During the pandemic, a lost sense of smell was quickly identified as one of the key symptoms of COVID. Nearly four years later, one in five people in the UK is living with a decreased or distorted sense of smell, and one in twenty have anosmia – the total loss of the ability to perceive any odours at all. Smell training is one of the few treatment options for recovering a lost sense of smell – but can we make it more effective?

Smell training is a therapy that is recommended by experts for recovering a lost sense of smell. It is a simple process that involves sniffing a set of different odours – usually essential oils, or herbs and spices – every day.

The olfactory system has a unique ability to regenerate sensory neurons (nerve cells). So, just like physiotherapy where exercise helps to restore movement and function following an injury, repeated exposure to odours helps to recover the sense of smell following an infection, or other cause of smell loss (for example, traumatic head injury).

Several studies have demonstrated the effectiveness of smell training under laboratory conditions. But recent findings have suggested that the real-world results might be disappointing.

One reason for this is that smell training is a long-term therapy. It can take months before patients detect anything, and some people may not get any benefit at all.

In one study, researchers found that after three months of smell training, participation dropped to 88%, and further declined to 56% after six months. The reason given was that these people did not feel as though they noticed any improvement in their ability to smell.

Cross-modal associations

To remedy this, researchers are now investigating how smell training can be improved. One interesting idea is that information from our other senses, or “cross-modal associations”, can be applied to smell training to promote odour perception and improve the results.

Cross-modal associations are described as the tendency for sensory cues from different sensory systems to be matched. For example, brightness tends to be associated with loudness. Pitch is related to size. Colours are linked to temperature, and softness is matched with round shapes, while spiky shapes feel more rough. In previous studies, these associations have been shown to have a considerable influence on how sensory information is processed. Especially when it comes to olfaction.

Recent research has shown that the sense of smell is influenced by a combination of different sensory inputs – not just odours. Sensory cues such as colour, shape, and pitch are believed to play a role in the ability to correctly identify and name odours, and can influence perceptions of odour pleasantness and intensity.

In one study, participants were asked to complete a test that measured their ability to discriminate between different odours while they were presented with the colour red or yellow, an outline drawing of a strawberry or a lemon, or a combination of these colours and shapes. The results suggested that corresponding odour and colour associations (for example, the colour red and strawberry) were linked to increased olfactory performance compared with odours and colours that were not associated (for example, the colour yellow and strawberry).

While projects focusing on harnessing these cross-modal associations to improve treatments for smell loss are underway, research has already started to deliver some promising results.

In a recent study that aimed to investigate whether the effects of smell training could be improved with the addition of cross-modal associations, participants watched a guidance video containing sounds that matched the odours that they were training with. The results suggest that cross-modal interactions plus smell training improved olfactory function compared to smell training alone.

The results reported in recent studies have been promising and offer new insights into the field of olfactory science. It is hoped that this will soon lead to the development of more effective treatment options for smell recovery.

In the meantime, smell training is one of the best things you can do for a lost sense of smell, so patients are encouraged to stick with it so that they give themselves the best chance at recovery.

Emily Spencer, PhD Candidate, Olfaction, Edinburgh Napier University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Have you ever been instructed to take your medicine with food and wondered why? Perhaps you’ve wondered if you really need to?

There are varied reasons, and sometimes complex science and chemistry, behind why you may be advised to take a medicine with food.

To complicate matters, some similar medicines need to be taken differently. The antibiotic amoxicillin with clavulanic acid (sold as Amoxil Duo Forte), for example, is recommended to be taken with food, while amoxicillin alone (sold as Amoxil), can be taken with or without food.

Different brands of the same medicine may also have different recommendations when it comes to taking it with food.

Food impacts drug absorption

Food can affect how fast and how much a drug is absorbed into the body in up to 40% of medicines taken orally.

When you have food in your stomach, the makeup of the digestive juices change. This includes things like the fluid volume, thickness, pH (which becomes less acidic with food), surface tension, movement and how much salt is in your bile. These changes can impair or enhance drug absorption.

Eating a meal also delays how fast the contents of the stomach move into the small intestine – this is known as gastric emptying. The small intestine has a large surface area and rich blood supply – and this is the primary site of drug absorption.

Eating a larger meal, or one with lots of fibre, delays gastric emptying more than a smaller meal. Sometimes, health professionals will advise you to take a medicine with food, to help your body absorb the drug more slowly.

But if a drug can be taken with or without food – such as paracetamol – and you want it to work faster, take it on an empty stomach.

Food can make medicines more tolerable

Have you ever taken a medicine on an empty stomach and felt nauseated soon after? Some medicines can cause stomach upsets.

Metformin, for example, is a drug that reduces blood glucose and treats type 2 diabetes and polycystic ovary syndrome. It commonly causes gastrointestinal symptoms, with one in four users affected. To combat these side effects, it is generally recommended to be taken with food.

The same advice is given for corticosteroids (such as prednisolone/prednisone) and certain antibiotics (such as doxycycline).

Taking some medicines with food makes them more tolerable and improves the chance you’ll take it for the duration it’s prescribed.

Can food make medicines safer?

Ibuprofen is one of the most widely used over-the-counter medicines, with around one in five Australians reporting use within a two-week period.

While effective for pain and inflammation, ibuprofen can impact the stomach by inhibiting protective prostaglandins, increasing the risk of bleeding, ulceration and perforation with long-term use.

But there isn’t enough research to show taking ibuprofen with food reduces this risk.

Prolonged use may also affect kidney function, particularly in those with pre-existing conditions or dehydration.

The Australian Medicines Handbook, which guides prescribers about medicine usage and dosage, advises taking ibuprofen (sold as Nurofen and Advil) with a glass of water – or with a meal if it upsets your stomach.

A systematic review published in 2015 found food delays the transit of ibuprofen to the small intestine and absorption, which delays therapeutic effect and the time before pain relief. It also found taking short courses of ibuprofen without food reduced the need for additional doses.

To reduce the risk of ibuprofen causing damage to your stomach or kidneys, use the lowest effective dose for the shortest duration, stay hydrated and avoid taking other non-steroidal anti-inflammatory medicines at the same time.

For people who use ibuprofen for prolonged periods and are at higher risk of gastrointestinal side effects (such as people with a history of ulcers or older adults), your prescriber may start you on a proton pump inhibitor, a medicine that reduces stomach acid and protects the stomach lining.

How much food do you need?

When you need to take a medicine with food, how much is enough?

Sometimes a full glass of milk or a couple of crackers may be enough, for medicines such as prednisone/prednisolone.

However, most head-to-head studies that compare the effects of a medicine “with food” and without, usually use a heavy meal to define “with food”. So, a cracker may not be enough, particularly for those with a sensitive stomach. A more substantial meal that includes a mix of fat, protein and carbohydrates is generally advised.

Your health professional can advise you on which of your medicines need to be taken with food and how they interact with your digestive system.

Mary Bushell, Clinical Associate Professor in Pharmacy, University of Canberra

This article is republished from The Conversation under a Creative Commons license. Read the original article.