There is good evidence to show that some vitamins or supplements are associated with early death, seriously!
Some supplements however are beneficial for healing. Vitamin D3, along with sunlight, helps to reduce relapse rates in people with MS. Vitamin D blood levels should be monitored regularly and supplements taken if required.
The one supplement that everyone on a plant-based diet should take is vitamin B12. Naturally found in micro-organisms in the soil, we are no longer exposed to this vitamin due to eating sanitised food and water. It's necessary for red blood cell formation, normal nerve function and for the replication of DNA.
Animals are supplemented with B12, so if these are off the menu (although meat eaters are often B12 deficient!) then we need to take a supplement in the form of cyanocobalamin. It's best to have a chewable tablet or spray, at least 2500 milligrams per week.