Not to knock vegan diets, but with all these health promotions about going vegetarian or vegan and the benefits of 'healthier' skin... I feel like it's slightly misinforming the public.
On the other hand, I'm not saying that a vegan diet is completely bad, because it's true that there are a number of health benefits from switching to greens. It's just that it does NOT guarantee better looking skin in the long run. I'll explain my reasoning later.
As for me, my main motivation for eating healthier is to feel better, manage my weight, and to achieve the best skin health possible for me. I eat lots of salad, especially as a meal, but I am not a vegan nor am I vegetarian. What I like to do is limit the amount of meat I eat. Not cut it out completely.
So why would not eating meat, fish, or dairy foods be bad for your skin?
Because of collagen production.
Adequate collagen production is the key to all skin problems having to do with aging and appearance. Collagen is the binding network of protein fibers in the skin that keeps it elastic, looking smooth, and preventing it from sagging.
The way our body's skin gets is collagen is by making it. To do this, the skin uses building blocks such as amino acids. Where do we get amino acids? From protein. And if you think about it, collagen is found in the body of a living animal, not exactly in a plant wouldn't you say? There's also zinc and vitamin B12 to think about (there is a deficiency commonly found in vegans and vegetarians) and higher amounts are found in animal sources. Not only that, but the bioavailability (the amount of the nutrient readily absorbed by our body) is higher in animal sources.
Fruits and veggies have tons of great vitamins and minerals that are beneficial to the skin. But they lack one of the most important building blocks of collagen and that is amino acids, which are best found and absorbed in the body with animal protein. Depriving skin of the building blocks it needs to produce adequate amounts of collagen can be detrimental if you want your skin looking its best.