A new review from the Eastern Virginia Medical School has examined the literature around dietary vitamin supplements.
It found that evidence exists only for a benefit from vitamin D and omega 3 supplementation, unless there are specific deficiencies that require vitamin replacement.
Further it reinforces the potentially harmful effect of taking beta carotene, vitamin A or vitamin E supplements, as shown in other research.
While this applies to the average person rather than someone with a serious illness, it is interesting to note that it accords with the OMS recommendations that supplementation is only routinely required with vitamin D and omega 3s.
Of course, for people eating plant-based diets, attention needs to be paid to vitamin B12 and iron status, but these don't require routine supplementation unless there is a deficiency.