Originally posted by: Saint Michael
Most beer isn't vegetarian, so only non-practicing vegetarians should be drinking it without doing research.
Couple of points of interest here:
First, yeast is neither plant nor animal... It is classified in the Fungi Kingdom. So Beer is usually made with the following:
1) malted grain - usually barley, but often with other adjunct in 1-10% ratios. These adjuncts are probably plant derived (e.g., wheat, oatmeal, rice, corn) but may not be (e.g., lactose -aka milk sugar)
2) water - and its local characteristic mineral profiles
3) hops - these are the flowers of one or more types of hop vines.
4) and yeast
However, mass produced beer is often (usually) filtered in some way. One of the most common filtering systems will use animal byproducts (gelatin) as a filter bed.
Isinglass
Made from the dried swim bladders of sturgeons. Used a
great deal in British brewing.
Irish Moss
Also known as carragheen, a type of dried seaweed.
Gelatin
The same stuff used to make Jello (tm). Made from animal
(mostly cow) hooves, skin and connective tissues.
Polyclar
A brand name for PVP (polyvinylpyrdlidone), a man-made,
plastic substance.
Sparkalloid
More commonly known as diatemaceous earth.
Also, a brewery may use an additive to encourage head retention (insert joke here).
Heading agents
Various products added to a beer to increase its ability to form
and hold a head. Used most often in beers made with large
quantities of corn and/or rice. Pepsin is a common heading agent
and is often derived from pork. Beers using only malted barley
or wheat don't need heading agents.
Finally, many breweries will sell their spent grain to animal farming institutions as feed product. See
http://www.veganvanguard.com/vegism/beer.html for an example.
So depending on how you define a vegetarian life style you may be hard pressed to find a beer that is not linked to animal supply chains. Brewing your own beer will be your best option if you really want access to a good variety of vegan/vegetarian beer. Especially if you live in a small market where there is no beer specialty store or local brewpub.