An allergy to baker's yeast is fairly rare, but sometimes it goes undiagnosed for many years or is misdiagnosed as an intolerance or allergy to gluten. Baker's yeast allergies are rarely confined to the few species used to cause bread to rise. More often, a baker's yeast allergy is also triggered by brewer's yeast and environmental molds and fungi. Apple cider vinegar doesn't contain baker's yeast, but it may contain remnants of brewer's yeast. As such, be cautious using apple cider vinegar and other fermented products if eating bread triggers an allergic response. Ask your doctor about methods of allergy testing.
Yeasts are a form of fungi. The most common yeast species used for baking are Saccharomyces cerevisiae, S. ellipsoideus and S. minor. Yeast is added to cause dough to rise; yeast consumes sugar in the flour and produces carbon dioxide gas. In contrast, dough baked without yeast produces flat bread. Baker's yeast is similar to brewer's yeast, which is used to ferment grains and fruits in order to produce beer, wine and apple cider vinegar. Consuming baker's yeast cannot lead to yeast infections of the gastrointestinal tract or vagina, which are most commonly caused by a different species known as Candida albicans. However, it's possible to be allergic to baker's yeast.
Although not common, it's possible to have an Ig-E mediated allergy to yeast, which is a response triggered by the immune system. Those who have a yeast allergy are likely to be affected by all species, including the types used by bakers and brewers as well as environmental fungi and molds. Getting a skin test from your doctor can give you better idea of what yeasts, molds and fungi cause your allergy. Common symptoms include swelling of the face, mouth and throat; trouble breathing; hives; nasal discharge and fatigue. Foods that contain baker's yeast include bread, pizza dough, yeast extract and some vitamin supplements.
Apple Cider Vinegar
Apple cider vinegar is made by fermenting apple cider with bacteria and brewer's yeast. The yeast eats the fructose in the apples and leaves behind alcohol that bacteria turn into acids. The end product is high in acetic acid and vitamin C, which typically kill the microbes in the vinegar, but it's possible that some remaining components of the yeast, such as cell walls, can trigger an allergic reaction. Other commonly consumed products that contain brewer's yeast include beer, wine, grain alcohol, soy sauce, cider and malt.
It's possible to be allergic to baker's yeast but not other types of yeast, mold or fungi. If that's the case with you, then eating a piece of bread will produce an allergic response while drinking beer or apple cider vinegar won't. On the other hand, you may be allergic, or at least hypersensitive, to all products that contain yeast. If this is the case, then you must eliminate all foods and drinks containing yeast from your diet, which is no easy task. Consult with a nutritionist about the widespread use of yeast in foods, condiments and beverages.