Gluten free beer is an important consideration if you have a gluten allergy or celiac.
Most beer is made with gluten-containing wheat, or more often barley. This has made drinking regular beer pretty much out of the question for many people.
As the number of people avoiding gluten increases rapidly, a relatively new market for gluten-free beer has been filled by a number of companies.
There are a number of types of gluten-free beer, and in some cases, the beer is not actually 100% gluten-free. This is disturbing, as some companies prefer to argue that their low-gluten beer is safe to grab market share, rather than either properly label their beer, or reformulate it to be truly gluten-free.
Some countries, Australia for example, have a very strict definition of what can be called "gluten-free": no detectable gluten in the food. This sounds good, but as gluten tests become more sensitive, some foods, previously labeled gluten-free, will not longer meet the requirements. Never the less, this is a good standard to aim for.
Other countries, such as UK, have a specific level below which the food can be labeled "gluten-free": 20 ppm (parts per million). Whether this is is a truly safe level or not can not be stated with 100% confidence.
Another consideration is that drinking enough beer that such low levels of gluten become a big problem probably meaning that the intake of alcohol itself will be even more problematic.
Since even tiny amounts of gluten can have serious long-term consequences for celiacs, all gluten is best avoided.
If you have a gluten allergy, then the amount of gluten you can tolerate is more at your discretion – if you do not notice any symptoms, then you are probably fine.
Gluten free beer is usually made with pseudograins – grain-like crops such as sorghum, and buckwheat, as well as true cereals, such as rice and corn.
According to Wikipedia, some bees from England and Finland may be safe to drink even though they are not specifically labeled gluten-free. Some examples follow. Make your own decision according to your own standards:
13 Against the Grain
You may prefer to avoid all beers that are not specifically gluten-free by way of their ingredients, not their processing.
Some brands of beer use rice and barley. They state that no gluten from the barley ends up in the beer, but there is no certainty that the resulting beer is truly safe for celiacs. Instead, they explain that the barley is converted into amino acids.