Gut. 2004 Oct; 53(10): 1459–1464. doi: 10.1136/gut.2003.037697 PMCID: PMC1774223
Food elimination based on IgG antibodies in irritable bowel syndrome: a randomised controlled trial
W Atkinson,1 T A Sheldon,2 N Shaath,1 and P J Whorwell1
Irritable bowel syndrome (IBS) is a relatively common condition, characterized by abdominal distension and pain, diarrhea, constipation, or a fluctuation between these two extremes. This condition significantly impairs quality of life and places a large burden on health care resources. Treatment of IBS is largely based on the use of antispasmodics, antidepressants, and medications that modify bowel habit, depending on whether diarrhea or constipation more common. Generally, these combinations leave many patients dissatisfied and often lead them to seek alternatives.
IBS Patients often suspect that certain foods exacerbate their symptoms and have tried various forms of elimination diets. To date, systematic approaches to identify problem foods have failed, yet there has been nothing published with IgG.
Aims: To assess potential benefits from dietary elimination based on reactivity to IgG antibodies to food.
Patients: A total of 150 IBS patients randomized to receive, either (1) a diet excluding all foods to which they had elevated IgG antibodies or (2) a sham diet excluding the same number of foods but not those to which they had IgG antibodies. The experimental period lasted three months. Enzyme linked immunosorbant assay test (ELISA) was used to assess IgG antibodies.
Primary outcome measures were change in IBS symptom severity and global rating scores. Additionally, non-colonic symptomatology, quality of life, anxiety, and depression were secondary outcomes. Patients were provided a book of explanations regarding substitutions and compliance tips. Subjects could continue their medications they had been on but were encouraged not to alter them. Statistically, Intention-to-treat analysis was used with a generalized linear model.
Between January 2001 and July 2002, 176 176 patients were screened in, but 26 were eliminated, leaving 150 who tested positive to at least one food via IgG testing. Seventy-five were randomized to receive the real elimination diet and an equal number received the sham diet. By the three-month mark, 65 and 66 were eligible for analysis.
The two groups were similar at baseline, although the sham group had a higher percentage of males and the IBS score was higher in the true food group.
Foods (in alphabetical order) that were Eliminated and Percentages
After 12 weeks, for those compliant individuals, the true diet group resulted in a 26% improved symptom score than the sham diet (mean difference 98 (95% confidence intervals (CI) 52–144); p < 0.001). For the same time, all those who met the intent-to-treat criteria that included the non-compliant patients, there was a 10% improved symptom score (difference 39 (95% CI 5–72); p<0.024). The difference in the symptom was 100 (real diet) and 61.5 (sham diet).
The benefit improved by another 39 points for each food above the mean number of reactive foods (12%, 95% CI 7, 70, p=0.016). Multiple regression assessing time-to-maximum improvement showed that the maximum benefits were reached at the two-month time.
Global rating also significantly improved in the true diet group as a whole (p = 0.048, NNT = 9) and even more in compliant patients (p = 0.006, NNT = 2.5). All other outcomes showed trends favoring the true diet. Relaxing the diet led to a 24% greater deterioration in symptoms in those on the true diet (difference 52 (95% CI 18–88); p = 0.003).
Food elimination based on IgG antibodies may be effective in reducing IBS symptoms and is worthy of further biomedical research.
Two very important aspects must be noted. The first is that there is a substantial improvement for those individuals with a higher than average number of reactive foods. This indicates those with higher degrees of inflammation will benefit more than the average individual. The second piece of information gleaned from this study is that the maximum benefit was reached in two months.