The efficacy of vitamin D supplementation on painful diabetic neuropathy: Protocol for a systematic review and meta-analysis

The role of the gut microbiome in neuroinflammation and chemotherapy-induced peripheral neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is one of the most debilitating adverse effects caused by chemotherapy drugs such as paclitaxel, oxaliplatin and vincristine. It is untreatable and often leads to the discontinuation of cancer therapy and a decrease in the quality of life of cancer patients. It is well-established that neuroinflammation and the activation of immune and glial cells are among the major drivers of CIPN. However, these processes are still poorly understood, and while many chemotherapy drugs alone can drive the activation of these cells and consequent neuroinflammation, it remains elusive to what extent the gut microbiome influences these processes. In this review, we focus on the peripheral mechanisms driving CIPN, and we address the bidirectional pathways by which the gut microbiome communicates with the immune and nervous systems. Additionally, we critically evaluate literature addressing how chemotherapy-induced dysbiosis and the consequent imbalance in bacterial products may contribute to the activation of immune and glial cells, both of which drive neuroinflammation and possibly CIPN development, and how we could use this knowledge for the development of effective treatment strategies.

Effects of vitamin family members on insulin resistance and diabetes complications

The following letter to the editor highlights the article "Effects of vitamin D supplementation on glucose and lipid metabolism in patients with type 2 diabetes mellitus and risk factors for insulin resistance" in World J Diabetes 2023 Oct 15; 14 (10): 1514-1523. It is necessary to explore the role of vitamin family members in insulin resistance and diabetes complications.

Vitamin D as adjuvant therapy for diabetic foot ulcers: Systematic review and meta-analysis approach

BACKGROUND

Diabetic Foot Ulcer (DFU) is a combination of neuropathy and ischaemia on diabetic patient's lower limbs. It has a high burden of limb amputation rate, mortality rate, disability, economic burden, and lower quality of life on diabetic patients. It took mostly 3-6 months and up to 1 year for DFU to heal. DFU patients also have an increased risk of vitamin D deficiency. Meanwhile vitamin D has effects on immune response, insulin secretion, and sensitivity. The long duration of DFU healing is a problem for the patient's health, job, income, quality of life, economy and healthcare. Therefore, we aim to conduct a meta-analysis to assess reliability of vitamin D supplementation on diabetic foot ulcer clinical outcome.

METHODS

We conducted systematic literature search according to PRISMA guideline on Cochrane Library, PubMed, Google Scholar, ProQuest, EBSCO and ScienceDirect from 16 until 24 June 2022. Effect of vitamin D supplementation on diabetic foot ulcer patients was analyzed with a comprehensive meta-analysis tool. Pooled ulcer area, total cholesterol, triglyceride, C-reactive protein, HbA1c, and fasting plasma glucose assessed with 95% confidence intervals were estimated using fixed-effects or random-effects models.

RESULTS

We included 4 papers with 197 people as sample reporting vitamin D capability as treatment for DFU patients. The pooled analysis showed significant differences in ulcer area, serum Vitamin D, Total Cholesterol, Fasting Plasma Glucose, Triglyceride, C-Reactive Protein, and HbA1c. Insignificant results on Erythrocyte Sedimentation Rate and High Density Lipoprotein levels.

CONCLUSION

Vitamin D supplementation is beneficial to be given as adjuvant treatment for diabetic foot ulcer. It may fasten the wound healing and decrease the burden caused by diabetic foot ulcers.

Vitamin D in Neurological Diseases

Vitamin D may have multiple effects on the nervous system and its deficiency can represent a possible risk factor for the development of many neurological diseases. Recent studies are also trying to clarify the different effects of vitamin D supplementation over the course of progressive neurological diseases. In this narrative review, we summarise vitamin D chemistry, metabolism, mechanisms of action, and the recommended daily intake. The role of vitamin D on gene transcription and the immune response is also reviewed. Finally, we discuss the scientific evidence that links low 25-hydroxyvitamin D concentrations to the onset and progression of severe neurological diseases, such as multiple sclerosis, Parkinson's disease, Alzheimer's disease, migraine, diabetic neuropathy and amyotrophic lateral sclerosis. Completed and ongoing clinical trials on vitamin D supplementation in neurological diseases are listed.

Molecular Aspects in the Potential of Vitamins and Supplements for Treating Diabetic Neuropathy

To discuss and provide evidence-based data on dietary supplements as part of treating diabetic neuropathy RECENT FINDINGS: Few randomized controlled trials are available, but some have shown beneficial efficacy of various dietary supplements on objective primary endpoints including nerve conduction velocities and axon potentials as well as subjective patient-reported outcomes. No medical cure for diabetic neuropathy exists, and prevention is therefore crucial. Tight glucose control slows the progression of nerve damage in diabetes, but an unmet clinical need for effective interventions is warranted. Consequently, a growing number of patients turn to dietary supplements proposed to possess neuroprotective properties. However, the postulated effects are often not evidence-based as they have not been tested scientifically. Taken together, this review will focus on dietary supplements investigated in clinical trials for their potential capabilities in targeting the molecular mechanisms involved in the underlying pathogenesis of diabetic neuropathy.

Vitamin D Supplementation in Diabetic Foot Ulcers: A Current Perspective

INTRODUCTION

Diabetic foot ulcer (DFU) is a major complication of diabetes mellitus, as it can physically and emotionally impact the person. Its management can be challenging and expensive, depending on the severity of the wound and the presence of infection.

BACKGROUND

The fat-soluble molecule, vitamin D, has gained great importance ever since its pleiotropism has been recognized. Its efficacy could be attributed to the presence of vitamin D receptors in most of the body tissues. Vitamin D plays a significant role in cell proliferation, differentiation, and immune modulation. It modulates the T and B cells resulting in the suppression of the immunoglobulins, autoimmunity, and inflammation.

METHODS

We performed a literature search with the objective to highlight the role of vitamin D in peripheral vascular disease and peripheral neuropathy, which are the major risk factors for DFU, as well as evidences of its role in wound healing and management of DFU.

RESULTS

Preclinical and clinical studies have shown that vitamin D influences multiple phases of wound healing and thereby accelerates the process. It modulates various cells involved in proliferation and remodelling phases. Vitamin D also enhances the expression of antimicrobial peptides that help to eliminate the microbes, as well as suppress the proinflammatory responses while enhancing the anti-inflammatory responses.

CONCLUSION

This review concludes vitamin D to have a protective role in the immune and vascular system, improve glycaemic outcomes, and wound healing. Therefore, vitamin D could be a preferred adjuvant in the management of DFU.

Improvement in Cardiovascular Autonomic Neuropathy After High-Dose Vitamin D Supplementation in Patients With Type 1 Diabetes

BACKGROUND

Cardiovascular autonomic neuropathy (CAN) is associated with diabetes mellitus, increasing morbidity and mortality. Some cross-sectional studies associated CAN with low 25-hydroxyvitamin D levels. The aim of our study was to evaluate the effect of high-dose vitamin D (VD) supplementation on CAN in Type 1 Diabetes Mellitus (T1DM) patients.

METHODS

We performed a prospective study with 23 patients diagnosed with T1DM and CAN. Subjects with VD levels <30 ng/ml received 10,000 IU/day; the ones with VD levels between 30-60 ng/ml were given 4,000 IU/day for 12 weeks.

RESULTS

There was an improvement in CAN parameters related to resting heart rate variability, such as time domain parameters [Maximum RR interval (0.77 ± 0.11 vs 0.94 ± 0.51 s, p <0.05), Mean length of regular RR intervals (0.71 ± 0.10 vs 0.76 ± 0.09 s, p <0.05) and Standard deviation of all NN intervals (0.02 ± 0.01 vs 0.03 ± 0.02 s; p <0.01)] and frequency domain parameters [Low Frequency (1.9 ± 0.5 vs 2.5 ± 0.9 s, p < 0.001), Total Power (2.5 ± 0.4 vs 2.8 ± 0.6 s, p <0.05)]. In addition, there was a correlation between absolute VD level variation and posttreatment High Frequency (%), as well as among percent variation in VD level and end-of-study Low Frequency/High Frequency ratio (r=0.6, p<0.01; r= -0.5, p<0.05, respectively).

CONCLUSION

Our pilot study is the first to suggest a strong association between high-dose vitamin D supplementation and improved cardiovascular autonomic neuropathy in T1DM patients. It occurred without any variation in HbA1C, blood pressure levels, lipids, and insulin dose.

CLINICAL TRIAL REGISTRATION

http://www.isrctn.com/ISRCTN32601947, identifier ISRCTN32601947.