I have been vegan for around 2 years now and have found that it certainly seems to have a lot of health benefits. Speaking from personal experience, I have lost nearly 2 stone in weight (which I was struggling to lose before! I was a bit too fond of those high-fat dairy products, especially cheese). Once I gave up dairy, the weight seemed to come off quite easily; although I have replaced the milk, cheese, butter and eggs with their plant-derived vegan substitutes, they don't seem to be as fattening (I don't eat vegan cheese very often in any case, as I am still trying to find one that really appeals to me).
Another health benefit is that I have really noticed that my skin has improved, immeasurably. I used to still get a lot of spots before, despite being in my forties; now, I rarely get them. So I am convinced there is a direct correlation between dairy and skin eruptions! I have heard a lot of other vegans say the same. I have never had high levels of energy naturally, but since becoming vegan, my energy levels do seem to have improved (not that I am exactly a living dynamo even now! But I do feel less sluggish than I used to). I also have fewer sinus problems; I gather that dairy products contain some substance which is mucus-forming in humans. So it makes sense to avoid them, if you are a martyr to your nose and sinuses, like me! I also have fewer digestive problems, and, without getting too graphic, maintain more regularity. I now eat less processed food and cook more meals from scratch, using fresh produce.
It is a logical assumption that a vegan diet will benefit your health anyway, as we are all being recommended to eat at least 5 portions of fruit and vegetables per day, so naturally a vegan diet will usually ensure that you get your 5 a day. Additionally nuts, seeds, soya-based products and wholegrains are extremely beneficial, and naturally a vegan diet includes quite a lot of those. It is also increasingly being scientifically proven that meat and dairy products are not good for human health in many ways, not least in their carcinogenic effect and the effect they have on the heart, arteries, etc. Veganism can also reverse diabetes, from what I have heard.
I know it is a common assumption in non-vegans that you cannot get enough protein from a vegan diet, but this is complete nonsense: plant sources contain quite a lot of protein and, in any case, humans only need around 5%-10% of protein in their dietary intake. So you can get all you need from plants. I would recommend anyone to go vegan, if only for their own health, and not because of the ethical considerations.