The decline of smell in the elderly is more complex than previously believed

Contrary to what science once suggested, older people with declining sense of smell don’t have a completely suppressed scent capacity for odors in general – it just depends on the type of smell. Researchers at the University of Copenhagen came to this conclusion after examining a large group of older Danes and their perception of the intensity of common food odors.

That grandpa and grandma don’t feel as good as they used to be is something many can relate to. And, it has also been scientifically proven. The sense of smell gradually begins to decline from around the age of 55. Until now, it was believed that the sense of smell greatly diminished with age. However, a study from the University of Copenhagen reports that some food odors are significantly more affected than others.

Eva Honnens of Lichtenberg Broge of the Department of Food Sciences and her fellow researchers tested the ability of older Danes to perceive everyday food smells. The researchers measured the intensity with which the elderly perceived different smells of food, as well as their degree of appreciation of the smells.

Our study shows that the decline in smell in the elderly is more complex than previously believed. Although their ability to smell fried meat, onions, and mushrooms is significantly lower, they smell of orange, raspberry, and vanilla just as well as young adults. Thus, a declining sense of smell in older people seems rather odor-specific. What is really interesting is that the degree of appreciation of a scent does not necessarily depend on the perception of intensity. “

Eva Honnens de Lichtenberg Broge, Researcher, Department of Food Sciences, University of Copenhagen

For example, the rating of seems to be largely unchanged for fried meat, onions and mushrooms, although the greatest drop in the perception of intensity was observed for these specific odors. The ability to smell coffee also decreased, among other things, although they did not like the aroma of coffee to the same degree as young adults.

Test subjects included 251 Danes aged 60 to 98 and a control group of 92 people aged 20 to 39.

What is the story?

Researchers can only speculate as to why the decline in smell in older people appears to be odor-specific and why, in some cases, appreciation is largely unaffected. However, they can only speculate on why the drop in intensity was most pronounced for fried meat, onions, and mushrooms – foods referred to as “salty” or umami by nature.

“This may be because these are common food odors in which salty or umami is a dominant taste element. It is widely recognized that salty is the basic taste most affected by aging. Since taste and smell are strongly associated when it comes to food, our perception of aroma may be disrupted if taste perception of salty taste is initially impaired, ”explains Eva Honnens of Lichtenberg Broge.

Health and quality of life

The researchers hope their findings can be used by those working to improve the meals and culinary experiences of older people. Figures show that half of people over 65 admitted to Danish hospitals suffer from malnutrition. The same is true for one in five nursing home residents.

While smell is important for stimulating appetite and our serotonin levels, according to Eva Honnens of Lichtenberg Broge, our study shows that smell sensitivity does not need to be decisive. For many of the food smells, the respondent’s taste for an odor remained unchanged, although their ability to perceive it had diminished.

“Our results show that as long as a food smell is recognizable, its intensity won’t determine whether you like it or not. So, if we want to improve the eating experiences of the elderly, it is more relevant to pay attention to what they enjoy. to eat than to wonder which aromas seem weakest to them, ”concludes Eva Honnens of Lichtenberg Broge.

The study is published in the scientific journal Food quality and preference.

Facts:

• The study was conducted in the Future Consumer Lab of the Department of Food Sciences at the University of Copenhagen by Eva Honnens of Lichtenberg Broge, Karin Wendin, Morten A. Rasmussen and Wender Bredie.
• The study involved 251 Danish elderly from five different regions. The subjects tested were between 60 and 98 years old. As a control group, 92 people aged 20 to 39 participated.
• Instead of using chemical odors, which is commonly the procedure for testing smell, Eva Honnens of Lichtenberg Broge developed a test kit comprising 14 natural food smells familiar from everyday life, including bacon, onions, toast, asparagus, coffee, cinnamon, orange and vanilla. The scents were mostly made up of essential oils and presented to test subjects by sniffing sticks.
• Food smells were chosen based on the commonly eaten foods and dishes that older people eat and enjoy most often, according to meal plans and surveys from a Danish catering company that provides food to older people.
• The study is part of the ELDORADO project. The project aims to study how Danish municipalities can increase the desire of older people living at home to eat more, in order to help them avoid suffering from malnutrition. The ELDORADO project is based in the Department of Food Sciences and led by Wender Bredie.