Vitamin A nasal drops might be able to treat the loss or altered sense of smell in some people who have had Covid, UK researchers say.

The University of East Anglia is conducting a 12-week trial.

Only some of the volunteer patients will receive the treatment but all will be asked to sniff powerful odors such as rotten eggs and roses.

And brain scans will check if the vitamin has repaired injured olfactory pathways or “smell nerves”.

Loss or altered sense of smell is a common symptom of Covid, although many other viruses, such as flu, can also cause it.

And while most people naturally regain it within a couple of weeks, many have been left with continuing smell disorders.

Lina Alnadi, 29, from London, developed parosmia after Covid, which means the odour of many common things has changed for her.

Tap water, for example, smells horrendous, the odour you or I might get from a swamp or sewer.

Olfactory bulb

Lead researcher Prof Carl Philpott, from UEA’s Norwich Medical School and James Paget University Hospitals NHS Trust, said: “We want to find out whether there is an increase in the size and activity of damaged smell pathways in patients’ brains when they are treated with vitamin-A nasal drops.

“We will look for changes in the size of the olfactory bulb – an area above the nose where the smell nerves join together and connect to the brain.

“We will also look at activity in areas of the brain linked to recognizing smells.”

Vitamin A, or retinol, helps maintain:

The immune system – the body’s defence against illness and infection

Eyesight, particularly vision in dim light

The skin and lining of some parts of the body, including the nose

Many dairy foods, as well as some vegetables, contain this fat-soluble vitamin.

But people taking vitamin-A supplements should be aware that too much can be harmful.