Psoriasis is a chronic inflammatory disorder affecting more than 2-8% of United Kingdom population. (Springate et al., 2017) It is characterized by erythematous, well-demarcated, scaly plaques that are prominent on visual inspection, psychologically depressing and disfiguring for the patients. This disease has been known to have close relationship with metabolic syndrome, obesity, and cardiovascular diseases to name a few. The exact mechanism is not clearly understood but we know that adipocytes do release pro-inflammatory cytokines for example IL-6, TNF-alpha and MCP-1. IL-17 and IL-23 have been found elevated in obese patients with psoriasis. Now we even have drugs targeting these particular cytokine receptors. These are the very mediators that are released in obese psoriasis patient as compared to patients that have low body fat that make the disease worsen. In this paper I will try to discuss the effect of weight loss and dietary change in psoriasis severity. (Debbaneh et al., 2014)
Body mass index and psoriasis:
Several studies conducted in the past decade has compared the relation between psoriasis and body mass index. One of the case-control studies of around 373 psoriasis patients compared with healthy control found a 9% increased risk for psoriasis onset and 7% higher risk of increased PASI score for every one unit increase in body mass index. (Wolk et al., 2009). The Nurses’ Health Study prospectively studied around 67,300 female nurses and found a 1.63 times increased risk for psoriasis incidence in nurses with BMI more than 35. (Kumar et al., 2012). A large population study of 75,395 patients found that obesity was a risk factor for developing psoriatic arthritis. The pathophysiology of TNF-alpha in psoriatic arthritis and release of the very cytokine by adipocytes make it have a strong correlation. (Jon Love et al., 2012)
Diet changes on the severity of psoriasis:
- Low-calorie diet (LCD): Di Minno et. al have shown that low-calorie diet is able to reduce the severity of psoriasis if weight loss is more than 5% of baseline. (Di Minno et al., 2014) In another study, calorie restriction with topical steroids was given to 40 patients for four weeks and compared to control. The patients in treatment group had a more significant decrease in psoriasis severity, serum triglyceride, cholesterol, and LDL as compared to the control group. (Rucević et al., 2003)
- Gluten-free diet (GFD): Patients with psoriasis and anti-gliadin antibodies have shown some improvements in their psoriasis severity (Chalmers and Kirby, 2000) however patients without having anti-gliadin antibodies if put on gluten free diet showed no or minimal improvement in their psoriasis. (Zamani et al., 2010)
- Mediterranean diet: Barrea L. et al did a cross-sectional case-control observational study in 2015 that patients on a Mediterranean diet showed a lower PREDIMED score and improved PASI scores. The concluded that Mediterranean food pattern rich in extra virgin olive oil, fruits, vegetables, fish, chicken and whole grains could be a cheap alternative in addition to medications for improvement in psoriatic patients. (Barrea et al., 2015).
- Ketogenic diet: Castaldo et. al. in 2015 debated with a case report that low-calorie low-carbohydrate and protein rich diet also known as ketogenic diet improved the psoriasis in their patient and pointed out the importance of weight loss in psoriasis as an adjuvant therapy in psoriasis patients. (Castaldo et al., 2016)
- High-fat diet: Higashi et. al. in 2018 did a observational study on genetically modified mice who were fed with high-fat diet where the fat content was 32% of the diet mimicking “modern human diet including junk food”. The mice were induced with psoriasis and fed the diet to see the effect. They found that mice fed with high-fat diet showed marked severity of their dermatitis as compared with normal diet mice concluding that high-fat diet may have strong linkage with development and severity of psoriasis. (Higashi et al., 2018)
- Pagano diet: Brown AC et al. in 2004 showed that diet rich in fresh fruits and vegetables, fiber supplements, olive oil and fish protein improved psoriasis. Red med and processed foods were not included in Pagano diet. (Brown et al., 2004)
- Alcohol: Alcohol has been shown to have close link with psoriasis severity and have been found to exacerbate the psoriasis. (Behnam, Behnam and Koo, 2005)
Supplements and severity of psoriasis:
- Fish oil: Most of the trials from 1980s to 1990s showed that addition of fish oil in the diet of psoriasis patients improved their PASI scores and increased their favorable neutrophilic cytokines. The docosahexanoic acid dose with most effect was found out to be 1.2 g or more. (Bittiner et al., 1988; Grimminger et al., 1993; Mayser et al., 1998)
- Vitamin D: Vitamin D deficiency has been reported to be linked with psoriasis and psoriatic arthritis. (El-Moaty Zaher et al., 2013) There have been few studies done on the linkage between supplementation of Vitamin D in psoriasis and its effects. The trials varied from using 1,25-dihydroxyvitamin D3 to 1-alpha-hydroxyvitamin D3. The results varied from 12% patients (el-Azhary et al., 1993) showing improvement all the way to 76% showing improvement. (Morimoto et al., 1986)
- Vitamin B12: Just like in the case of vitamin D, vitamin B12 deficiency has also been linked to psoriasis. Brazelli et al. demonstrated that psoriatic patients had lower levels of vitamin B12. (Brazzelli et al., 2010) Ruedemann Jr. showed in 1954 around 32% psoriatic patients in his study improved when given vitamin B12. (RUEDEMANN, 1954) In response to his study Baker and Comaish did a double-blinded trial in 1962 in which supplementation of Vitamin B12 showed no difference in control and study group. (BAKER and COMAISH, 1962)
- Selenium: Serwin et al found in 2002 that lower levels of selenium were linked with increased severity of psoriasis. (Serwin et al., 2002) Although Karaeva et al debated the possible management of psoriasis patients with selenium and anti-oxidants in patients deficient in selenium (Kharaeva et al., 2009), Servin et all in 2006 countered it with a double-blinded study where selenium supplementation was found non efficacious in active psoriatic patients. (Serwin, Wasowicz and Chodynicka, 2006)
- Vitamin A: Decreased Vitamin A levels have been shown in plaque psoriasis and erythrodermic psoriasis. (Marrakchi et al., 1994) Although topical and systemic vitamin A derivatives have been used in psoriasis patients to control the disease however supplementation with Vitamin A has not shown much improvement. (Reichrath et al., 2007)
Surgical weight loss strategies and psoriasis:
- Gastric bypass surgery: Hossler et. al conducted a retrospective study on 34 patients and found that 62% of respondents reported improvement in their psoriasis after surgery. (Hossler et al., 2013). A case series done by Farias et. al on patients with a BMI of 38.3 kg/m2 undergoing bariatric surgery seventy percent reported complete resolution of their psoriasis lesions. (Farias et al., 2012) Al though bariatric surgery is not the first line treatment in psoriatic patients but patients undergoing this procedure for other indications and had psoriasis showed these observations.
Weight loss and dietary changes have shown in the literature to have positive outcome on the severity of psoriasis. One diet and supplement can be debated not to be the answer for disease control. A multi-disciplinary approach with nutritionist, rheumatologist and dermatologist is required to control psoriasis. Dietary changed that could be done in the patient’s diet could include: (Barrea et al., 2016)
- Whole grains, legumes, vegetables, and fruits as rich source dietary fiber, trace elements, including zinc and selenium, and vitamins.
- Fresh water fish should be added for their high content of omega-3 PUFA and vitamin D.
- Extra virgin olive oil, as main source of dietary fat as seen in Mediterranean diet.
- Alcohol, gluten, red meat, and processed dairy products and high sugar foods should be avoided.
Supplementation with multivitamins is still debatable and require more research and trials to be done for adjuvant treatment addition in psoriatic patients.
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