A condition known as lactose intolerance is characterized by painful abdominal cramping, gas, and diarrhea. The cause of the problem is an inability to digest the milk sugar, lactose. How would this cause the observed symptoms? Why is yogurt less likely to trigger the symptoms?
What will be an ideal response?
If an individual cannot digest lactose, then the sugar will pass through to the large intestine in an undigested form. The presence of the extra sugar in the chyme increases the osmolarity of the chyme, resulting in less water being reabsorbed by the intestinal mucosa. The bacteria that inhabit the large intestine can metabolize the lactose, and in the process they produce large amounts of carbon dioxide. The gas overstretches the intestine, which stimulates local reflexes that increase peristalsis. The combination of more fluid contents and increased peristalsis produces the symptom of diarrhea. The overexpansion of the intestine by gas causes the severe pain and abdominal cramping, and of course, the increase in intestinal gas release is directly related to increased gas production by the bacteria. Yogurt contains bacteria that digest the lactose prior to the consumption of the yogurt.
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