutrient availability and, consequently, cell proliferation and growth.
"Phosphate is an essential nutrient to living organisms, and can activate some signals," he added. "This study demonstrates that high intake of inorganic phosphates may strongly stimulate lung cancer development by altering those (signaling) pathways."
In the study, lung cancer-model mice were studied for four weeks and were randomly assigned to receive a diet of either 0.5 or 1.0 percent phosphate, a range roughly equivalent to modern human diets. At the end of the four-week period, the lung tissue was analyzed to determine the effects of the inorganic phosphates on tumors.
"Our results clearly demonstrated that the diet higher in inorganic phosphates caused an increase in the size of the tumors and stimulated growth of the tumors," Dr. Cho said.
Dr. Cho noted that while a moderate level of phosphate plays an essential role in living organisms, the rapidly increasing use of phosphates as a food additive has resulted in significantly higher levels in average daily diets. Phosphates are added to many food products to increase water retention and improve food texture.
"In the 1990s, phosphorous-containing food additives contributed an estimated 470 mg per day to the average daily adult diet," he said. "However, phosphates are currently being added much more frequently to a large number of processed foods, including meats, cheeses, beverages, and bakery products. As a result, depending on individual food choices, phosphorous intake could be increased by as much as 1000 mg per day."
"Although the 0.5 percent was defined as close to 'normal,' the average diet today is actually closer to the one percent diet and may actually exceed it," Dr. Cho noted. "Therefore, the 0.5 percent intake level is actually a reduced phosphate diet by today's scale."
Dr. Cho said future studies will help refine what constitutes a "safe" level of dietary inorganic phosphate, with recommendations that will be easily achievable in the average population.
"The results of this study suggest that dietary regulation of inorganic phosphates has a place in lung cancer treatment, and our eventual goal is to collect sufficient information to accurately assess the risk of these phosphates," he said.
John Heffner, M.D., past president of the ATS, stated that this line of investigation in animals addresses the complex interactions between host factors and the environment that underlie cancer in man. "We know that only some patients who smoke develop lung cancer but the reasons for this varying risk are unknown. This study now provides a rationale for funding case-control studies in humans to determine the potential role of dietary phosphates in promoting cancer."
[ 本帖最后由 大壮 于 2009-6-21 21:14 编辑 ] |
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