Metabolism
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Bloating, flatulence and diarrhoea after drinking milk - but not yogurt or cheese
Abdul is a 25 year old doctor from Sudan; he came to London to study for a PhD 6 months ago and has suffered from diarrhoea and flatulence since arriving, although in Sudan he rarely suffered from gastrointestinal upsets of any kind. His diet is not very different from what he ate in Sudan, but he has been introduced to taking milk in his tea and coffee. At first he thought this was strange, because he remembered his grandfather telling him that when he was constipated he drank a glass of the milk that his grandmother was about to use to make yogurt.
Since his
diarrhoea was worrying him, he went to see a gastroenterologist, who sent him
for a lactose tolerance test. This involved coming in to outpatients in the
morning, not having eaten or drunk anything since the night before, drinking
a solution containing 50 g of lactose, then measuring the increase in blood
glucose over 3 hours. Within about half an hour of drinking the lactose solution
he suffered painful abdominal cramps, and "explosive" watery diarrhoea
with abdominal bloating and severe flatulence.
The results of the lactose tolerance test are shown below, with Abdul's results in red and the mean and standard deviation for 10 control subjects in blue.
What conclusions can you draw from this graph?
It is obvious that there is no rise in blood glucose at all after Abdul has drunk the lactose solution. This suggests that he lacks the enzyme lactase, and so cannot hydrolyse lactose to glucose and galactose.