Our ability to fully enjoy food requires stimulation of many nerve endings in the mouth and nose. Taste is the mouth’s ability to identify what is salty, sweet, sour or bitter. There’s also a fifth type of taste called umami, from the Japanese for delicious. It’s triggered by monosodium glutamate (MSG).

But what we commonly refer to as the taste of food is actually its flavor. And flavor is determined more by the food’s aroma, which is more a function of our sense of smell than by pure taste.

Some loss of smell and taste almost always happens as we get older. This usually starts after about age 60. But before accepting older age as the cause of loss of taste, it’s worth considering reasons for losing the sense of smell that aren’t related to getting older. Topping the list is blockage of the nasal passages. This might be caused by:

• Allergies
• Secondhand smoke or other irritants
• A persistent sinus infection
• Polyps in the nose

Sometimes people lose their sense of smell after an upper respiratory tract infection.

People with high blood pressure seem to be more likely to lose the sense of taste and smell. It’s not clear whether this is related to high blood pressure itself or to the drugs used to treat it. These types of high blood pressure drugs have been reported to cause taste loss: diuretics (water pills) such as hydrochlorothiazide, and ACE inhibitors such as captopril (Capoten), enalapril (Vasotec) and lisinopril (Prinivil, Zestril).

If it is related to one of your blood pressure pills, it’s probably reversible. But don’t stop taking any of them until you talk with your doctor. He or she might suggest switching to a different class of drugs or taking other steps to regain some taste. For example, if your mouth is dry from diuretics, you might try sipping water between bites. Sometimes, the moisture can help make food more flavorful.