It is known that in milk sugar present in higher quantities is lactose, a disaccharide consisting of one glucose molecule and a galactose. Lactose, for a small part of the population, can cause a lactose intolerance, due to a deficiency of the enzyme lactase which, in some cases, the human body no longer is able to synthesize it after weaning. In most cases, the deficiency is due to a prolonged abstention of milk and dairy products in the diet and can be gradually reintroduced over time.

It should be noted that the lactose in the medium and long maturing cheeses is almost non-existent, since it constitutes elective fermentation substrate for the lactic acid bacteria both during the milk-processing process in the process of cheese ripening. Pecorino Toscano PDO, like other aged and semi-aged cheeses, has no appreciable lactose content. A recent survey commissioned by the Pecorino Toscano PDO Protection Consortium showed that the content of lactose in fresh pecorino is around 0.4 g / 100g of cheese, while it is absent in mature specimens more than four months old, as reported in the label.