Outside of celiac disease, a gluten-free diet is prescribed for patients with IgE and non-IgE wheat allergy⁽¹⁾. In wheat allergy, the patient develops an allergic reaction ranging from mild skin rash to severe anaphylactic reaction, hypotension, oral allergic syndrome, or respiratory distress when consuming wheat. This is similar to allergies to other foods (e.g., eggs) or medications (e.g., penicillins). Restriction of wheat intake is essential to treat this condition. However, consumption of barley and rye is likely safe in patients with a wheat allergy. This is slightly different from the restricted life-long gluten-free diet required in celiac disease individuals. Another use of gluten-free diet is in patients with non-celiac disease gluten sensitivity. In this condition, the patient develops many gastrointestinal and non-gastrointestinal symptoms such as abdominal pain, bloating, diarrhea, fatigue, and joint pain after gluten ingestion, but does not develop the same intestinal damage (inflammatory changes and villous atrophy) seen in celiac disease. Tissue transglutaminase (tTg) IgA and IgA titers which are abnormal in celiac disease patients are usually normal in patients with gluten sensitivity. Some people with irritable bowel syndrome may also benefit from a gluten-free diet. In these cases, slight or intermittent exposure to gluten is not associated with inflammatory changes in the GI tract. However, a gluten-free diet is not routinely recommended for healthy individuals. Many studies have shown that restricting wheat, barley, and rye from the diet results in lower fiber intake. A gluten-free diet also lacks several micronutrients including calcium, iron, zinc and folate⁽²⁾.

References:
(1) Staudacher, H. M., & Gibson, P. R. (2015). How healthy is a gluten-free diet?. British Journal of Nutrition, 114(10), 1539-1541
(2) Palmieri, B., Vadala, M., & Laurino, C. (2018). Gluten-free diet in non-celiac patients: beliefs, truths, advantages and disadvantages. Minerva gastroenterologica e dietologica, 65(2), 153-162