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Enhancing immunity in viral infections, with special emphasis on COVID-19: A review.
Jayawardena, R, Sooriyaarachchi, P, Chourdakis, M, Jeewandara, C, Ranasinghe, P
Diabetes & metabolic syndrome. 2020;14(4):367-382
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A healthy immune system is one of the most important weapons in relation to the current pandemic of COVID-19 where no effective preventive and curative medicine is available. The main aim of this study was to evaluate the evidence on enhancing immunity in viral infections. This review focuses on influenza-like viral infections; however, other studies on viral infections have also been included. It included 43 articles of which 13 were on vitamins, 8 on minerals, 18 on nutraceuticals and 4 on probiotics. Results indicate that: - vitamin supplementation, especially vitamin D may be beneficial in people who are either deficient or insufficient. - adverse effects of vitamin E supplementation on the immune response have been reported. - there are several beneficial nutraceuticals, however their efficacy and safety depend on their ingredients, as well as various other factors including, methods of extraction. - in addition to basic hygienic practices, proper dietary and lifestyle behaviours are essential for prevention and treatment of respiratory viral diseases. Authors conclude that achieving recommended amounts of calories and micronutrient will be a challenge and elective micronutrient supplementations may be beneficial especially for vulnerable populations such as the elderly.
Abstract
BACKGROUND AND AIMS Balanced nutrition which can help in maintaining immunity is essential for prevention and management of viral infections. While data regarding nutrition in coronavirus infection (COVID-19) are not available, in this review, we aimed to evaluate evidence from previous clinical trials that studied nutrition-based interventions for viral diseases (with special emphasis on respiratory infections), and summarise our observations. METHODS A systematic search strategy was employed using keywords to search the literature in 3 key medical databases: PubMed®, Web of Science® and SciVerse Scopus®. Studies were considered eligible if they were controlled trials in humans, measuring immunological parameters, on viral and respiratory infections. Clinical trials on vitamins, minerals, nutraceuticals and probiotics were included. RESULTS A total of 640 records were identified initially and 22 studies were included from other sources. After excluding duplicates and articles that did not meet the inclusion criteria, 43 studies were obtained (vitamins: 13; minerals: 8; nutraceuticals: 18 and probiotics: 4). Among vitamins, A and D showed a potential benefit, especially in deficient populations. Among trace elements, selenium and zinc have also shown favourable immune-modulatory effects in viral respiratory infections. Several nutraceuticals and probiotics may also have some role in enhancing immune functions. Micronutrients may be beneficial in nutritionally depleted elderly population. CONCLUSIONS We summaries possible benefits of some vitamins, trace elements, nutraceuticals and probiotics in viral infections. Nutrition principles based on these data could be useful in possible prevention and management of COVID-19.
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Immunomodulatory Effects of Diet and Nutrients in Systemic Lupus Erythematosus (SLE): A Systematic Review.
Islam, MA, Khandker, SS, Kotyla, PJ, Hassan, R
Frontiers in immunology. 2020;11:1477
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Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by an abnormal inflammation affecting multiple organs, blood formation processes and the central nervous system. The condition is still not well understood and hence more specific and effective treatment options are lacking. How diet and lifestyle may play a role in the disease’s onset and development is still disputed, yet some nutritional aspects appear to be associated with SLE. This systematic review gathered clinical and preclinical evidence from animal and human studies, investigating dietary and nutritional interventions that either proved helpful in the management of SLE or had adverse effects. The review considered the impact of reduced calorie intake and body weight. It discussed the value of lower protein intake, in the context of SLE-related kidney complications and polyunsaturated fats such as omega-3 and olive oil and their role in regulating inflammatory pathways. Furthermore, it stressed the importance of fibre in gut health and immune regulation in SLE. The study also included evidence from Vitamin A, B, C, D and E, with particular detail on Vitamin D and its relation to disease prevention, progression and its immune regulatory capacity. Towards the end is a brief table displaying the more limited finding on some minerals, before exploring the plant-derived compound group of polyphenols and finally Royal jelly. In short, the authors suggested that moving towards a balanced diet can address unfavourable nutritional shortages commonly observed in SLE patients. A diet that is low in calories and protein but plentiful in fibre, polyunsaturated fats, vitamin A, B, C, D, and E, minerals and polyphenol-containing foods. Evidently, the components of such a diet have favourable effects on regulating inflammation and immune function and thus overall disease activity. This review affirms the importance of nutritional adequacy for the management of SLE.
Abstract
Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by multiple organ involvement, including the skin, joints, kidneys, lungs, central nervous system and the haematopoietic system, with a large number of complications. Despite years of study, the etiology of SLE remains unclear; thus, safe and specifically targeted therapies are lacking. In the last 20 years, researchers have explored the potential of nutritional factors on SLE and have suggested complementary treatment options through diet. This study systematically reviews and evaluates the clinical and preclinical scientific evidence of diet and dietary supplementation that either alleviate or exacerbate the symptoms of SLE. For this review, a systematic literature search was conducted using PubMed, Scopus and Google Scholar databases only for articles written in the English language. Based on the currently published literature, it was observed that a low-calorie and low-protein diet with high contents of fiber, polyunsaturated fatty acids, vitamins, minerals and polyphenols contain sufficient potential macronutrients and micronutrients to regulate the activity of the overall disease by modulating the inflammation and immune functions of SLE.
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The Role of Bacteria and Its Derived Metabolites in Chronic Pain and Depression: Recent Findings and Research Progress.
Li, S, Hua, D, Wang, Q, Yang, L, Wang, X, Luo, A, Yang, C
The international journal of neuropsychopharmacology. 2020;23(1):26-41
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Depression is closely associated with chronic pain yet the connection between these comorbidities is ambiguous. Recent studies have shown alterations in the gut microbiome may contribute to cognitive dysfunction via the microbiota-gut-brain axis. The aim of this systematic review is to summarize the existing evidence of the role of the gut microbiome in chronic pain and depression and explore potential mechanisms of gut dysbiosis in the development of these conditions. This review found metabolic products from the gut microbiota can mediate neuro-inflammation and neuro-immunity pathways in pain and depression, and that dysbiosis in the gut may contribute to the cause of chronic pain and depression. The authors conclude the metabolic products from the gut bacteria offer new insights to the connection between the gut microbiota and mechanisms of pain and depression, while showing potential as a therapeutic target.
Abstract
BACKGROUND Chronic pain is frequently comorbid with depression in clinical practice. Recently, alterations in gut microbiota and metabolites derived therefrom have been found to potentially contribute to abnormal behaviors and cognitive dysfunction via the "microbiota-gut-brain" axis. METHODS PubMed was searched and we selected relevant studies before October 1, 2019. The search keyword string included "pain OR chronic pain" AND "gut microbiota OR metabolites"; "depression OR depressive disorder" AND "gut microbiota OR metabolites". We also searched the reference lists of key articles manually. RESULTS This review systematically summarized the recent evidence of gut microbiota and metabolites in chronic pain and depression in animal and human studies. The results showed the pathogenesis and therapeutics of chronic pain and depression might be partially due to gut microbiota dysbiosis. Importantly, bacteria-derived metabolites, including short-chain fatty acids, tryptophan-derived metabolites, and secondary bile acids, offer new insights into the potential linkage between key triggers in gut microbiota and potential mechanisms of depression. CONCLUSION Studying gut microbiota and its metabolites has contributed to the understanding of comorbidity of chronic pain and depression. Consequently, modulating dietary structures or supplementation of specific bacteria may be an available strategy for treating chronic pain and depression.
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Could Vitamins Help in the Fight Against COVID-19?
Jovic, TH, Ali, SR, Ibrahim, N, Jessop, ZM, Tarassoli, SP, Dobbs, TD, Holford, P, Thornton, CA, Whitaker, IS
Nutrients. 2020;12(9)
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Immunonutrition is the role of nutrient supplementation in modulating the immune system. While there are limited approaches to the prevention and treatment of Covid-19, the aim of this review was to critically assess the current evidence to identify vitamins in the context of respiratory disease and extrapolate the evidence to evaluate the role of immunonutrition in Covid-19. Over 200 studies were included in this review to assess the physiological role, therapeutic application in respiratory disease and relevance to Covid-19 of each vitamin. Based on the existing literature, the authors conclude the there is a potential preventative and supportive role for vitamin supplementation in fighting Covid-19, specifically vitamin A, E and D.
Abstract
There are limited proven therapeutic options for the prevention and treatment of COVID-19. The role of vitamin and mineral supplementation or "immunonutrition" has previously been explored in a number of clinical trials in intensive care settings, and there are several hypotheses to support their routine use. The aim of this narrative review was to investigate whether vitamin supplementation is beneficial in COVID-19. A systematic search strategy with a narrative literature summary was designed, using the Medline, EMBASE, Cochrane Trials Register, WHO International Clinical Trial Registry, and Nexis media databases. The immune-mediating, antioxidant and antimicrobial roles of vitamins A to E were explored and their potential role in the fight against COVID-19 was evaluated. The major topics extracted for narrative synthesis were physiological and immunological roles of each vitamin, their role in respiratory infections, acute respiratory distress syndrome (ARDS), and COVID-19. Vitamins A to E highlighted potentially beneficial roles in the fight against COVID-19 via antioxidant effects, immunomodulation, enhancing natural barriers, and local paracrine signaling. Level 1 and 2 evidence supports the use of thiamine, vitamin C, and vitamin D in COVID-like respiratory diseases, ARDS, and sepsis. Although there are currently no published clinical trials due to the novelty of SARS-CoV-2 infection, there is pathophysiologic rationale for exploring the use of vitamins in this global pandemic, supported by early anecdotal reports from international groups. The final outcomes of ongoing trials of vitamin supplementation are awaited with interest.
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The Neuropathology of Gluten-Related Neurological Disorders: A Systematic Review.
Rouvroye, MD, Zis, P, Van Dam, AM, Rozemuller, AJM, Bouma, G, Hadjivassiliou, M
Nutrients. 2020;12(3)
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Coeliac disease (CD) is an autoimmune disorder triggered by the ingestion of gluten in genetically susceptible individuals. A wide range of extraintestinal manifestations has been attributed to CD, changing the classic perception of a disease limited to the intestine, to a multisystem disorder. The aim of this study was to analyse the published neuropathology of confirmed cases of gluten-related neurological dysfunction to aid our understanding of the pathogenesis. CD can therefore manifest with dental problems, consequences of malabsorption, skin and neurological disorders. This study is a systematic review of thirty-two neurological disorder focused studies. Results show that: - the neuropathological findings in gluten-related neurological disorders are widespread and not limited to the cerebellum. - the pathology is immune mediated and not related to vitamin or trace elements deficiencies. - the pathophysiology of neurological damage in the context of gluten sensitivity has an immune mediated basis. - more gluten-related neurological disorders affected men (57%), which was even higher in the ataxia group (76%). - transglutaminase 6 antibodies might be helpful in the diagnostic workup of gluten-related neurological disorders. Authors conclude that the current evidence is suggestive of both humoral and cell-mediated immunological responses. Further research is required to investigate the underlying neuropathological mechanism by characterisation of the inflammatory cell infiltrate and identification of target epitopes.
Abstract
Gluten-related neurological disorders (GRND) represent a spectrum of neurological manifestations that are triggered by gluten. In coeliac disease, a T-cell mediated enteropathy is triggered by gluten in genetically predisposed individuals. The underlying pathological mechanism of the neurological dysfunction is not yet clear. The aim of this review is to collate existing neuropathological findings in GRND as a means of aiding the understanding of the pathophysiology. A systematic search of the Pubmed Database yielded 188 articles, of which 32 were included, containing 98 eligible cases with a description of pathological findings in GRND. In gluten ataxia, loss of Purkinje cells, atrophy, gliosis and astrocytosis were apparent, as well as diffuse lymphocytic infiltration and perivascular cuffing with lymphocytes. In patients with large-fiber neuropathy, nerve biopsies revealed axonopathy, loss of myelinated fibers and focal and perivascular infiltration by inflammatory cells. Inflammatory infiltrate was also observed in muscle in myopathy and in cerebrum of patients with encephalopathy and patients with epilepsy. Such changes were not seen in skin biopsies from patients with small fiber neuropathies. The findings from this systematic review suggest an immune mediated pathogenesis for GRND. Future research should focus on the characterization of the inflammatory cell infiltrates and identifying target epitopes.
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Nutritional Interventions to Improve Asthma-Related Outcomes through Immunomodulation: A Systematic Review.
van Brakel, L, Mensink, RP, Wesseling, G, Plat, J
Nutrients. 2020;12(12)
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Asthma is a chronic inflammatory disease of the airways, with the infiltration of immune cells into the airways leading to localized inflammation and asthmatic symptoms. This review sought to establish whether nutritional interventions can help improve asthma and if this happens via regulation of the immune system. 28 studies were included that investigated the impact on both asthma and immunological parameters. The interventions include herbs (Nigella sativa, Crocus sativa, Boswellia serrata gum, Aegle marmelos), supplements (Vitamin E, soy isoflavones, tomato extract), weight loss and reduced-calorie diets, Vitamin D3, omega-3 fatty acids and whole-food approaches such as the Mediterranean diet. Half of the studies reported improvements in either asthma symptoms or immunological parameters. Two studies showed worsening. The herbal mixtures had the most consistent impact in both areas, followed by omega-3 fatty acids. Of interest here was that low to moderate dosages seemingly obtained wider-ranging improvements than higher dosages. The least evidence was found for vitamin D in the studies included. Overall only a couple of studies showed clinically relevant improvements and the authors insist that more research is needed before further nutritional interventions can be included in guidelines for asthma management. According to this review, the evidence for nutritional evidence for asthma management is still limited, in particular for those interventions where symptoms improvements correlate with beneficial immunological changes.
Abstract
Asthma is a chronic inflammatory disease of the airways, characterized by T-helper (Th) 2 inflammation. Current lifestyle recommendations for asthma patients are to consume a diet high in fruits and vegetables and to maintain a healthy weight. This raises the question of whether other nutritional interventions may also improve asthma-related outcomes and whether these changes occur via immunomodulation. Therefore, we systematically reviewed studies that reported both asthma-related outcomes as well as immunological parameters and searched for relations between these two domains. A systematic search identified 808 studies, of which 28 studies met the inclusion criteria. These studies were divided over six nutritional clusters: herbs, herbal mixtures and extracts (N = 6); supplements (N = 4); weight loss (N = 3); vitamin D3 (N = 5); omega-3 long-chain polyunsaturated fatty acids (LCPUFAs) (N = 5); and whole-food approaches (N = 5). Fifteen studies reported improvements in either asthma-related outcomes or immunological parameters, of which eight studies reported simultaneous improvements in both domains. Two studies reported worsening in either asthma-related outcomes or immunological parameters, of which one study reported a worsening in both domains. Promising interventions used herbs, herbal mixtures or extracts, and omega-3 LCPUFAs, although limited interventions resulted in clinically relevant results. Future studies should focus on further optimizing the beneficial effects of nutritional interventions in asthma patients, e.g., by considering the phenotypes and endotypes of asthma.
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Vitamin B12 in Relation to Oxidative Stress: A Systematic Review.
van de Lagemaat, EE, de Groot, LCPGM, van den Heuvel, EGHM
Nutrients. 2019;11(2)
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Research suggests that vitamin B12 may possess antioxidant properties (i.e. they neutralise free radicals that can cause damage to cells or ‘oxidative stress’). The triage theory suggests that nutrients may be reallocated to necessary functions for survival if there is not enough for all processes. As such, lower than optimum levels of B12 may contribute to oxidative stress and free radicals which may relate to age-related disease development. This systematic review explores if low vitamin B12 is related to increased oxidative stress. The systematic review included 15 articles and found evidence to suggest there is a relationship between lower vitamin B12, low antioxidant status and oxidative stress. However, there is a lack of robust studies (in the form of randomised controlled trials and prospective studies) in humans suggesting that further research is needed to establish cause and effect.
Abstract
The triage theory posits that modest micronutrient deficiencies may induce reallocation of nutrients to processes necessary for immediate survival at the expense of long-term health. Neglected processes could in time contribute to the onset of age-related diseases, in which oxidative stress is believed to be a major factor. Vitamin B12 (B12) appears to possess antioxidant properties. This review aims to summarise the potential antioxidant mechanisms of B12 and investigate B12 status in relation to oxidative stress markers. A systematic query-based search of PubMed was performed to identify eligible publications. The potential antioxidant properties of B12 include: (1) direct scavenging of reactive oxygen species (ROS), particularly superoxide; (2) indirect stimulation of ROS scavenging by preservation of glutathione; (3) modulation of cytokine and growth factor production to offer protection from immune response-induced oxidative stress; (4) reduction of homocysteine-induced oxidative stress; and (5) reduction of oxidative stress caused by advanced glycation end products. Some evidence appears to suggest that lower B12 status is related to increased pro-oxidant and decreased antioxidant status, both overall and for subclinically deficient individuals compared to those with normal B12 status. However, there is a lack of randomised controlled trials and prospective studies focusing specifically on the relation between B12 and oxidative stress in humans, resulting in a low strength of evidence. Further work is warranted.
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Neurological Manifestations of Neuropathy and Ataxia in Celiac Disease: A Systematic Review.
Mearns, ES, Taylor, A, Thomas Craig, KJ, Puglielli, S, Leffler, DA, Sanders, DS, Lebwohl, B, Hadjivassiliou, M
Nutrients. 2019;11(2)
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Coeliac disease (CD) is a chronic, immune-mediated enteropathy in which dietary gluten triggers an inflammatory reaction of the small intestine in genetically predisposed individuals. The clinical presentation of the disease varies broadly and may include both intestinal symptoms and extra-intestinal manifestations, including iron-deficiency anaemia, osteoporosis, dermatitis herpetiformis, and neurological disorders, such as peripheral neuropathies and ataxia (a condition that affects co-ordination, balance and speech). Many patients who present with neurological manifestations of CD have no gastrointestinal symptoms, commonly leading to a delay in diagnosis. The aim of this systematic review was to assess the prevalence of peripheral neuropathies and gluten ataxia. Nine studies on gluten ataxia and 13 on gluten neuropathy were included in this review. The prevalence of both, neuropathy and ataxia, in the general population is very low, but this risk is increased in patients with CD. Estimates of the prevalence of neuropathy in CD patients ranged from 0% to 39%, with an increased risk in older and female patients. Prevalence of gluten ataxia varied from 0% to 6%. Symptoms of gluten neuropathy improve when patients with CD follow a gluten free diet (GFD), whilst the benefits of a GFD for ataxia vary between studies, possibly due to differences in study design. The authors note that this review primarily concentrated on patients with CD (i.e. those with evidence of enteropathy). However, neurological manifestations may exist in the presence of anti-gliadin antibodies alone (gluten sensitivity without evidence of enteropathy), and such patients benefit equally from a GFD. The authors conclude that patients with CD have an increased risk of gluten ataxia and gluten neuropathy, and that clinicians should check for gluten sensitivity in patients with ataxia and neuropathy of unknown origin.
Abstract
Celiac disease (CD) is an immune-mediated gastrointestinal disorder driven by innate and adaptive immune responses to gluten. Patients with CD are at an increased risk of several neurological manifestations, frequently peripheral neuropathy and gluten ataxia. A systematic literature review of the most commonly reported neurological manifestations (neuropathy and ataxia) associated with CD was performed. MEDLINE, Embase, the Cochrane Library, and conference proceedings were systematically searched from January 2007 through September 2018. Included studies evaluated patients with CD with at least one neurological manifestation of interest and reported prevalence, and/or incidence, and/or clinical outcomes. Sixteen studies were included describing the risk of gluten neuropathy and/or gluten ataxia in patients with CD. Gluten neuropathy was a neurological manifestation in CD (up to 39%) in 13 studies. Nine studies reported a lower risk and/or prevalence of gluten ataxia with a range of 0%⁻6%. Adherence to a gluten-free diet appeared to improve symptoms of both neuropathy and ataxia. The prevalence of gluten neuropathy and gluten ataxia in patients with CD varied in reported studies, but the increased risk supports the need for physicians to consider CD in patients with ataxia and neurological manifestations of unknown etiology.
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Nutritional strategies for psoriasis: current scientific evidence in clinical trials.
Zuccotti, E, Oliveri, M, Girometta, C, Ratto, D, Di Iorio, C, Occhinegro, A, Rossi, P
European review for medical and pharmacological sciences. 2018;22(23):8537-8551
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Psoriasis is an inflammatory skin disease that results in patches of dry, scaly skin that can be itchy or sore. This review looked at the evidence for a variety of nutritional and herbal strategies for reducing the risk and severity of psoriasis. Obesity is associated with both an increased risk of psoriasis, and increased severity of the disease, with obese patients being twice as likely to suffer from psoriasis as people of normal weight. Abdominal obesity in particular is associated with chronic low-grade inflammation that contributes to immune dysregulation. In obese patients, weight reduction via a low-calorie diet has been shown to reduce the severity of psoriasis. A Mediterranean-style diet, rich in extra virgin olive oil, fish, fruit vegetables, legumes, nuts and seeds is associated with a lower incidence of psoriasis. In contrast, a diet high in simple carbohydrates, high in arachidonic acid, and a low omega 3: omega 6 ratio is likely to drive inflammation, worsening severity of the disease. The microbiota plays a role in the development of psoriasis, with disruption of the gut and skin microbiomes both associated with psoriasis. In particular, psoriasis patients have a reduced abundance of Akkermansia muciniphilia in their gut. Several Lactobacillus strains have demonstrated potential for therapeutic effects in psoriasis patients when taken as a supplement. Common nutritional supplements used by psoriasis patients are fish oil, selenium, and zinc. In a review of the efficacy of fish oil supplementation, 12 of 15 trials showed a benefit. The evidence for zinc supplementation is less robust. There is limited data on the effectiveness of selenium supplementation, however low serum selenium levels are associated with increased psoriasis severity. Vitamin D levels are lower in psoriasis patients and correlate with disease severity. In individuals who are deficient, supplementing with vitamin D may prevent psoriasis-related comorbidities. Amongst the herbal and botanical remedies studied, neem, turmeric, Tripterygium wilfordii (Thunder God Vine), and the carotenoid-rich alga Dunaliella bardawil may reduce the severity of psoriasis. The review authors concluded that an integrated multidisciplinary approach should be considered for the management of psoriasis patients. Education to modify lifestyle and environmental risk factors is important. A collaboration between nutritionists and medical specialists with a holistic approach may be useful for psoriasis patients.
Abstract
OBJECTIVE Several nutritional strategies for the management of psoriasis are promising. Even if recent data support that nutrition may play a pivotal role in prevention and co-treatment and despite patient's concerns regarding the best nutritional habits, the consensus regarding the nutritional strategies to be adopted lacks in clinical settings. In this manuscript, the effects of several nutritional strategies for psoriasis patients such as hypocaloric diet, vitamin D, fish oil, selenium, and zinc supplementation were systematically reviewed. Randomized controlled trials (RCTs) on beneficial botanical oral supplements were also included in the analysis. MATERIALS AND METHODS For each topic, a search was conducted in MEDLINE electronic databases for articles published in English between January 1, 1990 and September 2018. Two independent reviewers assessed and extracted the data. Only controlled clinical trials were selected. RESULTS The evidence regarding the current nutritional strategies for psoriasis patients were summarized and translated into a global, comprehensible recommendation. CONCLUSIONS Weight loss combined with a healthy lifestyle was shown to be very beneficial for patients with moderate to severe disease with a significant reduction of the Psoriasis Area and Severity Index (PASI) score. Currently, oral vitamin D supplementation for prevention or treatment of psoriasis in adults with normal vitamin D levels is not recommended; however, psoriasis patients with a deficit in plasma vitamin D levels are advised to complement with oral supplements to prevent psoriasis-related comorbidities. Instead of zinc, selenium, and omega 3 supplements have been proven beneficial for psoriasis patients. Among botanical species, Dunaliella bardawil (D. bardawil), Tripterygium wilfordii (T. wilfordii), Azadirachta indica (A. indica), Curcuma longa (C. longa), and HESA-A are the most beneficial. In conclusion, a close cooperation between nutritionists and dermatologists may be useful for the management of psoriasis.
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Body mass index, abdominal fatness, weight gain and the risk of psoriasis: a systematic review and dose-response meta-analysis of prospective studies.
Aune, D, Snekvik, I, Schlesinger, S, Norat, T, Riboli, E, Vatten, LJ
European journal of epidemiology. 2018;33(12):1163-1178
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Psoriasis is an immune-mediated inflammatory skin disease characterised by red, itchy, scaly and flaky skin. Research has shown an association between adiposity and inflammation cytokine release triggered by adipose tissue and increased body mass index and psoriasis. In this meta-analysis, seven prospective studies were included, and the association between BMI, abdominal fat, and psoriasis was examined. According to this meta-analysis, the relative risk of psoriasis increases by 19% for every 5-unit increase in BMI, 24% for a 10 cm increase in waist circumference, 37% for a 0.1-unit increase in waist-to-hip ratio, and 11% for a 5 kg weight gain. The risk of psoriasis was lower for people with a BMI below 20, and it was significantly higher for those with a BMI between 22.5-24. Psoriasis risk was positively associated with waist circumference, waist-to-hip ratio, and weight gain. Psoriasis risk escalates by 2-4 times with an increase in each measure of adiposity. Several potential strategies to reduce the risk of psoriasis are identified in this meta-analysis, including weight loss, dietary factors, and physical activity. To evaluate their effectiveness and develop appropriate strategies, further robust studies are needed. Healthcare professionals can use the results of this study to develop potential therapeutic strategies to reduce the risk of psoriasis by understanding the mechanisms and factors associated with the disease.
Abstract
Greater body mass index (BMI) has been associated with increased risk of psoriasis in case-control and cross-sectional studies, however, the evidence from prospective studies has been limited. We conducted a systematic review and dose-response meta-analysis of different adiposity measures and the risk of psoriasis to provide a more robust summary of the evidence based on data from prospective studies. PubMed and Embase databases were searched for relevant studies up to August 8th 2017. Summary relative risks (RRs) and 95% confidence intervals (CIs) were calculated using a random effects model. The summary relative risk (RR) for a 5 unit increment in BMI was 1.19 (95% CI 1.10-1.28, I2 = 83%, n = 7). The association appeared to be stronger at higher compared to lower levels of BMI, pnonlinearity < 0.0001, and the lowest risk was observed at a BMI around 20. The summary RR was 1.24 (95% CI 1.17-1.31, I2 = 0%, pheterogeneity = 0.72, n = 3) per 10 cm increase in waist circumference, 1.37 (95% CI 1.23-1.53, I2 = 0%, pheterogeneity = 0.93, n = 3) per 0.1 unit increase in waist-to-hip ratio, and 1.11 (95% CI 1.07-1.16, I2 = 47%, pheterogeneity = 0.15, n = 3) per 5 kg of weight gain. Adiposity as measured by BMI, waist circumference, waist-to-hip ratio, and weight gain is associated with increased risk of psoriasis.