Last month's column on sulfite myths generated quite a bit of feedback. Most ran along the lines of "I'll grant you the point on sulfites not being the cause, but any idea then of why I can drink white wines without any problem, but end up with a headache from just a glass of red?" A few more prodigious imbibers also asked for hangover prevention tips, which we're always happy to share.

Although most people can enjoy both red and white wines, unfortunately for some drinkers, even a small glass of red can trigger a hot, flushed feeling along with nausea and a pounding headache.

There is no shortage of theories as to the cause of "red-wine headaches," but no hard data exists. The culprit certainly isn't the alcohol (modern whites can easily contain as high a percentage of alcohol as reds). As we explained previously, neither is it sulfites, as whites contain much higher levels of sulfites than reds do. There are hundreds of organic compounds in grape skins, and hundreds more produced during fermentation, but it is still unknown which are the villains.

Of particular interest to those susceptible to hay fever is a theory that posits that histamines may be the cause, as these naturally occur at much higher levels in reds than in whites. Anecdotal evidence indicates that some wine lovers who take a nondrowsy antihistamine before drinking avoid their usual headache altogether, although some researchers claim that actual histamine concentrations in wine are too low to be relevant.

Another school of thought holds that tannins are the cause, as reds certainly have more tannins than whites, particularly since these compounds have already been implicated as triggers for migraines. However, many people who don't get migraines still get red-wine headaches, and no one ever complains about tea, soy or chocolate headaches, even though these contain large amounts of tannins as well.

Other sufferers have found that taking an aspirin before drinking red wine can alleviate the problem, although the verdict is still out on the root cause and the best way to prevent this mysterious phenomenon.

We are big believers in moderation in all things, including moderation. So we must admit to occasionally overimbibing, whether it is at a trade tasting of 80 Austrian Gruner Veltliners before lunch, or a dinner with friends that is punctuated by periodic raids on the wine cellar.

Ah, but how to avoid the dreaded morning after?

We've found a number of tricks over the years that professional wine drinkers swear by (or swear at, when they don't work). First and foremost is to drink a minimum of one glass of water for each glass of wine. This isn't always easy, as some restaurants intentionally underserve water in order to sell more alcohol, and dinner hosts often overlook an empty water glass.

But drinking a sufficient amount of water is absolutely critical, as what is commonly considered a hangover is actually two separate water-related factors. The first is simply dehydration -- the headache-inducing bane of marathon runners and desert troops. The second is a buildup of the toxic byproducts of alcohol metabolism at a rate greater than that which the liver and kidneys can flush them out of the body. Since these organs need plenty of water to work efficiently, dehydration is a real double-whammy.

As a prophylactic, U.K.-based wine writer Jancis Robinson swears by milk thistle, a herbal dietary supplement that is supposed to help the liver process toxins. As with most products of this type, the manufacturer encourages you to take it multiple times daily, but Robinson says, "I reserve this magic compound for when I suspect I'll really need it."

One winemaker we know recommends the "123" program: Before going to sleep after a big night out, take one aspirin, eat two bananas and drink three glasses of water.

Some or all of these techniques may avert a hangover, but be forewarned that none will prevent drunkenness. As Ernest Hemingway said, "Always do sober what you said you'd do drunk. That will teach you to keep your mouth shut."

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Those in pursuit of more serious wine knowledge will be pleased to know that Tokyo is blessed with not one, but two, Wine and Spirits Education Trust ("WSET") Diploma-holders, both of whom will be teaching wine courses in English this fall.

Sandra Shoji teaches her highly regarded eight-Saturday wine appreciation course at Temple University in Azabujuban beginning Sept. 25. Fee is 62,000 yen; more info can be found at www.tuj.ac.jp/newsite/main/cont-ed/Artandculture.html

For those looking to go into greater depth, Carl Robinson teaches a six-month WSET Advanced Certificate course. Classes are held in Ginza on Monday evenings, beginning Oct. 4. For more info please see www.jalbrand.co.jp/wine