According to Beerandhealth.com the yeast cells added to the beer during the brewing process produce vitamin B while growing and many of these vitamins stay in the beer. The more the beer is filtered and clarified, the more vitamins are lost.
A 25cl glass of lager still contains 0.07 mg vitamin B2, 0.01 mg vitamin B1, and 0.12 mg vitamin B6. 
As a comparison: one slice of brown bread contains 0.02 mg vitamin B2, 0.06 mg vitamin B1, and 0.05 mg vitamin B6.

Table 1. Vitamin content in a 25 cl glass of lager and light beer, average values.

1 glass

Vit B1

Vit B6

Vit B3

Pantothenic
acid

Vit B6

Folic
acid

Vit B12

 

mg

mg

mg

mg

mg

mcg

mcg

Lager

0,021

0,093

1,613

0,206

0,178

21

0,07

Light beer*

0,032

0,106

1,388

0,127

0,120

15

0,04

(*)Light beer contains fewer calories but has the same alcohol content as ordinary beers.


With a moderate intake of beer this product can make a contribution to the vitamin requirements. On the other hand, it is not the case that a good reserve of vitamins is created with excessive consumption. On the contrary, the more beer consumed the greater the vitamin requirement (especially vitamin B1).