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A recent study in Thorax described margarine intake as a risk factor for allergic diseases (Thorax 2007;62:677–83). This association has now been replicated in about 10 studies, but without any convincing explanation.1 Margarine is the only food factor to date that is associated with allergic diseases without provoking any direct allergic reaction.
Margarine was invented by the French chemist Hippolyte Mège-Mouriès at the demand of emperor Napoleon IIIrd 1869 as a cheap replacement food for his troops. The initial recipe contained water, skimmed milk and suet. Its use spread rapidly as a butter substitute, with the first factory in Oss/Netherlands exporting approximately 40 000 tons of margarine to Great Britain in 1883. As a raw material, lard was used at that time as well as copra, palm or train oil. As sales in the mid of the last century suffered from a somewhat poor quality image, modifications have been introduced, for example, to raise the content of polyunsaturated fats by using sunflower oil.
Since 1952, vitamin D3 has also been added to margarine in West Germany. According to a new monograph on the history of vitamin D supplementation in Germany,2 the company Merck delivered a highly concentrated oily vitamin solution to the Margarine Union who supplemented about the half of the 230 000 tons annually produced at that time. Since then margarine has been one of the few if not the only continuously fortified food in Germany with a major brand containing ∼1 IU/g D3.
Given more recent experimental and epidemiological findings on the immunological action of vitamin D and its metabolites,3 it is possible that this vitamin D supplement may be responsible for the observed effect. Changing from butter to margarine indeed leads to ∼30% higher 25-OH-calciferol serum level4 which may be in the effective range of serum levels linked to allergic rhinitis in the NHANES study.5
Possibly a trial on the Creete island could answer the question of whether or not there is any causal relationship between a margarine ingredient and allergy. Vitamin D supplements could be banned from margarine for a limited time as on a sunny island there is no major fear of vitamin D deficiency in the population. Will the allergy risk remain?
Competing interests: None.