Olfactory Threshold and Perception Intensity of Fatty Acids in Relation to Sex

In humans, food choice, nutrient intake and meal size are strongly influenced by their sense of smell. Recent studies have shown that humans can perceive the odor of free fatty acids (FFAs), which provide information about the nutritional content of foods. Other studies suggest that the odor perceived is that of secondary oxidation products. The aim of this research was to study the orthonasal perception of palmitic (PA), oleic (OA) and linoleic (LA) fatty acids (FAs) as they elute from the chromatographic column, to correlate the perceived intensity to the olfactory threshold for FAs, and to explore differences related to sex and the general olfactory function of individuals. The ability to perceive the odor of FAs was assessed in 70 healthy subjects, previously classified as normosmic or hyposmic. The number of participants who smelled PA was significantly lower than that of OA and LA. Normosmic participants and females reported perceiving the FA odor with a higher intensity than hyposmic ones and males, respectively. The perception intensity of FA odor reported by participants showed a decreasing order: LA=OA>PA for males, normosmic and hyposmic individuals and LA>OA>PA for females. The olfactory threshold for FA odor reported by the participants was in decreasing order: PA>OA=LA for males, normosmic and hyposmic individuals and PA>OA>LA for females. The results confirm the human ability, with females and normosmic individuals performing better than males and hyposmic ones respectively, to perceive the FA odor and show that the intensity of perception increases with decreasing FA lipophilicity; consequently, the olfactory threshold also decreases.