If you don't enjoy your favorite foods as much as you used to, it may be time to see your doctor. Strange as it seems, your problem may lie in your nose or mouth. Seemingly flavorless food can result from either a diminished sensation of smell or taste, but usually not both.
In fact, the loss of smell is actually more common than loss of taste. Studies have found that even when food seems to become less flavorful, the ability to sense the basic four tastes—salty, sweet, sour, and bitter—often remains intact.
Certain medical conditions, medicines, and a lack of certain nutrients can all contribute to decreased senses of smell and taste.
Smell and taste work as a team to allow for the sensation of flavors. With one sensation diminished, the flavor experience can be entirely different.
Think of freshly baked chocolate chip cookies, for example. Nerves in the nose sense the airborne molecules released from the odor-causing agents in the cookies. After the molecules drift up to the nose or are drawn up through breathing or sniffing, the detected odor is sent to the smell area of the brain.
The average adult has 10,000 taste buds coating the tongue's surface, all of which are responsible for the sensation of taste. Taste buds on the tip of the tongue detect sweetness; bitterness is detected by the back taste buds, while the side taste buds detect salt and sour tastes.
Taste receptors send nerve impulses to the taste center of the brain. The brain then uses both the taste and smell sensations to distinguish the flavors you recognize.
Simple tastes such as salty, sweet, sour, and bitter can be detected without smell, but the more complicated flavors—like the rich, velvety sensation of a mixture of chocolate chips, walnuts, butter, and brown sugar—require the sensations of both smell and taste to be fully appreciated.
Some common medical conditions, such as sinus infections , nasal polyps , upper respiratory infections, and allergies can trigger a loss of smell with subsequent alteration in taste perception.
Other medical problems that may affect smell include head trauma , Alzheimer's disease , Parkinson's disease , and multiple sclerosis .
Even certain dental conditions can affect taste perception. Gingivitis , tooth infections, and periodontal disease can leave enough of an unpleasant taste in your mouth to disrupt normal taste perception.
Using prescription medicines typically increases with age. Many commonly prescribed medicines have the potential to alter taste perception due either to their own bad taste or the potential to cause a dry mouth.
Certain protease inhibitors, which are used to treat HIV infection , have also been shown to modify taste perception. These protease inhibitors are predominantly bitter tasting, but patients also report an astringent, metallic, sour, and burning taste. Antidepressants, such as amitriptyline (Elavil), have a bitter and unpleasant taste and lead to dry mouth.
If medicines are causing dry mouth, your doctor may be able to prescribe a different one. In order to help manage dry mouth, artificial "saliva" is available by prescription. Drinking plenty of water is also encouraged for dry mouth disorders.
A deficiency of certain nutrients, such as zinc , can foster altered taste perception. Foods that contain significant amounts of zinc include meat, fish, poultry, milk, whole grains, nuts, and lentils.
Although deficiencies of other nutrients, such as vitamins A , B6 , and B12 , have been implicated as triggering taste alteration, there have been few published studies to actually confirm or refute this connection. However, researchers know that vitamin A and some of the B complex vitamins contribute to a healthy mouth. A deficiency of vitamin A can cause texture changes in the tongue, particularly the taste buds. Deficiencies of some B vitamins can lead to a condition called glossitis, which causes the tongue to become swollen and red with some sensation of pain or burning upon eating.
The American Dietetic Association offers some more tips on increasing the flavor of your foods:
RESOURCES:
International Food Information Center
http://www.ific.org/
NIH Senior Health
http://nihseniorhealth.gov/arthritis/toc.html/
CANADIAN RESOURCES:
Health Canada
http://www.hc-sc.gc.ca/index_e.html/
Seniors Canada On-line
http://www.seniors.gc.ca/
References
Bromley S. Smell and taste disorders: A primary care approach. Am Fam Physician. 2000;61:427-36.
Netter F. Nervous system: Anatomy and physiology. In: The Ciba Collection of Medical Illustrations. Vol 1. CIBA Pharmaceutical Company; 1986.
Spielman AI. Chemosensory function and dysfunction. Crit Rev Oral Biol & Med. 1998;9:267-291.
Zinc. EBSCO Natural and Alternative Treatments website. Available at: http://www.ebscohost.com/thisTopic.php?marketID=15topicID=114. Updated July 2008. Accessed July 29, 2008.
Last reviewed June 2010 by Brian P. Randall, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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