Refined and unrefined oils

Edible oils commonly used in the UK can come from many different types of plants and seeds including rapeseed, sunflower seed, soya, maize, palm, coconut and palm kernel. Oils can also be derived from peanuts, sesame and tree nuts (such as walnut). Regulations state that the source of the vegetable oil used must be indicated on the label of pre-packaged foods. It is important to always thoroughly check food ingredient labels.

 

The oilseed industry tells us that when you buy a pre-packed food product containing an edible oil, usually that oil will have been refined. The refining process removes the allergy-causing proteins from the oil to the point where they are barely detectable, even by very sensitive scientific techniques. This suggests fully refined oils are unlikely to pose an allergy risk.
However, in the case of some refined vegetable oils, research is incomplete. Formal safety assessments would need to be carried out by scientists working in food safety before they are declared no risk or low risk to people with allergies. The two oils which have been subject of research are soya and peanut.

 

Some oils are used in their unrefined state in order to provide a particular flavour to the food. An unrefined oil is more likely to cause allergic reactions if you are allergic to the food from which that oil is derived.

 

 

Peanut oil (also known as groundnut oil)

Peanut is a legume and one of the 14 major allergens which need to be declared when they are used as ingredients in a food.
  • right_arrow_orange_icon Refined peanut oil is likely to be safe for the vast majority of people with peanut allergy. This was the conclusion of a 1997 scientific study carried out in Southampton. However, peanut oil must always be declared – whether refined or unrefined – on the labels of prepacked food.
  • right_arrow_orange_icon Unrefined peanut oil is more likely to trigger allergic reactions. According to the oilseed industry, the use of unrefined oil in pre-packed food products is rare but it could be used to give a peanut flavour. It must be declared and highlighted on packaging.

Soya oil

Soya is one of the 14 major allergens which need to be declared when they are used as ingredients in a food. Soya oil, which may be found in foods including salad dressings, margarine and spreads, has been subject to research and a full risk assessment. Taking into account this research, EFSA declared in 2007 that “it is not very likely” that fully refined soya oils would trigger a severe allergic reaction in susceptible individuals. Anaphylaxis UK understands it is more likely that unrefined soya oil will trigger allergic reactions.

 

You can also read the European Food Safety Authority’s statement about soya oil

Therefore:
  • right_arrow_orange_icon Unrefined soya oil must be declared and highlighted (for example, in bold type) within the ingredients when it appears in pre-packed food. It may be declared simply as soya oil.
  • right_arrow_orange_icon Fully refined soya oil does not have to be highlighted in the way major allergens must be, but it still needs to be declared as soya oil in line with the regulations stating that the origins of all vegetable oils must be indicated.

Other vegetable oils

At the time of publication of this article, other oils such as rapeseed, sunflower, maize/corn, and palm kernel have not been subjected to research to test whether refining them makes them safe for people with allergies to those specific foods. We would therefore recommend you speak to your GP or allergy specialist for specific advice about whether you need to avoid these oils. Even refined oils can pose a risk if they are contaminated with residual protein, so allergy medications should be available at all times in case they are required.

Coconut oil

Coconut is a member of the palm family and only distantly related to tree nuts. Coconut oil is usually found as a cold-pressed oil, which is unrefined and is therefore considered more likely to present an allergy risk for people allergic to coconut.

Sesame oil

Sesame is one of the 14 major allergens which need to be declared when they are used as ingredients in a food. Although further research needs to be conducted, sesame oil is most commonly unrefined and is therefore considered likely to present an allergy risk.

Tree nut oils

Tree nuts are among the 14 major allergens which need to be declared when they are used as ingredients in a pre-packed food. Although further research needs to be conducted, specialist tree nut oils such as walnut oil are unrefined and are therefore considered likely to present an allergy risk.

Shea nut oil (shea nut butter)

Shea nut oil is used primarily in confectionery products such as chocolate and is sometimes known as shea nut butter. The information we have on shea nuts is that they appear low risk for most people with nut allergy as the oil is likely to be highly refined.

Reviewer

This article has been peer reviewed by Tanya Wright, Specialist Allergy Dietitian, Children’s Allergy Service at Guys and St Thomas` Hospital, London.
All the information we produce is evidence based or follows expert opinion and is checked by our Clinical and research reviewers. If you wish to know the sources we used in producing any of our information products, please let us know, and we will gladly supply details.

 

Disclaimer

The information provided in this article is given in good faith. Every effort has been taken to ensure accuracy. All patients are different, and specific cases need specific advice. There is no substitute for good medical advice provided by a medical professional.

 

Publication Date: May 2021
Review Date: May 2024