Following a vegan diet means avoiding any foods that are derived from animals, like meat, dairy, fish and even honey (since it's made by bees). But what about yeast? Yeast is commonly referred to as an "organism," so does that mean it's an animal?
What Is Yeast?
Yeast plays a hugely important role in the culinary arts, both in baking, where it functions as a leavening agent that makes breads rise, and in the making of beer and wine.
A leavening agent is something that produces CO2 gas (aka carbon dioxide), which causes baked goods to rise. When describing how yeast functions in baking, it's often compared with leavening agents like baking powder and baking soda, which produce CO2 via a chemical reaction: a base ingredient interacts with an acid which generates a burst of CO2.
Yeast produces CO2 as well, but it does so via a biological process, not a chemical one. Yeast is a species of single-celled organism, Saccharomyces cerevisiae, that is a member of the fungi kingdom, which comprises yeasts, molds and mushrooms—organisms that are neither plants nor animals.
S. cerevisiae consumes carbohydrates such as starches and sugars and produces CO2 gas along with ethanol (aka alcohol). It also produces more of itself, multiplying rapidly over time, which is how a relatively small amount of yeast can create enough CO2 to cause an entire loaf of bread to rise.
When the dough goes into the oven, the yeast give off one last blast of CO2 before dying.
Yeast are unquestionably alive. So can vegans consume foods and drinks that are made with yeast?
What Does Vegan Mean?
Being vegan can mean different things to different people, but most would agree that it means, at a minimum, not eating any food products that come from an animal, including meat, fish, dairy and eggs. Others avoid using animal-based products like leather, wool and so on, as well as honey.
Obviously it's impossible to be 100 percent vegan in our society, since everything from cars, cell phones, and even the building components in our homes contain materials that are derived from animals.
But perhaps the best way of describing veganism is in terms of an individual making choices, and aligning those choices with their own personal ethics. So it's not so much a matter of what vegans can eat, as what they choose, or choose not, to eat. And that choice is a personal one, that each individual vegan makes for her or himself.
Can Vegans Eat Yeast?
So can vegans eat yeast? The fact is, most do. Even the animals rights organization PETA says it's OK. And by the way, this goes for all types of yeast, including nutritional yeast, brewers' yeast and so on.
The reason being, as we discussed earlier, yeast is not an animal, but a fungus. Specifically, they are single-celled organisms, whereas most definitions of animals specify that they are multicellular. Yeast do not move, which is another characteristic of animals. Nor do they reproduce sexually. From a biological standpoint, yeast are definitively not animals.
And stepping back further, what about the question of whether yeast suffer or perceive pain when they're baked in the oven? Avoiding the infliction of suffering on animals is indeed one, but by no means the only, rationale for many people who choose to follow a vegan diet and lifestyle.
And by this measure, as with the others, vegans can eat yeast. This is because yeast do not have brains or central nervous systems, which means there is no mechanism for sensations of pain to be transmitted or perceived. Which, if course, is to be expected, since yeast aren't animals, and only animals have central nervous systems.
So yes, vegans can eat yeast, and the vast majority do. But given the fact that veganism is a lifestyle comprised of a series of choices unique to each specific individual, rather than a set doctrine that every vegan must adhere to, there are some vegans who choose not to east yeast. It's up to each individual.
Can Vegans Eat Bread?
Even though yeast is vegan, that doesn't necessarily mean that all types of bread are vegan. Lean breads, which are made with nothing but flour, salt and yeast, are fine. Some bread recipes call for a small amount of sugar, and some richer breads might have a bit of oil in them. These are all fine as well.
Other breads, though, may contain ingredients like milk, as many soft white breads do, as well as butter or eggs, like challah. Occasional loaves of bread might have honey in them. So unlike the question of yeast, which is clearly something that vegans can eat, when it comes to bread, it's strictly a case by case matter of what ingredients happen to be in any given loaf.