There is provided in accordance with embodiments of the invention a method of treating or reducing the effects in a subject of a condition selected from fructose intolerance and impaired fructose metabolism, the method comprising administering to a subject in need of such treatment or reduction an efficacious amount of a glucose isomerase, other than in combination with 5-D-fructose dehydrogenase. Other embodiments are also disclosed. There is provided a method for treating or reducing the effects of fructose intolerance and health problems associated with excessive fructose intake by administration of glucose isomerase. Other embodiments are also disclosed.
