Dietary exclusions for established atopic eczema
Editorial Group: Cochrane Skin Group
Published Online: 23 JAN 2008
Assessed as up-to-date: 5 NOV 2007
Copyright © 2008 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
How to Cite
Bath-Hextall FJ, Delamere FM, Williams HC. Dietary exclusions for established atopic eczema. Cochrane Database of Systematic Reviews 2008, Issue 1. Art. No.: CD005203. DOI: 10.1002/14651858.CD005203.pub2.
- Publication Status: Edited (no change to conclusions)
- Published Online: 23 JAN 2008
Atopic eczema (AE) is a non-infective chronic inflammatory skin disease characterised by an itchy red rash.
To assess the effects of dietary exclusions for the treatment of established atopic eczema.
We searched The Cochrane Skin Group Specialised Register (to March 2006), The Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (Issue 1, 2006), MEDLINE (2003 to March 2006), EMBASE (2003 to March 2006), LILACS (to March 2006), PsycINFO (1806 to March 2006), AMED (1985 to March 2006), ISI Web of Science (March 2006), www.controlled-trials.com, www.clinicaltrials.gov and www.nottingham.ac.uk/ongoingskintrials (March 2006). Pharmaceutical companies were contacted where appropriate for reviews or unpublished trials.
People who have atopic eczema as diagnosed by a doctor.
Data collection and analysis
Two independent authors carried out study selection and assessment of methodological quality.
We found 9 RCTs involving a total of 421 participants of which 6 were studies of egg and milk exclusion (N=288), 1 was a study of few foods (N=85) and 2 were studies of an elemental diet (N=48).
There appears to be no benefit of an egg and milk free diet in unselected participants with atopic eczema. There is also no evidence of benefit in the use of an elemental or few-foods diet in unselected cases of atopic eczema. There may be some benefit in using an egg-free diet in infants with suspected egg allergy who have positive specific IgE to eggs - one study found 51% of the children had a significant improvement in body surface area with the exclusion diet compared to normal diet (RR 1.51, 95% CI 1.07 to 2.11) and change in surface area and severity score was significantly improved in the exclusion diet compared to the normal diet at the end of 6 weeks (MD 5.50, 95% CI 0.19 to 10.81) and end of treatment (MD 6.10, 95% CI 0.06 to12.14).
Methodological difficulties have made it difficult to interpret these studies. Poor concealment of randomisation allocation, lack of blinding and high dropout rates without an intention-to-treat analysis indicates that these studies should be interpreted with great caution.
There may be some benefit in using an egg-free diet in infants with suspected egg allergy who have positive specific IgE to eggs. Little evidence supports the use of various exclusion diets in unselected people with atopic eczema, but that may be because they were not allergic to those substances in the first place. Lack of any benefit may also be because the studies were too small and poorly reported. Future studies should be appropriately powered focusing on participants with a proven food allergy. In addition a distinction should be made between young children whose food allergies improve with time and older children/adults.
Plain language summary
Dietary exclusions for improving established atopic eczema in adults and children
Atopic eczema is the most common inflammatory skin disease of childhood in developed countries. The cause of atopic eczema is probably due to a combination of genetic and environmental factors. Atopic eczema varies in severity, often from one hour to the next and the disease can be associated with complications such as bacterial and viral infections. There is a substantial economic cost not only to the family of the person with atopic eczema but also to health services. Although there is currently no cure for atopic eczema, a wide range of treatments are used to control the symptoms. One such approach is a dietary one, whereby certain foods such as cows' milk are excluded on the basis that they are thought to cause eczema to worsen. The reason for undertaking this review is because the effectiveness of removing various foods from the diet in the short term management of atopic eczema is unclear.
The general quality of the studies was poor. The main findings of the review suggest that there is some evidence from one study for the use of an egg-free diet in infants with a suspected egg allergy who have positive specific IgE antibodies to eggs in their blood. Other studies that compared a dietary exclusion with ordinary diets did not test the people taking part to see if they were allergic to the foods concerned. There appears to be little benefit in eliminating cows milk from the diet or using an elemental (liquid diet containing only amino acids, carbohydrates, fat, minerals and vitamins) or 'few foods diet' for improving atopic eczema in people who have not undergone any form of testing.
Three of the studies used soya based substitute which itself can be allergenic to people with atopic eczema.
Adhering to elimination diets is difficult. The studies were performed in different populations with only one study describing the severity of the atopic eczema. The clinical relevance of changes in severity scores obtained in many studies is unknown.
我們搜尋以下資料庫：The Cochrane Skin Group Specialised Register (到2006年3月), The Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (第 1 期 ，2006年), MEDLINE (從2003年到2006年3月), EMBASE (2003年到2006年3月), LILACS (到2006年3月), PsycINFO (從1806年到2006年3月), AMED (從1985到2006年3月), ISI Web of Science (2006年3月), www.controlledtrials.com, www.clinicaltrials.gov and www.nottingham.ac.uk/ongoingskintrials (2006年3月). 我們與製藥公司進行了接觸酌情未發表的評論或醫學回顧。
我們搜尋共包含421名受測者的9項隨機對照試驗，其中6項 (288人) 是排除蛋與牛奶的研究，1項 (85人) 研究少量食物，2項 (48人) 研究元素食品。似乎食用不含蛋或牛奶的飲食對於異位性皮膚炎並無明顯的助益。而食用少量或元素飲食對於異味性皮膚炎也無益處。使用不含雞蛋食品在於對雞蛋過敏且含有特異性IgE的嬰兒身上有一些幫助有一項研究發現51% 的小孩在受影響的體表面積方面有明顯的進步 (RR 1.51, 95% CI 1.07 to 2.11) ，.相較於正常飲食，在實驗六週之後 (MD 5.50,95% CI 0.19 to 10.81) 以及實驗結束之後 (MD 6.10, 95% CI 0.06 to12.14) 體表面積與疾病嚴重度也都有顯著的進步。方法學上的困難使人們難以判讀解釋這些研究結果。不易隱瞞隨機分配、缺乏雙盲測試、過高的退出率以及缺少治療意向分析均使得在解釋研究結果時都要十分的小心。
此翻譯計畫由臺灣國家衛生研究院 (National Health Research Institutes, Taiwan) 統籌。
異位性皮膚炎是已開發國家兒童中最常見的發炎性皮膚病。病因可能合併有基因與環境的因素。 這疾病的嚴重度時時刻刻都在改變，並可能併發細菌或病毒的感染。對於個人、家庭或整體醫療體系都是經濟上的沉重負擔。雖然目前無法完全治癒異位性皮膚炎，但是有許多方式可以控制並改善症狀。飲食控制就是其中一個方法，牛奶被視為會惡化濕疹所以有時會被排除在食物清單之外。由於從食物中移除某些成分對於短期在治療異位性皮膚炎的效果尚未明確，因此進行本回顧。但是大致上這些回顧的研究品質都不佳。本回顧主要的發現在於有篇研究指出使用不含雞蛋食品或許在於對雞蛋過敏且含有特異性IgE的嬰兒身上有一些幫助。其他一些比較正常飲食與移除某些成分的飲食之研究，並未測試受測者是否對於這些被移除的成分會過敏。對於在飲食中移除牛奶、使用元素飲食 (僅含有胺基酸、碳水化合物、脂肪、礦物質與維他命) 、或少量飲食對於異位性皮膚炎的助益似乎沒有明確的證據。有三項研究使用大豆替代物，而這本身對異位性皮膚炎也可能是一項過敏原。能有恆心的實用替代食品是相當困難的。這些研究在不同族群之中進行，只有一項描述異位皮膚炎的嚴重度。在眾多研究之中所得到的嚴重度改變之臨床意義仍然未知。