Taste (reduced taste, loss of taste)

What is taste?

The five (or six or seven) basic tastes

Causes of ageusia (complete loss of taste)

Causes of hypogeusia (reduced sense of taste)

Causes of dysgeusia (distortion in sense of taste

Prevention / remedies / cures / treatment for taste disorders

What is taste?

Taste (gustation) is one of the five traditional senses. Taste is the ability to detect the flavour of substances held in the mouth. Foods, poisons and other substances held in the mouth produce taste sensations when they react with taste receptor cells located on taste buds in the oral cavity. Taste enables us to distinguish between safe and harmful foods, and to gauge a foods' nutritional value.

In humans and most other vertebrates, the senses of taste and smell work together.

Most taste receptors are on upper surface of the tongue, though they are also located right around the mouth along the soft palate, and in the epithelium of the pharynx and epiglottis.

The tongue is covered with thousands of small bumps called papillae, which are big enough to see. Within each papilla are hundreds of taste buds. In total there are between 2000 and 5000 taste buds located on the back and front of the tongue. Others are located on the roof, sides and back of the mouth, and in the throat. Each taste bud contains 50 to 100 taste receptor cells.

Ageing. Among humans, taste perception begins to fade around 50 years of age because of loss of tongue papillae and a general decrease in saliva production. Older people can also suffer from a distortion of their tastes (dysgeusia).

The five (or six or seven) basic tastes

The five traditional basic tastes are bitter, sweet, sour, salt, savoury (umami). Bitter foods are generally unpleasant, whereas the other tastes are usually pleasurable.

The five basic tastes do not provide the full sensation of flavour in the mouth. Most importantly, the sense of smell is essential for taste even to exist. Other factors include texture, temperature, coolness (such as from menthol) and pungency (heat) such as from hot chillies.

Bitter taste is almost universally unpleasant to humans, because most bitter substances are in fact poison. Examples of bitter chemicals include caffeine, nicotine, and strychnine. Humans have overcome their aversion to the first two of these because they have some benefits. Many common medicines have a bitter taste if you chew them. Most but not all bitter plants are toxic, but healthy exceptions include bitter vegetable leaves such as dandelion and blackjack.

Sweet taste signals the presence of carbohydrates. Since carbohydrates and particularly saccharides have lots of calories (energy), we evolved a sweet taste to help seek out what were then rare high calorie foods. Many non-carbohydrate molecules can also trigger a sweet response, leading to the development of many artificial sweeteners such as saccharin, sucralose and aspartame.

Sour is pleasant-tasting when diluted or on small quantities, but becomes increasingly unpleasant as more is taken. Sour taste can signal under-ripe fruit, rotten meat, and other spoiled foods. Sour taste also signals acids, some of which are totally healthy (apple cider vinegar, lemon juice, fermented foods) and others which may be dangerous (mould, pathogenic (bad) bacteria.

Salt taste can be pleasant in small quantities, but in larger quantities become more and more unpleasant to taste.

Savoury taste (known in Japanese as "umami") which signals the presence of the valuable amino acids such as L-glutamate, of which we need a steady supply.

Pungent. In Asian countries such as India, China, Vietnam and Thailand, pungency (piquancy or hotness) is traditionally considered a sixth basic taste.

Fat. There are some strong arguments that we can taste fats: an evolutionary advantage to oral fat detection; fat receptors have been located on taste bud cells; and that fatty acids evoke specific responses in the mouth.

Causes of ageusia (complete loss of taste)

• Neurological damage.
• Endocrine (hormonal damage).
• Local trauma and inflammation including radiation therapy, tobacco use, denture use.
• Ageing.
• Anxiety disorder.
• Cancer.
• Renal (kidney) failure.
• Liver failure.
• Pharmaceutical drugs including antirheumatic drugs such as penicillamine, antiproliferative drugs such as cisplatin, ACE inhibitors, and other drugs including Tamiflu, azelastine, clarithromycin, terbinafine, and zopiclone.
• Deficiency of vitamin B3 (niacin) and zinc.
• Cushing's syndrome.
• Hypothyroidism.
• Diabetes mellitus.

Causes of hypogeusia (reduced sense of taste)

• Toothpaste for sensitive teeth (de-sensitising toothpaste).
• Covid-19 can cause loss of smell and / or taste, at levels varying from hardly noticeable to complete loss. The time period can also vary from one day to several years. It seems that in nearly all cases there is partial or complete recovery over a period of months or years.
• Sjogren's syndrome. Between 2% and 6% of adults suffer from this ailment, with the prevalence being nine times higher in women than men, and in older people rather than younger. Between 2% and 6% of adults suffer from this ailment, with the prevalence being nine times higher in women than men, and in older people rather than younger.
• Severe cold, influenza or other viral infection.
• Tamiflu.
• Chemotherapy drug bleomycin (an anti-tumour antibiotic).
• Zinc deficiency.
• Vitamin B3 (niacin) deficiency.

Causes of dysgeusia (distortion in sense of taste)

• Asthma treatment with albuterol.
• Chemotherapy.
• Zinc deficiency.

Hypergeusia, an abnormally heightened sense of taste, is sometimes associated with a lesion of the posterior fossa or with Addison's disease.

Prevention / remedies / cures / treatment for taste disorders

If you use any remedies from Grow Youthful, please come back next week (or whenever you have an outcome) and let us know about your experience. Please leave a comment as many people are interested.

See details of remedies recommended by Grow Youthful visitors, and their experience with them.

• Zinc.
• Vitamin B3 (niacin). The best food source of vitamin B3 is red meat, followed by fish and poultry. Other food sources include nuts and bananas. The best way to supplement is with unfortified nutritional yeast that has been minimally processed, which should include the whole range of B vitamins.
• ALA (alpha lipoic acid).
• Fenugreek.
• Toothpaste. Avoid sensitive relief toothpaste for sensitive teeth. Only use a small amount of toothpaste on your brush, less than the size of a pea. Rinse your mouth thoroughly after brushing. See sodium bicarbonate as a better natural toothpaste.
• Hydration - ensure you are drinking sufficient fluoride-free water every day.
• Oil pulling.
• Iodine.