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

The food allergies to vegetable oils almost exclusively stem from residual allergenic proteins originating from the oilseeds or tree nuts from which they are extracted. During refining, the majority of these proteins is removed, but infinitesimal traces may sometimes persist, notably in partially refined or cold-pressed oils. These traces can be enough to provoke an immune response in certain individuals.

From an immunological perspective, a food allergy is defined as an immune system reaction to a foreign protein. Upon first contact, the body does not react immediately: it becomes sensitised, producing IgE antibodies specific to the allergen. On subsequent exposure, these IgE recognise the protein in question and trigger a rapid inflammatory cascade: release of histamine, vasodilation, oedema, pruritus, even severe systemic reactions such as anaphylaxis or Quincke’s oedema. Thus, although refined oils are generally considered safe, a theoretical risk remains for the most sensitive individuals, even 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 the majority of cases, individuals with a food allergy to a vegetable oil can use it without an allergic reaction when applied topically, particularly when the oil is highly refined. Indeed, skin application exposes one to lower amounts of allergenic proteins than ingestion does, often insufficient to provoke a systemic immune response.

However, caution remains necessary, as the medical literature reports a few isolated cases suggesting that cross-sensitisation between the digestive and cutaneous routes is possible. For example, a 33-year-old individual experienced episodes of generalised urticaria after ingesting dishes containing sesame, and also upon cutaneous contact with a lipstick and a moisturising cream containing sesame oil. Another case involved a 30-year-old man suffering from recurrent urticaria after consuming sesame-containing hamburgers. This patient subsequently developed immediate contact urticaria when handling a cosmetic oil that also contained sesame oil. These observations, whilst rare, demonstrate that cutaneous exposure to traces of residual allergens can, in certain cases, reproduce a reaction in highly sensitised individuals.

Thus, while a link between food allergy and cosmetic allergy remains plausible for vegetable oils, it is relatively rare in practice. Nonetheless, as a precautionary measure, we recommend you seek advice from your general practitioner before any use and carry out a preliminary skin test on a small area of skin. This simple step helps to verify individual tolerance and to prevent any generalised reaction.

Some vegetable oils exhibit a higher allergenic potential than others. Among them, peanut oil is most frequently implicated. Indeed, the peanut (Arachis hypogea) is known to be one of the most potent food allergens, with reactions that can sometimes be severe, even anaphylactic. Several studies have reported cases of urticaria and eczema exacerbation following application or ingestion of peanut oil, even when refined. However, other clinical trials show that fully refined oil triggers no reaction, as the refining process almost entirely removes the proteins responsible for the allergy.

The soybean oil and sunflower oil are also considered to have allergenic potential, although allergic reactions upon contact or ingestion are relatively rare. Other oils warrant increased vigilance, notably sesame oil, sweet almond oil, hazelnut oil or macadamia oil, all derived from tree nuts and therefore more likely to be allergenic. Sesame oil, often used unrefined for its aromatic qualities, contains higher protein levels and has already led to documented cases of anaphylaxis.

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

• SAÏAG P. & al. Immediate hypersensitivity to sesame in foods and cosmetics. Contact Dermatitis (1998).

• CREVEL R. W. R. & al. Allergenicity of refined vegetable oils. Food and Chemical Toxicology (2000).

• GARVEY L. H. & al. Natural ingredients in cosmetic products – A suggestion for a screening series for skin allergy. Contact Dermatitis (2020).

• KOMARNYTSKY S. & al. The enigma of bioactivity and toxicity of botanical oils for skin care. Frontiers in Pharmacology (2020).

• GLAVAC N. K. & al. Vegetable butters and oils as therapeutically and cosmetically active ingredients for dermal use: A review of clinical studies. Frontiers in Pharmacology (2022).