Your sense of smell enriches your experience of the world around you. Different scents can change your mood, transport you back to a distant memory, and may even help you bond with loved ones. Your ability to smell also plays a key role in your health. If your ability to smell declines, it can affect your diet and nutrition, physical well-being, and everyday safety. Whether coffee brewing, pine trees in a forest, or smoke from a fire, the things we smell are actually tiny molecules released by substances all around us. When we breathe in these molecules, they stimulate specialized sensory cells high inside the nose. Each of these sensory cells has only one type of odor receptor ó a structure on the cell that selectively latches onto a specific type of ìsmellyî molecule. There are more smells in the environment than there are odor receptors. But a given molecule can stimulate a combination of these receptors, creating a unique representation in the brain of a particular smell.ìItís estimated that the number of odors that people can detect is somewhere between 10,000 and 100 billion, or even more,î says Dr. Gary Beauchamp, a taste and smell researcher at Monell Chemical Senses Center in Philadelphia. People have different combinations of odor-detecting cells in their noses, so people vary greatly in their sensitivity to smells, Beauchamp said.For thousands of years, fragrant plants have been used in healing practices across many cultures, including ancient China, India, and Egypt. Aromatherapy, for example, uses essential oils from flowers, herbs, or trees to improve physical and emotional well-being.Smell is also important for taste. Chewing food releases aromas that travel from your mouth and throat to the nose. Without smell, we can detect only five basic tastes: sweet, salty, bitter, sour and umami (savory). But our brains incorporate information from both taste and smell receptors to create the perception of many different flavors.Some people may think theyíve lost their sense of taste if food begins to taste bland or slightly ìoff.î But in fact, they may have lost their ability to smell.Many things can cause smell loss. A stuffy nose or a harmless growth in the nose (called a polyp) can block air and thus odors from reaching the sensory cells. Certain medications, like some antibiotics or blood pressure pills, can alter smell. These effects are usually temporary. Your smell should come back once youíve recovered or stopped the treatments.But some things can cause a long-lasting loss of smell. A head injury or virus, for example, can sometimes damage the nerves related to smell. And your ability to smell may naturally fade as you get older.People whoíve lost their sense of smell sometimes try to boost flavor by adding more salt or sugar to their foods. But these additions might cause problems for those at risk for certain medical conditions, such as high blood pressure, kidney disease, or diabetes. Talk with your doctor if you think a smell deficit might be affecting your quality of life.Smell loss can also put you in harmís way if you donít notice a ìwarningî smell. The recent national health and nutrition survey found that one in 10 people couldnít identify the smell of smoke, and about 15 percent couldnít identify the smell of natural gas.ìWith age, there is a decline in the ability to smell to some extent in the nose, but much more in the brain itself,î said Dr. Davangere Devanand at Columbia University, an expert on neurodegenerative diseases and smell loss. ìThe main reason appears to be that the functioning of the brain regions involved in smell and memory become impaired as we grow older.îBut problems with your ability to smell may be more than normal aging. They can sometimes be an early sign of serious health conditions, such as Parkinsonís disease, Alzheimerís disease or multiple sclerosis. Devanandís group is currently studying the relationships between smell dysfunction and Alzheimerís disease.Like all of your senses, your sense of smell plays an important part in your life. If you think youíre experiencing a loss of taste or smell, see your health care provider. There may be ways to help fix the problem. If not, your doctor can help you learn to cope with the changes in smell and taste.
