Psoriasis has long been linked with poor nutrition and increased body mass index in patients. Doctors at the Psoriasis: From Gene to Clinic International Congress in London have today presented evidence suggesting that a reduced sense of taste and smell, caused by inflammation, may be part of the explanation.

Psoriasis is a common inflammatory skin disease affecting two per cent of the population. It occurs equally in men and women, can appear at any age, and tends to come and go unpredictably. The link between psoriasis and higher rates of obesity has generally been explained by obesity being a risk factor for psoriasis.

Nutrition is a major issue in patient care for psoriasis. Metabolic disorders, disorders that affect your body’s ability to process food into energy, and increased body mass index are common and may result from the inflammatory characteristics of the disease or unbalanced diet.

It is already known that in chronic inflammatory bowel diseases, patients’ sense of smell and taste can be impaired. This can change the food a patient eats, but diet returns to normal once the disease has been successfully treated. The researchers wanted to test whether the same was true of psoriasis.

In this study, before any treatment, 50 patients with psoriasis were asked to complete a taste test to try to identify sweet, sour, salty, bitter and umami. They were tested with solutions sprayed onto the back of the tongue, as well as by using sniffing sticks. The results were compared with those in a group of healthy volunteers. Whereas sweet taste was detected by all psoriasis patients, bitter could not be tasted by 33 patients and umami by 15 patients. Altogether, a distinct impairment of taste and smell was found in patients with psoriasis.

The implication of this study is that inflammation impairs our sense of smell and taste. This may influence food uptake and adequate nutrition resulting in the discrepancy in average BMI compared to the rest of the population. However, more study is necessary to learn how taste impacts on nutrition, and how this in turn impacts on BMI in psoriasis patients.

Michael Sticherling MD, one of the researchers from the Department of Dermatology at University Hospitals Erlangen in Germany, said:

“Patients with psoriasis commonly have issues with nutrition, which can have an impact on their overall health. We wanted to explore in greater detail the reasons for this. Our results show that psoriasis patients may have greater difficulty identifying tastes than the general population, with the exception of sweet flavours. It’s possible that this is part of the reason for nutrition issues amongst people with the disease. More study is needed before we can say this for sure, but in the meantime there is compelling evidence that inflammation does have an impact on our ability to taste and smell things.”

Matthew Gass of the British Association of Dermatologists said:

“Patients with psoriasis don’t just have to manage the main symptoms of the condition, they also have an increased risk of a whole host of other issues, including obesity. Research that helps us better understand why this happens, will help us come up with better strategies for helping future patients.”

-Ends-

Notes to editors:

For more information please contact the media team: comms@bad.org.uk, 0207 391 6084. Website: www.bad.org.uk

The 8th International Congress of Psoriasis from gene to clinic is taking place in London from Thursday 30th November to Saturday 2nd December 2017. For more information, visit: www.psoriasisg2c.com

About us:
The British Association of Dermatologists is the central association of practising UK dermatologists. Our aim is to continually improve the treatment and understanding of skin disease. For further information about the charity, visit www.bad.org.uk

Please note that this is the original abstract submitted for the conference, since submission the authors have continued their research on more subjects, hence the discrepancies with the press release.

Impairment of gustatory and olfactory senses in plaque psoriasis

P. Rüter,1 V. Grünthaler,1 Y. Zopf2 and M. Sticherling1

1Hautklinik Universitätsklinikum Erlangen, Erlangen, Germany and 2Medizinische Klinik 1, Universitätsklinikum Erlangen, Erlangen, Germany

The various aspects of nutrition are a major issue in patient care for psoriasis. Metabolic disorders and increased body mass index are frequently encountered in this patients group and may result from systemic inflammation characteristic for the disease and/or unbalanced intake of food calories by the patients. Interestingly, in chronic inflammatory bowel diseases relevant gustatory and olfactory changes have been detected. These result in a disturbed food intake and are normalized again upon successful treatment of the disease. Here, patients with psoriasis were tested before any systemic treatment for the gustatory qualities sweet, sour, salty, bitter and umami. They were tested with appropriate solutions sprayed onto the back of the tongue in a standardized procedure, as well as by using sniffing sticks for olfaction. Thirty-three patients were tested: 18 women and 15 men with a mean age of 54.3 years (range 21–85), a mean Psoriasis Area and Severity Index (PASI) of 8 (range 0.7–24) and mean C-reactive protein (CRP) of 5.4 ng mL−1 (range 0.6–24.1). The results were compared with those in a group of healthy volunteers. Whereas sweet taste was detected by all patients, bitter could not be tasted by 21 patients and umami by 11 patients. Two and 23 patients showed hyposmia with results off the 10% and 50% percentiles of normal volunteers, respectively. Altogether, a distinct impairment of gustatory and olfactory senses was found in patients with psoriasis. Considering the low number of patients, the correlation to PASI and CRP was barely significant. In addition, a normalization of sensory capacity in relation to therapeutic responses and improvement of psoriasis has to be monitored.