Brewer's yeast can be purchased at many a fine health food store, and is used as a dietary supplement. I recently paid 12 U.S. dollars for a 16 ounce canister. It is a source of B-vitamins, amino acids, proteins, minerals, enzymes and nucleic acids. Brewer's yeast may be helpful in reducing serum cholesterol, elevating high density lipoproteins (HDL), is rich in glucose tolerance factor nutrient chromium, and has immune enhancing properties. This supplement was suggested to me to aid in muscle healing after strenuous workouts.

This from the label on a canister of Lewis Labs brewer's yeast:
LEWIS LABS BREWER'S YEAST. 100% Pure. Premium. Imported. Dietary supplement. Not blended or fortified. Nothing added. Superb taste. Exceptional nutritional content. This is the only brewer's yeast that actually tastes good! Absolutely no aftertaste. Totally digestible. It will change your idea of what brewer's yeast really is.

To use as a supplement consume 1 to 4 tablespoons daily. It can be added to milk, juice, or various other foods. The taste is actually kind of funky, although not nasty. It reminds one of whole wheat cereal, except more pungent. I personally suggest dissolving it in chocolate milk, so it will go down quickly. Refrigerate after opening.

Update 8-30-2002: My girlfriend suggests that this stuff is far better sprinkled on yogurt. So give it a shot!
Tem42 says re Brewer's yeast: It is also very good on popcorn.