Introduction

Ageusia is the inability to taste any of the five recognised flavours - sweet, bitter, sour, salty, and umami. Losing taste robs us of the pleasure of experiencing flavours and new foods. This can affect quality of life and even lead to weight loss due to a lack of appetite. Ageusia can occur at any age, but it is predominantly observed in the elderly. This phenomenon poses a key question: Is ageusia a natural part of ageing, or is it a sign of an underlying problem? In this article, we will explore this.¹ 

What is ageusia?

Ageusia is the condition of losing taste. It is often confused with the following taste disorders:

• Hypogeusia: decreased sensitivity to flavours
• Hypergeusia: increased sensitivity to flavours
• Dysgeusia: altered perception of a flavour

While all these conditions differ, they all share the same root cause: the taste function of the tongue is compromised or lost. Ageusia can occur as a result of:

• Infections
• Medications
• Neurological conditions
• Head and neck injuries

Many times, it can be reversible once the root cause is identified and managed. Permanent loss of taste, on the other hand, is relatively rare. It affects approximately 2 people out of 1,000.¹

How does taste work?

The human adult tongue has around 2,000 to 4,000 taste buds, and each one has from 10 to 50 sensory cells. The chemical factors in food and drinks activate those receptors, and they respond by sending signals to the brain via sensory nerves. This is how you recognise different flavours.

Flavour is a multisensory experience. It involves taste, smell, and even texture or temperature. The human brain is remarkably adaptable and can make complex associations between taste and smell. Over time, what we perceive as flavour comes from not only taste but also smell and texture, too.²

Is taste loss a normal part of ageing?

As an individual ages, senses start to decline. Hearing and smelling abilities are compromised, and so is tasting. Taste loss is usually mild, and it is a symptom of fewer and less sensitive taste buds. Other factors include:

Decreased saliva production

Saliva helps break down food. Small food particles are the ones that can activate the taste buds. Therefore, less saliva can lead to fewer flavour signals being sent to the brain.³

Medications

An increasing number of older people are prescribed antidepressants, blood pressure medication (antihypertensives), and diuretics. These medications can interfere with taste, causing everything from distorted taste to ageusia.⁴

While a small to moderate decline in taste can be expected with advancing age, complete loss of taste is not typical.

When is ageusia a sign of something more?

Complete loss of taste in older individuals is relatively uncommon. In most cases, ageusia is a result of underlying causes that need to be investigated further. Neurological conditions, inadequate nourishment and infections, whether respiratory or oral, can be contributing factors to losing taste temporarily or even permanently in older adults. 

In most cases, taste loss due to ageing or any of the mentioned causes happens gradually. If taste is completely lost all of a sudden, consulting a healthcare provider promptly is important, as it may be a signal of an underlying condition that needs attention.

Neurological conditions

Older adults are more likely to develop neurological conditions, which can lead to ageusia or hypogeusia. Examples include:

• Stroke: if the stroke affects the brain region responsible for processing taste, such as the insular cortex or brain stem, the ability to taste flavour can be significantly impacted. Taste might be completely lost, compromised, or even experienced only on one side of the tongue⁵
• Parkinson’s disease: the disease affects the function of the central nervous system, leading to impaired taste and smell. Many patients cannot smell fully, and many also report reduced intensity of flavours⁶
• Alzheimer’s disease: while taste is not directly impacted in alzheimer’s patients, the brain’s ability to “read” sensory information is impaired. Patients may not recognise certain flavours, or even distinguish them

All these conditions can lead to ageusia, and apart from the emotional toll it can have on an individual’s life, it can also lead to more serious problems such as poor appetite and reduced nutrient intake.⁷

Lack of nutrients 

Certain foods provide a feeling of pleasure, and this comes from the flavour and the smell. 

Individuals of certain ages tend to progressively lose the ability to smell and taste food and drinks. When food is no longer appealing, individuals might skip certain meals, which can cause inadequate nutrient intake over time. Subsequently, weight loss might occur. 

Weight loss in the elderly is also associated with reduced muscle mass (sarcopenia), which is important for the elderly to avoid slow healing in case of injuries or infections.⁸

Infections

Infections of the respiratory system, such as COVID-19, can cause temporary loss of taste in all individuals. The elderly, however, have a slower recovery rate and might suffer from ageusia for longer. Immunocompromised people may experience a permanent loss of taste if an infection directly impacts the taste buds or taste receptors.  

Oral infections are common in the elderly and can alter flavour. Oral thrush, common in individuals with dentures or those on antibiotics, and gum disease can cause inflammation, which may result in weakened taste buds, reduced saliva production and decreased flavour sensitivity.⁹

Why taste matters as you age

For some, ageusia might be considered a minor inconvenience. However, losing taste can have a big impact on physical and mental health, especially in older adults.

Ageusia can lead to loss of appetite and inadequate nutrition. Psychologically, food is described as one of life’s pleasures. Scientifically, food provides a sensory experience that is associated with happiness and improved well-being. 

Older adults with ageusia do not get to experience the psychological pleasure and sensory enjoyment coming from food. This loss can lead to social withdrawal from gatherings and events that involve food, which are many, considering that food is a significant factor in most human interactions.

Management of ageusia 

Dealing with ageusia can feel overwhelming, but there are certain things to incorporate daily to improve taste, including:

An increased diversity of foods is necessary to pinpoint and eliminate those that affect flavours and diminish aroma. Elements such as fat, heat, and sealed containers can amplify the taste and scent of food. The existing diet is overly reliant on simple carbohydrates, unhealthy fats, and salt, which increases the likelihood of conditions such as diabetes and obesity. Maintaining a healthy diet involves achieving a balance between energy consumption and expenditure.¹⁰

Currently, there are no approved medications to treat ageusia. Treatment involves identifying and managing the underlying cause, and most time, ageusia is temporary or partially reversible once the triggering cause is treated. Age-related ageusia may not be reversible, but the impact can be reduced. 

Summary

Loss of taste can affect everyone at all stages of life, and it is usually a symptom of infection, certain medications, and injuries. Most times, the ability to taste returns shortly after the triggering cause is managed. In the elderly, ageusia can often occur due to neurological conditions, injuries, and infections. Older adults usually take longer to heal from such conditions, and this can prolong ageusia caused by these conditions. However, there is a sensory decline with advancing age, and some individuals may deal with ageusia without having any underlying cause or even after the underlying cause is managed. Consulting a healthcare provider is important to rule out any triggering cause that needs immediate attention.  In such cases, reviewing medications with a healthcare provider, ensuring optimal oral hygiene and getting creative with flavours may improve the overall eating experience.