When you drink wine, what exactly are you pouring into your glass -- and your body?

Usually, it's impossible to know. Unlike food producers, wine makers aren't required to disclose ingredients on the label.

In the United States, it's legal for winemakers to add up to 200 ingredients without telling anyone, including the consumer.

A Berkeley winemaker called Donkey & Goat is among an extreme minority of winemakers that is voluntarily adding ingredients lists to their wines. (Full disclosure: We are major fans of, and minor investors in, Donkey & Goat.)

Donkey & Goat wines contain either one ingredient ("Hand-Harvested Grapes") or two ingredients ("Hand-Harvested Grapes and Sulphur"). As such, they're proud to list ingredients, and should be. (The ingredients list barely scratches the surface of the winery's methods, which include sustainably grown grapes, the avoidance of contact with reactive materials like plastic during wine-making, extremely low quantities of sulphur.)

What about that other wine you're drinking? Are they proud of the ingredients? Or do they want to make sure you don't find out what you're putting into your body?

In other words, can we trust winemakers who conceal what's in the wine? Far too often, the answer is: no.

Winemakers routinely add more than just the ingredients you probably know about, such as yeast, nutrients for the yeast, sugar and acid.

They can and do also add clay, enzymes, gelatin, charcoal, egg whites, casein (a milk protein), isinglass (made from fish bladder), tartaric acid, ascorbic acid, malic acid, tannins, diammonium phosphate, acacia, velcorin, trypsin, pepsin, chalk, acetaldehyde, dimethyl bicarbonate and many other additives.

Many cheap wines add a product called "Mega Purple," which is concentrated low-quality teinturer grapes (grapes with pigment in both skin and pulp). "Mega Purple" is added to give cheap wine color, body and texture designed to simulate good wine.

And, of course, wine grapes can be grown using pesticides and herbicides, and trace amounts of these can make it into the wine -- pesticides like dimethoate, myclobutanil, tetraconazole, azoxystrobin and pyrimethanil.

Most of these ingredients are assumed to be "safe" to consume. And it's up to each of us to decide whether "safe" is a high enough standard.

It's also unnecessary to throw up your hands in confusion and give up. It's important to do your own research. Talk to the winemakers by visiting wineries for a tasting. Ask them directly about their methods for growing grapes and making wine and about any additives they include.

The easiest way to bring astonishingly great natural wine into your life is to join the Donkey & Goat wine club. They'll ship directly to your home on a subscription basis.

And seek out other wineries that share the Donkey & Goat philosophy of maximizing the true quality of the wine and adding the ingredients to the label.

And as with all food producers, it's a good idea to withhold trust from any producer who tries to conceal what's in the product or how it was produced.

If a winemaker is concealing what's in the wine or how it was made, you probably don't want to drink it.