Yeasts are living single-celled organisms that are found in plants and animals. Yeast cells are egg-shaped and can only be seen through a microscope.

What is yeast

If we weigh the yeast and count the cells in it, then there will be about 20 billion cells in about 1 g of the substance. Since the human eye is unable to see a 5 micron cell, these organisms have long been one of the most mysterious. Until the middle of the 19th century, mankind knew little about them at all. It was not until 1866 that the microbiologist Louis Pasteur, who devoted his entire life to studying the principles of fermentation, became interested in the process of yeast fermentation using beer as an example. And 15 years later, in a laboratory in Copenhagen, Emil Hansen isolated and purified individual strains of yeast. Methods for cultivating yeast fungi according to the Hansen method are still used.

Yeast cells are living organisms and need air to reproduce. These cells need to be fed to get energy. And their favorite food is anything sweet: sucrose (cane and beet sugar), fructose and glucose (honey, fruits, maple syrup), maltose (starch).

The size of a yeast cell does not exceed eight thousandths of a millimeter. There are approximately 1500 types of yeast. There can be thousands of genetically different strains within a single species, but perhaps the most famous is Saccharomyces Cerevisiae, which is Latin for sugar, fungus, and brewing. More often they are called by more understandable names - brewer's yeast or baker's yeast. Each of these species has certain characteristics, and they determine the scope of yeast. In brewing, for example, different strains are used to produce different types of drink. But the scope of this substance is much wider. Yeast is used for the production of many products, they play the role of flavoring agents, and have also found application in pharmacology, animal husbandry and other areas.

General characteristics

Yeasts are organisms that need food, heat and moisture for life and reproduction.

As a result of fermentation, they convert sugars and starches into carbon dioxide and alcohol. There are different types of yeast that are beneficial to human health. They can strengthen the immune system, improve digestion, but some cause fungal infections.

The most famous types of yeast:

  • beer;
  • bakery;
  • pressed (or confectionery);
  • dry;
  • ​​
  • forage.

The discussion about unicellular fungi is not new. Many are interested in what baker's yeast actually is, the benefits or harms of them, some are frightened by their composition according to GOST, so more and more housewives choose not domestic, but French yeast. In fact, if you understand what yeast is, how these microorganisms multiply and how they affect baking, it becomes clear that there is nothing to worry about by and large. Whether these substances are beneficial or, conversely, harmful to the body depends on the amount of their consumption, the sensitivity of the body, and the presence of Candida in the body. In small quantities, yeast can improve health by replenishing B-group vitamins, but an excess of the substance can adversely affect a person.

Interesting scientific facts

Studies have shown that yeast cells are very similar to human cells. But while our bodies have tens of billions of cells, yeast only has one.

Man, as scientists say, is a eukaryotic organism. In simpler terms, this means that all of our genetic material is contained in the cell nucleus and mitochondria. According to the same principle, nature created yeast, but bacteria are already representatives of prokaryotic organisms. And due to the fact that yeast is single-celled, it is easier for scientists to study their structure, properties and life stages. And from the point of view of structure, metabolism, of all biological models, it is yeast that is closest to a person. In addition, this fungus is the first eukaryotic microorganism whose genome scientists have deciphered by studying the exact sequence of all its 16 chromosomes.

The importance of the study of these microorganisms is also evidenced by the fact that over the past 15 years the Nobel Prize in Medicine and Physiology has been awarded twice to researchers of yeast. Using human genes in the study of the fungus, scientists test the effectiveness of new drugs, study the specifics of certain diseases.

Most of the research has focused on the potential use of yeast in the health care and food industries. Meanwhile, scientists conducted other experiments. For example, not so long ago it became clear that some of the yeast strains can serve as the basis for the creation of biofuels for transport. By the way, a significant proportion of the insulin created by chemists to treat diabetes was produced with the help of yeast.

But this is not all that a person has to learn about yeast. This, at least, is convinced by scientists involved in the study of these microsubstances.

The life cycle of fungi

It is worth noting that the development of yeast cells proceeds differently under different circumstances. And although these substances, from the point of view of biologists, are living organisms, they are so unique that they can live without air.

When the yeast does not receive oxygen, it acts on the sugar to convert it into alcohol. In addition, carbon dioxide is released. This process occurs mainly during baking. As a result of this reaction, energy is released - the dough grows. Meanwhile, this energy is not enough for the yeast to continue to live. In the presence of oxygen, they, nourished by sugar, grow and multiply very quickly, releasing carbon dioxide, water and a relatively (by the standards of a fungus) huge amount of energy.

"Good" and "bad" yeast

Yeast, like bacteria, is necessary for the human body. But the first thing that is important to know about these microorganisms is that there are good and bad bacteria, and similarly with yeast. The fungus can affect organs and tissues, cause allergies and many diseases. Now let's try to understand the types of fungi and understand which ones are useful and which ones should be avoided.

Candida Albicans

Almost 80 percent of the world's population is said to be struggling with this pathogenic yeast-like fungus that causes various inflammations in the body. Candida, like all yeast, is a single-celled organism that multiplies rapidly in the presence of a large amount of sugar in the diet. This fungus robs the body of many nutrients, including iron and other minerals, making the blood acidic. Against the background of a sweet diet, candida is activated even more. If this process is not stopped in time, then harmful yeast will practically destroy the digestive and immune systems, and deprive you of vitality. And in return, they will cause frequent headaches, eczema, dandruff, dermatitis, hormonal disorders, vaginal infections, stomach diseases and confusion.

Beneficial yeast

But besides the bad ones, there are also good yeasts. Fungi found in probiotic foods are best for the body. They strengthen the immune system and help fight candida. But also not the best sources of this yeast are products that contain sugar.

Found in almost all probiotics, S. boulardii yeast has many beneficial properties:

  • strengthens the immune system, stimulates the production of antibodies;
  • protect the body from the harmful effects of antibiotics;
  • helps fight candida.

Another two extremely useful strains of yeast, Kluyveromyces marxianus var. Marxianus and Saccharomyces unisporus. They are contained mainly in kefir sourdough and play the role of a powerful booster for the immune system. Thanks to these components, kefir has been considered one of the best tonic drinks throughout the world for centuries. In ancient times, it was considered the drink of centenarians, and in Turkish its name sounds like "feel good."

Health Benefits

Yeast is a wonderful ingredient that helps maintain or restore health and beauty naturally.

They are found in many foods, dietary supplements, and in many cosmetics.

For many decades, yeast has been the focus of researchers, who unanimously recognize the extraordinary nutritional qualities and therapeutic properties of this fungus. And all - thanks to the unique biochemical composition of these organisms. For humans, they serve as a source of amino acids, minerals, vitamins, enzymes and many other useful substances necessary for growth, proper metabolism and strengthening the immune system.

Benefits of yeast

These microscopic substances are a source of nutrients and fiber, many types of nutritional yeast contain vitamin B12, which is usually eaten exclusively in food of animal origin. In addition, yeast is an excellent source of vegetable proteins, making it an important ingredient in vegetarian dishes. A high concentration of fiber provides a feeling of satiety for a long time. These elements are extremely important for the smooth functioning of the body. They are equally important for humans, animals and even plants.

For plants

The latter are just the object of recent research. As it turned out, yeast can act not only as a food additive, but also as a useful natural fertilizer. Some strains contribute to more efficient absorption of beneficial trace elements by plants from soils. In addition, they affect the growth of plants. At the same time, they are absolutely safe "fertilizer". Now scientists are trying to develop an effective yeast-based drug against mold in fruits and other diseases - as a safe alternative to chemical drugs.

Dietary Supplement

Perhaps no one is surprised by the information that yeast is a useful bioactive supplement used by people to treat and prevent a wide variety of conditions and diseases.


Yeast as a probiotic is a very promising solution. So scientists convince and add that the range of impact on humans of these microorganisms is very wide.

For intestinal flora

Scientists have discovered the relationship between yeast and intestinal microflora, in particular, the positive effect of the fungus on inflamed intestines.


  • brewer's yeast contains many vitamins and minerals, including zinc, chromium, iron, magnesium, folic acid, biotin and B-vitamins;
  • strengthen immunity;
  • normalize blood sugar;
  • promote the development of beneficial bacteria in the body;
  • Torula yeast is a source of chromium, selenium, amino acids and vitamins B ;
  • Baker's yeast strengthens the immune system.

Possible harm to yeast

An unpleasant side effect of taking yeast may be that it feeds not only beneficial bacteria, but also harmful ones, such as Candida, which cause asthma, gout and other diseases. With an exacerbation or occurrence of candidiasis, it is important to exclude all yeast food from the diet for the period of treatment.

Yeast and allergies

Yeast, as already noted, is a form of fungus. Most often used for baking and brewing. In this case, brewer's and baker's yeast are used. But besides them, there is also the so-called wild yeast, which can be found in fruits, berries (grapes) and grains.

Usually these microorganisms are well tolerated by humans, but there are people with intolerance. These are people who are allergic to all types of fungi and mold.

Yeast extract

Yeast extract is a food flavoring used in bread, beer, cheese, soy sauce, and some other foods.

To understand how this substance affects the body, first you need to understand what it is in general.

Yeast extract is produced by mixing yeast and sugar under warm conditions, followed by damage to cell membranes. Such an extract may be in gel or powder form. The use of yeast extract in products may be referred to as "natural flavors" or "additives" on product labels.

It should be known that this extract contains glutamine amino acid. This is the natural form of the amino acid and should not be confused with the dietary supplement monosodium glutamate which serves as a flavor enhancer. And although the yeast extract also affects the taste, it acts like a spice. In addition, it contains a high concentration of sodium. And this should be taken into account for people who have problems with blood pressure or those who, for other reasons, should not abuse sodium. In addition, the extract contains a very high concentration of B vitamins.

But despite all the benefits of this substance, it is important for people with food allergies or sensitivities to yeast to avoid products containing fungus extract. The easiest way to do this is to refuse semi-finished products and ready-made food from supermarkets.

Yeast in food

All products can be divided into 3 groups according to the content of yeast. The first is food that contains fungi under any circumstances. In the second group of products, microorganisms are present only under certain conditions. And the third group is food that does not contain these microorganisms.

The first group includes: baked goods, beer, cider, fruit skins (plums, grapes), grape juice, malt drinks, wine, yeast extract.

The second group includes: cakes, donuts, fruits (overripe), chocolate (some types), soy sauce.

The third group includes a huge number of products from different categories. In particular, you can not worry about the presence of yeast in eggs, seafood, various types of meat, raw nuts, beans, brown rice. You can also avoid excess consumption of yeast if you refuse soy sauce during cooking, and replace vinegar with lemon juice.

List of products containing yeast:


Yeast can interfere with the effectiveness of some medications. It is also important to avoid dietary supplements containing yeast for people who are allergic to the product or prone to yeast infections.

An important note for diabetics: Yeast can lower blood sugar, so it's a good idea to monitor your glucose levels regularly.

How to make yeast yourself

Surely, you wondered what yeast is made of and how this process occurs. Now you will learn how to grow these single-celled mushrooms yourself at home.


Method one. Take 1 glass of water and flour, mix and leave for 7 hours. Then supplement the mixture with a small spoonful of sugar and a glass of live beer (has a shelf life of up to 2 weeks). Leave for a couple of hours. Store prepared brewer's yeast in a glass container in the refrigerator.

Method two. In a glass container, mix 200 g of raisins, milk, warm water and a little sugar. Cover the vessel tightly with gauze (fold in 4 layers and tie). Keep in a warm place for 5 days.

With these recipes, you will create a common nutritional yeast that doctors recommend taking for various diseases. This natural product will help with metabolic disorders, lack of B vitamins, digestive diseases, anemia, atherosclerosis, strengthen the body after colds and infectious diseases. By the way, home-made brewer's yeast is similar in its effect to medications containing these fungi, such as gefefitin.

For baking

Perhaps this happened in every housewife. I wanted to bake pies for dinner, but there is no yeast. But this is not a reason to be upset if you know how to make homemade yeast in the form of a sourdough.

Method 1

Knead a lump of dough from 200 g of flour and a small amount of water, roll in flour and leave for several days. When the lump dries, hardens and becomes sour, it can be used instead of store-bought yeast.

Method 2

Peel and boil 10 potatoes, which are still hot, rub through a sieve. Add a tablespoon of flour, the same amount of honey and 25 grams of vodka. Leave the mixture for 2 days in heat. When a foam cap forms on the surface, you can use the sourdough for baking (take only foam).

Homemade yeast cosmetics

The fact that yeast is an effective ingredient in many beauty products has long been known. But not many people know that yeast cosmetics are easy to prepare on your own. Don't know how to do it? Read our recipes.

Yeast Body Mask

Dilute a bag of dry yeast in cream and add 4 tablespoons of honey to the mixture. Leave for 20 minutes. Apply to the body and leave for 15-20 minutes. Wash off with warm water. This mask improves blood circulation, tightens pores, makes the skin supple and smooth.

Hair product

Dilute a tablespoon of brewer's yeast in a glass of kefir. Leave the mixture in a warm place for several hours. Apply to hair and keep for about half an hour. This mask will get rid of dandruff.

Yeast for the face

Dilute about a teaspoon of brewer's yeast in a small amount of kefir. After the mixture has been infused a little in a warm place, and acquires the consistency of liquid sour cream, apply to the skin of the face and hold for about 20 minutes. This tool relieves acne, improves complexion, suitable for oily skin.

Interesting about yeast:

  1. The optimum temperature for yeast growth is 32.2 degrees Celsius, above 38 degrees the yeast will die.
  2. Some strains of the fungus clump together after fermentation (usually during brewing).
  3. Dry yeast was invented by the Romans (however, as often happened in the history of the discovery of great things, they did not yet understand that it was dry yeast). The ancients put baker's yeast (in dough) in the sun, dried it, and when necessary, "revived" it with sugar.
  4. The aroma of beer is determined by the yeast.
  5. There are more than half a thousand types of yeast.
  6. Back in 1200 BC. e. knew how to bake yeast products.
  7. Hops, whey, various herbs, oranges, grapefruits, honey drink can serve as raw materials for yeast.
  8. In laboratory conditions, about 100 tons of yeast milk can be grown in 2 weeks (then pressed, liquid, dry yeast is made from it).

Many people ask the question: "Yeast is fungi or bacteria." And there is nothing strange in this, because until relatively recently, scientists themselves did not know the answer to this question. Today, there are other discussions about how safe it is to take yeast. And again, the answer is banal simple: safe, if in moderation.