The nightshade family is often a problem for people with Celiac disease. Nightshades contain alkaloids which act as a natural pesticide for the plants. Many people can tolerate nightshades, but it's difficult for anyone with damaged intestines. The most common nightshades are tomatoes, potatoes, peppers, chili and egg plant (aubergine). There are theories that if Celiac disease is undiagnosed it often leads to extreme sensitivity and potentially leaky gut syndrome, where the toxins in nightshades can pass into the blood and cause a reaction. If this is the case then when the intestines recover there is a chance that alkaloids can be eaten again with no reaction.
Unfortunately potato flour is perhaps the savior of gluten free foods. It is what makes them work. You'll notice it in almost everything. To get a flavour and texture that can help to imitate wheat, potato flour is the magic ingredient. So for those with a problem with nightshades the downside is an upset, inflamed stomach and possibly other symptoms too.
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