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Virtual reality (VR) headsets provide immersive audio-visual experiences for users, but usually neglect to provide olfactory cues that can provide additional information about our environment in the real world. This paper examines whether the introduction of smells into the VR environment enhances users' experience, including their sense of presence through collection of both psychological and physiological measures. Using precise odour administration with an olfactometer, study participants were exposed to smells while they were immersed in the popular PlayStation VR game "Resident Evil 7". A within-subject study design was undertaken where participants (n = 22) walked-through the same VR environment twice, with or without the introduction of associated congruent odour stimuli. Directly after each gameplay, participants completed a questionnaire to determine their sense of presence from the overall gameplay and their sense of immersion in each of the virtual scenes. Additionally, physiological measurements (heart rate, body temperature and skin electrodermal activity) were collected from participants (n = 11) for each gameplay. The results showed the addition of odours significantly increased participants' sense of spatial presence in the VR environment compared to VR with no odour. Participants also rated the realism of VR experience with odour higher compared to no odour, however odour addition did not result in change in emotional state of participants (arousal, pleasure, dominance). Further, the participants' physiological responses were impacted by the addition of odour. Odour mediated physiological changes were dependent on whether the VR environment was novel, as the effect of odour on physiological response was lost when participants experienced the aroma on the second gameplay. Overall, the results indicate the addition of odours to a VR environment had a significant effect on both the psychological and physiological experience showing the addition of smell enhanced the VR environment. The incorporation of odours to VR environments presents an opportunity to create a more immersive experience to increase a person's presence within a VR environment. In addition to gaming, the results have broader applications for virtual training environments and virtual reality exposure therapy., Competing Interests: The authors have read the journal’s policy and have the following competing interests: Nicholas Archer and Damian Frank are paid employees of the Commonwealth Scientific and Industrial Research Organisation (CSIRO) Active Integrated Matter (AIM) Future Science Platform (FSP). There are no patents, products in development or marketed products associated with this research to declare. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Bouillon cubes are a staple ingredient used in Sub-saharan African countries providing flavor enhancement to savory foods. Bouillon has been identified as a vehicle for fortification to overcome micronutrient deficiencies in Sub-saharan Africa. However, bouillon has a high sodium content (and in addition with other foods) contributes to dietary sodium intake above recommended guidelines. High dietary sodium intake is a key risk factor for hypertension and cardiovascular disease (CVD). Africa has the highest rates of hypertension and CVD globally with nearly half the adult population above 25 years affected. This review presents current state of research on sodium reduction strategies in bouillon. The key challenge is to reduce sodium levels while maintaining optimal flavor at the lowest possible production cost to ensure bouillon continues to be affordable in Sub-saharan Africa. To produce lower sodium bouillon with acceptable flavor at low cost will likely involve multiple sodium reduction strategies; direct reduction in sodium, sodium replacement and saltiness boosting flavor technologies. Efforts to reduce the sodium content of bouillon in Sub-saharan Africa is a worthwhile strategy to: (i) lower the overall sodium consumption across the population, and (ii) deliver population-wide health benefits in a region with high rates of hypertension and CVD., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Archer, Cochet-Broch, Mihnea, Garrido-Bañuelos, Lopez-Sanchez, Lundin and Frank.)

Significant experimental evidence supports fat as a taste modality; however, the associated peripheral mechanisms are not well established. Several candidate taste receptors have been identified, but their expression pattern and potential functions in human fungiform papillae remain unknown. The aim of this study is to identify the fat taste candidate receptors and ion channels that were expressed in human fungiform taste buds and their association with oral sensory of fatty acids. For the expression analysis, quantitative RT-PCR (qRT-PCR) from RNA extracted from human fungiform papillae samples was used to determine the expression of candidate fatty acid receptors and ion channels. Western blotting analysis was used to confirm the presence of the proteins in fungiform papillae. Immunohistochemistry analysis was used to localise the expressed receptors or ion channels in the taste buds of fungiform papillae. The correlation study was analysed between the expression level of the expressed fat taste receptors or ion channels indicated by qRT-PCR and fat taste threshold, liking of fatty food and fat intake. As a result, qRT-PCR and western blotting indicated that mRNA and protein of CD36, FFAR4, FFAR2, GPR84 and delayed rectifying K+ channels are expressed in human fungiform taste buds. The expression level of CD36 was associated with the liking difference score (R -0·567, β=-0·04, P=0·04) between high-fat and low-fat food and FFAR2 was associated with total fat intake (ρ=-0·535, β=-0·01, P=0·003) and saturated fat intake (ρ=-0·641, β=-0·02, P=0·008).

Solute carrier family 11 member a1 (SLC11A1) exerts pleiotropic effects on macrophage function. Expression of SLC11A1 is regulated by a (GT)(n) microsatellite promoter repeat polymorphism of which nine alleles have been described. Enhanced activation of macrophages, associated with increased expression from allele 3, may be functionally linked to the development of autoimmune and inflammatory diseases. Conversely, low expression, driven by allele 2, may afford resistance. We have performed a meta-analysis to determine the association of SLC11A1 promoter alleles 2 and 3 with autoimmunity and inflammation. A random effects pooled odds ratio (OR) of 1.04 (95% confidence interval [CI]=0.20) for allele 3 suggested a weak association of this allele with an increased risk of disease. Calculation of the OR in the absence of asymmetry yielded a random effects pooled OR of 0.88 (95% CI=0.66), effectively reversing the above association. A fixed effects pooled OR of 0.90 (95% CI=0.24) was obtained for allele 2, suggesting a weak predominance of disease in the absence of this allele. Application of the trim-and-fill method resulted in a fixed effects OR of 0.80 (95% CI=0.22), thus strengthening this association. Associations of allele 3 with autoimmune and inflammatory diseases reported in several association studies may be attributable to some form of bias amongst published results.