Acquired lactose intolerance may occur due to a sudden and high intake of milk-based diets. Lactase is an inducible enzyme.

So if lactase is an inducible enzyme then why increase intake of lactose is causing negative effect? Why more lactase isn't produced in more lactose intake conditions?


Searching for the quote you included led me to the original source.

I wouldn't spend too much time worrying about this particular source, and look at some other sources for more information on acquired lactose intolerance. I think there may be some translation/language issues with this section in this particular source. I believe what the author is trying to convey is not that the intolerance is coming from the increased intake, but that the symptoms of intolerance are coming from a sudden increase in lactose intake following a period of low/no lactose intake, where "sudden" essentially means "faster than lactase induction can occur."

That said, I think this is really more an issue of poor wording in a textbook. The whole section is a bit strangely worded, particularly the part on "flatulence" which this author describes as "characterized by increased intestinal motility, cramps, and irritation" - while these issues may certainly accompany flatulence, this definition of these symptoms characterizing flatulence is not correct, as one can certainly have flatulence with normal intestinal function.

  • $\begingroup$ You are right about the source. Iam currently reading that book. Could you please suggest a better book? $\endgroup$
    – JM97
    Dec 27 '16 at 16:55
  • 1
    $\begingroup$ For biochemistry in general, or for lactose intolerance in particular? For the former, I just looked quickly and found a syllabus from my current institution using this book for an upper-level undergraduate/low-level graduate biochem course. Full disclosure: the textbook authors appear to be the instructors in that course, though I have no personal connection to those instructors or their department besides sharing a university. For the latter, I would suggest a scientific review article rather than a book. $\endgroup$
    – Bryan Krause
    Dec 27 '16 at 17:01

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