Date: January 2005
I understand that hormones cannot be taken as pills as
they are made up of proteins that would be broken down into amino acids
by the amylase in the mouth- this is why diabetes sufferers have to
inject themselves with insulin not take a pill, but why is it
possible to take a birth control pill that contains estrogen and progesterone?
A couple of comments:
Firstly, proteins are not affected by salivary amylase. They are broken
down by the enzymes trypsin and chymotrypsin in the stomach, and their
digestion continues in the duodenum. Amylase hydrolyzes starch, a
Secondly, not all hormones are proteins. In fact, estrogen and
progesterone are steroids, which are lipid derivatives. These
relatively small molecules are not broken down by digestive enzymes and
they are absorbed fairly quickly by body tissues.
Estrogen and progesterone are not proteins so they are not broken down by
digestive enzymes (proteases) like pepsin and trypsin in the stomach and
intestine. By the way, amylase is an enzyme that breaks down starch, not
protein. The molecular weights of hormones like estrogen and progesterone
are approximately 400 daltons so they are easily absorbed by the stomach
and intestine. In contrast, the molceular weight of insulin is around
5,000 daltons, which is too big to be absorbed before is is broken down to
individual amino acids which have molecular weight of ranging from 100
-200 daltons. A dalton is the equivalent mass of one hydrogen atom.
Ron Baker, Ph.D.
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Update: June 2012