Zeism is any condition attributed to excessive use of maize (corn) in the diet, such as pellagra, because maize is low in zinc, niacin and tryptophan, and the limited niacin found in maize is not assimilated in the intestinal tract unless it has been treated with alkalis, as in the preparation of tortillas. A type of pellagra attributed to amino acid imbalance is common in India among persons who eat a millet with a high leucine content. The deficiencies are usually seasonal.