Of the five senses, taste and smell are very closely related. To perceive a smell, molecules float into the nose and bind to tiny hairs called cilia, triggering neurons that pick up on the odor. Taste buds on the tongue have taste cells that sense primary flavors. Occasionally, people experience heightened senses of taste or smell, making them more sensitive to flavors and odors. There are many reasons that a person may experience these heightened senses.
During pregnancy, heightened levels of estrogen and progesterone are responsible for many changes in the body. Women may experience both heightened sense of smell and taste. Heightened sense of taste during pregnancy is known as dysguesia. Dysguesia differs from the cravings or aversions that women may experience. This heightened sense of taste comes from changes in taste bud structure that causes women to experience tastes differently, making certain tastes, such as bitter flavors, much more acute.
Dysguesia may be due to the heightened sense of smell that women also experience during pregnancy. Higher levels of estrogen can make even the slightest smells seem overwhelming. Heightened sense of smell is experienced by all women during pregnancy, and can be a primary contributor to morning sickness. (See Reference 3)
Body mass index may be a contributor to heightened sense of smell. People with a larger body mass index have a much higher sense of smell compared to those with a BMI in the normal range. This heightened smell may be the reason that people continue to eat even after they are full, leading to obesity. Obesity can also be linked to a heightened sense of taste, as foods that are high in sugar and fat pack strong flavors. This craving for flavorful junk foods is due to dysfunction of opipoid receptors in the brain that drive the palatability of foods.
Prolonged stress can contribute to heightened sense of smell. Sense of smell can become more acute following an accident, injury or operation. This is triggered by our most innate survival instincts. When we are subject to prolonged stress, our adrenal glands kick into overdrive. That stress and fatigue can cause increased sensitivity to offensive odors, perfumes and even pheromones. Once the stress subsides and the adrenal glands have time to heal, sense of smell can return to normal.
While taste disorders are typically associated with the loss of taste, a taste disorder that heightens your sense of taste is a problem that affects 25 percent of the U.S. population. These people are known as supertasters. Affecting women more than men, supertasters experience such strong tastes that food like coffee, alcohol, tomatoes, desserts, parmesan cheese, green vegetables and certain condiments are unpalatable. Supertasters detect spicy, salty and bitter flavors that others cannot typically detect in foods. This is due to a greater density of taste buds. Supertasters have 10 to 100 more taste buds than the average person.