After age 50, the ability to smell and to taste gradually begins to decrease. The membranes lining the nose become thinner and drier, and the nerves involved in smell deteriorate. Older people can still detect strong odors, but detecting subtle odors is more difficult.
As people age, the number of taste buds also decreases, and those that are left become less sensitive. These changes tend to reduce the ability to taste sweet and salt more than the ability to taste sour and bitter. Thus, many foods start to taste bitter.
Because smell and taste are diminished as people age, many foods taste bland. The mouth tends to be dry more often, further reducing the ability to taste and smell. Also, many older people have a disorder or take drugs that contribute to dry mouth. Because of these changes, older people may eat less. Then, they may not get the nutrition they need, and if they already have a disorder, their condition may worsen.