Choosing a strict gluten-free diet when you only require a low FODMAP diet can lead to over-restriction. For example, oats and spelt bread contain gluten but are relatively low in FODMAPs so are suitable to have on a low FODMAP diet in appropriate servings. In addition, gluten is found in products derived from wheat, rye and barley, such as wheat starch, wheat thickeners and barley malt. These are common ingredients in a wide range of commercial products including soy sauce, confectionary, mayonnaise, yoghurts and more. They contain gluten and must be avoided on a gluten free diet for coeliac disease, but they are not high in fructans and are suitable to include in a low FODMAP diet.
Natural supplements won't hurt you. They can only help. They won't make chemotherapy or radiation therapy less effective. Instead they amplify the power of whatever cancer treatments you may be doing by attacking cancer in other ways, or supporting the health of the body and immune system. For example, research studies have shown that when you oxygenate cancer cells, radiation therapy is more effective at killing those cells. And beta glucan, when used in conjunction with some types of chemotherapy, produced marked improvement over chemotherapy alone.