Tannin covers a large group of substances and is not uniform from one food or plant to another. As tannins have reduced water solubility, the amount of tannins in our food extracts is not high and varies with the ripeness of the fruit. So you cannot relate or correlate reaction to tannin to the proper reaction of a tannin containing food. We use synthetic tannic acid in our tests. Sensitization is more likely due to exposure to added tannic acid in either drugs, creams, or transformed food. The advice is to reduce tannic rich food. The risk for adverse reaction of this patient´s immune system is probably more to added tannic acids in products rather than in naturally complex tannin containing foods. If you are uncertain about tannin in foods, we recommend consulting a nutritionist.