Some people have very acute taste, with a lot of taste buds, and are especially sensitive to sweet and sour. Yet others have fewer taste buds and a dulled sense of taste. Taste sensitivity diminishes with aging, beginning around 60 years of age, making it more difficult to recognize and identify subtle flavors. Certain diseases, including diabetes, may also significantly alter taste. A bad case of the flu can impair taste for an extended period of time even up to several years.
Poor nutrition can be a main factor.
Some medications can distort taste, often by causing a metallic or bitter taste. They were found to eat more high fat, high sugar foods, and avoided the healthful fruits and vegetables with sour or bitter flavors. Those with decreased sense of smell tended to be heavier, possibly due to continuing eating with the hope that the next bite would taste better. Due to these factors, it is important to compensate for decreased sense of smell and taste by emphasizing other food attributes such as texture and color. Along with improving digestion, chewing food more thoroughly also increases flavor by releasing compounds in foods that tell the brain what you are eating.