Diet and cystic acne relationship

I have heard of many people who claim to have solved their cystic acne problems through diet, but unfortunately it doesnt work for everyone. There is some ambiguity on what a "good diet" consists of. For example, some diets are not too keen on grain and carbohydrate based foods while most nutritionists recommend a grain based diet. Also there are lots of books on diet and foods, and there are some differences in opinion.

Interestingly, many studies had been performed on the diet and cystic acne relationship, and none was found. Also, a sickness or disease caused by malnutrition or poor diet tends to linger on until the poor diet is rectified. For example, if you had a low iron intake, you would continue to feel tired and run down until your iron intake increased. Cystic acne (in most cases) disappears in the mid-twenties even though sufferers have made no change in their diet. Now, if cystic acne is a disease caused by poor diet, why should it suddenly disappear?

One thing I would object strongly to, is the idea that cystic acne is a symptom of western diet. In fact, those of us who have travelled may have noticed that traditional Asian and African diets are no better for their culture than western diets, at least in terms of the incidence of cystic acne amongst their people. There may well be strong evidence to suggest that western diets are not actually very good for us - but there really is no evidence that it can either cause or worsen cystic acne.

I am not seeking to totally discredit the claim that diet has a part to play in cystic acne but still there are lots of other factors that can trigger this skin condition like hormones, genetics, vitamin deficiency, stress and much more.