Appetite-enhancing Effects of Trans-Cinnamaldehyde, Benzylacetone and 1-Phenyl-2-butanone by Inhalation

Fragrance in the air and odours of foods and drinks are reported to affect feeding behaviours of humans and other animals. Many previous studies focusing on the relationship between fragrance and appetite have described a reduction of food intake by fragrance administration to help prevent lifestyle diseases. Aromatic herbal medicines, such as cinnamon bark and fennel fruit, are considered to have appetite-enhancing effects and they are often blended in stomachics for relief of asitia and gastric distress in Japan. These fragrant herbal medicines contain many essential oils and their fragrances are hypothesised to be active substances. In this study, food intake and the expression of neuropeptide Y and proopiomelanocortin in the hypothalamus after inhalation of fragrant compounds or essential oils were investigated in mice. Food intake was increased 1.2-fold and the neuropeptide Y mRNA expression in the hypothalamus was increased significantly in mice that inhaled trans-cinnamaldehyde, benzylacetone or 1-phenyl-2-butanone, compared with the control group. These compounds might be effective for treating loss of appetite (anorexia) or eating disorders in elderly and infirm people via a non-invasive route of administration, namely, inhalation.