I have never heard of that, but I can tell you that Soy will destroy your ligaments, joints and cause MASSIVE inflammation. I've eaten a lot of tomatoes and I have no such issues. Some people might have reactions to tomatoes, that would be a personal thing and not common, but you can try phasing them out for 6 weeks and see what happens. If there is no change after 6 weeks it is not the tomatoes. There are a few foods that can cause joint inflammation, but mostly gluten and grains are the cause of that. Now that you are Vegan, make sure you phase out white rice and potatoes and see if they still hurt in 6 weeks. Sweet Potatoes are on the safe list.