On the plus side yogurt, cheeses, and ice cream have a much reduced effect due to how they're processed, so they don't have as much of an impact as fresh milk does.
I'm the person who wrote the article on milk and acne on AcneEinstein.com. Not to rain on your parade, but I'm not aware of any reason why cheese and ice cream would be less acnegenic than milk. In fact, I think they can be more acnegenic because they are concentrated forms of dairy (at least cheese).
Yogurt may, and I emphasize the word may, have less of an impact because during the fermentation process bacteria consume a lot of the IGF-1 hormones in the milk. That said, yogurt still has whey and other substances that will spike insulin. Thread carefully.
Nobody can really say how much damage a course in antibiotics causes. To my knowledge it has never been thoroughly studied. I looked into this once, and the papers on this generally note that the gut microbiota is fairly stable and bounces back after a disturbance (such as antibiotics).
Many studies note that the microbiota had rebounded back within a few weeks of finishing the antibiotics, but I'm not sure that's the whole story. The problem is that scientists have a limited ability to detect changes in the gut microbiota. And earlier studies used techniques that weren't sensitive enough to detect minor changes. More recent studies have shown that small disturbances persist 2 and 4 years after a 7-day course or clindamycin. To be fair, it's hard to know whether these small disturbances have any health effects.
Our scientific understanding of the gut microbiota still leaves a lot to be desired. There's a lot we don't know. So this question can't be answered definitively yet.
I would be careful with antibiotics. Simply because there's no evidence they have any long-term beneficial effects. They work while you take them, but that's all. Acne comes back when you stop them. And there's a definitive possibility of risk. Not to mention the coming antibiotic shortages because of resistance bacteria.
This is a summary of a more detailed post on the topic I wrote here:
No! Fish oil and other antioxidants, such as vitamin C and E, can offer some sun protection, but in the studies I've seen they show moderate effect but I wouldn't trust them as sun screens. If my memory serves me right some studies showed that antioxidants can double the amount of sunshine skin can take before it burns. So they can help, but I wouldn't count them as sunscreens.
The value of green tea/EGCG has been known for a while, but this study identifies several factors affected by topical EGCG
There are also a few other green tea studies. The problem is that none of them are definitive. The study you referred was mostly in vitro, though it also had an in vivo part. These studies are interesting and provide some evidence for green tea and EGCG but the problem is that they don't have proper controls. Once we see a few studies with 100 or so participants that compare EGCG cream to BP head to head then I can say that there's reasonably good evidence for it. Such studies exists for vitamin B3 and vitamin C derivates.
I believe the argument here is still that benzoyl peroxide works for some, and doesn't for others. And for the people it does work for, they are still subjecting their skin to extremely high levels of oxidative stress, which causes the redness, dryness, itchiness, and long term skin damage from free radicals. So...while it may be effective at treating acne for many people, it comes with a price.
The same can be said for most if not all modern medicines. They may serve the purpose they are prescribed for, but they come with a whole host of side-effects that interfere with other important metabolic processes. They are band-aid fixes, and most illness/disease can be prevented and even reversed via proper nutrition and avoidance of toxic foods so commonly found in the western diet.
Also, what about green tea cream? Apparently there was a study conducted by a Dr. Jennifer Gan-Wong from the Memorial Medical Center in the Philippines that showed a 3% concentration of green tea cream was as effective at treating acne as a 4% concentration of benzoyl peroxide. I wish i could find the actual study itself. It is cited repeatedly, but i'd still love to see the study. I think you have to pay a monthly fee to get access to some of these studies, which is unfortunate.
I'm not arguing against the statement that BP has side-effects, or that it's an oxidizing agent and causes oxidative damage in the skin. I argue against black and white thinking that's so prevalent here. I argue against statements like 'BP causes oxidative damage, therefore it's automatically bad and should be shunned'.
Here's the point that argument misses. ACNE itself causes a lot of oxidative damage on the skin. So if something reduces acne it most likely reduces inflammation in the skin.
The way I see it is that BP causes little oxidative damage to prevent bigger damage from occuring. This is evident from the fact that for many people, but not for everybody, acne goes away and skin becomes less red and irritated when they use BP.
I'm the first person to admit that BP can also make your skin worse. If you use too much of it or the concentration is too strong. And with moisturizers or antioxidant creams you can mitigate the damage even further.
If you can find a natural cream that gets the same results, then fantastic. So far there has been done, and I'm pretty up to date with research on acne. As I said, there are some promising candidates, like niacin and vitamin C derivates. Green tea catechins might also work, but so far the studies have been way too small and inconclusive to say for sure.
I'm not aware of the study you are referring to. This is the latest green tea related acne study in the PubMed index: