Have you seen anyone's health improve after going vegan?

No actually it got worse. I had to come off because I could not get my iron to improve despite even taking a high dose supplement. My body needs animal products. There are lots of people who do the vegan thing very unhealthily: I call them "junk food vegans". People who have great intentions with going vegan but basically live on processed carbs and sugar and rarely actually eat real whole foods. I have a vegan friend who drinks coke all day. I just shake my head because I dont understand being morally appalled by eating animal products, but not morally appalled by the soda industry's complicitness in the introduction of obesity to 3rd world countries and the use of chemicals in their beverages that have long been shown to cause horrendous health effects.

Some background first, I raise dairy goats and study animal nutrition extensively. I found that in many cases, processed feeds and supplements create problems equal to or greater than the prior condition. Most diverse [emphasis on diverse] natural diets are imbalanced in the short run, but balanced in the long run. Short-term "balanced" meals often create problems because vital nutrients are artificially balanced and unused excesses of one nutrient chemically inhibit the body's ability to absorb another. The body's recognition that it lacks an inhibited nutrient can stimulate additional eating (cravings) where the nutrient is needed but the calories aren't.

I've experienced significant improvement in overall well-being through reduction of processed foods in my diet. Other than cooking, the majority of food I eat, gets to my plate in its natural state. Most processed foods have stabilizers, preservatives, and simple sugars that enhance shelf life, appearance, arguably flavor; but do nothing good for my body. These additives may inhibit chemically alter absorption and satiation, and through enhanced sensory input, increase consumption.

Now to get to your point. My diet now includes much higher portions of fiber rich, unprocessed Fruits, nuts, vegetables, and starches; and almost no processed foods. As an unintentional side effect, I eat less meat. My wife and I now commonly split a steak that I used to consume by myself and hope she didn't finish all of hers. But I also do things my Doctor thinks are nuts, but the lab results don't lie.

_I drink whole milk (unpasteurized and unhomogenized). There are studies that show that pasteurization and homogenization changes the nature of the milk solids and produces unhealthy cholesterol problems. Additionally, since I drink goats milk it is naturally homogenized the body cannot as readily absorb the fats like it can from milk that is mechanically homogenized. As a result, my cholesterol levels have improved.
_I eat cheese (home made) like there is no tomorrow. But because I make it myself, I don't have near the sodium levels of store bought cheese. As a result my blood pressure has not risen nearly as sharply as most men in their 50's. I went from six blood pressure meds to none.
_I eat fried foods, but I don't use vegetable oils. I use olive oil, or lard (yeah in comparison to vegetable oils it is heart healthy particularly if you render it at home), depending on what I am frying.

So when I give dietary advice:
-Grow it at home if you can
-If you have to buy it, by from the farm.
-If you can't buy from the farm, shop the perimeter of the grocery store
-Stay away from box meals and processed foods.
-Eat whole foods

Neither God nor Evolution (take your pick) intended for you to be a herbivore. There's a reason you have incisors.