Research has shown that refined peanut oil will not cause allergic reactions for the overwhelming majority of people who are allergic to peanuts and if anyone does suffer a reaction it is likely to be mild. However, unrefined (crude) peanut oil is more likely to cause symptoms.
The first major research on this subject was published in the British Medical Journal (BMJ) in 1997. Under strict medical surveillance, 60 adults with peanut allergy were fed refined peanut oil and also unrefined (crude) peanut oil. As a result, six of them suffered allergic reactions to the crude oil, but these were only mild reactions. None reacted to the refined oil.
The research was part-funded by the London-based Seed Crushers and Oil Processors Association (SCOPA), and carried out by a team of independent researchers based in Southampton. All papers published in the BMJ are subject to thorough scrutiny by peer groups.
Refined peanut oil could be used in a wide range of manufactured food products such as biscuits, cakes, crisps and ready meals. It could also be present in food bought in catering establishments such as restaurants, hotels, takeaways and other places where food is served. However, the oilseed industry has told us that peanut oil is expensive at present (August 2017) and that manufacturers are more likely to use other, similar refined vegetable oils such as rapeseed, sunflower or soya.
Peanut oil has unique properties; its stability and long life can make it a preferred choice for frying. Some fish and chip shops choose refined peanut oil because it performs well at high temperatures and lasts well.
Being a stable oil, it is used as a base in some pharmaceutical products.
Unrefined oil may be blended with refined oil to provide a peanut flavour. This would be sold in bottled form as peanut oil or groundnut oil. Where unrefined oil is present in bottled oil, a code of practice accepted by the UK and European oilseed industry states this will be indicated on the label.
According to the oilseed industry, the use of unrefined oil in pre-packed food products is rare but it could be used to impart peanut flavour.
A more common use for unrefined peanut oil is in ethnic foods in restaurants, such as Indian or Oriental, or food sold in small ethnic shops. Typical dishes would be Thai or Chinese dishes including stir fries where the peanut flavour can be a characteristic of some recipes.
European legislation lists 14 major allergens that must be declared and highlighted whenever they are used as ingredients in pre-packed food. Those allergens include peanuts and products thereof. The regulation still applies to the UK even though we have left the EU.
Some ingredients derived from allergens will not cause an allergic reaction because they have been highly processed (for example fully refined soya oil or wheat glucose syrups) and they are therefore exempt from compulsory labelling, following an assessment by the European Food Safety Authority (EFSA).
Although the Southampton research showed that refined peanut oil is highly unlikely to trigger allergic reactions, peanut oil must always be declared – whether refined or unrefined – following EFSA assessment.
According to the oilseed industry, the way peanut oil is refined has not changed. Many scientific experts believe the Southampton conclusions are still valid. In the experience of the Anaphylaxis UK reports of allergic reactions allegedly caused by refined peanut oil have been few and far between – in fact our helpline staff cannot recall a single confirmed case. Many of the medical experts we consult agree that refined peanut oil is unlikely to present a problem. But it is up to individuals with peanut allergy (or their parents or guardians, in the case of young children) to weigh the evidence and make up their own minds.
Sixty adults; all were known to be allergic to peanuts and 36 of them had suffered severe symptoms such as breathing difficulties. In the study, each person was fed refined peanut oil and, on a separate occasion, each was fed unrefined peanut oil. This was a “blind study”, meaning that participants did not know which of the oils they were being given and neither did the staff who were giving the oils.
None of the 60 people tested had a reaction to the refined oil. Six people had a reaction to the unrefined oil.
Unrefined peanut oil contains small amounts of peanut protein (the part of the peanut which causes the allergic reaction), but these are believed to be removed during the refining process.
If any protein solids are left, the amount is so small as to be undetectable by standard laboratory methods.
To prove this would mean testing everybody with an allergy to peanuts, which is impossible. The sample of 60 people proves to a high level of statistical probability that refined peanut oil is safe for people with peanut allergy.
Since the Southampton study was done, more information has become available about the amounts of allergen to which peanut-allergic people react and how they vary. A recently published report confirms that the probability of any reaction to refined peanut oil is remote.
This would not have been ethical. However, the researchers believe refined peanut oil is highly unlikely to trigger allergic reactions in people with peanut allergy, even if their reactions to peanut solids have been anaphylactic.
Doctors have now learned how to safely test people who have experienced very severe reactions, including anaphylaxis. Recent studies on peanut have included people at risk of anaphylaxis (where they have agreed, of course). Results confirm that the amounts of protein found in refined peanut oil do not trigger reactions in people who have experienced very severe reactions.
Not as far as we know. The European oilseed industry (FEDIOL) agreed a common refining standard in 1999 based on the earlier UK SCOPA standard, which itself was inspired by the results of the Southampton study. It is our understanding that all refined peanut oil is processed in the same way, going through the stages of degumming, neutralising, bleaching, filtration and deodorisation. According to the oilseed industry, there is no such thing as “partially” or “less” refined peanut oil. In March 2020, FEDIOL revised its Code on refining, which applies to all botanical origins, and is available on the FEDIOL website.
Based on the Southampton research, if a restaurant uses refined peanut oil, it is likely to be safe for the vast proportion of people with peanut allergy and if anyone does suffer a reaction it is likely to be mild. We would advise you to check with the staff whether the food you have chosen contains peanut oil, and whether it has been refined; if you are left in any doubt, it is best to make a different choice.
Bear in mind that if refined oil has been used previously to fry a nutty product – for example, peanut cutlets or spring rolls – then this oil might be contaminated with peanut allergens. This therefore might not be safe for people with peanut allergy.
Incidentally, the same holds true if an oil has been used to cook any allergenic food. For example, an oil used to fry fish would not be safe for someone with fish allergy.
As far as we know, no deaths have been proven to be caused by peanut oil.
A few researchers have suggested that there may be a link between the use of these creams and the development of peanut allergy in some children. This may be because tiny residues of peanut protein are present: not enough to cause allergic reactions but enough, in some cases, to “set up” an allergy to peanuts if the cream is applied to damaged skin (e.g. to alleviate eczema). We believe that skin preparations, cosmetics and pharmaceutical products (for example, ear drops) known to contain arachis oil (peanut oil) are best avoided by families in which there is a history of allergy.