Yeast is great for you. Loads of vitamin B complexes. Might give you some gas but unless it smells or tastes funky I say lock & load. No known pathogens can exist in beer, so it's not like you'll kill yourself.
Some styles even encourage you to stir up the yeasties from the sediment and drink it all down to add to the flavor.
At any rate, here's what the University of Maryland says about the vitamin content of Brewer's Yeast:
Brewer's yeast is often used as a source of B-complex vitamins, chromium, and selenium. The B-complex vitamins in brewer's yeast include B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), B9 (folic acid), and H or B7 (biotin). These vitamins help break down carbohydrates, fats, and proteins, which provide the body with energy. They also support the nervous system, help maintain the muscles used for digestion, and keep skin, hair, eyes, mouth, and liver healthy. However, brewer's yeast does not contain vitamin B12, an essential vitamin found in meat and dairy products; vegetarians sometimes take brewer's yeast mistakenly believing that it provides B12, which can be lacking in their diet.