I have recently commenced a gluten free diet as suggested by my doctor to help with hypothyroidism from Hashimoto's disease. I am feeling a lot better and will continue to improve as it takes a few months to get out of your system.
Gluten is in all wheat products. If you google 'gluten' or 'gluten free' you will come up with lots of information. There are recipes, information on reading product labels and lots of other tips about gluten online. Gluten free products are more accessable now but are a lot more expensive to buy. Some food in super markets is labeled 'gluten free' also some takeaway franchises list the food that does not contain gluten which is helpful.
I have lost weight and am feeling a lot better so if you have thyroid problems I would suggest you give it a go for a few months to see if you feel any improvement.