Are people who have a better smell sense, more affected from satiation?

Ulusoy, Seçkin; Dinç, Mehmet Emre; Dalğıç, Abdullah; Topak, Murat; Dizdar, Denizhan; Is, Abdulhalim

doi:10.1016/j.bjorl.2016.08.011

Cited by 12 publications

(7 citation statements)

References 20 publications

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“…Patients of obstructive sleep apnea (also a low 5-HT state) show reduced olfactory function which improves after treatment with SSRIs [57] , [58] , [59] . An interesting observation is the improvement in olfactory sensitivity during fasting [60] and, incidentally, 5-HT in fasting state is significantly increased [61] . Another interesting observation is the disruption of olfactory (and also gustatory) functions at high altitude [62] , [63] and it is known that low oxygen at high altitude lowers 5-HT as the synthesis of 5-HT from tryptophan is hindered because the enzyme tryptophan hydroxylase involved in the synthesis of 5-HT requires molecular oxygen [64] , [65] .…”

Section: Implications and Importance Of The Hypothesismentioning

confidence: 95%

Does serotonin deficiency lead to anosmia, ageusia, dysfunctional chemesthesis and increased severity of illness in COVID-19?

Sen¹

2021

Medical Hypotheses

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Different mechanisms forwarded to understand anosmia and ageusia in coronavirus patients are not adequate to explain reversible anosmia and ageusia, which are resolved quickly. In addition, the reason behind the impaired chemesthetic sensations in some coronavirus patients remains unknown. In the present paper it is proposed that SARS-CoV-2 patients suffer from depletion of tryptophan, as ACE2, a key element in the process of absorption of tryptophan from the food, is significantly reduced in the patients as coronavirus uses ACE2 as the receptor to enter the host cells. The tryptophan depletion leads to a deficit of serotonin (5-HT) in SARS-COV-2 patients because tryptophan is the precursor in the synthesis of 5-HT. Such 5-HT deficiency can explain anosmia, ageusia and dysfunctional chemesthesis in COVID-19, given the fact that 5-HT is an important neuromodulator in the olfactory neurons, taste receptor cells and transient receptor potential channels (TRP channels) involved in chemesthesis. In addition, 5-HT deficiency worsens silent hypoxemia and depresses hypoxic pulmonary vasoconstriction leading to increased severity of the disease. Also, the levels of anti-inflammatory melatonin (synthesized from 5-HT) and nicotinamide adenine dinucleotide (NAD + , produced from niacin whose precursor is the tryptophan) might decrease in coronavirus patients resulting in the aggravation of the disease. Interestingly, selective serotonin reuptake inhibitors (SSRIs) may not be of much help in correcting the 5-HT deficiency in COVID-19 patients, as their efficacy goes down significantly when there is depletion of tryptophan in the system. Hence, tryptophan supplementation may herald a radical change in the treatment of COVID-19 and accordingly, clinical trials (therapeutic / prophylactic) should be conducted on coronavirus patients to find out how tryptophan supplementation (oral or parenteral, the latter in severe cases where there is hardly any absorption of tryptophan from the food) helps in curing, relieving or preventing the olfactory, gustatory and chemesthetic dysfunctions and in lessening the severity of the disease.

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Section: Implications and Importance Of The Hypothesismentioning

confidence: 95%

Does serotonin deficiency lead to anosmia, ageusia, dysfunctional chemesthesis and increased severity of illness in COVID-19?

Sen¹

2021

Medical Hypotheses

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“…Therefore, odor sensitivity may also depend on the hunger status (hungry vs. sated), a notion that has been clearly shown in animals before: rats show enhanced sniffing behavior and higher sensitivity to odors [18] in the fasted when compared to the sated state. In humans, however, results are divergent and show both higher [19] and lower sensitivity [20] in fasted states, or no difference at all [21]. While these studies predominantly used non-food odors, we reasoned that food odors are more relevant in the context of obesity.…”

Section: Introductionmentioning

confidence: 99%

Insulin Resistance Is Associated with Reduced Food Odor Sensitivity across a Wide Range of Body Weights

et al. 2020

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The worldwide obesity epidemic is a major health problem driven by the modern food environment. Recently, it has been shown that smell perception plays a key role in eating behavior and is altered in obesity. However, the underlying mechanisms of this phenomenon are not well understood yet. Since the olfactory system is closely linked to the endocrine system, we hypothesized that hormonal shifts in obesity might explain this relationship. In a within-subject, repeated-measures design, we investigated sensitivity to a food and a non-food odor in the hungry and sated state in 75 young healthy (26 normal weight, 25 overweight, and 24 obese) participants (37 women). To determine metabolic health status and hormonal reactivity in response to food intake, we assessed pre- and postprandial levels of insulin, leptin, glucose, and ghrelin. Odor sensitivity did not directly depend on body weight status/body mass index (BMI) or hunger state. However, we could establish a strong negative mediating effect of insulin resistance on the relationship between BMI/waist-hip ratio and olfactory sensitivity for the food odor. These findings indicate an impact of metabolic health status on sensitivity to food odors. Our results contribute to a better understanding of the mechanisms behind altered smell perception in obesity.

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“…Patients of obstructive sleep apnea (also a low 5-HT state) show reduced olfactory function which improves after treatment with SSRIs [57][58][59]. An interesting observation is the improvement in olfactory sensitivity during fasting [60] and, incidentally, 5-HT in fasting state is significantly increased [61]. Another interesting observation is the disruption of olfactory (and also gustatory) functions at high altitude [62,63] and it is known that low oxygen at high altitude lowers 5-HT as the synthesis of 5-HT from tryptophan is hindered because the enzyme tryptophan hydroxylase involved in the synthesis of 5-HT requires molecular oxygen [64,65].…”

Section: Second Does Anosmia Then Results From Coronavirus Induced Damage Of the Olfactory Neurons?mentioning

confidence: 99%

Does serotonin deficiency lead to anosmia, ageusia, dysfunctional chemesthesis and increased severity of illness in COVID-19?

Sen¹

2021

Preprint

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Anosmia, ageusia and impaired chemesthetic sensations are quite common in coronavirus patients. Different mechanisms have been proposed to explain the anosmia and ageusia of COVID-19 patients, though for reversible anosmia and ageusia, which are resolved quickly, the proposed mechanisms seem to be incomplete. In addition, the reason behind the impaired chemesthetic sensations of some coronavirus patients remains unknown. It is proposed that in coronavirus patients, there is depletion of tryptophan (an essential amino acid), as ACE2, a key element in the process of absorption of tryptophan from food, is significantly reduced due to the attack of coronavirus which use ACE2 as the receptor for its entry into the host cells. Incidentally, the depletion of tryptophan should lead to deficiency of serotonin (5-HT) in SARS-COV-2 patients because tryptophan is the precursor in the synthesis of 5-HT. Such 5-HT deficiency not only explains fast resolved anosmia and ageusia, but also dysfunctional chemesthesis, given the fact that 5-HT is an important neuromodulator in the olfactory neurons and taste receptor cells and 5-HT also enhances the nociceptor activity of transient receptor potential channels (TRP channels) responsible for chemesthetic sensations. The female predominance of olfactory and gustatory dysfunctions can also be explained by considering low 5-HT levels in women. In addition, 5-HT deficiency worsens silent hypoxemia and explains why hypoxic pulmonary vasoconstriction is nearly absent in coronavirus patients leading to poor outcome. Hence, clinical trials should be conducted on coronavirus patients to find out how different selective serotonin reuptake inhibitors (SSRIs) and serotonin agonists work out in eliminating or improving the olfactory, gustatory and chemesthetic dysfunctions as well as hypoxemia.

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Are people who have a better smell sense, more affected from satiation?

Cited by 12 publications

References 20 publications

Does serotonin deficiency lead to anosmia, ageusia, dysfunctional chemesthesis and increased severity of illness in COVID-19?

Does serotonin deficiency lead to anosmia, ageusia, dysfunctional chemesthesis and increased severity of illness in COVID-19?

Insulin Resistance Is Associated with Reduced Food Odor Sensitivity across a Wide Range of Body Weights

Does serotonin deficiency lead to anosmia, ageusia, dysfunctional chemesthesis and increased severity of illness in COVID-19?

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