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Lactose: Nutritional and health considerations |
E. N. ALCANTARA, Nutrition & Regulatory Affairs, Dairy Council of Wisconsin, Inc., 999 Oakmont Plaza Dr., Ste. 510, Westmont, IL 60559 Lactose is the primary carbohydrate in mammalian milk. It is a disaccharide composed of glucose and galactose. Lactose is usually the first carbohydrate every newborn mammal consumes in significant amounts. Milk from various species ranges in lactose content from 2.1% to 7.4%. Human milk is at the upper end of the range, with an average content of 7.1% lactose, while cow's milk averages about 4.8%. Whey, a byproduct of cheesemaking, is a major source of lactose. The typical range is 63-75% lactose in dry sweet-type whey, and 61-70% in dry acid-type whey. Lactose has several nutritional properties. It serves as a source of energy; enhances mineral absorption especially in the young; serves as a prebiotic, encouraging the growth of beneficial bacteria; has a relatively low glycemic index which makes it beneficial for diabetics; and has low cariogenicity compared to other sugars. Most of the health interest surrounding lactose focuses on a clinical condition known as lactose intolerance. This condition is diagnosed when a test dose of lactose is incompletely digested because of a deficiency in the enzyme lactase, resulting in gastrointestinal symptoms. The usual test dose is 50g lactose in aqueous solution, which is equivalent to the amount of lactose in one quart of milk. For many individuals, there is a natural decline in the level of lactase with age. It has been estimated that up to 75% of the world's adult population (approximately 25% of American adults) has a reduced level of this enzyme. However, research has shown that even with reduced lactase levels, most individuals can handle the usual amounts of lactose in the diet without any problem. Several strategies for managing low lactase levels will be discussed.
Session 36, Whey products and lactose: Properties and applications
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