Dr R. J. Schmidt, MRPharmS
SIR,—I am not sure that Mr D. J. Morl (PJ, October 14, p557),
nor indeed Mr W. J. Bowler (PJ, September 30, p482),
are correct in their belief that the idea that detergent consumption can be
harmful is novel. And on the basis of comments made by Mr D. J. Marl, I would
say that it is he who is the “flat-earther” in this debate.
I recall having a conversation regarding detergent consumption and ill health
with my sister-in-law soon after she left university with a degree in nutrition.
The relevant point here is that the conversation to which I refer dates back
to the mid-1970s. The reason why we were discussing this topic was because I
had read somewhere a report linking detergent consumption with either Crohn’s
disease or coeliac disease, I cannot now remember the detail, nor indeed whether
the report referred to an hypothesis or to an observed correlation.
We should recall that we all produce bile which passes from the liver through
the bile duct into the duodenum. Bile contains bile salts. These bile salts
are detergent molecules which our digestive system uses to solubilise fats.
I would imagine that traces of washing up liquid residues in a meal would not
in themselves add significantly to the total amount of detergent present in
the small intestine after a meal and therefore the total amount of fat we absorb
from a meal. So perhaps Mr Bowler should not worry unduly about increased fat
absorption.
Two further questions remain. Firstly, detergents are not all identical in their
solubilising ability nor in their mammalian toxicity. Many detergents in sufficient
concentration will lyse mammalian cells; others do not. A good deal of research
now suggests that other more specific mechanisms of toxicity (such as to molluscs)
are exhibited by some plant-derived saponins, which are natural detergents.
So, the question I would like to have answered is: Do the detergents used in
washing up liquid cause any damage of any sort to the lining of the gut? And,
if so, does a chronic low-grade insult to the lining of the gut lead eventually
to disease?
The second question again relates to background science I have read but for
which unfortunately I cannot quickly provide a literature reference. This background
science dates back to the earliest days following the discovery of insulin when
attempts were being made to develop an oral delivery system. The strategy being
explored was to co-
administer the insulin (a protein) with a detergent to facilitate absorption.
As I recall, insulin could be delivered intact by this method, but the clinical
outcome was so variable that the work had to be abandoned. Nevertheless, this
ties in to literature on plant-derived saponins in older pharmacognosy text
books which asserts that such saponins can facilitate absorption of substances
that would not otherwise be absorbed — a toxifying effect. So, if some
detergents are able to facilitate absorption of intact proteins, and if our
gut wall is immunologically competent, it follows that we should expect to see
a rising incidence of immunologic disease of the gut. Coeliac disease does seem
to be on the increase in the middle aged.
I have always rinsed the detergent off when washing up; and have preferred not
to use the dishwasher at home because I know too little about the extent to
which rinse aids succeed in aiding rinsing, and nothing about the chemical nature
of brighteners we are urged to use.
Richard J. Schmidt
Barnoldswick
Lancashire