Up to 15 million Americans suffer from a severe-to-total loss of sense of smell. By age 65, up to half of adults have a reduced sense of smell. What to do…


It's estimated that the average adult can detect between 10,000 and 30,000 distinct odors. The nasal membranes are lined with cellular receptors that match the shape of different scent molecules. These molecules bind to cell walls at the top of the nose, where they trigger the release of neurochemicals. These, in turn, generate nerve signals that stimulate the parts of the brain that identify different scents.

Cigarette smokers are far more likely to experience a loss of smell than nonsmokers. Damage to the sense of smell also can be caused by brain injury, nasal polyps, a brain tumor or nervous system diseases, such as Parkinson's.

Other causes: Diabetes, a deficiency of some B vitamins and the use of cholesterol-lowering statins or antihypertensive drugs.

Many patients with a diminished sense of smell also suffer from chronic depression or anxiety disorders. It's possible that the air contains yet-to-be-identified molecules with druglike, anti-anxiety effects—benefits that don't occur in those with smelling disorders.

Smell Test

To test for a diminished sense of smell, most doctors take an alcohol pad and hold it beneath the patient's chin. (You can do this at home with an alcohol pad from a first-aid kit.) If you can smell alcohol at that distance, your sense of smell is fine. If you can smell the alcohol only when the pad is raised closer to your nose, you have a problem.

Self-test: Put vanilla ice cream in one bowl and chocolate ice cream in another. Close your eyes, and move the bowls around so that you don't know which is which. Take a taste from each bowl. Because taste is largely determined by smell, an inability to tell them apart indicates that there's a problem somewhere in your olfactory system.

What To Do

Often, when the underlying problem is corrected, the sense of smell returns. People who quit smoking usually regain all or most of their sense of smell, but this can take years. Also…

  • The nutrients thiamine (100 milligrams daily) and phosphatidylcholine (9 grams daily) can elevate levels of neurotransmitters that improve the sense of smell. In one study, about 40% of patients improved significantly after taking phosphatidylcholine for three months. The success rate with thiamine is somewhat lower.
  • Sniff therapy. People who expose themselves to the same scent 20 to 50 times a day for several weeks will have an increase in scent receptors and will sometimes regain their ability to smell that particular scent.

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