Olfactory Stimulation with Japanese Soy Sauce Improves Upper Limb Performance

Abstract

Background We have observed changes in body reactions during cooking, which is one of the treatment modalities used in occupational therapy. The perception of food-related odors during cooking may have behavioral effects on human activities through the activation of appetitive motivation. Objectives We investigated whether odor components contained in seasonings could facilitate the human motor system and the specificity of this effect. Methods The subjects were 72 healthy adults, randomly assigned to a water exposure group, a phenylethyl alcohol (PEA, pleasant rose-like odor) exposure group, and a Japanese soy sauce (Koikuchi Shoyu) exposure group (n = 24 each). The subjects' olfactory sense was stimulated by their sniffing of three different test tubes containing 5 ml of water, PEA, or Japanese soy sauce for 20 sec while they were seated. The modified Functional Reach Test (mFRT), which mimics a functional activity that is required in daily living and assesses a reliable measure of sitting balance, was performed prior to and immediately after the sniffing. Results Sniffing the soy sauce increased the subjects' mFRT scores. This facilitation effect was odorant-specific and was absent when the subjects were presented with water or PEA. Conclusions Cooking interventions are aimed at improving tool-handling skills such as using knives and chopsticks. The results indicate that treatment interventions using odors of seasonings would be effective for improving subjects' physical functions.

Effects of odors on posture

“…Specifically, exposure to pleasant odors, in comparison to no odor, may reduce anterior/posterior postural sways, while exposure to unpleasant odors may enhance lateral fluctuations and introduce postural imbalance in contrast to pleasant or no odor conditions. This finding corroborates the stream of research showing that action and postural stability benefits from pleasant odors (Ebihara et al, 2011; Freeman et al, 2009; Gim et al, 2015; Ryan & Hummel, 2013; Welge‐Lüssen et al, 2009; Yano et al, 2019) and contradicts the initial findings on that matter, suggesting that olfactory stimulation, with the generally pleasant phenylethyl alcohol odor (PEA, smell resembling rose) enhances postural sways (Nieschalk et al, 1995). Furthermore, findings reported here extend our knowledge about the beneficial effects of pleasant edible odors on postural stability (Yano et al, 2019) by demonstrating that this effect emerges also in the presence of non‐edible pleasant odors.…”

“…This finding corroborates the stream of research showing that action and postural stability benefits from pleasant odors (Ebihara et al, 2011; Freeman et al, 2009; Gim et al, 2015; Ryan & Hummel, 2013; Welge‐Lüssen et al, 2009; Yano et al, 2019) and contradicts the initial findings on that matter, suggesting that olfactory stimulation, with the generally pleasant phenylethyl alcohol odor (PEA, smell resembling rose) enhances postural sways (Nieschalk et al, 1995). Furthermore, findings reported here extend our knowledge about the beneficial effects of pleasant edible odors on postural stability (Yano et al, 2019) by demonstrating that this effect emerges also in the presence of non‐edible pleasant odors. We were also able to confirm that postural stability may be compromised in the presence of an unpleasant odor (Schaefer et al, 2021).…”

“…More recent evidence seems to contradict these initial findings of odors causing postural sways. It has been reported that exposure to food‐related soy sauce odor during cooking, comparing to PEA and control no‐odor condition, improved upper limb performance of the participants in the modified Functional Reach Test, a reliable measure of sitting balance (Yano et al, 2019). Food‐related odor‐specific effect on motor skills has also been revealed in a study including dysphagic older adults, whose difficulties with swallowing were reduced when exposed to the smell of black pepper, compared to lavender oil (Ebihara, Kohzuki, Sumi, & Ebihara, 2011), and both these odors were earlier shown to have beneficial effects for postural stability in older people (Freeman et al, 2009).…”

Soy sauce and vanilla odors improve balance ability in children

“…Examination per person was completed within 1 day, starting roughly 1 h before lunch and lasting 20-30 min (Yano et al, 2019).…”

“…In adults, olfactory stimulation with lavender oil or black pepper oil improved postural stability (Freeman et al, 2009). Olfactory stimulation with Japanese soy sauce improves upper extremity performance (Yano et al, 2019). Food‐related olfactory stimulation with apple, orange, ginger, and garlic improves hand reach‐to‐grasp movements, particularly when odors of the objects congruent with the size of the ensuing target motions are delivered (Yang & Wang, 2020).…”