Vegetable oils: is there a correlation between food allergy and topical application?

The food allergies to vegetable oils arise almost exclusively from the presence of residual allergenic proteins originating from the oilseed or oil-bearing fruits from which they are extracted. During refining, most of these proteins are removed, but infinitesimal traces can sometimes persist, particularly in partially refined or cold-pressed oils. These traces can be sufficient to trigger an immune response in some individuals.

From an immunological standpoint, a food allergy is defined as an immune system reaction to an external protein. Upon first exposure, the body does not respond immediately: it becomes sensitised, producing allergen-specific IgE antibodies. Upon subsequent exposure, these IgE recognise the protein in question and trigger a rapid inflammatory cascade: release of histamine, vasodilatation, swelling, itching, and even severe systemic reactions such as anaphylaxis or Quincke’s oedema. Thus, although refined oils are generally regarded as safe, a theoretical risk remains for the most sensitive individuals, including when the oil is applied to the skin.

To date, scientific evidence demonstrating a direct correlation between a food allergy and a skin reaction to the same vegetable oil remains limited.

In most cases, individuals with a food allergy to a vegetable oil can use it without an allergic reaction upon topical application, particularly when the oil is highly refined. Indeed, its use on the skin exposes one to lower quantities of allergenic proteins than ingestion, often insufficient to elicit a systemic immunological reaction.

However, caution remains advisable, as the medical literature reports a few isolated cases suggesting that cross-sensitisation between the gastrointestinal and cutaneous routes is possible. For example, a 33-year-old individual experienced episodes of generalised urticaria after consuming dishes containing sesame, but also during cutaneous contact with a lipstick and a moisturising cream containing sesame oil. Another case involved a 30-year-old man suffering repeated episodes of urticaria after consuming hamburgers containing sesame. This patient subsequently developed immediate contact urticaria when handling a cosmetic oil that also contained sesame oil.

Moreover, a large investigation from the Avon Longitudinal Study of Parents and Children, involving nearly 14,000 children, examined factors associated with the development of peanut allergy. Among the 49 children with suggestive histories, allergy was confirmed in 23 by a double-blind, placebo-controlled food challenge. The analyses provided no evidence of prenatal sensitisation: no peanut-specific IgE was detectable in cord blood, and maternal diet during pregnancy was not linked to allergic risk. In contrast, several factors were significantly associated with allergy, notably a family history of atopy, early inflammatory eczema and the consumption of soy protein in infancy. One of the most striking findings concerned early cutaneous exposure to preparations containing peanut oil.

More than 80% of the allergic children had been exposed to peanut-oil-based products during the first six months of life, a proportion markedly higher than that observed in the control group.

This association persisted after adjustment for eczema and diet, suggesting that the cutaneous route could represent an independent sensitisation pathway. The authors propose the hypothesis that small amounts of peanut proteins present in certain oils could cross the skin barrier, still developing in infants, and trigger an IgE-mediated immune response.

These findings thus support the idea that a repeated cutaneous exposure to food allergens, particularly on fragile skin, could promote allergic sensitisation, independent of oral exposure. However, the authors highlight the observational nature of the study and the need for further confirmation. This hypothesis nonetheless remains crucial for understanding the potential links between food-derived vegetable oils applied to the skin and the subsequent development of allergies.

Thus, a link between food allergy and cosmetic allergy remains plausible for vegetable oils. As a precautionary measure, we advise you to seek advice from your general practitioner before any use and to perform a preliminary skin test on a small area of skin. This simple measure allows you to verify individual tolerance and prevent any generalised reaction.

Some vegetable oils exhibit a higher allergenic potential than others. Among these, peanut oil is most frequently implicated. The peanut (Arachis hypogaea) is indeed recognised as one of the most potent food allergens, capable of triggering severe, even anaphylactic, reactions. Analyses have shown that some peanut oils can contain approximately 0.1 to 0.2 µg of allergenic proteins per gram of oil, with molecular masses ranging from 14 to 76 kDa, including allergens able to bind to IgE in sensitised patients. However, the actual protein content depends strongly on the degree of refining: a fully refined oil generally contains only trace amounts, which explains the lack of reaction observed in certain clinical trials.

The soybean oil and the sunflower oil are also regarded as potentially allergenic, although clinical reactions remain uncommon. In cold-pressed soybean oils, protein levels ranging from approximately 0.10 to 1.8 µg/mL have been detected, with protein profiles varying between batches. Some of these proteins, notably those around 56 kDa and 28 kDa, can bind to IgE from allergic patients, which could account for the onset of reactions. Similarly, cold-pressed sunflower oil may contain trace storage proteins (such as 11S globulins or 2S albumins, including the Hel a 3 allergen), at concentrations of approximately 13.6 µg/mL in the crude oil, decreasing to around 0.22 µg/mL after refining, yet still detectable as traces.

Other oils require increased vigilance, notably sesame oil, sweet almond oil, hazelnut oil or macadamia oil, all derived from tree nuts and therefore more likely to cause allergic reactions. Sesame oil, often used unrefined for its aromatic properties, has a higher protein content and has been implicated in documented cases of anaphylaxis.

Finally, certain oils present specific risks related to their chemical composition : those rich in salicylates, such as meadowsweet oil macerate, may be poorly tolerated by aspirin-sensitive individuals. Those from the Asteraceae family, such as calendula oils or safflower, are not recommended for individuals allergic to this botanical family.

It should be noted that the extraction and refining method is a major determinant of allergenic risk: cold-pressed oils, more common in cosmetics for preserving their bioactive compounds, generally retain more protein residues than highly refined oils, which can affect their tolerance in sensitised individuals.

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