Hi carcos,
There's some evidence that dairy may promote acne, and taking a very small zinc supplement (around or below the RDA of 10mg a day) might help if you are low on zinc (or eating more zinc rich foods like pumpkin seeds).
However, effects of diet and even supplements are likely modest compared to medical intervention.
Can you improve your symptoms a little with diet? Probably. Should you do that instead of taking medicine? No way.
For cyctic acne, your best approach will be a medication like accutane (isotretinoin). A short course of treatment can be rough (dry skin, and some other annoying side effects), but it changes the structure of your pores and can provide long-term reduction of cystic acne.
So, you should see a dermatologist for that (and talk to your doctor).
Otherwise for pcos, taking the medications your doctor prescribes is the best bet. Don't be afraid of androgen blockers if you need it.
As an adjunct treatment (that is, in addition to medicine), if you're over weight then any diet that helps you lose weight will likely help with pcos symptoms. So that's mainly about restricting calories.
In the case of insulin resistance, it may also be wise to cut down on carbs which might provide some short term relief.
Have you heard about Eco-Atkins? That might be your best bet. It's basically a low-carb vegan diet.
Lots of veggies and nuts with good fats, some beans, tofu, some low-sugar fruits like blackberries, and limiting grains.
Restriction like that can be a little more tricky in terms of nutrition, though, so make sure you plan well with a nutrition tracking program like chronometer until you get the hang of it. Here's how to set it properly:
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