(31-01-06) Allergies and Red Blood Cell Fatty Acids: EPA Linked to Lower Risk in Adults

Increasing prevalence in western countries of allergies and atopic conditions??atopic eczema, asthma, and rhinitis??reflect changes in environmental factors along with family history of atopy. As noted in the preceding article, [insert link] atopy is accompanied by increased levels of serum immunoglobulin E. Prominent among the environmental factors associated with these conditions are dietary polyunsaturated fatty acids (PUFAs). High levels of linoleic acid and disturbances in the metabolism both omega-6 (n-6) and omega-3 (n-3) PUFAs have been reported in children with atopic conditions. These alterations may favor the production pro-inflammatory prostaglandins and cytokines which mediate allergic responses. Some evidence supports the moderation of these conditions by long-chain (LC) n-3 PUFAs.

Many allergic conditions are established in childhood, but they can develop in adults also. Whether PUFA metabolism is involved in adult-onset allergies is unclear. Several studies have reported a positive association between consumption of monounsaturated fat and allergic sensitization (defined by the amount of immunoglobulin E produced), and oleic acid and asthma in adults.

To explore the possible associations of various fatty acids with allergic sensitization in adults, the research team of Dr. Jakob Linseisen at the German Cancer Research Center in Heidelberg, Germany, examined data from the Bavarian Nutrition Survey II, designed to investigate dietary and lifestyle habits. From a representative sample of about 1,000 adults aged 13-80 years, 568 qualified for the final analysis according to the availability of questionnaire data and blood samples. At least two dietary recall questionnaires and one blood sample were obtained for assessment of nutrient intake and red blood cell membrane fatty acid composition. Prevalence of atopic sensitization by inhalant allergens was determined by an in vitro screening test (CAPSX1) of blood serum. Cases of allergic rhinitis were identified from questionnaire responses about physician-diagnosed conditions. Allergic sensitization was defined as specific immunoglobulin E concentration ?? 0.7 kU/L.

In this population, the prevalence of allergic sensitization was 26.5% and allergic rhinitis, 13.6%. Men were more likely to be sensitized than women (29.3% vs 24.4%), but women had twice the prevalence of allergic rhinitis as men (17.5% vs 8.2%). For comparison purposes, the prevalence of skin-test reactivity to at least one of eight allergens in the U.S. between 1976 and 1980 was 20.2%, with the prevalence higher in men than in women (22.2% vs 18.4%). Sensitized individuals were younger, had a lower body mass index, higher socioeconomic status, and were more likely to be nonsmokers than the entire group.

When the fatty acid composition of the red cell membranes was examined, a significant inverse association was observed between eicosapentaenoic acid (EPA) concentration and sensitization. No other PUFA was associated with sensitization. In contrast to other reports, oleic acid concentration was unrelated to sensitization.

Table 1. (Attached as Allegato) Adjusted* odds ratios (95% confidence interval) for the association between allergic sensitization and red blood cell membrane fatty acid concentration


When participants were stratified by age group, those in the highest quartile of red cell EPA had lower risk of sensitization compared with people in the lowest quartile, significantly so in the youngest group, those under 40 years (OR=0.36, CI=0.15-0.87, P=0.012).

As with allergic sensitization, the chance of having allergic rhinitis was significantly reduced with increasing EPA concentration in red cell membranes. Risk of rhinitis in the highest quartile of EPA was half that observed in the lowest quartile (OR=0.50 (CI=0.24-1.03, P= 0.027).

The investigators examined whether dietary PUFAs were related to sensitization or rhinitis. Only the consumption of alpha-linolenic acid was related to sensitization and rhinitis. Red cell membrane fatty acid composition is a better reflection of long-term n-3 LC-PUFA intake than estimates from diet histories, especially when consumption of these fatty acids is low.

Results from this study do not support observations from other epidemiological studies in the U.S. and Japan reporting a positive association between fish consumption and wheezing in adults or between n-6 PUFA intake and allergic rhinoconjunctivitis. Arachidonic acid has also been associated with increased allergic sensitization. However, there are other reports of an inverse association between EPA and reduced allergic conditions, consistent with the observations described here. It is plausible that n-6 PUFAs might contribute to or exacerbate allergic conditions and n-3 PUFAs diminish them, but whether such associations relate to the cause or onset of allergic conditions is unknown. These findings may be saying, give fish a chance.
Hoff S, Seiler H, Heinrich J, Kompauer I, Nieters A, Becker N, Nagel G, Gedrich K, Karg G, Wolfram G, Linseisen J. ??Allergic sensitisation and allergic rhinitis are associated with n-3 polyunsaturated fatty acids in the diet and in red blood cell membranes.??

Eur J Clin Nutr 2005;59:1071-1080.

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