Several researchers (1, 2, 3, 4) have reported a significant improvement in lactose digestion and a virtual elimination of maldigestion symptoms when yogurt is the source of lactose. Although yogurt may contain more lactose than milk (depending on the addition of milk solids to improve texture and viscosity), the lack of maldigestion symptoms is believed to be due to the lactase activity of the bacteria in the yogurt cultures (3). Since pasteurization destroys lactase activity, only yogurt containing a live bacterial culture appears to be well tolerated by lactose maldigesters (5). This means the culture has to be added after pasteurization, which is the case for all yogurt made in B.C. (6). Lactase is also sensitive to freezing. Frozen yogurts, as currently manufactured, may have little enzyme activity (6, 7) and therefore are less likely to improve digestion. It may be particularly important to improve lactose digestion in the elderly, since lactase activity declines with age. The results of a Spanish study (8) indicated that lactose digestion in the elderly improved considerably with yogurt.
(1) Devit O., P. Pochart, J.F. Desjeux.1988. Breath hydrogen concentration and plasma glucose, insulin and free fatty acid levels after lactose, milk, fresh or heated yogourt ingestion by healthy young adults with or without lactose malabsorption. Nutr.4:131–135.
(2) Kolars J.C., M.D. Levitt, M. Ajouji, D.A. Savaiano. 1984. Yogurt - an autodigesting source of lastose. New Engl.J.Med. 310:1–3.
(3) McDonough F.E., A.D. Hitchins, N.P. Wong, P. Wells, C.E. Bodwell. 1987. Modification of sweet acidophilus milk to improve utilization by lactose-intolerant persons. Am. J. Clin. Nutr. 45 570–574.
(4) Murao K., K. Igaki, H. Hasebe, T. Kaneko, H.Suzuki.1992. Differences in breath hydrogen excretion and abdominal symptoms after ingestion of milk and yogurt by lactose intolerant individuals. J. Jap. Society of Nutr. & Food Sc. 45:507–512.
(5) Savaiano D.A., A. Abou El Anouar, D.E. Smith, M.D. Levitt.1984. Lactose malabsorption from yogurt, pasteurized yogurt, sweet acidophilus milk, and cultured milk in lactase-deficient individuals. Am.J.Clin.Nutr. 40:1219–1223.
(6) Astro Dairy Products, Dairyland Foods, Foremost Foods, Island Farms, Lucerne Foods, Olympic Dairy Products. 1994. Personal communication.
(7) Martini M.C., D.E. Smith, D A. Savaiano.1987. Lactose digestion from flavored and frozen yogurts, ice milk, and ice cream by lactasedeficientpersons.Am.J.Clin. Nutr.46:636–640.
(8) Varela-Moreiras G., J.M. Antoine, B. Ruiz-Roso, G. Varela. 1992. Effects of yogurt and fermented-then-pasteurized milk on lactose absorption in an institutionalized elderly group. J.Am.College Nutr.11:168–171.