Studies have shown that incorporating oats uncontaminated with wheat, barley or rye, into a gluten-free dietary pattern for people with celiac disease, at intake levels of approximately 50 g dry oats per day, is generally safe and improves compliance. However, many studies report that the introduction of oats may result in gastrointestinal symptoms such as diarrhea and abdominal discomfort. These symptoms tend to be the primary reason for study subject withdrawal. Additional adverse effects that have been reported include dermatitis herpetiformis, villous atrophy and an increased density of intraepithelial lymphocytes, indicating that some persons with celiac disease may be unable to tolerate oats. Since limited research has been conducted on the similarities among those with adverse reactions to oats, further research is needed in this area. Further research is also needed regarding the contamination of oats by wheat, barley and rye.

• Grade I means there is Good/Strong evidence supporting the statement;
• Grade II is Fair;
• Grade III is Limited/Weak;
• Grade IV is Expert Opinion Only;
• Grade V is Not Assignable.
• High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
• Moderate (B) means we are moderately confident in the effect estimate;
• Low (C) means our confidence in the effect estimate is limited;
• Very Low (D) means we have very little confidence in the effect estimate.
• Ungraded means a grade is not assignable.