That's one of the circumstances that got my cousin hooked on them. Just to prove a point to me, she volunteered to be a lab rat by doing without her vitamins and supplements for three months, to demonstrate that her adult acne, dandruff problems, mouth ulcerations, and increased susceptibility to mundane illnesses would return. I got so tired of her updating on me her latest canker sores, pimples, and scalp snowstorms that I told her to quit after 7 weeks. I suspect she's one of those people with a diminished ability to absorb only certain nutrients, but she's convinced that she must keep taking the whole works to escape adolescent disfigurement arising from the grave again. That might well be for the best, anyway, for assembled reasons that would take too many ScienceDaily articles to track down. When it comes to a B-complex, though, she seems to require at least 50 milligrams of each vitamin precursor rather than the tinier standards of common multi-vitamins.