1. In this meta-analysis, vitamin D supplementation was associated with reduced ICU admission and mechanical ventilation rates in patients with SARS-CoV-2 infection.
2. However, vitamin D supplementation did not significantly affect mortality associated with SARS-CoV-2 infection.
Evidence Rating Level: 1 (Excellent)
SARS-CoV-2 infection continues to be a life-threatening respiratory illness even three years after the onset of the COVID-19 pandemic. In parallel to the development of vaccines and anti-viral medications, there has also been a growing body of work examining additional disease-modifying therapeutics. Vitamin D has been shown to affect immune cell function, and therefore, there is an interest in investigating whether vitamin D supplementation could play a role in SARS-CoV-2 infections and outcomes. This study sought to review the current evidence to determine if vitamin D supplementation had therapeutic and preventative effects on SARS-CoV-2 infection.
This meta-analysis included 25 randomized controlled trials (n=8,128 participants) published up to April 2023 that evaluated the role of vitamin D supplementation in preventing and treating SARS-CoV-2 infection. Studies were included if they compared the effect of vitamin D supplementation to a control in SARS-CoV-2 infection and reported appropriate outcomes. Studies were excluded if they were not randomized controlled trials or investigated patients with infections other than SARS-CoV-2. The study was conducted according to PRISMA guidelines, and the risk of bias was assessed using the Cochrane Collaboration’s Risk of Bias Tool. The primary outcomes were the rates of ICU admission, mechanical ventilation, and mortality.
The results demonstrated that vitamin D supplementation significantly reduced the rates of ICU admission and mechanical ventilation in patients with SARS-CoV-2 infection. Vitamin D supplementation did not significantly affect other clinical outcomes, including length of hospital stay, mortality, or prevention of SARS-CoV-2 infection. However, in those with vitamin D deficiency, supplementation was associated with decreased mortality. The study was limited by the heterogeneity of the dosing and frequency of vitamin D supplementation and the small number of studies examining the preventative effects of vitamin D. Nonetheless, the present study demonstrated that vitamin D supplementation has beneficial effects on some clinical outcomes in SARS-CoV-2.
1. In this randomized controlled trial, a walnut-enriched diet was associated with a greater diversity of actively expressed genes in the gut microbiome than the other study diets.
2. A walnut-enriched diet also led to greater expression of metabolism-related genes and increased expression of the gene glycine amidinotransferase (GATM) in the gut microbiota.
Evidence Rating Level: 1 (Excellent)
Cardiovascular disease (CVD) affects a large population worldwide. Dietary patterns and consequent changes to the gut microbiome have been suggested to play a role in the development of CVD. Higher nut intake has been shown to be associated with decreased CVD risks, but the effect of specific nut intake on the gut microbiome is poorly understood. The present study aimed to evaluate the effect of walnut intake on the gut microbiome and determine potential implications for CVD reduction.
This randomized, cross-over study included 35 adult participants (aged 30-65) who were recruited between October 2014 and September 2017. Participants were included if they
had overweight or obesity and had elevated blood pressure and/or elevated low-density lipoprotein (LDL) cholesterol. Participants who smoked, had a systolic blood pressure ≥160, or a history of myocardial infarction, stroke, diabetes, liver, kidney, thyroid, gastrointestinal, and inflammatory diseases were excluded. Participants were provided a 2-week standard western diet and were then randomized to a random sequence of walnut-enriched diet (WD), a fatty-acid matched diet devoid of walnuts (WFMD), and a diet where oleic acid replaces alpha-linolenic acid (ORAD) for two weeks each. The primary outcome measured was the microbiome species and gene expression in the fecal samples after each test diet period.
The results demonstrated that the diversity of actively expressed genes was greater following WD than the WFMD and ORAD diets. Specifically, greater expression of metabolism-related genes and the gene glycine amidinotransferase (GATM) by gut microbiota Gordonibacter was observed following WD versus the WFMD and ORAD diets. Lastly, several species from the Actinobacteria and Firmicutes phyla were differentially more abundant following the WD, WFMD, and ORAD compared to the standard western diet. This study was limited by the exploratory nature of the observation, which limited the ability to make interpretations about causality. Nonetheless, these results suggested possible mechanisms underpinning the potential benefit of walnut consumption in CVD risk reduction and should be further explored.
1. In this randomized controlled trial, in non-alcohol fatty liver disease (NAFLD) patients who were on a weight-loss diet, pomegranate peel extract supplementation lowered mean body weight, waist circumference, body mass index, body fat index, blood pressure, lipid measures, and fasting blood sugar compared to controls.
2. Furthermore, pomegranate peel extract supplementation resulted in improved high-density lipoprotein and fatty liver changes.
Evidence Rating Level: 1 (Excellent)
Non-alcoholic fatty liver disease (NAFLD) is a progressive spectrum of liver disease that can range from mild fatty changes of the liver to fibrosis, cirrhosis, and malignant changes. There are currently no specific targeted therapeutics for NAFLD. Therefore, most efforts are focused on targeting modifiable risk factors such as obesity, insulin resistance, dyslipidemia, hypertension, and cardiovascular disease. Pomegranate fruit has high levels of phytochemicals, demonstrating various clinical benefits in clinical trials on NAFLD and other diseases. However, the pomegranate peel has the highest amount of these beneficial phytochemicals. This study aimed to examine the effect of pomegranate peel extract (PP) supplementation on liver tissue changes and metabolic syndrome risk factors in patients with NAFLD.
This was a randomized control study of 76 adult patients in Iran with NAFLD. Participants were included if they were between the ages of 18 and 60 years and were diagnosed with liver fibrosis and steatosis through elastography or liver fibro scan. Patients who were pregnant, had morbid obesity, or a history of high alcohol consumption, autoimmune or immune disorders, cancer, or liver or kidney failure, were excluded. Participants were initiated on a 500-kcal deficit diet and randomized to receive either a placebo (37 patients) or 1500mg of PP supplement (39 patients) for eight weeks. Primary outcomes measured were lipid and glycemic profiles, blood pressure, body composition, insulin resistance indexes, and liver tissue changes.
The results demonstrated that patients randomized to receive PP extract supplementation had lower mean body weight, waist circumference, body mass index, body fat index, blood pressure, lipid measures, and fasting blood sugar than the controls. Patients who received PP extract supplementation also had improved high-density lipoprotein and fatty liver changes compared to the control group. However, there were no significant differences between the PP and control groups in fasting insulin or homeostatic model assessment for insulin resistance. The study was limited by incomplete adherence to the study diet in some participants, which may have confounded the results. Nonetheless, these results suggested PP supplementation as a potential novel strategy to improve metabolic syndrome risk factors in patients with NAFLD.
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