For 42-year-old Percival Smith,
the long list of foods he's supposed to avoid in order
to appease his irritable bowel is akin to a jail sentence.
"No alcohol, no cream, no coffee" laments the pastry chef,
"and who knows if it will do any good." Indeed, restrictive
diets aren't necessarily successful in eliminating the
foods that trigger irritable bowel syndrome (IBS). This
is partly because, up to now "tests attempting to predict
food sensitivity in IBS have been disappointing and none
have utilized IgG antibodies," according to the authors
of a paper published in the October issue of Gut.
Dr Peter Whorwell and colleagues from the University of
South Manchester, UK, report that the elimination of food
based on IgG antibodies markedly reduced symptoms in people
suffering from IBS.
 The
150 IBS patients involved in the study were randomly
selected to either dine for three months on a "true
diet" or a "sham diet." The true diet cut out all foods
that stimulated the production of IgG antibodies, as
detected using enzyme-linked immunosorbent assay, while
the sham regime cut out the same number of foods but
not those that put IgG production into high gear.
The researchers analyzed changes
in IBS symptoms in the two groups, as well as looking
at symptoms in other parts of the body, quality of life
measurements, and the occurrence of anxiety or depression.
After the dieting days were done,
the folks who stuck fairly close to the true diet had
a 10% greater reduction of their symptom scores, compared
to their counterparts on the sham diet. Those eager
beavers who religiously adhered to the IgG-free regime
did even better, registering a whopping 26% reduction
in their symptom scores.
Go
with your gut
Folks who followed the immune-friendly diet were also
healthier on the whole, as seen using a number needed
to treat (NNT) rating index, which assessed the efficacy
of the IgG-free diet. The index reading for those on
the "true diet" (NNT 9) stacked up very well when compared
to the reading for patients who were treated for three
months with tegaserod (NNT 17), a drug recently licensed
for use in IBS. Even better, those who fanatically stuck
to the diet had an even more impressive score (NNT 2.5).
This indicates that a restrictive diet is even more
successful at minimizing the effects of IBS than tegaserod.
So although giving up goodies may
irritate patients, their bowels did behave. Human nature
being what it is, however, some of those on the true
diet could not stick it out, and began to chow down
on foods that perturbed their immune systems. For those
who fell off the wagon, the cost was a reappearance
of some of the IBS symptoms.
Dr Whorwell and his colleagues
conclude that "food elimination based on IgG antibodies
may be effective in reducing IBS symptoms and is worthy
of further research." This is great news for IBS sufferers
who want to seize control of their own treatment. Relief
could be found on the shelves of the supermarket instead
of the drugstore, provided that they come armed with
an IgG-friendly grocery list. Moreover, write the authors,
the economic benefits from fewer doctor's visits and
prescriptions "are obvious."
"It's well known that patients
expend large sums of money on a variety of unsubstantiated
tests in a vain attempt to identify dietary intolerances,"
say the authors. This is not to say that diet is the
be-all-and-end-all. "IBS is multifactorial so food is
not the whole answer," says Dr Whorwell. But the right
diet goes a long way. "When a patient responds to the
diet the [improvement] does not wear off," says Dr Whorwell.
"However, other factors can still make patients worse."
All in all, "the findings... should
encourage studies dissecting the mechanisms responsible
for IgG production against dietary antigens and their
putative role in IBS. This may serve not only IBS research
but also that into allergy and allergic diseases," writes
the Finnish pediatrician Dr Erika Isolauri in an editorial
accompanying the Gut paper.
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