1.
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
-
-
-
Free full text
-
Plain language summary
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.
2.
Vitamin C and Immune Function.
Carr, AC, Maggini, S
Nutrients. 2017;9(11)
-
-
-
Free full text
Plain language summary
Vitamin C is essential to immune function and performs several crucial roles supporting cellular function in both the innate and adaptive immune system. Low storage capacity means a regular intake of a minimum 100-200mg of Vit C daily is necessary for adequate plasma levels. A potent antioxidant, Vit C can readily donate electrons as part of its immuno-protective role protecting against oxidative damage. VitC is a cofactor for the transportation of fatty acids into the cell mitochondria as well as numerous gene regulatory enzymes, including those involved in the cardiovascular response to infection. Structurally, Vit C supports barrier integrity and wound healing and concentrations of the vitamin accumulate in the epidermis. White leukocyte cells actively accumulate intracellular stores of Vit C indicating an important role in immune signalling. Neutrophils use Vit C to help migration to infection sites in the body and it enhances the differentiation and proliferation of B- and T-cells. Vit C has been shown to moderate inflammatory cytokines and reduce infection severity and longevity. Specifically, supplementation with high dose Vit C appears to be able to both prevent and ameliorate respiratory and systemic infections such as pneumonia. In summary, optimal levels of Vit C are necessary for proper immune function and resistance to infections.
Abstract
Vitamin C is an essential micronutrient for humans, with pleiotropic functions related to its ability to donate electrons. It is a potent antioxidant and a cofactor for a family of biosynthetic and gene regulatory enzymes. Vitamin C contributes to immune defense by supporting various cellular functions of both the innate and adaptive immune system. Vitamin C supports epithelial barrier function against pathogens and promotes the oxidant scavenging activity of the skin, thereby potentially protecting against environmental oxidative stress. Vitamin C accumulates in phagocytic cells, such as neutrophils, and can enhance chemotaxis, phagocytosis, generation of reactive oxygen species, and ultimately microbial killing. It is also needed for apoptosis and clearance of the spent neutrophils from sites of infection by macrophages, thereby decreasing necrosis/NETosis and potential tissue damage. The role of vitamin C in lymphocytes is less clear, but it has been shown to enhance differentiation and proliferation of B- and T-cells, likely due to its gene regulating effects. Vitamin C deficiency results in impaired immunity and higher susceptibility to infections. In turn, infections significantly impact on vitamin C levels due to enhanced inflammation and metabolic requirements. Furthermore, supplementation with vitamin C appears to be able to both prevent and treat respiratory and systemic infections. Prophylactic prevention of infection requires dietary vitamin C intakes that provide at least adequate, if not saturating plasma levels (i.e., 100-200 mg/day), which optimize cell and tissue levels. In contrast, treatment of established infections requires significantly higher (gram) doses of the vitamin to compensate for the increased inflammatory response and metabolic demand.