Based on the first link, an examination of a few references yields different stories.
They typically use isolates only like alpha-tocopherol and beta-carotene to assess Vitamin E and A efficacy. Oh, they used vitamin isolates in conjunction with radiation therapy too, stating that vitamins could interfere with the therapy - but such studies neglect other isolates and nutrient complexes. http://jco.ascopubs.org/content/23/24/5805.abstract
Stage 1 of the following study DID show improvement. Then, they cherry picked the Stage 2 effect to show no effect and that children exhibited disruptive classroom behavior. DUHHH! Give CHILDREN nutrition and watch their energy levels rise. Oh, what do children do with energy? Use it perhaps?! They MEGADOSED children by the way. Hepatotoxic, how can it not be? http://www.ncbi.nlm.nih.gov/pubmed/6234505