5 Replies. The most commonly deficient vitamins for people dealing with rheumatoid arthritis are vitamin C, vitamin B6, folate (vitamin B9), vitamin D, vitamin B12 and vitamin E. It is preferable to get these vitamins in your diet however if that is not possible then supplements can be used. Vitamin E is a fat soluble vitamin. 2  It is found naturally in some foods and is an antioxidant. 3  Antioxidants protect cells from free radicals which damage cells. 4  Vitamin E is important for healthy immune function. 5  Vitamin E is found in avocados, egg yolk, nuts, wheat germ, whole grains, and peanut butter.