- 學位論文
母乳的短鏈脂肪酸組成與嬰兒異位性皮膚炎的相關性探討
Study on the correlation between composition of short-chain fatty acids in breast milk and atopic dermatitis in infants
摘要
異位性皮膚炎 (atopic dermatitis, eczema) 係常見的過敏炎症，嬰兒為好發族群之一。母乳為嬰兒主要營養來源，哺餵母乳有助嬰兒發育、免疫調節，因此以往建議親餵母乳。然而近年研究發現哺餵母乳的嬰兒也有過敏風險，推論可能為母乳的營養成分差異造成。母乳含微量游離的短鏈脂肪酸，已知短鏈脂肪酸具抗發炎作用，可改善過敏氣喘、腸道發炎等疾病，故本研究欲探討母乳的短鏈脂肪酸含量與嬰兒異位性皮膚炎的相關性。本研究建立以氣相層析-質譜法 (gas chromatography-mass spectrometry, GC-MS) 分析母乳游離短鏈脂肪酸之分析方法，並進行方法確效，評估乙醇 (ethanol)、三氯醋酸 (trichloroacetic acid, TCA)、乙腈 (acetonitrile, ACN) 共三種溶劑處理方式，再檢測來自臺大醫院小兒過敏門診，嬰兒小於6月齡的母乳樣品，分析病例組 (n=47) 與控制組 (n=47) 的母乳游離短鏈脂肪酸含量，並對母親進行為期1個月的飲食頻率問卷調查。結果顯示，乙醇處理可能令乙酸 (acetic acid)、丙酸 (propionic acid)、丁酸 (butyric acid) 與己酸 (caproic acid) 等分析物酯化；TCA干擾層析圖譜，不利於建立檢量線。ACN可有效去除母乳樣品的蛋白質，且各分析物於檢量線濃度範圍內的線性關係良好 (R2 ≥ 0.999)；定量極限均為0.5 μg/mL且無明顯基質效應。各分析物同日間 (intraday) 與異日間 (inter-day) 分析之回收率與CV如下，乙酸回收率85.4-113.6%，同日間不同濃度CV為5.9%、4.7%，異日間不同濃度CV為12.4%、8.6%；丙酸回收率85.4-113.6%，同日間不同濃度CV為1.7%、0.8%，異日間不同濃度CV為0.7%、0.4%；丁酸回收率96.3-114.6%，同日間不同濃度CV為6.0%、3.0%，異日間不同濃度CV為0.5%、1.5%；己酸回收率113.8%-116.9%，同日間不同濃度CV為1.1%、0.9%，異日間不同濃度CV為1.3%、1.2%；均符合食藥署公布之食品化學檢驗方法之確效規範。病例組嬰兒所攝取的母乳己酸含量較高，乙酸、丁酸無差異，且均未測得丙酸。飲食頻率問卷結果發現，母親飲食的n-6 PUFAs對母乳乙酸呈正相關趨勢，EPA對母乳乙酸含量呈負相關趨勢；母親飲食的膳食纖維與n-6 PUFAs攝取量和母乳丁酸呈負相關趨勢，脂肪、n-3 PUFAs、EPA與DHA攝取量對丁酸含量負相關；膳食纖維、EPA、DHA攝取量與母乳己酸含量呈負相關趨勢，脂肪、n-3 PUFAs、n-6 PUFAs對己酸含量呈負相關。綜上所述，哺乳期間母親攝取較多的膳食纖維、EPA、DHA與n-6 PUFA，可能有助降低母乳己酸含量，進而降低嬰兒患有異位性皮膚炎的風險。
並列摘要
Atopic dermatitis (AD), also known as eczema, is a common allergic disease. Breast milk is the main nutrition of infants, and it contains many complex lipids, proteins, carbohydrates, and vitamins. Breastfeeding was thought to be helpful for developing and immune regulation, however, some studies showed that breastfeeding would increase risk of allergy. There are trace of free short-chain fatty acids (SCFAs) in breast milk, and it has been known that SCFAs have the anti-inflammatory effect to ameliorate asthma and intestinal inflammation. Therefore, the aim of this study is to investigate the association between SCFA levels in breast milk and atopic dermatitis status. This study built free SCFA analysis by gas chromatography-mass spectrometry, evaluated 3 different pretreatments from ethanol, trichloroacetic acid (TCA), and acetonitrile (ACN), further performed method validation, then analyzed SCFAs component of breast milk from infants younger than 6 months of age from the department of the pediatric allergy at NTU hospital in the case of AD group (n=47) and normal group (n=47). The data showed pretreatment by ethanol caused SCFAs esterification, TCA might interrupt the chromatogram, and ACN could remove protein effectively. Linearity was verified for all analytes, acetic acid, propionic acid, butyric acid, and caproic acid (R2 ≥ 0.999). LOQ for all analytes were set to be 0.5 μg/mL on the basis of S/N ratio ≥ 10 and did not show obvious matrix effect. Each analytes’ recoveries and CV of intraday and inter-day analysis met the current method validation guidelines set by Taiwan Food and Drug Administration (TFDA). We also analyzed maternal diet by food frequency questionnaire (FFQ). Concentration of caproic acid in breast milk was higher in the AD group than the normal group, but acetic acid and butyric acid had no significant difference between two groups, and propionate was not detected. The food frequency questionnaire (FFQ) of maternal diet showed the correlation between n-6 PUFAs in maternal diet and acetic acid in milk was positive, EPA and acetate showed opposite result. The correlation between fiber or n-6 PUFAs and butyrate in milk were negative; fat, n-3 PUFAs, EPA or DHA and butyrate showed significantly negative. The correlation between fiber, EPA or DHA and caproate in milk showed negative; fat, n-3 PUFAs or n-6 PUFAs and caproate showed significantly negative. Taken together, increasing maternal dietary fat, fiber, EPA, DHA and n-6 PUFAs during lactation might decrease risk of infant AD.