Yeast are single celled fungi. As fungi, they are related to the other fungi that people are more familiar like edible mushrooms. The shape of yeast is egg like and can only be seen with a microscope. It takes 20 billion yeasts cells to weigh 1 gram . There feed on sugar to obtain energy from food.
Although it's fine to eat baked goods made with yeast but one should never eat raw active yeast as these fungus are still alive and can ferment our digestive system where they will eat our body B-vitamins and produce gas.(1)
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