Dennis A. Savaiano, Ph.D. Professor and Dean of College of Consumer and Family Sciences Foods and Nutrition
Purdue University 700 W. State Street Room 110 Stone Hall West Lafayette, IN 47907-1260 Phone: (765)494-8210 Email: savaiano@purdue.edu
EDUCATION BACKGROUND
B.A. in Biology at Claremont McKenna College Claremont, CA in 1975
M.S. in Nutrition at University of California at Davis in 1977
Ph.D. in Nutrition at University of California at Davis in 1980
DISCOVERY
Adequate calcium intake in the US diet depends on dairy food consumption. Dairy foods account for approximately 3/4 of the calcium consumed in the US diet. Approximately 1/4 of the US population and 3/4 of the World population maldigests lactose, due to a genetically controlled loss of intestinal lactase activity post weaning. Among this population of maldigesters, dairy food consumption is often limited due to perceived and real symptoms resulting from intake.
Our research group has studied numerous factors which influence lactose digestion and tolerance including lactose load, gastric and intestinal transit, the use of lactose digestive aids, colon fermentation of lactose and the consumption of fermented dairy foods and lactic acid bacteria. Major findings from these studies include: (1) The identification of a microbial lactase in yogurts that assists lactose digestion in the intestinal tract following the consumption of yogurt. (2) The characterization of the amount of lactose required to cause symptoms in lactose maldigesters, being 12g or more of lactose (one cup of milk). (3) The finding that lactose consumed with a meal is tolerated about 3 times better than lactose consumed in a fasted state. (4) Identifying the colonic flora as key in determining tolerance to lactose. The colonic flora readily adapts to lactose in the diet of maldigesters. Thus, maldigesters who routinely consume lactose have less symptoms due to more efficient metabolism of lactose by the colon microflora. (5) The identification of a population of digesters and maldigesters who believe that they are extremely intolerant to lactose, but who tolerate lactose quite well in double-blinded clinical trials. (6) The characterization of the ability of lactic acid bacteria including acidophilus and bifidus to improve lactose digestion in vivo in the gastro-intestinal system.
The results of these studies, conducted over the past 20 years, indicate that almost all maldigesters can consume significant amounts of dairy foods without experiencing symptoms of intolerance. Yet, a substantial group of maldigesters continue to believe that dairy foods, consumed in even small amounts, will result in gastrointestinal distress. Work in our lab is currently aimed at understanding why these maldigesters have developed a strong belief that is not supported by blinded, clinical trials. Further, we are interested in methods of intervention that will allow "lactose intolerant" individuals to learn that they can consume dairy foods without experiencing gastrointestinal symptoms. We continue to assess lactose digestion and tolerance in special populations such as adolescent women. Finally, we are working with the dairy industry to attempt to develop food products that are well tolerated by the lactose maldigester.
Discovery Publications (selected)
Matlik, L., Savaiano, D., McCabe, G., VanLoan, M., Blue, CL., Boushey, Carol. Perceived milk intolerance is related to bone content in 10-13-year-old female adolescents. Pediatrics. 2007; Vol 120, Iss 3, pp E669-E677.
Savaiano, D.A., Boushey, C.J., McCabe, G.P. Lactose Intolerance Symptoms Assessed by Meta-Analysis: A Grain of Truth That Leads to Exaggeration. J. of Nutr. 136: 1-7, 2006.
Pribila, B.A., Hertzler, S.R., Martin, B.R., Weaver. C.M., Savaiano, D.A.
Lactose digestion and tolerance among African-American adolescent girls fed a dairy-rich diet. Journal of the American Dietetic Association. J Am Diet Assoc. 2000; 100: 524-528.
Hertzler, S.R., Savaiano, D.A., and Levitt, M.D. Fecal Hydrogen Production and Consumption Measurements: Response to Daily Lactose Ingestion by Lactose Maldigesters. Dig. Dis. Sci. 1997 42 (2): 348-353.
Suarez, F.L., Savaiano, D.A., and Levitt, M.D. Tolerance to the daily ingestion of two cups of milk by individuals claiming lactose intolerance. Am. J. Clin. Nutr. 1997. 65: 1502-1506.
Jiang, T., and Savaiano, D.A. In Vitro Lactose Fermentation by Human Colonic Bacteria is Modified by Lactobacillus acidophilus Supplementation. J. of Nutr. 1997. 127 (8): 1489-1495.
Mustapha, A., Jiang, T., and Savaiano, D.A. Improvement of Lactose Digestion by Humans Following Ingestion of Unfermented Acidophilus Milk: Influence of Bile Sensitivity, Lactose Transport, and Acid Tolerance of Lactobacillus acidophilus. J. Dairy Science. 1997. 80 (8): 1537-1545.
Jiang, T., Savaiano, D.A. Modification of colonic fermentation by bifidobacteria and pH in vitro: Impact on lactose metaboism, short-chain fatty acid and lactate production, Dig. Dis. Sci. 1997. 42 (11): 2370-2377.
Hertzler, S.R., Huynh, Bao-Chau L., and Savaiano, D.A. How much lactose is low lactose? Journal of the American Dietetic Association. 1996. 96: 243-246.
Hertzler, S., and Savaiano, D.A. Colonic adaptation to daily lactose feeding in lactose maldigesters reduces lactose intolerance. Am. J. Clin. Nutr. 1996. 64: 232-36.
LEARNING
Courses
Freshman Honors Seminar (CFS 190H)
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Contact Information
Foods and Nutrition Purdue University 700 W. State Street West Lafayette, IN 47907-2059
