Positive Health Online

Abstract

BLACK and SHARPE, Dept of Medicine, University of Auckland, Auckland Hospital, New Zealand review (72 references) the possible connection between the fall in the consumption of saturated fat, the increased consumption of polyunsaturated fat in the diet and the increased prevalence of asthma, eczema and allergic rhinitis in developed countries.

Background

Methodology

Results

The changes in the types of fats consumed in the diet is largely due to a reduction in the consumption of animal fat and the increased use of margarine and vegetable oils containing omega-6 polyunsaturated fatty acids (PUFAs) including linoleic acid. There has also been a reduced consumption of oily fish containing omega-3 PUFAs including eicosapentaenoic acid (EPA). In some countries, there are social class and regional differences between the prevalence of allergic disease which are associated with differences in the consumption of PUFAs. Linoleic acid is a precursor to arachidonic acid, which can be converted to prostaglandin E2 (PGE2), whereas EPA inhibits PGE2 formation. PGE2 acts upon T-lymphocytes, reducing the formation of interferon-gamma (IFN-gamma) but not affecting the formation of interleukin-4 (IL-4). This may lead to allergic sensitisation, as IL-4 promotes immunoglobulin E (IgE) synthesis, whereas IFN-gamma has the opposite effect.

Conclusion

Changes in diet may explain the increased prevalence of asthma, eczema and allergic rhinitis. The effects of diet may be mediated through an increased synthesis of prostaglandin E2, which in turn may promote the formation of immunoglobulin E.

References

Black PN and Sharpe S. Dietary fat and asthma: is there a connection? Eur Respir J 10(1): 6-12. Jan 1997.

Comment

For perhaps a partial answer to this question, please read the next research update, where researchers have determined the presence of allergenic proteins in commercially available butter and margarine.