Lactose intolerance is a condition characterised by a deficiency in the production or secretion of lactase. This is nutritionally relevant because lactase is required for the digestion of lactose, the main disaccharide found in milk and other dairy products. Inability to digest lactose results in the sugar passing to the large intestine, when bacterial fermentation results in the formation of hydrogen gas that then causes bloating and gastrointestinal discomfort. The traditional and most preferred method of treating lactose intolerance is to avoid products containing lactose, thereby avoiding the cause of the symptoms. However, lactose intolerance appears to have a graduated severity, whereby some individuals show increase tolerance compared to others. Therefore a number of strategies have been suggested to allow consumption of dairy in some individuals with lactose intolerance. Research suggests that some of these solutions may provide some relief to those with mild lactose intolerance.
One method of decreasing gut problems associated with lactose intolerance is to consume an exogenous source of lactase with the dairy product. Lactase is available in tablets, and the consumption of lactase in supplemental form can relieve the gastrointestinal symptoms in some individuals. Yoghurt also contains an exogenous source of lactase which may aid digestion of some of the lactose present. Sweet acidophilus milk, a product that combines milk with the bacteria Lactobacillus acidophilus has also been investigated for its beneficial effects because it contains lactase. Alternatively, milk that has been pre-hydrolysed to convert the lactose to galactose and glucose can also be consumed, thereby avoiding the consumption of lactose altogether. A study comparing the effects of these products on 10 lactose intolerant individuals was published in the American Journal of Clinical Nutrition in 19891 by direct comparison through feeding subjects each of the products and then measuring hydrogen production and discomfort.
The results of this study showed that the hydrogen produces in the breath for the yoghurt, sweet acidophilus milk, lactase tablet, hydrolysed lactose milk and untreated whole milk were 12, 37, 29, 18 and 33, respectively. Therefore consumption of yoghurt as a source of dairy was as effective as lactase pre-treated milk in the relief of symptoms. However, when the subjects were asked for their opinion on the most palatable of the products, consumption of yoghurt was graded as the least favourite of all products. Lactase tablets showed a minor improvement over consumption of untreated whole milk, but the improvement was not substantial. The reason exogenous yoghurt lactase is more effective than lactase tablets may be due to the loss of lactose from yoghurt during fermentation, where 40 to 50 % of the lactose may by hydrolysed, thus reducing the amount of lactose available for fermentation in the gut upon consumption. .
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