1.
The Role of Genetically Engineered Probiotics for Treatment of Inflammatory Bowel Disease: A Systematic Review.
Zhang, T, Zhang, J, Duan, L
Nutrients. 2023;15(7)
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Inflammatory bowel disease (IBD), largely classified as Crohn’s disease (CD) or ulcerative colitis (UC), is a chronic intestinal inflammatory disorder mediated by genetic, immune, microbial, and environmental factors. The aim of this study was to summarise the efficacy of different genetically modified probiotics compared to wild-type probiotics in the treatment of IBD in animal models and patients and to investigate the specific effects and main mechanisms involved. This study was a systematic review of forty-five preclinical studies and one clinical study. Results showed a protective effect of genetically modified organisms (gm) probiotics in colitis. Several protective mechanisms have been identified: reduction of the pro- to anti-inflammatory cytokine ratio in colonic tissue and plasma, modulation of the activity of oxidative stress in the colon, improvement of intestinal barrier integrity, modulation of the diversity and composition of gut microbiota, and production of favourable metabolites, including short-chain fatty acids, by beneficial bacteria. Authors concluded that gm probiotics are more effective and safer than wild-type probiotics, to facilitate clinical translation.
Expert Review
Conflicts of interest:
None
Take Home Message:
Conclusions of this review were largely based on mouse models and although treatment using probiotics is generally considered safe in humans, with only minor side-effects (flatulence), practitioners need to be aware that in an IBD population the use of GM formulations might not be completely without risk.
Evidence Category:
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A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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X
B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Introduction
This paper summarises the efficacy of specific genetically modified (GM) probiotic formulations for Inflammatory Bowel Disease (IBD) when compared to wild type probiotics. The aim was to ascertain what specific effects and mechanisms such probiotics have on IBD symptomatology.
Methods
- A total of 46 published articles were included; 45 mouse experimental models (induced acute or chronic colitis) (n=15-130) and 1 human IBD population clinical trial (n=10)
- The effect of GM probiotics were compared to placebo and wild-type probiotics in trials including preclinical studies, randomised controlled trials and cohort studies
- Animals received probiotics via gastric gavage (105 - 4 x 1012 CFU) for 3-6 weeks
- The human placebo-uncontrolled trial lasted 7 days and patients received 10 GM capsules of L.lactis (1 x 1010 CFU) twice daily.
Results
- GM probiotics that secrete immunoregulatory cytokines such as IL-10 appear to reduce intestinal damage
- The human trial using GM L.lactis resulted in 5 patients who went into complete clinical remission (CDAI, <150) with 3 patients exhibiting a clinical response (decrease in CDAI, >70). with only minor adverse events (flatulence)
- However, human cytokines that promote intestinal barrier function and epithelial restitution were not enhanced with oral administration of probiotics
- Two studies concluded that GM L.lactis and S.boulardii, that secrete atrial natriuretic peptide, might be the most effective options in supporting colitis
- GM L.casei resulted in faster recovery from weight loss in acute colitis models
- Superoxide dismutase (SOD) producing GM L.fermentum increased SOD activity by almost eightfold compared to the wild type
- GM Lact. fermentum furthermore showed a higher survival rate and lower disease activity index (P <0·05) in colitis models
- GM L.lactis improved gut microbial composition and GM S.cerevisiae improved microbial diversity whilst reducing the Firmicutes to Bacteroides ratio
- GM E.coli significantly reduced weight loss, colon shortening plus lower disease activity and histological changes (P < 0.05).
Conclusion
Despite the heterogeneity of the trials, GM probiotics appear to play a notable part in ameliorating IBD symptomatology and disease severity when compared to wild-type probiotics. Human efficacy and potential adverse effects require more in-depth trials to ascertain safety and optimal dosages.
Clinical practice applications:
- Probiotics species used in the trials included S.thermophilus, E.coli, L.lactis, B.ovatus, S.boulardii, L.fermentum, B.longhum, L.casei, L.plantarum, and S.cerevisiae. Wild-types of some of these are already available to use in clinical practice
- Note that oral administration in the human trial showed no significant health outcome, therefore efficacy and safety need to be ascertained on an individual patient level
- Colonisation of beneficial bacteria in the gut of IBD patients might be difficult and any form of supplementation therefore needs to be closely monitored.
Considerations for future research:
- More evidence is needed to demonstrate that GM probiotic formulations result in significantly improved outcomes when compared to wild-types
- Future randomised placebo-controlled trials need to include larger cohorts to determine supplement efficacy
- Longer periods of intervention are needed to confirm efficacy, safety, and tolerance for both Crohn’s Disease and Colitis
- Optimal GM probiotic formulation, doses, and means of application need to be identified.
Abstract
BACKGROUND Many preclinical studies have demonstrated the effectiveness of genetically modified probiotics (gm probiotics) in animal models of inflammatory bowel disease (IBD). OBJECTIVE This systematic review was performed to investigate the role of gm probiotics in treating IBD and to clarify the involved mechanisms. METHODS PubMed, Web of Science, Cochrane Library, and Medline were searched from their inception to 18 September 2022 to identify preclinical and clinical studies exploring the efficacy of gm probiotics in IBD animal models or IBD patients. Two independent researchers extracted data from the included studies, and the data were pooled by the type of study; that is, preclinical or clinical. RESULTS Forty-five preclinical studies were included. In these studies, sodium dextran sulfate and trinitrobenzene sulfonic acid were used to induce colitis. Eleven probiotic species have been genetically modified to produce therapeutic substances, including IL-10, antimicrobial peptides, antioxidant enzymes, and short-chain fatty acids, with potential therapeutic properties against colitis. The results showed generally positive effects of gm probiotics in reducing disease activity and ameliorating intestinal damage in IBD models; however, the efficacy of gm probiotics compared to that of wild-type probiotics in many studies was unclear. The main mechanisms identified include modulation of the diversity and composition of the gut microbiota, production of regulatory metabolites by beneficial bacteria, reduction of the pro- to anti-inflammatory cytokine ratio in colonic tissue and plasma, modulation of oxidative stress activity in the colon, and improvement of intestinal barrier integrity. Moreover, only one clinical trial with 10 patients with Crohn's disease was included, which showed that L. lactis producing IL-10 was safe, and a decrease in disease activity was observed in these patients. CONCLUSIONS Gm probiotics have a certain efficacy in colitis models through several mechanisms. However, given the scarcity of clinical trials, it is important for researchers to pay more attention to gm probiotics that are more effective and safer than wild-type probiotics to facilitate further clinical translation.
2.
Cadmium exposure and risk of diabetes and prediabetes: A systematic review and dose-response meta-analysis.
Filippini, T, Wise, LA, Vinceti, M
Environment international. 2022;158:106920
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Cadmium is a toxic metal released in the environment after both natural and anthropogenic activities, particularly in contaminated and industrial areas devoted to smelting and refining of metals, and the manufacturing of batteries, coatings, or plastics. Exposure to cadmium may occur through occupational activities, smoking, food, and air pollution. The aim of this study was to provide updated literature on cadmium exposure and the risk of both type 2 diabetes and prediabetes, and to model the shape of these associations using a dose response approach. This study is a systematic review and meta-analysis of forty-two studies. Diabetes was investigated as an outcome in thirty-one studies, prediabetes in four studies, and both diabetes and prediabetes in seven studies. Results show that higher cadmium exposure was associated with increased risks of both diabetes and prediabetes. Diabetes risk increased linearly in studies using urinary cadmium concentrations, while disease risk increased only at the highest exposure levels when assessed using blood concentrations. The analysis for prediabetes also showed a linear increase in risk from low exposure, with a flattening effect at higher urinary cadmium concentrations. Authors conclude that their findings add to the available evidence on potential adverse health effects of environmental exposure to cadmium.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Cadmium exposure through diet, occupational exposure and smoking may increase the risk of type 2 diabetes in affected individuals.
Evidence Category:
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X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Background
Cadmium exposure might occur through occupational activities, food, air pollution, and smoking. Smokers, in particular, have higher blood cadmium concentrations than non-smokers. Food is the main transmission route for non-smokers, particularly cereals, vegetables, mollusks, and offal. Females and older adults are at a greater risk due to an increased risk of iron deficiency in these population groups, leading to increased absorption, as well as greater age-related bioaccumulation.
Furthermore, cadmium exposure has been associated with an increased risk of diabetes in a number of studies, as referenced in the present manuscript. However, the magnitude and shape of the correlation are uncertain.This systematic review and meta-analysis therefore investigates the relationship between exposure to cadmium and type 2 diabetes and prediabetes risk.
Methods
- The systematic review was conducted and reported in line with the PRISMA 2020 statement. Search strings related to the terms “cadmium” and “diabetes”, or “prediabetes state” in PubMed/MEDLINE, Web of Science and EMBASE databases were employed to search for relevant articles. Latest search date: 1 October 2021.
- Eligibility criteria included: studies evaluating cadmium exposure via biomarker levels with outcomes of interest being type 2 diabetes or prediabetes using WHO criteria and the American Diabetes Association; and reporting of relative risk estimates using the hazard ratio (HR), risk ratio (RR), or odds ratio (OR) with the corresponding 95% confidence interval (CIs). For inclusion in dose-response meta-analysis: reported effect estimates for all exposure categories along with dose in each category.
- Studies were assessed for risk of bias using theROBINS-E tool. Overall certainty of the evidence was assessed using the GRADE approach.
- The meta-analysis involved estimating RRs with corresponding 95% CIs from each study. Generalised least-squares regression with a random effects model and restricted maximum likelihood estimation were used. The highest versus lowest exposure categories were compared. The association between exposure and risk of diabetes or prediabetes was investigated using a one-stage dose-response meta-analysis. Sensitivity analyses were performed and heterogeneity between studies was assessed..
Results
- 42 eligible studies (case-control, cross-sectional, and cohort studies), ranging 65-34, 814 male and female adult participants, were identified investigating the association between cadmium exposure and risk of diabetes or prediabetes. Seven of the included studies were at overall high risk of bias; heterogeneity in the resulting meta-analyses was moderate to substantial. Sensitivity analyses indicated comparable results. Assessment with GRADE found no major inconsistency, indirectness or imprecision for either outcome.
- Comparing the highest versus lowest cadmium exposure concentrations associated with type 2 diabetes resulted in a RR of 1.24 (95% CI 0.96–1.59), RR 1.21 (CI 95% 1.00–1.45), and RR 1.47 (CI 95% 1.01–2.13) for blood, urinary, and toenail matrices, respectively. Concurrently, there was an elevated risk of prediabetes for cadmium levels in urine of RR 1.41 (95% CI: 1.15–1.73) and blood RR 1.38 (95% CI: 1.16–1.63), respectively.
- In the dose-response meta-analysis, a linear positive correlation between increasing urinary cadmium levels and diabetes risk was observed, with a RR 1.25 (95% CI 0.90–1.72) at concentration 2.0 µg/g of creatinine compared with no exposure. Conversely, for blood cadmium concentrations, the diabetes risk seemed to rise above 1 µg/L compared with no exposure. Moreover, prediabetes risk increased up to approximately 2 µg/g creatinine beyond which a plateau was reached with RR 1.40 (95% CI 1.12–1.76) at 2 µg/g creatinine.
- The meta-regression showed a negligible correlation between blood cadmium levels and diabetes risk. However, a positive yet imprecise association was found with increasing urinary cadmium concentrations. Similarly, no association was observed between blood cadmium concentrations and risk of prediabetes, whereas a positive relationship with urinary cadmium levels was observed. However, these findings were based on a limited cohort of studies.
Conclusions
- A positive linear correlation between cadmium concentration (measured in multiple matrices) and risk of both type 2 diabetes and prediabetes with a dose-response relationship (moderate-certainty evidence) were observed in this systematic review and meta-analysis. Diabetes risk increased linearly in studies using urinary cadmium concentrations, whereas disease risk increased only at the highest exposure levels when assessed using blood levels. The analysis for prediabetes also demonstrated a linear increase in risk from low exposure, which plateaued at higher urinary cadmium concentrations.
Clinical practice applications:
- To inform practitioners and clients of the risks of cadmium exposure in the diet, through occupational exposure, and through smoking.
- To motivate practitioners to educate themselves and their clients regarding the foods which may pose a higher risk of cadmium exposure (not reviewed in the present article).
- To advise clients on prediabetes and type 2 diabetes risk from cadmium exposure through smoking.
Considerations for future research:
- As cited by the authors, future studies could incorporate stratified analysis in specific subgroups, e.g., non-smokers, or could be restricted to prospective cohort studies with more sufficient data,
- Large-scale observational studies could be conducted investigating cadmium exposure in smokers versus non-smokers.
- Clinical trials could be performed to evaluate the effect of reduction or cessation of tobacco smoking on total body cadmium concentrations .
- Continuous surveillance of dietary cadmium exposure and other heavy metals should be prioritised to inform public health.
- Dietary interventions could assess the possibility to attenuate the risk of cadmium exposure.
Abstract
BACKGROUND Cadmium exposure has been associated with increased diabetes risk in several studies, though there is still considerable debate about the magnitude and shape of the association. OBJECTIVE To perform a systematic review and meta-analysis of observational studies investigating the relation between cadmium exposure and risk of type 2 diabetes and prediabetes, and to summarize data on the magnitude and shape of the association. DATA SOURCE After conducting an online literature search through October 1, 2021, we identified 42 eligible studies investigating the association between cadmium exposure and risk of diabetes and prediabetes. STUDY ELIGIBILITY CRITERIA We included studies that assessed cadmium exposure through biomarker levels; examined type 2 diabetes or prediabetes among outcomes; and reported effect estimates for cadmium exposure for meta-analysis only. STUDY APPRAISAL AND SYNTHESIS METHODS Studies were evaluated using ROBINS-E risk of bias tool. We quantitively assessed the relation between exposure and study outcomes using one-stage dose-response meta-analysis with a random effects meta-analytical model. RESULTS In the meta-analysis, comparing highest-versus-lowest cadmium exposure levels, summary relative risks (RRs) for type 2 diabetes were 1.24 (95% confidence interval 0.96-1.59), 1.21 (1.00-1.45), and 1.47 (1.01-2.13) for blood, urinary, and toenail matrices, respectively. Similarly, there was an increased risk of prediabetes for cadmium concentrations in both urine (RR = 1.41, 95% CI: 1.15-1.73) and blood (RR = 1.38, 95% CI: 1.16-1.63). In the dose-response meta-analysis, we observed a consistent linear positive association between cadmium exposure and diabetes risk, with RRs of 1.25 (0.90-1.72) at 2.0 µg/g of creatinine. Conversely for blood cadmium, diabetes risk appeared to increase only above 1 µg/L. Prediabetes risk increased up to approximately 2 µg/g creatinine above which it reached a plateau with RR of 1.42 (1.12-1.76) at 2 µg/g creatinine. LIMITATIONS AND CONCLUSIONS This analysis provides moderate-certainty evidence for a positive association between cadmium exposure (measured in multiple matrices) and risk of both diabetes and prediabetes.
3.
The vaginal microbiome and the risk of preterm birth: a systematic review and network meta-analysis.
Gudnadottir, U, Debelius, JW, Du, J, Hugerth, LW, Danielsson, H, Schuppe-Koistinen, I, Fransson, E, Brusselaers, N
Scientific reports. 2022;12(1):7926
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Preterm birth is a major cause of neonatal mortality and morbidity. Many factors can trigger premature labour onset, including preterm premature rupture of membranes, infections and microbial invasion of the amniotic cavity. The vaginal microbiome is thought to protect from such infections. The aim of this study was to assess the association between the vaginal microbiome and the risk of preterm birth. This study is a systematic review and meta-analysis of 17 cohort studies. The number of pregnancies per study ranged between 38 and 539, with 8 and 107 preterm births. Results show that women with a “low-lactobacilli” vaginal microbiome composition were at higher risk of preterm birth (spontaneous and overall) compared to women with L. crispatus (microbiome) dominant microbiome compositions. Authors conclude that the diversity of the vaginal microbiome seems to play a part in the risk of preterm birth.
Expert Review
Conflicts of interest:
None
Take Home Message:
- The diversity of the vaginal microbiome is reported to play a part in the risk of preterm births.
- Practitioners could consider testing the virginal microbiome for low Lactobacilli or the dominance of Gardnerella and Prevotella and then recommending a probiotic supplement to pregnant patients who have low Lactobacilli vaginal microbiome.
Evidence Category:
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A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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X
B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Introduction
A systematic review and network meta-analysis was conducted to investigate the association between vaginal microbiome and risk of preterm births.
Methodology
- Seventeen longitudinal cohort studies were included. Seven originated from North America, three from Europe, two from South America, three from Asia, and two from Africa. The number of pregnancies per study ranged between 38 and 539, with 8 and 107 preterm births. 16S Sequencing techniques were used to identify the microbial species. Preterm birth was defined as birth before 37 weeks of gestation.
- Microbiome community state types (CSTs) were grouped into five categories based on dominating species: L. crispatus, L. gasseri, L. iners,“low-lactobacilli” and L. jensenii. “Low-lactobacilli” was defined as an increased diversity of anaerobic or mixture of aerobe and facultative anaerobe bacteria (such as Gardnerella and Prevotella) based on the cut-offs and categorization used in the individual studies.
Results
Primary clinical outcomes were:
- Among women who delivered preterm, the pooled proportion with “low-lactobacilli” was 0.41 (95% CI 0.30-0.53) compared to 0.29 (95% CI 0.20-0.38) of women with full-term deliveries.
- The risk of preterm births was higher among women with “low-lactobacilli” compared to L. crispatus (OR 1.69, 95%CI 1.15 -2.49).”Low-lactobacilli” included Garnerella and Provotella, both of which are known to promote inflammatory cytokines and are commonly found in vaginal microbiome just before preterm premature rupture of membranes (PPROM).
Clinical practice applications:
- The diversity of the vaginal microbiome is reported to play an important role in the risk of preterm births.
- Women with low Lactobacilli seem to be at a greater risk of delivering preterm compared to women with L. crispatus dominant microbiome.
- Based on this study, practitioners could therefore consider testing the vaginal microbiome of their patients for low Lactobacilli and/or the dominance of Gardnerella and Prevotella.
- Practitioners may also consider recommending specific probiotic supplementation during pregnancy to increase the dominance of Lactobacilli and L. crispatus vaginal microbiome.
Considerations for future research:
- In the past, researchers have grouped the microbiome into categories based on dominating species, which is not ideal. Therefore, further studies are needed where individual microbiome sequencing data is used to make comparisons.
- Additionally, longitudinal studies are needed with higher sample sizes to investigate the natural changes of the vaginal microbiome during pregnancy and the physiological mechanisms underlying these apparent different risk profiles.
- Furthermore, randomized-controlled trials are needed to establish if pregnant women could benefit from specific probiotic supplementation during pregnancy.
Abstract
Preterm birth is a major cause of neonatal morbidity and mortality worldwide. Increasing evidence links the vaginal microbiome to the risk of spontaneous preterm labour that leads to preterm birth. The aim of this systematic review and network meta-analysis was to investigate the association between the vaginal microbiome, defined as community state types (CSTs, i.e. dominance of specific lactobacilli spp, or not (low-lactobacilli)), and the risk of preterm birth. Systematic review using PubMed, Web of Science, Embase and Cochrane library was performed. Longitudinal studies using culture-independent methods categorizing the vaginal microbiome in at least three different CSTs to assess the risk of preterm birth were included. A (network) meta-analysis was conducted, presenting pooled odds ratios (OR) and 95% confidence intervals (CI); and weighted proportions and 95% CI. All 17 studies were published between 2014 and 2021 and included 38-539 pregnancies and 8-107 preterm births. Women presenting with "low-lactobacilli" vaginal microbiome were at increased risk (OR 1.69, 95% CI 1.15-2.49) for delivering preterm compared to Lactobacillus crispatus dominant women. Our network meta-analysis supports the microbiome being predictive of preterm birth, where low abundance of lactobacilli is associated with the highest risk, and L. crispatus dominance the lowest.
4.
Serum vitamin E levels and chronic inflammatory skin diseases: A systematic review and meta-analysis.
Liu, X, Yang, G, Luo, M, Lan, Q, Shi, X, Deng, H, Wang, N, Xu, X, Zhang, C
PloS one. 2021;16(12):e0261259
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Plain language summary
Vitiligo, Psoriasis, Acne and Atopic Dermatitis are chronic immune-mediated inflammatory skin conditions characterised by itchy skin. In previous studies, decreased serum vitamin E levels have been associated with an increased risk of skin diseases. Nuts, oils from plants, and vegetables contain vitamin E, which is a dietary bioactive compound that has anti-inflammatory and antioxidant properties. In this systematic review and meta-analysis, twenty case-controlled studies were included, of which thirteen specifically examined alpha-tocopherol levels. Psoriasis, Vitiligo, atopic dermatitis, and acne patient groups had significantly lower levels of serum Vitamin E than the control groups. There is no clear understanding of the pathogenesis of chronic inflammatory skin conditions. One of the underlying mechanisms is the interaction between oxidative stress and the immune system, as well as the accumulation of free radicals in the epidermal layers of the skin. As there is limited evidence regarding the benefits of Vitamin E in improving chronic inflammatory skin conditions, further robust studies are necessary. Healthcare professionals can use this research to gain a better understanding of the potential clinical applications of vitamin E in the treatment of skin disorders.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Low serum vitamin E levels are reported to be associated with several chronic inflammatory skin diseases, such as vitiligo, psoriasis, atopic dermatitis, and acne.
- Practitioners could consider vitamin E therapy in those with low serum concentrations
Evidence Category:
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X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
This systematic review and meta-analysis report on the association between serum vitamin E levels and chronic inflammatory skin diseases.
The review which followed PRISMA reporting guidelines, screened 892 studies. After the selection and exclusions, 20 case-control studies were included involving a total of 1172 patients.
The studies that were included focused mainly on chronic inflammatory diseases, including vitiligo, psoriasis, atopic dermatitis, and acne. Eight studies included only adults, five included only children or teenagers and six studies included adults and children. One study had no age description.
Thirteen studies stated that alpha-tocopherol was used in their investigations. However, seven studies did not describe the subunit of vitamin E.
Primary clinical outcomes were:
- Seven studies, with 351 cases and 350 controls reported that compared with the control group, vitiligo patients had lower serum vitamin E concentrations (Standard Mean Difference (SMD):0.70, 95% Cl:121-0.19.
- Six studies investigated the change of serum vitamin E levels in patients with psoriasis, with 278 cases and 257 controls. Compared with the control group, psoriasis patients had lower serum vitamin E concentrations (SMD: -2.37, 95% CI: -3.57 to -1.18).
- The serum vitamin E Levels in patients with atopic dermatitis were observed in 4 studies, with 259 cases and 307 controls. Compared with the control group atopic dermatitis patients had lower serum vitamin E concentrations (SMD: -1.08, 95% CI: -1.80 to -0.36).
Levels of serum vitamin E in acne patients were reported in 3 studies, with 284 cases and 186 controls. Compared with the control group, acne patients had lower serum concentration levels of vitamin E (SMD: -0.67, 95% CI: -1.05 to -0.30).
No publication bias was found in any association (Egger’s test >0.05), though heterogeneity was considerable in every case (I2 > 80%), though this interaction was not significant for acne (p=0.879). Associations were not split by age, or any other cofactor, however sensitivity analyses did not indicate modification of the results.
The authors also assessed the association between skin disease severity and serum vitamin E concentrations. Overall, more severe disease was associated with a lower serum vitamin E concentration (SMD -1.56, 95% CI:-2.53 to -059).
Clinical practice applications:
- Vitamin E has gained the attention of researchers as a potential adjuvant therapy for various skin disorders due to its excellent antioxidant and anti-inflammatory properties.
- This review reports on the low levels of serum vitamin E found in patients with vitiligo, psoriasis, atopic dermatitis, and acne, and also suggests that serum concentrations of vitamin E are lower in those with more severe disease. Based on these findings, practitioners could therefore consider investigating the serum vitamin E levels of patients with inflammatory skin diseases and consider including vitamin E in their treatment protocols if their serum vitamin E levels are low.
Considerations for future research:
- The small number of studies in this review indicates the need for further research to be done on vitamin E and inflammatory skin diseases.
- Although there are reports on the antioxidant and anti-inflammatory properties of vitamin E, further investigations are needed to determine the exact mechanism of action in inflammatory skin diseases.
- Additionally, further investigation is needed to evaluate which chemical forms of vitamin E and their dosage amounts have beneficial effects on inflammatory skin diseases.
Abstract
BACKGROUND Vitamin E has long been linked to skin health, including all of its possible functions in cosmetic products, to its roles in membrane integrity and even the aging process. However, reports on the relationship between serum vitamin E levels and the risk of chronic inflammatory skin diseases have been inconsistent. We performed a systematic review and meta-analysis to evaluate the association between serum vitamin E levels and chronic inflammatory skin diseases. METHODS We searched the PubMed, Web of Science and Scopus databases, with no time limit up to 30.06.2021. Studies examining serum vitamin E levels in patients with chronic inflammatory skin diseases were selected. RESULTS Twenty articles met the inclusion criteria. Compared with controls, a lower vitamin E level was found in patients with vitiligo (SMD: -0.70, 95% CI: -1.21 to -0.19), psoriasis (SMD: -2.73, 95% CI: -3.57 to -1.18), atopic dermatitis (SMD: -1.08, 95% CI: -1.80 to -0.36) and acne (SMD: -0.67, 95% CI: -1.05 to -0.30). CONCLUSIONS Our meta-analysis showed that serum vitamin E levels were lower in patients suffering from vitiligo, psoriasis, atopic dermatitis and acne. This study highlights the need to evaluate vitamin E status to improve its level in patients with skin diseases.