In large doses, some vitamins have documented side-effects that tend to be more severe with a larger dosage. To give a sense of just how closely the patterns line up, the chart below shows the relationship between education and taking vitamin D supplements (in the 2009-2010 NHANES), and also the relationship between education and whether the individual is overweight or has diabetes.
The low energy and mood of sesonal affective disorder could be an effect of both low levels of light and inadequate levels of vitamin D. It is particularly vital to take a vitamin D supplement during the winter, in addition to getting more exercise and as much sunlight exposure as possible.
The reason that the set of vitamins skips directly from E to K is that the vitamins corresponding to letters F-J were either reclassified over time, discarded as false leads, or renamed because of their relationship to vitamin B, which became a complex of vitamins.
Antioxidants can also be found in fruits and vegetables – specifically, selenium, beta-carotene, and vitamins A, C, and E. Studies have shown that people who eat more fruits and vegetables have a lower incidence of cancer and heart disease and live longer.
There appears to be no consensus on any vitamins Q, R, T, V, W, X, Y or Z, nor are there substances officially designated as Vitamins N or I, although the latter may have been another form of one of the other vitamins or a known and named nutrient of another type.