The high purine content of brewer's yeast makes it unsuitable for people with gout, kidney disease, or arthritis. About 20 percent of the crude protein nitrogen in yeast is in the form of purines. If consumed in large amounts - more than three tablespoons of nutritional yeast daily - these purines can cause problems in anyone, since a high intake can result in elevated blood levels of uric acid. When blood levels of uric acid are high, it tends to crystallize and precipitate in joints, where it can cause gout or arthritis. In addition, high levels of uric acid in the bloodstream stress the kidneys.
Since the chromium-niacin combination found in chromium-enriched brewer's yeast may affect blood glucose and insulin levels, people with diabetes or hypoglycemia should consult their doctors before supplementing their diets with these forms of brewer's yeast.
Some people may be allergic to brewer's yeast. In a study using an elimination diet to treat 60 migraine patients, brewer's yeast was found to be one of the foods likely to contribute to the initiation of a migraine.
Brewer's yeast is not related to Candida albicans, the typical culprit in vaginal yeast infections in women. The nutritional and chemical profile of brewer's yeast depends on the medium on which it was grown. Therefore, purchase organic brewer's yeast when possible.