Magnesium — we think adding Mg supplements (as magnesium glycinate, ideally) is likely to help most people, and you can take them pretty much forever, AFAIK. (clearskinforever.net)
Never exceed 150 mg of zinc per day; it's easy to stay within the limit with the 15mg - 30 mg supplements recommended here. (supernaturalacnetreatment.com)
If you take a 30 mg supplement everyday (a standard dose), and combine this with the boost you get from foods, you'll probably get to about 45 mg, much lower than the safe limit and easily enough to provide extra acne benefits. (supernaturalacnetreatment.com)