Brewer's yeast is lawful
1-11-2016 | IslamWeb
Question:
Asalaamu alaykum. I wanted to know if brewer's yeast supplement is halal or permissible to consume? I found one that is made from beet. The website shares the following information about their brewer's yeast supplement: Solgar® Brewer’s Yeast is produced from beet molasses under carefully controlled conditions. After fermentation, the yeast is collected and dried using special techniques to preserve its protein, vitamin and mineral content. So will this be halal? I will greatly appreciate your guidance. May Allaah reward you.
Answer:
All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad 
is His slave and Messenger.
After investigation, we came to know that brewer's yeast is extracted from the fermentation of starches, and it is also extracted from sugar-rich natural substances, and that it is in principle useful and beneficial.
We also came to know that the reason for naming it with this name is that it was manufactured from leftovers of beer fermentation in the ancient times or that it plays an important role in the production of beer.
According to the scholars of Fiqh, it is established that all foods are permissible in principle. Al-Buhooti 
from the Hanbali School of Fiqh, said in his book Ar-Rawdh about foods, “In principle, all foods are lawful; as Allaah says (what means): {It is He Who created for you all of that which is on the earth.} [Quran 2:29], so all pure food that is not harmful is lawful, contrary to the food that is impure or stained with impurity.”
Accordingly, the basic principle is that the foods that contain brewer's yeast are lawful.
Even if we presume that this yeast is impure, then if it is transformed while manufacturing it, and the description of impurity no longer exists in it and it was transformed into another substance, then there is no harm in using it.
Ibn Taymiyyah said, “This analogy in water is the same analogy in all liquids; that they do not become impure if the impurity is transformed (into another substance) in them and there is no effect of impurity in them any more, in which case it is among the good (lawful) things and not among the impure (unlawful) ones.”
Allaah knows best.