Introduction:
Dysgeusia is an alteration in taste due to any underlying conditions. A person with dysgeusia loses the sensation to perceive the taste and cannot differentiate between different taste flavors like sweet, salty, sour, bitter, and savory. Taste buds are located in the papilla, like circumvallate, foliate, and fungiform papillae. Filiform papillae do not contain any taste buds but function to sense the touch, temperature, and nerve stimulus as the food is kept in the mouth. Taste buds send the signal to the brain along with the olfactory nerve (nerve supply to the nose), which senses the smell. The brain perceives both the information of taste and smell together, creating a sense of flavors.
What Is the Prevalence of Taste Disorders?
The prevalence of taste disorders has been reported to be around 0.3 % to 17 % of the general population.
What Are the Causes of Dysgeusia?
Various factors that can lead to disturbances in taste are:
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Infections: Bacterial, viral, and fungal infections like viral fever, common cold, and sinus infection can cause alteration in the taste.
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Nutritional Deficiencies: The deficiency of vitamins and minerals like vitamin A, vitamin B12, or zinc can lead to inflammation or swelling and redness of the tongue as it blocks the taste bud pores leading to an altered taste.
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Glossitis: Glossitis (swelling of the tongue) can lead to the closure of the taste pores, thereby causing abnormal taste sensations.
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Xerostomia (Dry Mouth): Damage to the salivary glands can lead to reduced secretions of saliva, which is needed to dissolve the food, and result in a dry mouth, which changes the taste by disrupting the stimulation of taste receptors.
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Medications: Certain drugs, if taken for a longer duration, distort the sensation of taste leading to a metallic taste in the mouth. The drugs that lead to altered taste are:
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Metronidazole.
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Amoxycillin.
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Clarithromycin.
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Chemotherapeutic agents like Cisplatin and Bleomycin.
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Diuretics like Acetazolamide.
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Neurological (Nerve) Disorders: Any damage to the nerve supplying the tongue that is the chorda tympani nerve (branch of the facial nerve), the glossopharyngeal nerve (ninth cranial nerve), and the vagus nerve (tenth cranial nerve) can result in damage of both the general sensation and taste sensation of the tongue. Nerve damage due to trauma, bell palsy, multiple sclerosis, and Parkinson's disease can lead to an altered or reduced taste sensation.
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Metabolic Disorders: Systemic diseases like diabetes, hypothyroidism, and kidney disorder also lead to taste disturbances.
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Gastrointestinal Reflux Disease (Acid Reflux): Persons with an increased frequency of acid reflux have a bitter or sour taste in their mouth.
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Pregnancy: Dysgeusia during pregnancy is common in the first trimester due to hormonal fluctuations. It subsides after the first trimester.
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Tobacco: Excess tobacco consumption can cause a coating on the tongue that blocks the taste pores, and chemicals like nicotine present in tobacco can disrupt the taste sensation.
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Aging: Perception of taste gets reduced with aging due to a reduction in the taste bud receptors with age. Usually, receptors of the taste buds renew every nine to ten days. However, with aging, the renewal of taste bud receptors is either delayed, reduced, or stopped.
What Are the Symptoms of Dysgeusia?
Symptoms of dysgeusia are:
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Bitter taste in the mouth.
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Food tastes metallic or bitter.
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Inability to differentiate between different tastes like sweet or salty.
How Can We Diagnose Dysgeusia?
Dysgeusia can be diagnosed by:
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History and Clinical Examination: Complete history of patients of any recent surgery, drug history, chemotherapy, radiotherapy, presence of metallic taste in the mouth, chronic smoking, and or any symptoms of loss of smell should be noted. Physical examination of the oral cavity should be done to check for any abnormalities in the oral mucosal tissues or any discoloration of the tongue and to rule out the presence of bacterial or fungal infections.
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Electrogustometry: It helps to check the electrical nerve impulse response of the soft tissue areas supplied by the chorda tympani nerve (branch of the facial nerve) and glossopharyngeal nerve (ninth cranial nerve) to rule out nerve damage.
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Filter Paper Disk Method: In this method, samples of the test disk are soaked in various high-concentration taste solutions like salty, sweet, bitter, and sour. These test disks are then placed on specific parts of the oral cavity, and the patient is asked to identify the taste.
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Taste Strip Method: In this method, a filter paper strip dipped in a high concentration of four different tastes that are sweet, bitter, sour, and salty is placed on the anterior two-thirds of the patient's tongue while protruding (taking tongue out) and the patient is asked to identify the correct taste.
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Whole Mouth Method: In this method, a high concentrate taste solution of four basic tastes is kept, and the patient is asked to rinse the mouth with each solution and identify the correct taste.
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E-Tongue Method: An instrument that detects electrical impulse signals generated by taste fibers is used in this method. The sensor present in the instrument helps to interpret recorded data. This method is widely used in pharmaceutical research.
What Are the Methods to Manage Dysgeusia?
Methods used in the management of dysgeusia are:
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Home Remedies: Some home remedies like using lemon juice before meals, brushing teeth or cleaning the tongue before each meal, using mouthwashes to rinse the mouth before and after the meal, and drinking plenty of water to keep oral mucosa hydrated and to prevent dry mouth.
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Treatment of Underlying Cause: Underlying causes of dysgeusia, such as the presence of any bacterial, fungal or viral infections, is identified, and medications should be started for it under the supervision of doctors.
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Avoid Smoking: Smoking should be avoided to prevent excessive heat in the mouth from causing damage to taste buds. Quitting smoking allows the oral mucosal cells to heal gradually.
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Avoid Excessive Tobacco: Chemicals in tobacco coat the tongue surface, thereby reducing taste. Avoiding tobacco use and cleaning the tongue regularly helps regain or improve the lost taste sensations.
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Treat Acid Reflux Disease: Medications like proton pump inhibitors and antacids should be taken to manage the acid reflux creating a sour taste in the mouth.
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Stop Medications Causing Metallic Taste: Any medications causing altered taste should be avoided by reporting it to the doctor and asking them to replace it with an alternative drug. Stopping the medication causing altered taste will automatically reverse dysgeusia.
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Nutritional Supplements: Any vitamin and mineral deficiency should be ruled by getting checked with the doctor, and nutritional supplements should be started as suggested by the doctor to treat the nutritional deficiencies induced by dysgeusia.
Conclusion:
Dysgeusia is a very bad experience for a person as they lose the ability to differentiate between different tastes by affecting the quality of life of a patient. Long-term dysgeusia indicates warning signs for the presence of underlying health issues. Any symptoms of altered or loss of taste sensation should be reported to the doctor for early diagnosis and the necessary treatment.
