Hi there,
I know this post is a few months old, but if you were still interested in knowing about vitamin E then perhaps I may be able to help? I'm a registered dietitian so know a fair bit about human nutrition - obviously the physiology between a hamster and a human is vastly different, and the metabolic pathways aren't going to be the same, but I can say a bit about the vitamin itself, if that helps? Regardless of the species, common sense would suggest they had similar functions in the body. I say this first - I know almost nothing on hamster physiology so please bear this in mind!!
Vitamin E is one of the fat soluble vitamins (along with A, D and K), meaning that you need fatty acids (i.e. fat) in the diet for it to be properly absorbed in the body. Vitamin E actually exists in 8 different forms, with varying potencies, but they all act as antioxidants - which protect the body against free radicals (which damage cells and tissues in the body). Free radicals come from the environment (e.g. pollutants) but also arise naturally within the body as part of normal metabolic reactions. Fats, whether they are veg oils, olive oil, butter etc, are prone to oxidation (which involves free radicals), which contributes to fats going rancid. Vitamin E helps to keep them stable and reduce fat oxidation (hence the term 'antioxidant'). When it comes to human requirements of Vit E, the more fat you have in the diet then the more vit E you need as well. You'll find that a lot of oily foods naturally contain vit E.
In humans, Vitamin E acts to protect tissues and cells, inside and out, so sarah was absolutely right about it being good for skin and fur. Sarah's already mentioned sunflower seeds, spinach and broccoli, but you will also get vitamin E in almonds, brazils, hazelnuts, sweet potato, asparagus. All plant oils will contain vitamin E, but I'm not qualified to recommend on if they are appropriate to mix in with hamster foods! As nuts and seeds are very high in oils, (and this applies to humans too), beware that they will be very high in calories and may need to be watched if weight is an issue! For instance, 100g of most nuts/seeds will have somewhere in the region of 600-680kcal.
Again, as I know very little about hamster science, I wouldn't know about toxicity in them. I humans, side effects are not usually common unless you are really mega-dosing on it, where you can get fatigue, headaches, nausea, muscle weakness and diarrhoea - which is very similar to what sarah said that hamsters can get. For people, side effects usually go away once the overdosing stops.
Well, I'll stop writing now - my boyfriend just looked over my shoulder and mentioned that I might be getting a bit carried away...
sorry!
Anyways, if anyone wants any info on anything nutritional, I may be able to help - but bear in mind my training is only in humans, so whilst in some cases the info can be transferred across to hamsters, I am not trained/qualified in animal nutrition/veterinary science!!!