Crocodile,
re. alcohol: the CDCA reccomendations are 2 drinks max per day for adult males, and such a quantity (which is the equivalent of 2 glasses of wine per day) is also the max amount suggested by physicians I know and to whom I asked an opinion.
More than that, you may be in for liver disorders, metabolic disorders, cancer and else. So, the rule is that there is no problem in occasional use but regular use should be within those amounts.
A standard drink is equal to 14.0 grams (0.6 ounces) of pure alcohol. Generally, this amount of pure alcohol is found in
12-ounces of beer (5% alcohol content).
8-ounces of malt liquor (7% alcohol content).
5-ounces of wine (12% alcohol content).
1.5-ounces or a “shot” of 80-proof (40% alcohol content) distilled spirits or liquor (e.g., gin, rum, vodka, whiskey).
Pls read the relevant CDC page:
https://www.cdc.gov/alcohol/faqs.htmI myself enjoy half a glass of good wine once in a while (usually when eating with my brother in law who brings the bottle), but when I don't drink it I do not miss it.
re. spiritual life and alcohol: probably, the above threshold is the safe threshold for brain impairment as well. I have no scientific explanation for it, but wine is the classic substance which blunts spiritual perceptions. Again, if you are able to moderate yourself within the above limits, then I believe the effect is all but negligible. The real danger here is that you have a karmic propensity to alcohol dependence and, without realizing it, you become addict to booze. No such danger, you're safe but should respect the bodily chemical tolerance to ethanol.
Re. diet: my reasoned opinion is that it's of the greatest importance. By eating properly you decrease the likelyhood of disease, and disease is not conducive to meditation at all. Also, longevity and healthspan may have their importance in allowing us more time to perfect our spiritual practices.
Any practical suggestion with diet you should need, I'm currently studying the subject, I find it is not necessary to go to extremes to have a reasonably healthy diet. Meat should be eaten with soem precautions and together with many vegetables. Barbecued meat may be dangerous if you have a genetic polymorphism which doesn't make you metabolize heterociclic ammines. Red and processed meats are officially cancerogenic to the human being. Fish is better off (watch out for mercury, though, the smaller the fish, the better!).