Hello and welcome to Just Answer, I recently worked on a case where it was confirmed that a nut allergy can potentially amount to a disability under the Equality Act if the impact of the allergy was considered to be significant on the individuals ability to carry out day to day activities.
It is possible that your employee may be considered to be disabled for employment law purposes. You can request that they see a specialist to determine whether they have allergies and what they are and whether the consultant involved believes that the allergies have a significant impact on the employees ability to carry out day to day activities. If the allergies are relatively mild and limited then they may not be considered to be disabled for employment law purposes.
Once you have this report you will have to decide if you think that the employee has protection under the Equality Act as a disabled employee. If you think that they have then you must make all reasonable adjustments to support them in the workplace which may include removing allergens from the workplace. I do not believe that this would extend to removing possible allergens as this could be potentially limitless.
I hope that this has answered your question. If you have any further questions please do ask. If I have answered your quesiton I would be grateful if you would take the time to rate my answer. Thank you and all the best.