摄取腌渍肉类与气喘症状恶化有关


  【24drs.com】根据在线发表于12月20日Thorax期刊的一篇纵向研究,随著摄取的腌渍肉类量越多,成年人的气喘症状会越恶化,而身体质量指数也会微幅上升。
  
  腌渍肉类已被确认为癌症、所有原因死亡率、慢性阻塞性肺部疾病等诸多慢性疾病的风险因素之一。
  
  法国Villejuif Paul Brousse医院的Zhen Li医师等人写道,腌渍肉类的亚硝酸盐含量高这点广为人知,会导致亚硝化压力相关的呼吸道发炎-与气喘有关的多种生理过程之一-可以合理地假设,摄取腌渍肉类是气喘的独立危险因素之一。
  
  他们指出,由于肥胖是气喘发病和恶化的可能危险因素之一,且饮食会影响身体质量指数(BMI),BMI在饮食和气喘之间存在因果关系是有可能的。
  
  因此,研究者分析了在2003-2007年间参与「Epidemiological Study on the Genetics and Environment of Asthma (EGEA)」这项前瞻研究的971名、其中42%有气喘之研究对象的资料,纳入的研究对象都是成年人(平均年龄43岁),完成饮食频率问卷且有气喘症状相关资料。在饮食问卷的118个项目中,火腿(2片/份)、香肠(1条香肠/份)和乾香肠(2片/份)被分类为腌渍肉类。
  
  将近半数研究对象(48%)摄取量为中度,亦即每周1-3.9份,每周摄取不到1份的有19%,每周至少4份的有33%;过重的比率略超过三分之一(35%)、肥胖的有9%;51%从未抽菸。
  
  在2011-2013年这段追踪期间,进行研究后平均7年时,20%的研究对象报告指出气喘症状恶化,其定义为:根据「气喘时呼吸困难、因胸闷而醒来、休息时呼吸短促、运动后呼吸短促、因呼吸短促而醒来」等5种症状,0-5分量表大于0分;大部份(53%)的症状没有改变、27%的症状有改善。
  
  在每周摄取至少4份腌渍肉类者中,22%表示气喘症状恶化,而每周摄取不到1份者、每周摄取1-3.9份者的此一比率分别是14%、20%。
  
  研究者使用边缘结构模型(一种用于推断流行病学中之因果关系的统计模型)估计摄取腌渍肉类对研究对象之气喘症状的直接影响;他们考虑了其它潜在的饮食混杂因素,使用两种「多因素饮食模式」:其一,摄取多量水果、蔬菜、全谷物、油和鱼;其二,摄取多量即食饮食、腌渍肉类、调味食品、酒、三明治、炸薯条和其它马铃薯制品。
  
  作者们也校正了年龄、性别、抽菸史、教育程度、运动等因素,特别是性别与抽菸史这两项因素,因为曾被认为与摄取腌渍肉类有关。在这篇研究中,摄取较多腌渍肉类者比较可能是男性、比较年轻、有抽菸、摄取较多热量、BMI较高、摄取较多钠与饱和脂肪、有气喘。
  
  校正这些因素之后,每周摄取至少4份腌渍肉类者之气喘恶化机率,比每周摄取不到1份者增加76% (多变项胜算比[OR]为1.76; 95%信赖区间[CI]为1.01 - 3.06)。当研究者考虑BMI对气喘症状的间接影响时,他们确认,BMI占腌渍肉类对气喘症状之总影响的14% (OR, 1.07; 95% CI, 1.01 - 1.14),不过,在与气喘的关联方面,在摄取腌渍肉类和BMI之间并未观察到相互影响(P = .90)。
  
  BMI对摄取多量腌渍肉类的间接影响,仅占与恶化气喘症状之关联的14%,作者们结论指出,所以,直接影响占更大的比率,表示腌渍肉类本身有独立于BMI的有害作用。不过,他们指出,两篇前瞻美国研究聚焦在不同的腌渍肉类—主要是培根、热狗和香肠 —校正BMI和其它混杂因素之后,没有发现对气喘发病率有任何影响。
  
  他们写道,这些不同的发现可能是因为BMI在这项关联之角色(混杂因素或者是调节因素),或者是呼吸表型的评估(气喘症状的发生率或变化),他们也指出,有15%的研究对象失去追踪。
  
  除了腌渍肉类所含的高硝酸盐值有产生亚硝化和氧化压力的可能性,研究者提出腌渍肉类会使气喘恶化的另外两种机转,其一,以前即已确认,摄取腌渍肉类和C反应蛋白质之间的关联,使全身性发炎增加;其二,仅有儿童气喘的少数证据支持,高盐与饱和脂肪摄取可能会影响气喘症状。
  
  资料来源:http://www.24drs.com/
  
  Native link:Cured Meat Intake Linked to Worsening Asthma Symptoms

Cured Meat Intake Linked to Worsening Asthma Symptoms

By Tara Haelle
Medscape Medical News

Asthma symptoms in adults worsened over time with greater consumption of cured meats, only slightly mediated by increases in body mass index, according to a longitudinal study published online December 20 in Thorax.

Cured meats have already been identified as a risk factor for cancer, all-cause mortality, and several chronic diseases, including chronic obstructive pulmonary disease.

"As cured meat is known for its high-nitrite content which may lead to nitrosative stress related airway inflammation — one of the several physiological processes involved in asthma [—] it is reasonable to posit that cured meat intake is an independent risk factor for asthma," write Zhen Li, MD, from the Paul Brousse Hospital in Villejuif, France, and colleagues.

"Since obesity is a likely risk factor for incidence and exacerbations of asthma," and diet affects body mass index (BMI), they note, "it is plausible that BMI lies in the causal pathway between diet and asthma."

The researchers therefore analyzed data from 971 participants, including 42% with asthma, who enrolled in the prospective Epidemiological Study on the Genetics and Environment of Asthma (EGEA) between 2003 and 2007. The researchers included only the adults (average age, 43 years) who completed the food frequency questionnaire and had data on asthma symptoms. Among the 118 items on the food questionnaire, ham (two slices/portion), sausage (one sausage/portion), and dried sausage (two slices/portion) were categorized as cured meats.

Nearly half the participants (48%) had a medium intake, at 1 to 3.9 servings per week, whereas 19% had less than one serving per week and 33% had at least four servings a week. Just more than a third (35%) were overweight and 9% were obese; 51% had never smoked.

During follow-up, conducted from 2011 to 2013, an average 7 years later, 20% of the participants reported having worsening asthma symptoms, defined as greater than 0 on a scale of 0 to 5, based on five symptoms: breathlessness while wheezing, waking up from chest tightness, shortness of breath at rest, shortness of breath after exercise, and waking up from shortness of breath. Most (53%) had no change in their symptoms, and 27% had improved symptoms.

Among those eating at least four servings of cured meats a week, 22% reported worsening asthma symptoms compared with 14% of those who ate less than one serving a week and 20% who ate 1 to 3.9 servings weekly.

The researchers used a marginal structure model, a type of statistical modeling used to infer causality in epidemiology, to estimate the direct effects of cured meat intake on the participants' asthma symptoms. They accounted for other potential dietary confounders using two multifactor dietary patterns: one with a high intake of fruits, vegetables, whole grains, oils, and fish, and one with a high intake of prepared meals, cured meats, condiments, alcohol, sandwiches, French fries, and other potatoes.

The authors also adjusted for age, sex, smoking history, educational level, and physical activity, particularly as sex and smoking history have both previously been associated with cured meat intake. In this study, those who ate more cured meats were also more likely to be men, to be younger, to smoke, to consume more calories, to have a higher BMI, to consume more sodium and saturated fat, and to have asthma.

After these adjustments, participants who ate at least four servings of cured meat per week had 76% greater odds of worsening asthma symptoms than those who consumed less than one serving of cured meat per week (multivariable odds ratio [OR], 1.76; 95% confidence interval [CI], 1.01 - 3.06). When the researchers considered the indirect effects of BMI on asthma symptoms, they determined that BMI accounted for 14% of the total effect of cured meats' influence on asthma symptoms (OR, 1.07; 95% CI, 1.01 - 1.14). However, "[n]o interaction was observed between cured meat intake and BMI...in the associations with asthma" (P = .90).

The indirect effect of high cured meat intake mediated through BMI accounted for only 14% of the association with worsening asthma symptoms, so "the direct effect explained a greater proportion, suggesting a deleterious role of cured meat independent of BMI," the authors conclude. They note, however, that two prospective American studies focused on different cured meats — primarily bacon, hot dogs and sausages — did not find any effect on asthma incidence after adjusting for BMI and other confounders.

"This different finding may result from the role of BMI in the association (confounder vs mediator) or the assessment of respiratory phenotypes (incidence vs change in asthma symptoms)," they write. They also noted a follow-up loss of 15% of participants.

Aside from the possibility of nitrosative and oxidative stress harming the lungs from cured meats' high nitrate levels, the researchers proposed two other mechanisms by which cured meats may worsen asthma. One is an increase in systemic inflammation considering previously identified associations between cured meat intake and C-reactive protein. The other, supported only by sparse evidence with childhood asthma, is that high salt and saturated fat intake may affect asthma symptoms.

The research was funded by Merck Sharp & Dohme, the GA2LEN project, Global Allergy and Asthma European Network, and Conseil scientifique AGIR pour les maladies chroniques, National Hospital program of clinical research. The authors have disclosed no relevant financial relationships.

Thorax. Published online December 20, 2016.

    
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