i think it's good that your son is concerned about his diet and seeking to become knowledgeable on the subject. that's a trait to encourage! however i think he's confusing several different issues here. let me see if i can briefly untangle this for you. first i know of no studies that support a direct connection between grain consumption in general and joint disease or damage. second there may be some connection between gluten (which is a protein found in wheat grains) and autoimmune diseases such as rheumatoid arthritis (which obviously affects the joints). again i don't know of any studies that confirm this but i do believe the issue is being studied right now. third people who have rheumatoid arthritis may be at higher risk of also being diagnosed with celiac disease which is an inability to digest gluten. so i think your son is confusing "carbohydrates from grains" with "gluten " and the two terms are not interchangeable. rice is a grain that does not contain gluten for example. importantly your son needs to know that at his age especially he needs to eat a well-balanced diet that includes plenty of complex carbohydrates -- including grains. if he's dead set against eating gluten i'd suggest he switch to brown rice (though recently brown rice was found to contain high levels of arsenic so he needs to monitor his consumption of this too). unless your son suffers from severe digestive problems after eating gluten products (like whole-grain breads white bread breakfast cereals etc. ) he probably is at very low risk of developing any joint problems from eating whole grains. if after this explanation your son is still concerned i'd suggest he visit his health care provider. he or she can work with your son to develop an eating plan that makes everyone happy -- and keeps your son healthy. best to you!
my son is 16 and he is convinces that cabohydrates from grains will damage his joint health. is this true?