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Powdered Meal Replacements Increase Gas in Lactose-Intolerant

What the Study Showed
How It was Done
Why It's Important

What the Study Showed

People who have difficulty absorbing lactose, the natural sugar in milk, may experience a large increase in flatulence when they try to lose weight with meal replacement drinks such as Slim-Fast. There is a significant difference, however, between the powdered forms that consumers mix with milk and the ready-to-drink canned varieties. Massive increases (up to four-fold) in both the frequency and the volume of flatulence resulted from consuming the reconstituted powder supplements, whereas the ready-to-drink form caused only minor problems.

This was the finding of two studies, conducted at the University of Minnesota, which are summarized in a 2001 article in the Journal of the American Dietetic Association. Adding over-the-counter lactase preparations to these products and leaving them overnight will markedly reduce their lactose content, the researchers say.

How It was Done

Ten healthy, lactose-intolerant women ranging in age from 24 to 49 volunteered to participate in these studies. For comparison, the subjects kept a symptom diary first while on their regular diets, and then while taking part in the studies. As an additional measure of intestinal gas, their breath hydrogen levels were measured every hour for eight hours after they consumed the meal replacement drinks.

On the first test day, each woman consumed one of two preparations on waking: vanilla flavored powdered Slim Fast dissolved in fat-free milk, or a soy powder dissolved in lactose-free, low-fat milk that was prepared by adding Lactaid and refrigerating the mixture for 48 hours. They drank a second serving of the same supplement at noon, and consumed no other food during the day.

For the second study, the women consumed fruit-based supplements with or without added lactose or ready-to-drink milk-based preparations that were either untreated or treated overnight with Lactaid. The second study confirmed the results of the first--that it was the supplements' lactose content, rather than some other component of milk, that produced flatulence. Two doses of the ready-to-drink supplements contained only 18.4 grams of lactose, as compared to 27.4 grams for the powdered form.

Why It's Important

An estimated 50 million Americans try to lose weight each year, and 11% to 21% use meal replacement supplements to do so. Because approximately 25% of adult Americans have trouble digesting the lactose in these products, this translates into considerable numbers of people who have trouble with flatulence.

Dieters can virtually eliminate this problem either by using the ready-to-drink rather than powdered forms of these supplements, or by pre-treating either type overnight with an added lactase product such as Lactaid. This treatment will add about 8 cents to the cost of each serving.


Date Published: 04/30/2002
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