User perception of fluoride mouthwashes for daily use: A randomized clinical trial

AIM

To assess user perceptions of different commercially available fluoride mouthwashes (FL-MWs).

METHODS

A single-blind, randomized clinical trial was conducted. Participants were randomly assigned to a sequence of six different FL-MWs, one of which contained alcohol. For each visit, participants rinsed with one specific mouthwash (15 mL) for 30 s. After rinsing, participants completed a questionnaire with a visual analogue scale. Questions focused on overall taste, mild/pungent feeling, taste duration, foaming effect, burning sensation, sensitivity, numbness, dryness, rinsing time, smell, and colour of the mouthwashes. Descriptive analyses and statistical tests regarding differences among and between the mouthwashes were performed.

RESULTS

Overall, 53 participants completed the study protocol, including nine who did, however, not rinse with the alcohol-containing mouthwash due to religious reasons. Among the mouthwashes, significant differences were found for foaming effect, sensitivity, rinsing time, smell, and colour (p < 0.05). Pairwise comparison for smell did not reveal a difference, and foaming was within the acceptance range (low to medium foaming). Coloured mouthwashes were more appreciated than transparent solutions (p = 0.00). The mouthwash containing essential oils and alcohol produced significantly more sensitivity (p = 0.00) and, in general, participants experienced the rinsing time significantly longer (p < 0.05) compared to the non-alcohol-containing mouthwashes.

CONCLUSION

There is heterogeneity in user perceptions and preferences for FL-MWs, with a significant difference in foaming effect, sensitivity, rinsing time, smell, and colour. Coloured mouthwashes are preferred. The mouthwash containing essential oils and alcohol was less acceptable in relation to sensitivity and rinsing time.

Characterizing the use, preferences, and perceptions of flavors in cigars in pregnant women

BACKGROUND

Flavors contribute to the appeal of tobacco products, but less is known about flavors in cigar products. The current study is the first to focus on characterizing the use and perceptions of flavors in cigar products among pregnant women.

METHODS

Pregnant women (N = 124) reported their use, preferences (liking, attractiveness, smoothness, interest), perceptions of harm (general, pregnancy-specific, fetal), and postpartum intention to use eight flavor categories (menthol/mint, spices, fruit, chocolate, alcohol, other beverages, candy/sweet, tobacco). We utilized correspondence analysis of contingency tables to investigate clustering of preferences and perceptions of flavors across the sample, and examined how preferences and perceptions of flavors may differ based on history of cigar use (none vs. lifetime vs. prenatal).

RESULTS

Overall, 37% reported never trying cigars, 51% reported lifetime use, and 12% reported prenatal use. Fruit (37%), tobacco (36%), and alcohol (14%) were the most common cigar flavors participants reported ever trying. Correspondence analysis revealed clustering in preferences for alcohol, fruit, and candy flavors compared to other flavors, and revealed lower intentions to use menthol/mint and tobacco flavors compared to other flavors. Participants who reported prenatal cigar use also reported more positive perceptions and greater intentions to use (1) spice and alcohol flavors compared to those who reported lifetime use (ps < .05); and (2) spice, alcohol, fruit, and tobacco cigar flavors compared to participants reporting never using cigars (ps < .04).

CONCLUSIONS

Regulations to restrict the availability of flavors, especially fruit, spice, and alcohol, may reduce the appeal and use of cigar products in pregnant women.

Histological analysis of neuronal changes in the olfactory cortex during pregnancy

Fluctuations in olfactory sensitivity are widely known to occur during pregnancy and may be responsible for hyperemesis gravidarum. These changes are thought to be caused by structural and functional alterations in neurons in response to marked changes of the hormonal milieu. In this study, we examined changes in neurons in the olfactory cortex during pregnancy and after delivery in rats. Dendritic spine densities were measured in the piriform cortex (PIR) and posterolateral cortical amygdala (COApl), which are involved in olfaction. The results showed increased numbers of dendritic spines in the PIR in mid-pregnancy and in the COApl during early and late pregnancy, but not in the motor area of the cerebral cortex, indicating a correlation with changes in olfactory sensitivity during pregnancy. Immunohistochemical analysis of expression of ovarian hormone receptors in these brain regions revealed a decrease in the number of estrogen receptor α-positive cells during pregnancy in the PIR and during pregnancy and the postpartum period in the COApl. Regarding pregnancy-related peptide hormones, oxytocin receptors were expressed in the PIR and COApl, while prolactin receptors were not found in these regions. Accordingly, oxytocin-containing neurites were distributed in both regions. These results suggest that the balance of these hormonal signals has an effect on olfactory sensitivity in pregnant females.

Gustatory and olfactory shifts during pregnancy and the postpartum period: A systematic review and meta-analysis

Pregnancy is a transformative phase marked by significant behavioral and physiological changes. Substantial changes in pregnancy-related hormones are thought to induce changes in chemosensory perception, as often observed in non-human animals. However, empirical behavioral research on pregnancy-related olfactory or gustatory changes has not yet reached a consensus. This PROSPERO pre-registered systematic review and meta-analysis evaluated published data of olfactory and gustatory changes in pregnant individuals, across the three pregnancy trimesters and postpartum period. Our comprehensive search strategy identified 20 relevant studies, for inclusion in the meta-analysis. The meta-analysis revealed that pregnant individuals, regardless of trimester, performed significantly poorer in terms of odour identification, however, no difference was detected between non-pregnant controls and women postpartum. Additionally, pregnant women in the second and third trimester rated olfactory stimuli to be more intense. A slight decline in odour pleasantness ratings was observed amongst those in the second trimester. No major difference was observed between pregnant and non-pregnant subjects in terms of gustatory functions, except the first trimester appeared to be associated with increased pleasantness for the sweet taste. Post-hoc meta-regression analyses revealed that pregnancy stage was a significant predictor for observed effect size for odour intensity ratings, but not for odour identification scores. These findings provide valuable insights into the interplay between pregnancy and chemosensory perception, highlighting systematic physiological changes due to pregnancy. Healthcare providers can also utilize the knowledge of sensory shifts to better support pregnant women in making appropriate dietary choices, managing sense-related discomfort, and leading to potential sensory interventions. Overall, this research enhances our comprehension of sensory shifts during pregnancy, benefiting maternal health and pregnancy-related care.

Research Progress on the effects of adverse exposure during pregnancy on skeletal muscle function in offspring

Skeletal muscle plays a crucial role in maintaining metabolic function, energy homeostasis, movement function, as well as endocrine function. The gestation period is a critical stage for the myogenesis and development of skeletal muscle. Adverse environmental exposures during pregnancy would impose various effects on the skeletal muscle health of offspring. Maternal obesity during pregnancy can mediate lipid deposition in skeletal muscle of offspring by affecting fetal skeletal muscle metabolism and inflammation-related pathways. Poor dietary habits during pregnancy, such as high sugar and high fat intake, can affect the autophagy function of skeletal muscle mitochondria and reduce the quality of offspring skeletal muscle. Nutritional deficiencies during pregnancy can affect the development of offspring skeletal muscle through epigenetic modifications. Gestational diabetes may affect the function of offspring skeletal muscle by upregulating the levels of miR-15a and miR-15b in offspring. Exposure to environmental endocrine disruptors during pregnancy may impair skeletal muscle function by interfering with insulin receptor-related signaling pathways in offspring. This article reviews the research progress on effects and possible mechanisms of adverse maternal exposures during pregnancy on offspring skeletal muscle function in clinical and animal studies, aiming to provide scientific evidence for the prevention and treatment strategy of birth defects in skeletal muscle.

Metabolic and feeding adjustments during pregnancy

Eating behaviours are determined by the integration of interoceptive and environmental inputs. During pregnancy, numerous physiological adaptations take place in the maternal organism to provide an adequate environment for embryonic growth. Among them, whole-body physiological remodelling directly influences eating patterns, commonly causing notable taste perception alterations, food aversions and cravings. Recurrent food cravings for and compulsive eating of highly palatable food can contribute to the development and maintenance of gestational overweight and obesity with potential adverse health consequences for the offspring. Although much is known about how maternal eating habits influence offspring health, the mechanisms that underlie changes in taste perception and food preference during pregnancy (which guide and promote feeding) are only just starting to be elucidated. Given the limited and diffuse understanding of the neurobiology of gestational eating patterns, the aim of this Review is to compile, integrate and discuss the research conducted on this topic in both experimental models and humans. This article sheds light on the mechanisms that drive changes in female feeding behaviours during distinct physiological states. Understanding these processes is crucial to improve gestational parent health and decrease the burden of metabolic and food-related diseases in future generations.

Dietary Intake and Its Association with Birth Outcomes in Women with Nausea and Vomiting during the Second Trimester of Pregnancy: A Prospective Cohort Study in Japan

Nausea and vomiting in pregnancy (NVP) is a common symptom. Although the influence of NVP during the first trimester on dietary intake and birth outcomes has been revealed, no study has focused on NVP during the second trimester. This study aimed to reveal whether NVP severity during the second trimester is associated with dietary intake, gestational weight gain (GWG), birth weight, and delivery week. Participants completed a questionnaire at 18-27 gestational weeks. NVP severity was assessed using the modified Pregnancy-Unique Quantification of Emesis and Nausea scale in the questionnaire. Dietary habits were assessed using a brief-type diet history questionnaire. In total, 825 responses were analyzed: 202 (24.5%), 135 (16.4%), and 8 (1.0%) women reported mild, moderate, and severe NVP, respectively; 480 (58.2%) women did not have NVP during the second trimester. No significant association was observed between energy and nutrient intake and no/mild and moderate/severe NVP. Women with moderate/severe NVP had lower total GWG than those with no/mild NVP (p = 0.007). There was no significant difference in low birth weight and preterm birth rates (p = 0.246 and p = 0.604). This is the first study to investigate whether NVP severity during the second trimester is associated with dietary intake and birth outcomes.

Longitudinal study of energy, neurosensory and eating responses durinG pregnancY (ENERGY cohort): A study protocol

BACKGROUND AND AIMS

Physiological changes that occur during pregnancy can have long-term impacts on metabolism and neurosensory responses to food, which can impact nutrition and health outcomes. The ENERGY cohort is a longitudinal study that aims to capitalizes on pregnancy as a natural model of metabolic reprogramming in order to understand the neurosensory mechanisms underpinning links between metabolism and dietary behaviour. The study objectives are to test for multi-sensory shifts during pregnancy, and the effect of sensory changes on dietary choices and bodyweights, and to identify neurosensory mechanisms that determine macronutrient selection before and after pregnancy.

METHODS

A longitudinal cohort study involving 130 pregravid women planning to conceive with the next 12-months and 65 pregravid women with no short-term plans to conceive. Participants will be recruited from Dunedin and Auckland, New Zealand. The study will test for changes in diet, neurosensory outcomes, and metabolism across the reproductive cycle, from pre-pregnancy to 1-year post-pregnancy. Data will be collected at six timepoint throughout the pregnancy which will occur approximately every 3 months. The primary response variables will be changes in supra-threshold sensitivity across modalities, dietary intake, and metabolism between pre-pregnancy and post-pregnancy. Longitudinal data analysis will use linear mixed models to assess changes in the response outcomes over time adjusted for age, ethnicity, and socioeconomic status.

DISCUSSION

Understanding the relationship between metabolism, sensory processing, and macronutrient preferences will provide crucial insights into diet-related health issues, including obesity. This study will lead to the formation of a prospective research cohort that is unique to Aotearoa New Zealand, and will develop multidisciplinary skills that are increasingly necessary to addressing the obesity epidemic.

Endocannabinoid administration affects taste preference and the expression of cannabinoid and opioid receptors in the amygdala of early lactating cows

The aim of the study was to investigate the influence of intraperitoneal N-arachidonoylethanolamide (AEA) on taste preference for feed and water, tongue taste receptor signalling (TAS1R2, GNAT3), and endocannabinoid (CNR1, CNR2, GPR55) and opioid (OPRD1, OPRK1, OPRM1, OPRL1) receptors in the amygdala and nucleus accumbens in periparturient cows. We conducted taste preference tests using unaltered, umami-tasting, and sweet-tasting water and feed, before and after calving. After calving, eight cows received AEA injections (3 µg/(kg bodyweight × day), 25 days), whereas eight control (CON) cows received saline injections. Tissue was sampled 30 days after calving. Before calving, both cow groups preferred sweet-tasting feed and umami-tasting water. After calving, only the AEA-treated group preferred sweet-tasting feed, whereas the CON group showed no clear taste preference. In the amygdala, the mRNA expression of CNR1, OPRD1 (left hemisphere) and OPRK1 (right hemisphere) was lower in AEA animals than in CON animals, whereas no differences were found in the nucleus accumbens and tongue taste receptor expression. In conclusion, AEA administration enhanced existing taste preferences and reduced the expression of specific endocannabinoid and opioid receptors in the amygdala. The results support endocannabinoid-opioid interactions in the control of taste-dependent feed preference in early lactating cows.

Flavored waterpipe tobacco preferences, perceptions, and use in pregnant women: A latent factor mapping approach

Waterpipe tobacco (WPT) use is increasingly common in young adults including pregnant and reproductive-age women. Sweet flavors contribute to the appeal of WPT and are a promising regulatory target. The present study utilized correspondence analysis of contingency tables, a latent factor mapping technique, to investigate preferences and perceptions of WPT flavors in a sample of racially/ethnically diverse, low-income pregnant women. One hundred pregnant women (mean age = 26 years, 65% racial/ethnic minorities) completed a detailed interview regarding their use, preferences, and perceptions of WPT flavors. Eighty-three percent of participants reported lifetime WPT use; 11% reported prenatal WPT use. Pregnant women reported greatest use of and stronger preferences for sweet (fruit, candy, alcohol) and menthol/mint flavors, and weaker preferences for tobacco flavored WPT. Latent factor mapping revealed clustering of preferred sweet (fruit, candy, alcohol) and menthol/mint flavors versus tobacco flavors, with pungent flavors (coffee, chocolate, spice) clustering between sweet and tobacco flavors. Preferences for sweet and menthol/mint flavors distinguished pregnant women who reported lifetime WPT versus no lifetime WPT use, and prenatal WPT use versus no prenatal WPT use. Harm perceptions did not vary by flavor. Regulations to restrict the availability of WPT flavors may reduce the appeal and use of WPT, especially among pregnant women.

Sex differences in the taste-evoked functional connectivity network

The central gustatory pathway encompasses multiple subcortical and cortical regions whose neural functional connectivity can be modulated by taste stimulation. While gustatory perception has been previously linked to sex, whether and how the gustatory network differently responds to basic tastes between men and women is unclear. Here, we defined the regions of the central gustatory network by a meta-analysis of 35 fMRI taste activation studies and then analyzed the taste-evoked functional connectivity between these regions in 44 subjects (19 women) in a separate 3 Tesla activation study where sweet and bitter solutions, at five concentrations each, were administered during scanning. From the meta-analysis, a network model was set up, including bilateral anterior, middle and inferior insula, thalamus, precentral gyrus, left amygdala, caudate and dorsolateral prefrontal cortex. Higher functional connectivity than in women was observed in men between the right middle insula and bilateral thalami for bitter taste. Men exhibited higher connectivity than women at low bitter concentrations and middle-high sweet concentrations between bilateral thalamus and insula. A graph-based analysis expressed similar results in terms of nodal characteristics of strength and centrality. Our findings add new insights into the mechanisms of taste processing by highlighting sex differences in the functional connectivity of the gustatory network as modulated by the perception of sweet and bitter tastes. These results shed more light on the neural origin of sex-related differences in gustatory perception and may guide future research on the pathophysiology of taste perception in humans.

Use and perceptions of menthol versus non-menthol cigarettes among pregnant women

BACKGROUND

Menthol cigarette use among women who smoke cigarettes during pregnancy is high, but little is known about the factors that contribute to preference for menthol cigarette use during pregnancy.

OBJECTIVE

This study investigated preferences, perceptions, and intentions to use menthol vs. non-menthol cigarettes in a sample of pregnant women.

METHODS

Pregnant women (N = 124, M_age = 26.2 years, 50% minorities) completed a study investigating the impact of maternal smoking on biobehavioral markers of fetal risk. During the third trimester, participants self-reported preferences (liking, attractiveness, smoothness, interest), perceptions of harm (general, pregnancy-specific), and intentions to use menthol and non-menthol cigarettes. We examined differences in responses based on whether participants endorsed (1) cigarette use during pregnancy (yes/no) and (2) lifetime cigarette use (yes/no).

RESULTS

Sixty-two participants endorsed cigarette smoking during pregnancy (85.5% smoked menthol cigarettes), and 94 participants reported lifetime use. Overall, menthol cigarettes were perceived as more likeable and smoother vs. non-menthol (ps < .001) - even among participants who never smoked cigarettes (ps < .05). All participants rated both menthol and non-menthol cigarette use as harmful. Compared to participants who did not smoke during pregnancy, participants who smoked during pregnancy rated menthol cigarettes as less harmful for pregnant women (p = .001), while there were no differences between groups in harm perceptions toward non-menthol cigarettes.

CONCLUSIONS

Menthol may increase cigarettes appeal for pregnant women. Implications for regulation of menthol cigarettes are discussed. Future studies may investigate the role of sensory perception, marketing, and health education in influencing these factors.

Impact of Nutritional Intervention on Taste Perception-A Scoping Review

The aim of the present scoping review was to evaluate the impact of experimental meal loads or observational diet changes/habits on taste tests in both healthy subjects and patients. A systematic search performed in PubMed, Scopus, and Institute for Scientific Information (ISI) Web of Science electronic databases retrieved, respectively 2981, 6258, and 7555 articles from January 2000 to December 2020. A total of 17 articles were included for full-text review. Literature results were stratified according to the observational/interventional approach, the involvement of healthy subjects or patients, the taste test, and the meal/dietary changes. The present scoping review reinforced the notions postulating that certain taste tests (for example focusing on fatty acid, salt, or sugar) might be specifically influenced by the nutritional intervention and that other ones might be susceptible to a wide span of changes beyond the extent of tastant included in the specific food changes. This could also depend on the inhomogeneity of literature trend: The short duration of the intervention or the random type of meal load, unsuitability of the taste test chosen, and the presence of underlying disorders. Future studies for a better comprehension of taste tests reliability in relation to specific food changes are thus to be fostered.

Changes in diet from pregnancy to one year after birth: a longitudinal study

Background

Pregnancy and the first year after giving birth are marked by physiological and psychological changes. While it is well known that energy requirements change during this time, the question of how a woman’s diet actually changes from pregnancy until 1 year postpartum has been left virtually unexplored. The present study employs a longitudinal design to investigate these changes.

Methods

Data were collected within the framework of the LIFE Child study (Leipzig, Germany). The diet composition and culture of eating of 110 women were assessed at 3 time points: in the 24th week of pregnancy, 3 months after giving birth (breastfeeding period), and 12 months after giving birth (after weaning). We assessed differences in nutritional health (Nutritional Health Score, NHS) and the consumption of different food items at each of these time points. We also investigated associations between nutritional health and age, socio-economic status (SES), BMI before pregnancy, and previous births at all three time points.

Results

The analyses revealed high correlations in the NHS values between the three time points (rho_t0/t1 = .55, rho_t0/t2 = .60). On average, nutritional health was lower in the breastfeeding period than during pregnancy. In more detail, women reported less healthy levels of treats and white bread consumption and a higher frequency of snacking in the breastfeeding period than during pregnancy. In contrast, overall nutritional health did not differ significantly between pregnancy and the time after weaning. Increased age was associated with a healthier diet during pregnancy, and a high SES was associated with healthier diet after weaning. Furthermore, the increase in nutritional health from the breastfeeding period to the time after weaning was significantly stronger in women with a higher BMI. We observed no significant associations between dietary nutritional health and previous births.

Conclusions

The present findings suggest that higher energy requirements in the breastfeeding period are met by consuming high-calorie and unhealthy food products rather than healthy and nutrient-rich food. Young mothers should be supported in taking care of their own nutritional health during the challenging time of breastfeeding and caring for a newborn child.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-04038-3.

Does Each Menstrual Cycle Elicit a Distinct Effect on Olfactory and Gustatory Perception?

The obesity pandemic has brought forth a scientific interest in food intake and sensory perception interactions. Olfactory perception and gustatory perception are very complex and under the influence of many factors, including the menstrual cycle. This study aims to clarify conflicting findings on the influence of the menstrual cycle on olfactory and gustatory perception. Women were assessed during four consecutive phases of one complete cycle (mid-follicular, ovulatory, mid-luteal, and late luteal phases (N = 21)), in contrast to women measured across the same phases belonging to two menstrual cycles (N = 29). Additional control groups were men (N = 17), postmenopausal women (N = 14), oral contraceptive users (N = 10), and women with an anovulatory cycle (N = 8). Olfactory threshold, odor discrimination, and identification were tested using the "Sniffin Sticks" test kit. Suprathreshold intensity and hedonic ratings for sweet, salty, sour, and bitter solutions were assessed. One-way ANOVA and ANOVA for repeated measurements was applied in the analysis, along with linear and trigonometric data fitting and linear mixed models. Linear increases in olfactory discrimination, identification, and overall olfactory performance were observed only in women followed across a complete menstrual cycle. Compared to other groups, these women displayed a cyclic pattern characterized by a predilection for sweet solution; reduced distaste for salty and sour solutions; and increased intensity perception of salty, sour, and bitter solutions towards the end of the cycle. These results suggest that a distinct hormonal milieu of a complete menstrual cycle may be affecting both olfactory and gustatory perception.

Dietary nitrate and population health: a narrative review of the translational potential of existing laboratory studies

BACKGROUND

Dietary inorganic nitrate (NO3-) is a polyatomic ion, which is present in large quantities in green leafy vegetables and beetroot, and has attracted considerable attention in recent years as a potential health-promoting dietary compound. Numerous small, well-controlled laboratory studies have reported beneficial health effects of inorganic NO3- consumption on blood pressure, endothelial function, cerebrovascular blood flow, cognitive function, and exercise performance. Translating the findings from small laboratory studies into 'real-world' applications requires careful consideration.

MAIN BODY

This article provides a brief overview of the existing empirical evidence basis for the purported health-promoting effects of dietary NO3- consumption. Key areas for future research are then proposed to evaluate whether promising findings observed in small animal and human laboratory studies can effectively translate into clinically relevant improvements in population health. These proposals include: 1) conducting large-scale, longer duration trials with hard clinical endpoints (e.g. cardiovascular disease incidence); 2) exploring the feasibility and acceptability of different strategies to facilitate a prolonged increase in dietary NO3- intake; 3) exploitation of existing cohort studies to explore associations between NO3- intake and health outcomes, a research approach allowing larger samples sizes and longer duration follow up than is feasible in randomised controlled trials; 4) identifying factors which might account for individual differences in the response to inorganic NO3- (e.g. sex, genetics, habitual diet) and could assist with targeted/personalised nutritional interventions; 5) exploring the influence of oral health and medication on the therapeutic potential of NO3- supplementation; and 6) examining potential risk of adverse events with long term high- NO3- diets.

CONCLUSION

The salutary effects of dietary NO3- are well established in small, well-controlled laboratory studies. Much less is known about the feasibility and efficacy of long-term dietary NO3- enrichment for promoting health, and the factors which might explain the variable responsiveness to dietary NO3- supplementation between individuals. Future research focussing on the translation of laboratory data will provide valuable insight into the potential applications of dietary NO3- supplementation to improve population health.

Sensory challenges experienced by autistic women during pregnancy and childbirth: a systematic review

PURPOSE

The aim of this systematic review was to identify challenges faced by autistic women during pregnancy and birth due to sensory issues or other features of Autism Spectrum Disorder.

METHODS

A systematic search of literature was conducted using Medline, PubMed, Embase, PsycINFO, CINAHL, MIDIRS, ProQuest Dissertations and Theses Global, and Open Access Theses and Dissertations. Eligible studies addressed autistic women's pregnancy or birth experiences, and were assessed for methodological quality.

RESULTS

The search generated 2656 results, with six meeting inclusion criteria. Data from 427 autistic participants were extracted from four qualitative and two quantitative studies for synthesis.

CONCLUSION

We found that the literature was exploratory and lacked focussed research questions addressing sensory issues in pregnancy. Sensory challenges were, however, identified as a key finding in all qualitative studies. Other challenges faced by autistic women during pregnancy and birth included communication issues in healthcare settings and lack of appropriate information and supports for pregnancy and birth. Implications for health professionals and challenges associated with research in this area are discussed.

Alteration, Reduction and Taste Loss: Main Causes and Potential Implications on Dietary Habits

Our sense of taste arises from the sensory information generated after compounds in the oral cavity and oropharynx activate taste receptor cells situated on taste buds. This produces the perception of sweet, bitter, salty, sour, or umami stimuli, depending on the chemical nature of the tastant. Taste impairments (dysgeusia) are alterations of this normal gustatory functioning that may result in complete taste losses (ageusia), partial reductions (hypogeusia), or over-acuteness of the sense of taste (hypergeusia). Taste impairments are not life-threatening conditions, but they can cause sufficient discomfort and lead to appetite loss and changes in eating habits, with possible effects on health. Determinants of such alterations are multiple and consist of both genetic and environmental factors, including aging, exposure to chemicals, drugs, trauma, high alcohol consumption, cigarette smoking, poor oral health, malnutrition, and viral upper respiratory infections including influenza. Disturbances or loss of smell, taste, and chemesthesis have also emerged as predominant neurological symptoms of infection by the recent Coronavirus disease 2019 (COVID-19), caused by Severe Acute Respiratory Syndrome Coronavirus strain 2 (SARS-CoV-2), as well as by previous both endemic and pandemic coronaviruses such as Middle East Respiratory Syndrome Coronavirus (MERS-CoV) and SARS-CoV. This review is focused on the main causes of alteration, reduction, and loss of taste and their potential repercussion on dietary habits and health, with a special focus on the recently developed hypotheses regarding the mechanisms through which SARS-CoV-2 might alter taste perception.

Decrease in sweet taste response and T1R3 sweet taste receptor expression in pregnant mice highlights a potential mechanism for increased caloric consumption in pregnancy

While much is known on how the maternal diet affects offspring fitness, less is known on the role of taste in guiding and promoting food intake during this crucial period. Women have intense food cravings and exhibit altered taste preferences during pregnancy, however the mechanistic details underlying these changes are presently unclear. We performed longitudinal brief-access taste testing in female mice before, during, and after pregnancy, along with quantitative PCR on taste buds and morphological analysis of taste tissues from pregnant and non-pregnant mice. Sucrose licking response decreased progressively during pregnancy compared to that prior to mating, with partial recovery in the post-partum period. No change in taste morphology was evident between pregnant and non-pregnant mice, however a notable decrease in T1R3 sweet taste receptor mRNA expression was recorded in pregnant dams. We conclude that altered taste preferences during pregnancy likely result from changes in the expression profile of taste buds in the mother, which may promote a less healthy diet while expecting.

Offspring of obese mice display enhanced intake and sensitivity for palatable stimuli, with altered expression of taste signaling elements

Maternal body mass index and gestational weight gain predict future obesity status of the offspring. In studies of both rodents and non-human primates, maternal obesity also predicts a preference for palatable foods in the offspring. In this study, we used C57BL/6J mice to investigate whether an underlying cause for an increase in palatable food consumption in the offspring of obese mice was a change in taste function. Adult female mice were fed a normal chow (NC) or a high fat diet (HFD) for 5 weeks before mating, then also during the gestation (3 weeks) and lactation (3 weeks) periods, with offspring always maintained on a normal chow diet; thus the only experience offspring had with high fat food was via maternal exposure. Offspring exhibited similar weight, blood glucose levels and baseline water and chow intake in adulthood. Taste response was assessed after reaching maturity, using brief-access taste testing, with female offspring of obese dams showing an enhanced response to sucrose, and both sexes consuming more sucrose, sucralose and high fat diet if from obese mothers. Offspring also exhibited increased taste bud expression of mRNA for sweet receptor subunits T1R (Taste receptor type) 2 and 3, as well as other markers associated with taste signaling. Taste morphology in both groups appeared similar. Results indicate that obesity in the mother may lead to unhealthy feeding behavior in the offspring, correlating with altered expression of taste signaling elements, which likely drive increased avidity for palatable foods.

Hypothyroidism Alters the Uterine Lipid Levels in Pregnant Rabbits and Affects the Fetal Size

BACKGROUND

Hypothyroidism has been related to low-weight births, abortion and prematurity, which have been associated with changes in the content of glycogen and vascularization of the placenta. Since hypothyroidism can cause dyslipidemia, it may affect the lipid content in the uterus affecting the development of fetuses.

OBJECTIVE

To investigate the effect of hypothyroidism on the lipid levels in serum and uterus during pregnancy and their possible association with the size of fetuses.

METHOD

Adult female rabbits were grouped in control (n = 6) and hypothyroid (n = 6; treated with methimazole for 29 days before and 19 days after copulation). Food intake and body weight were daily registered. At gestational day 19 (GD19), dams were sacrificed under an overdose of anesthesia. Morphometric measures of fetuses were taken. Total cholesterol (TC), triglyceride (TAG), and glucose concentrations were quantified in blood, uterus and ovaries of dams. The expression of uterine 3β- hydroxysteroid dehydrogenase (3β-HSD) was quantified by Western blot.

RESULTS

Hypothyroidism reduced food intake and body weight of dams, as well as promoted low abdominal diameters of fetuses. It did not induce dyslipidemia and hyperglycemia at GD19 and did not modify the content of lipids in the ovary. However, it reduced the content of TAG and TC in the uterus, which was associated with uterine hyperplasia and an increased expression of 3β-HSD in the uterus.

CONCLUSION

Hypothyroidism alters the lipid content in the uterus that might subsequently affect the energy production and lipid signaling important to fetal development.

Bitter taste signaling mediated by Tas2r144 is down-regulated by 17β-estradiol and progesterone in the rat choroid plexus

The blood-cerebrospinal fluid barrier is constituted by choroid plexus epithelial cells (CPEC) that regulate molecular trafficking between the blood and the cerebrospinal fluid. We hypothesize that taste receptors expressed in CPEC monitor the composition of these body fluids in a sex hormone dependent way. Thus, we compared the expression of taste related genes in the choroid plexus of sham and ovariectomized female rats, and then studied the effect of 17β-estradiol and progesterone in their expression and function. We found that the bitter receptors Tas2r109, Tas2r144, and the taste-related genes Plcb2 and Trpm5 were down-regulated by ovarian hormones in vivo and ex vivo with functional implications. Knocking-down Tas2r144 with a specific siRNA in a CPEC line (Z310) effectively reduced the Ca²⁺ response to the bitter compound denatonium benzoate, in a similar manner to female sex hormones alone, suggesting that female sex hormones downregulated the responses of CPEC to chemical stimuli by reducing Tas2r144.

Gustatory Function of Pregnant and Nonpregnant Women in a Tertiary Health Institution

Physiological changes in pregnancy may cause taste dysfunction. The aim of this study was to determine and compare gustatory function of pregnant women with nonpregnant women and also to investigate the effect of pregnancy on gustatory function. It was a case-control study of consecutive 70 healthy pregnant women (cases) and 70 healthy nonpregnant women (control). Participants scored their taste perception on a visual analogue scale (1-10) and their gustatory function was assessed using "taste strips" impregnated with graded concentration of sweet, sour, salty, and bitter taste substances applied on tongue surfaces. Subjective mean gustatory score, correct identification of taste in the strips and total taste strip (TTS) score were compared between both groups and analysis was done using appropriate statistics. The mean age of pregnant women (30.5 [3.9]) and controls (28.5 [6.6]) were comparable. Twenty-one (30%) pregnant women changed their diet in first trimester due to change in taste sensation. Almost all cases developed craving for spicy and salty foods and, aversions to fish, beans, and vegetables. There was a significant difference in the subjective rating of taste perception between the 2 groups ( P = .037). About 2.9% of pregnant women have hypogeusia. There was a significant difference between pregnant and nonpregnant women in sour taste ( P = .006; 2.90 [0.71] vs 3.92 [0.82]) and TTS ( P = .02; 27.50 [3.48] vs 29.21 [2.69]) scores, respectively. In conclusion, gustatory function was reduced in pregnancy compared to nonpregnant women and this led to dietary change in some pregnant women.

Environmental Immersion's Influence on Hedonics, Perceived Appropriateness, and Willingness to Pay in Alcoholic Beverages

The eating experience is multimodal. As we consume a dish, we perceive much more than that which initially activates the senses, including influences from our surroundings. Foods sampled in experimental settings are largely evaluated within a sensory booth, an environment designed to be devoid of such external or non-standardized stimuli, so that participants can focus solely on the sample itself. In natural experiences, we rarely consume food in such isolation—context is actually key to many dining experiences and can have an integral role in how we perceive the foods we eat. Using virtual reality to artificially provide this context, we tested how the setting in which a beverage was consumed influenced perception of two different samples. Virtual environments were formed by processing custom-recorded 360 degree videos and overlaying audio, text, and sensory scales to simulate a typical sensory evaluation. Participants were asked to taste two alcoholic beverages, a beer and a sparkling wine, in two virtual contexts, a bar and a winery. The results indicated that participants’ willingness to pay for, and overall enjoyment of the sparkling wine increased when placed in the winery context, with no change between the two virtual contexts for the beer sample. This occurred without alteration of the samples’ sensory properties or the ability of panelists to identify the beverage they were drinking; however, perceived appropriateness of the samples for the setting was strongly influenced by the context in which they were sampled, suggesting that perceived appropriateness for a surrounding may play a role in the degree to which we enjoy a food. Results provide further proof that artificially-applied context, such as that provided by virtual reality, can further the sensory testing of foods.

Prolonged Exposure to Monosodium Glutamate in Healthy Young Adults Decreases Perceived Umami Taste and Diminishes Appetite for Savory Foods

Background

Research suggests that increased consumption of sweet, salt, or fat is associated with diminished perceived taste intensity and shifted preferences for the respective stimulus. It is unknown whether a similar effect occurs with the consumption of umami.

Objective

The aim of the study was to investigate the influence of habitual exposure to umami stimuli on umami taste perception, hedonics, and satiety.

Methods

Fifty-eight healthy men (n = 16) and women (n = 42) participated in a parallel-group, randomized controlled study. The normal-weight [mean ± SD body mass index (kg/m2): 21.8 ± 2.2] group of young adults (mean ± SD age: 22.7 ± 6.2 y) consumed vegetable broth daily for 4 wk. The broth for the treatment group (n = 28) was supplemented with 3.8 g monosodium glutamate (MSG), whereas the control group (n = 30) consumed a sodium-matched broth without MSG. Perceived umami taste intensity and discrimination in MSG solutions; liking, wanting, and preference of a variety of umami-rich foods; satiation and satiety from an ad libitum meal; and anthropometric measures were evaluated at baseline and at week 4. General linear models assessed the effect of treatment on change from baseline for all outcomes and tested for effect modification of sex.

Results

Relative to controls, increased consumption of MSG for 4 wk diminished umami taste in women (8.4 units on generalized Labeled Magnitude Scale; 95% CI: -13.8, -3.1 units; P = 0.013). The desire for and intake of savory foods decreased after MSG treatment in both sexes with an ad libitum meal (desire: -7.7 units; 95% CI: -13.7, -1.7 units; P = 0.04; intake: -36 g; 95% CI: -91, 19 g; P = 0.04).

Conclusion

Our results highlight that a month-long diet high in umami stimuli attenuates perceived umami taste and appetite for savory foods in a young, healthy population. Our findings contribute to the understanding of food choice, a factor in the development and maintenance of obesity, as well as the etiology of protein-related health conditions such as osteoporosis and kidney disease. This study is registered at www.clinicaltrials.gov as NCT03010930.