We're supposed to get enough in the food we eat, but western diets these days are lacking proper nutrition. Deficiencies don't happen overnight. It builds up over time. Your mouth lesions might not be from a B deficiency, but that's a common symptom of it and the solution is cheap and easy so why not give it a try? Worst that will happen is you may have some constipation and your urine will be a little more yellow than usual. Try it for a coupe of weeks and see how it goes.