攝取醃漬肉類與氣喘症狀惡化有關


  【24drs.com】根據線上發表於12月20日Thorax期刊的一篇縱向研究,隨著攝取的醃漬肉類量越多,成年人的氣喘症狀會越惡化,而身體質量指數也會微幅上升。
  
  醃漬肉類已被確認為癌症、所有原因死亡率、慢性阻塞性肺部疾病等諸多慢性疾病的風險因素之一。
  
  法國Villejuif Paul Brousse醫院的Zhen Li醫師等人寫道,醃漬肉類的亞硝酸鹽含量高這點廣為人知,會導致亞硝化壓力相關的呼吸道發炎-與氣喘有關的多種生理過程之一-可以合理地假設,攝取醃漬肉類是氣喘的獨立危險因素之一。
  
  他們指出,由於肥胖是氣喘發病和惡化的可能危險因素之一,且飲食會影響身體質量指數(BMI),BMI在飲食和氣喘之間存在因果關係是有可能的。
  
  因此,研究者分析了在2003-2007年間參與「Epidemiological Study on the Genetics and Environment of Asthma (EGEA)」這項前瞻研究的971名、其中42%有氣喘之研究對象的資料,納入的研究對象都是成年人(平均年齡43歲),完成飲食頻率問卷且有氣喘症狀相關資料。在飲食問卷的118個項目中,火腿(2片/份)、香腸(1條香腸/份)和乾香腸(2片/份)被分類為醃漬肉類。
  
  將近半數研究對象(48%)攝取量為中度,亦即每週1-3.9份,每週攝取不到1份的有19%,每週至少4份的有33%;過重的比率略超過三分之一(35%)、肥胖的有9%;51%從未抽菸。
  
  在2011-2013年這段追蹤期間,進行研究後平均7年時,20%的研究對象報告指出氣喘症狀惡化,其定義為:根據「氣喘時呼吸困難、因胸悶而醒來、休息時呼吸短促、運動後呼吸短促、因呼吸短促而醒來」等5種症狀,0-5分量表大於0分;大部份(53%)的症狀沒有改變、27%的症狀有改善。
  
  在每週攝取至少4份醃漬肉類者中,22%表示氣喘症狀惡化,而每週攝取不到1份者、每週攝取1-3.9份者的此一比率分別是14%、20%。
  
  研究者使用邊緣結構模型(一種用於推斷流行病學中之因果關係的統計模型)估計攝取醃漬肉類對研究對象之氣喘症狀的直接影響;他們考慮了其他潛在的飲食混雜因素,使用兩種「多因素飲食模式」:其一,攝取多量水果、蔬菜、全穀物、油和魚;其二,攝取多量即食飲食、醃漬肉類、調味食品、酒、三明治、炸薯條和其他馬鈴薯製品。
  
  作者們也校正了年齡、性別、抽菸史、教育程度、運動等因素,特別是性別與抽菸史這兩項因素,因為曾被認為與攝取醃漬肉類有關。在這篇研究中,攝取較多醃漬肉類者比較可能是男性、比較年輕、有抽菸、攝取較多熱量、BMI較高、攝取較多鈉與飽和脂肪、有氣喘。
  
  校正這些因素之後,每週攝取至少4份醃漬肉類者之氣喘惡化機率,比每週攝取不到1份者增加76% (多變項勝算比[OR]為1.76; 95%信賴區間[CI]為1.01 - 3.06)。當研究者考慮BMI對氣喘症狀的間接影響時,他們確認,BMI佔醃漬肉類對氣喘症狀之總影響的14% (OR, 1.07; 95% CI, 1.01 - 1.14),不過,在與氣喘的關聯方面,在攝取醃漬肉類和BMI之間並未觀察到相互影響(P = .90)。
  
  BMI對攝取多量醃漬肉類的間接影響,僅佔與惡化氣喘症狀之關聯的14%,作者們結論指出,所以,直接影響佔更大的比率,表示醃漬肉類本身有獨立於BMI的有害作用。不過,他們指出,兩篇前瞻美國研究聚焦在不同的醃漬肉類—主要是培根、熱狗和香腸 —校正BMI和其他混雜因素之後,沒有發現對氣喘發病率有任何影響。
  
  他們寫道,這些不同的發現可能是因為BMI在這項關聯之角色(混雜因素或者是調節因素),或者是呼吸表型的評估(氣喘症狀的發生率或變化),他們也指出,有15%的研究對象失去追蹤。
  
  除了醃漬肉類所含的高硝酸鹽值有產生亞硝化和氧化壓力的可能性,研究者提出醃漬肉類會使氣喘惡化的另外兩種機轉,其一,以前即已確認,攝取醃漬肉類和C反應蛋白質之間的關聯,使全身性發炎增加;其二,僅有兒童氣喘的少數證據支持,高鹽與飽和脂肪攝取可能會影響氣喘症狀。
  
  資料來源: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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