When a person suffers from yeast allergy, his immune system is not able to react normally to the yeast protein. The immune system fails to recognize the yeast protein as a type of food protein, and mistakes it to be some harmful foreign body. As a result, it produces antibodies called immunoglobulin E (IgE), which attack the yeast proteins. They do this by attaching themselves to mast cells (type of white blood cells), which release chemicals called histamines, on contact with yeast proteins. The presence of these histamines in the bloodstream causes the allergic reactions we see.
Baker’s yeast, brewer’s yeast, natural yeast, etc. are known to cause yeast allergies. Moreover, C. albicans can also act as a potential allergen, however, this is very rare. Moreover, the role of C. albicans in allergic reactions is not still clear.
Yeast allergy symptoms generally develop after a few minutes or hours of yeast consumption or inhalation. The mild reactions are seen to last for not more than a day. Some of the commonly observed symptoms are as follows:
- Nasal congestion
- Runny nose
- Sore throat
- Itchy eyes and nose
- Teary eyes
- Skin rash
- Abdominal pain
- Puffy eyes
- Abdominal cramps
A severe allergic reaction known as anaphylactic shock (type of anaphylaxis) can even be life-threatening and result in death.
The British Allergy Foundation considers the skin prick testing (SPT), RAST blood tests and patch testing, as the only reputable methods of testing for allergies. The skin prick test involves exposing a small portion of the skin, to a small amount of yeast extract. If the person is allergic to yeast, allergic reactions like hives, skin rash, diarrhea, swelling of the face, tongue, etc. may occur. However, food allergies taking place due to less production of enzymes, which are responsible for its proper digestion, are difficult to detect using a prick test. They have to be identified solely by a food elimination diet.
Since a large number of food items contain yeast, one should start off with a simple diet, and then add yeast-containing food items one by one. Look out for symptoms like stomach aches, diarrhea, skin rash, etc. Go slow, so that identifying the allergy-causing food item becomes easier. If you find allergen number 1, wait for the allergic reactions to stop completely, before testing it again.
Yeast is added to various food items for fermentation purposes, especially in the form of baker’s and brewer’s yeast. Baked foods contain baker’s yeast, while beverages like beer, alcohol, wine, etc. contain brewer’s yeast. A person can be be allergic to baker’s yeast, yet not be allergic to brewer’s yeast. Thus, identifying it is possible only by the elimination diet plan.
Baker’s yeast (Saccharomyces cerevisiae)
Bread, pizza bases, muffins, etc. undergo the baking process, which kills the yeast, however, the allergy-causing components of the yeast still remain, which is why people encounter allergic reactions on consuming these baked items.
✦ Bread (even multigrain breads)
✦ Sourdough bread
✦ Cakes (sometimes)
Brewer’s yeast (Saccharomyces cerevisiae)
Brewer’s yeast does not undergo any kind of heat treatment, which is why the yeast in wine and beer, are still alive. This is the reason why most people are allergic to brewer’s yeast, as compared to baker’s yeast.
✦ Apple cider vinegar
✦ Barley malt or malt vinegar
✦ Vitamin B dietary supplements
Other Yeast-containing Food Items
Besides baker’s and brewer’s yeast, there also exists various other forms of yeast which are present in several other food items. Packaged and processed foods have yeast, thus, it is important to check the label. However, there also exists natural yeast in fruits, especially grapes and plums.
✦ Fruit juices (high sugar content)
✦ Dried fruits
✦ Strawberries and tomatoes
✦ Soy sauce
✦ Instant soups
✦ Potato chips
✦ Cured meats
Treatment involves medicines and topical applications to reduce associated symptoms. One will have to prevent if from occurring again, by consuming a yeast-free diet. Although yeast allergy narrows down your eating options, it does have its advantages. Yeast allergy helps keep the waistline in check. Because yeast allergy diet is directly linked to a low-carb diet, the person steers away from unwanted carbs that cause weight gain.