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

Food allergies to vegetable oils stem almost exclusively from the presence of residual allergenic proteins derived from the seeds 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 the 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 a reaction of the immune system to a foreign protein. Upon initial contact, the body does not react immediately: it becomes sensitized, producing allergen-specific IgE antibodies. Upon subsequent exposure, these IgE recognize the culprit protein and trigger a rapid inflammatory cascade: release of histamine, vasodilation, edema, pruritus, or even severe systemic reactions such as anaphylaxis or Quincke’s edema. Thus, even though refined oils are generally considered safe, a theoretical risk remains for the most sensitive individuals, including when the oil is applied to the skin.

To date, scientific evidence establishing 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 topically without an allergic reaction, especially when the oil is highly refined. Indeed, applying it to the skin exposes the user to lower levels of allergenic proteins than ingestion, often insufficient to trigger a systemic immune response.

However, caution is still warranted, as the medical literature documents a few isolated cases suggesting that cross-sensitization between the gastrointestinal and cutaneous routes is possible. For example, a 33-year-old individual experienced episodes of generalized urticaria after ingesting dishes containing sesame, as well as during skin contact with a lipstick and a moisturizing cream containing sesame oil. Another case involved a 30-year-old man suffering from repeated hives after consuming hamburgers containing sesame. This patient subsequently developed immediate contact urticaria when handling a cosmetic oil that also contained sesame oil.

Furthermore, a large study 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. Analyses showed no evidence of prenatal sensitization: no peanut-specific IgE was detectable in cord blood, and maternal diet during pregnancy was not associated with allergy risk. In contrast, several factors were significantly linked to allergy, including a family history of atopy, early inflammatory eczema, and infant consumption of soy proteins. One of the most striking findings concerned the early skin exposure to preparations containing peanut oil.

Over 80% of 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 control children.

This association persisted after adjusting for eczema and diet, suggesting that the cutaneous route might represent an independent sensitization pathway. The authors hypothesize that small amounts of peanut proteins present in certain oils could cross the skin barrier, which is 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 sensitization, independent of oral exposure. However, the authors emphasize the observational nature of the study and the need for further confirmation. Nonetheless, this hypothesis remains important 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 recommend consulting your primary care physician before any use and to perform a preliminary skin test on a small area of skin. This simple step helps verify individual tolerance and prevent any widespread reaction.

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

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

Other oils deserve heightened vigilance, including sesame, sweet almond, hazelnut, or macadamia oil, all originating from tree nuts and thus more likely to be allergenic. Sesame oil, often used unrefined for its aromatic properties, contains higher protein levels and has already been implicated in documented cases of anaphylaxis.

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

It should be noted that the extraction and refining process is a key determinant of allergenic risk: cold-pressed oils, more commonly used in cosmetics to preserve their bioactive compounds, generally retain higher levels of protein residues than highly refined oils, which can affect their tolerability in sensitized individuals.

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