培根、香肠、热狗等加工类肉食是不少人餐桌上的常客。美国哈佛大学最新研究显示，经常食用加工类肉食可能增加患心脏病和糖尿病风险，有害人体健康。
这一研究结果由美国《循环》（Circulation）月刊发表。
研究
哈佛大学公共卫生学院研究人员研究近1600项世界各地相关成果，探求食用红肉与患心脏病和糖尿病的关联。
他们把红肉分为加工类红肉和未加工类红肉。其中，经过烟熏、腌制或添加盐、化学防腐剂等物质的红肉均属于加工类，包括培根、香肠、腊肉、热狗、各类熟食和午餐肉等。未加工红肉包括牛肉、羊肉、猪肉，不包括禽肉。
研究发现，平均每天食用50克加工类肉食的人患心脏病风险增加42%，患糖尿病风险增加19%。每星期至多吃一次的人患心脏病和糖尿病等疾病风险较小。
与此同时，只吃未加工红肉的人患以上两种疾病的风险没有增加。
真凶
研究人员说，虽然吃肉与患心脏病、糖尿病之间存在关联，但食用未加工的牛肉、猪肉和羊肉没有增加患病风险。他们由此推断，盐和化学防腐剂可能是导致以上两种疾病的真正原因。
“通过对比加工类肉食和未加工类肉食的平均营养物质含量，我们发现，两种肉食中饱和脂肪与胆固醇平均含量相差无几，”路透社5月17日引述研究带头人雷娜塔米夏的话报道，“但加工类肉食中钠的含量比未加工类肉食多4倍，防腐剂多50%。”
米夏说：“想降低患心脏病和糖尿病风险的人应该关注自己正在食用哪种肉类……最重要的是避免食用培根、香肠、腊肉、热狗以及各类熟食等加工类肉食。”
质疑
米夏说，眼下针对加工类与未加工类肉食致病风险差异的研究并不多见。
不过，美国肉业协会对这一研究结果提出质疑。
协会认为，米夏小组是唯一持这一观点的研究小组，其结论与其他研究以及“美国居民膳食指南”意见相悖。
“这一假设仍需要进一步证实，人们当然没有必要为此改变饮食习惯，”美国肉业协会主席詹姆斯霍奇斯说。
路透社说，关注吃肉与患心血管疾病、糖尿病关系的研究不少，研究结果众说纷纭，不过，多数膳食指南建议人们少吃肉。
更多阅读
《循环》发表论文摘要（英文）
路透社相关报道（英文）
Circulation. 2010
Published online before print May 17, 2010, doi: 10.1161/CIRCULATIONAHA.109.924977
Submitted on November 25, 2009
Accepted on April 8, 2010
Red and Processed Meat Consumption and Risk of Incident Coronary Heart Disease, Stroke, and Diabetes Mellitus. A Systematic Review and Meta-Analysis
Renata Micha RD, PhD*, Sarah K. Wallace BA, and Dariush Mozaffarian MD, DrPH
Background―Meat consumption is inconsistently associated with development of coronary heart disease (CHD), stroke, and diabetes mellitus, limiting quantitative recommendations for consumption levels. Effects of meat intake on these different outcomes, as well as of red versus processed meat, may also vary.
Methods and Results―We performed a systematic review and meta-analysis of evidence for relationships of red (unprocessed), processed, and total meat consumption with incident CHD, stroke, and diabetes mellitus. We searched for any cohort study, case-control study, or randomized trial that assessed these exposures and outcomes in generally healthy adults. Of 1598 identified abstracts, 20 studies met inclusion criteria, including 17 prospective cohorts and 3 case-control studies. All data were abstracted independently in duplicate. Random-effects generalized least squares models for trend estimation were used to derive pooled dose-response estimates. The 20 studies included 1 218 380 individuals and 23 889 CHD, 2280 stroke, and 10 797 diabetes mellitus cases. Red meat intake was not associated with CHD (n=4 studies; relative risk per 100-g serving per day=1.00; 95% confidence interval, 0.81 to 1.23; P for heterogeneity=0.36) or diabetes mellitus (n=5; relative risk=1.16; 95% confidence interval, 0.92 to 1.46; P=0.25). Conversely, processed meat intake was associated with 42% higher risk of CHD (n=5; relative risk per 50-g serving per day=1.42; 95% confidence interval, 1.07 to 1.89; P=0.04) and 19% higher risk of diabetes mellitus (n=7; relative risk=1.19; 95% confidence interval, 1.11 to 1.27; P&0.001). Associations were intermediate for total meat intake. Consumption of red and processed meat were not associated with stroke, but only 3 studies evaluated these relationships.
Conclusions―Consumption of processed meats, but not red meats, is associated with higher incidence of CHD and diabetes mellitus. These results highlight the need for better understanding of potential mechanisms of effects and for particular focus on processed meats for dietary and policy recommendations.
Key words: cardiovascular diseases " diabetes mellitus " diet " meat " meta-analysis
