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Gastroenterologic
Disorders
C. Wayne Weart, Section
Advisor
How much gluten is too much for celiac disease patients?
Key point: There is insufficient evidence to
suggest a definitive threshold of gluten intake for patients with celiac
disease (CD); however, less than 10 mg of gluten daily is unlikely to
cause significant mucosal abnormalities.
Finer points: A systematic review of 13 clinical
trials evaluating CD patients and gluten intake tolerance revealed that
patients who consume more than 200 mg of gluten daily for a minimum of 4
weeks are likely to develop intestinal changes. Only three randomized,
controlled trials were identified in this review.
Overall, studies were conducted
in four continents and assessed gluten intake ranging from 1 to 200
mg/day for periods of 1 week to 8 years. Endpoints varied and included
quality of life, mucosal histology, and symptoms. Investigators were
unable to conduct a meta-analysis because of the significant
heterogeneity in study design, quantity of gluten ingested, length of
gluten exposure, and assessment of gluten effects among the clinical
trials.
What you need to know: CD is defined as a permanent intolerance
to gluten. Patients with the disease can present with irritability,
abdominal pain, diarrhea, constipation, or malnutrition and histologic
abnormalities of the small bowel mucosa. CD is considered an autoimmune
disorder and results in nutrient malabsorption when gluten is consumed
and clinical and histologic improvement when gluten is avoided. Gluten
is a protein found in barley, rye, and wheat. Treatment for CD consists
of avoiding gluten, which may be difficult for some patients.
CD appears to be greatly
underdiagnosed. U.S. prevalence of the disease has been estimated as 1
per 105 in the general population, while the prevalence in at-risk
groups such as first-degree relatives of CD patients was 1 per 22. CD
can affect persons of many ethnic backgrounds but is uncommon in those
of Chinese, Japanese, or Afro-Caribbean descent.
Controversy exists on what
constitutes a gluten-free product. According to the Codex Alimentarius
Commission, which sets international standards for food, gluten-free
products should contain fewer than 20 mg/kg (20 ppm) of the protein.
According to the authors, however, this limit may not be low enough for
some patients, depending on how much of the products patients consume.
Naturally gluten-free products may contain soy, corn, or
rice.
Studies included in the
systematic review had small sample sizes. Future studies should
investigate reasons for variable gluten tolerability and assess the
exact amount of gluten that is tolerable for a given period of time
using reproducible small bowel histologic evaluations and relevant
outcomes (quality of life, CD symptoms).
What your patients need to
know: Tell
patients with CD to avoid gluten to minimize symptoms. Encourage these
patients to consume products that are naturally gluten-free. Explain
that even products labeled "gluten free" typically contain the protein,
albeit in small amounts. No one knows for sure how much gluten is too
much for CD patients, but less than 10 mg daily is generally
well-tolerated. Tell patients to be aware of how much gluten their body
can tolerate and adjust their consumption accordingly.
Sources
Posted May 29, 2009, 4:00 pm EDT
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