Does Heart Bypass Surgery Alter the Sense of Taste?

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A potato chip, lemon or licorice may not taste quite the same to a patient after undergoing heart bypass surgery, hints a small study.

However, contrary to the researchers' predictions, detection of salty, sweet, sour and bitter appeared to be enhanced rather than reduced. The unexpected findings, they note, might be at least partially explained by hunger after fasting around the time of surgery.

Nearly half a million coronary artery bypass surgeries are performed in the U.S. every year, according to the American Heart Association.

"I had noticed that when I saw patients post-surgery that they would complain that food did not taste the same for them, even foods they loved previously," Mary Keith, a registered dietitian at St. Michael's Hospital in Toronto, Ontario, noted in an email to Reuters Health.

To better understand how heart surgery might influence tastes, Keith and her colleagues studied 33 adults who had heart bypass operations. Their average age was 62, and more than half were current or former smokers.

Participants' tastes were tested four times: before admission and at discharge from the hospital, and then again five weeks and four months after the surgery. Each time, patients underwent several rounds of sipping liquids from small cups until they could detect each taste. Only 13 patients completed all four tests.

Compared to pre-surgery, patients had significant improvement in their ability to pick out the four tastes during later tests, the researchers note in a report in the Journal of the American Dietetic Association.

According to earlier research, hunger naturally heightens the sense of taste, so the light diet consumed by patients before and after surgery could have influenced this result, they point out.

They also point to some limitations to their study, including its small size and the large proportion of patients who chose not to continue their participation following surgery. It may have been that these dropouts were in more discomfort and would have tested differently.

Still, the results point to a potentially important area for further research. "It is possible that if, as our results suggest, taste sensitivity is improved or heightened after surgery, then perhaps food becomes unpalatable for other reasons and therefore is perceived to taste different," said Keith.

Such changes could potentially limit food intake and put patients at risk of poor nutrition during the critical recovery period. For example, most nutritional supplements are sweet and may prove to be too sweet for altered tastes.

Doctors working with heart surgery patients, Keith added, need to be aware that changes in taste do occur in the post-surgery period "and that patients may find foods unappealing or unappetizing."

"Maintaining nutritional intake during this time of healing and recovery is important," Keith said, and she encourages doctors to "work with the patient to ensure that foods are palatable and subsequently consumed, particularly nutritional supplements."