Curcumin is one of the most frequently researched herbal substances; however, it has been reported to have a poor bioavailability and fast metabolism, which has led to doubts about its effectiveness. Curcumin has antioxidant and anti-inflammatory effects, and has demonstrated favorable health effects. Nevertheless, well-reported in vivo pharmacological activities of curcumin are limited by its poor solubility, bioavailability, and pharmacokinetic profile. The bidirectional interactions between curcumin and gut microbiota play key roles in understanding the ambiguity between the bioavailability and biological activity of curcumin, including its wider health impact.

In recent years, epidemiological studies have suggested that metabolic disorders are nutritionally dependent. A healthy diet that is rich in polyphenols may be beneficial in the treatment of metabolic diseases such as polycystic ovary syndrome, metabolic syndrome, non-alcoholic fatty liver disease, cardiovascular disease, and, in particular, atherosclerosis. Curcumin is a polyphenol found in turmeric and has been reported to have antioxidant, anti-inflammatory, hepatoprotective, anti-atherosclerotic, and antidiabetic properties, among others. This review summarizes the influence of supplementation with curcumin on metabolic parameters in selected metabolic disorders.

The microbiota is of interest for the development of a therapeutic strategy against SARS-CoV-2 coronavirus disease 2019 (COVID-19) due to its impact on the host immune system. Proven communications of the gut microbiota with the pulmonary microbiota (gut–lung axis) and the pathway of neural connections between the gut and brain (gut–brain axis) may be important in the face of the pandemic. SARS-CoV-2 was shown to affect almost all organs because of the presence of a host receptor known as angiotensin converting enzyme 2 (ACE2). The ACE2 receptor is mainly present in the brush border of intestinal enterocytes, ciliary cells, and type II alveolar epithelial cells in the lungs. The transport function of ACE2 has been linked to the ecology of gut microbes in the digestive tract, suggesting that COVID-19 may be related to the gut microbiota. The severity of COVID-19 may be associated with a number of comorbidities, such as hypertension, diabetes, obesity, and/or old age; therefore, attention is also paid to multiple morbidities and the modulation of microbiota through comorbidities and medications. This paper reviews the research in the context of the state of the intestinal microbiota and its impact on the cells of the immune system during the SARS-CoV-2 pandemic.

SARS-CoV-2 infection is associated with diverse clinical manifestations, immune dysfunction, and gut microbiota alterations. The nutritional and biochemical quality of one’s diet can influence the intestinal microbiota, which may play a role in the defense mechanisms against potential pathogens, by promoting a wide variety of immune–host interactions. In the COVID-19 pandemic, besides the development of pharmacological therapies, a healthy balanced diet, rich with food-derived antioxidants, may be a useful strategy. Many studies demonstrated that vitamins and probiotic therapies have positive effects on the treatment and prevention of oxidative stress and inflammation in COVID-19. The ecology of the gut microbiota in the digestive tract has been linked to the transport function of the host receptor known as angiotensin converting enzyme 2 (ACE2), suggesting that COVID-19 may be related to the gut microbiota. The angiotensin converting enzyme (ACE), and its receptor (ACE2), play central roles in modulating the renin–angiotensin system (RAS). In addition, ACE2 has functions that act independently of the RAS. ACE2 is the receptor for the SARS coronavirus, and ACE2 is essential for the expression of neutral amino acid transporters in the gut. In this context, ACE2 modulates innate immunity and influences the composition of the gut microbiota. Malnutrition is one of the leading underlying causes of morbidity and mortality worldwide and, including comorbidities, may be a major cause of worse outcomes and higher mortality among COVID-19 patients. This paper reviews the research on dietary components, with particular emphasis on vitamins, antioxidants, and probiotic therapies, and their impacts on the intestinal microbiota’s diversity during the SARS-CoV-2 pandemic.

Polycystic ovary syndrome (PCOS) contributes to endocrine and metabolic complications for women worldwide. The aim of this study was to establish the usefulness of new anthropometric indices and atherogenic indices in the evaluation of metabolic disorders, in particular, glucose and insulin abnormalities in the profiles of women with polycystic ovary syndrome (PCOS). In the study, a total of 49 women with PCOS aged between 18 and 39 years were recruited. All patients were tested for fasting glucose and insulin, lipid parameters, oral-glucose administration, and biochemical parameters. All of them underwent anthropometric measurements, such as BMI (body mass index), WHR (waist-to-hip ratio), WHtR (waist-to-height ratio), BAI (body adiposity index), VAI (visceral adiposity index), LAP (lipid accumulation product), BRI (body roundness index), ABSI (A body shape index), AIP (atherogenic risk of plasma), AC (atherogenic coefficient), Castelli risk index-I, Castelli risk index-II and (LCI) lipoprotein combine index, TG/HDL-C ratio, METS-IR (The metabolic score of insulin resistance), triglyceride glucose index (TyG index), triglyceride glucose-body mass index (TyG-BMI index) and triglyceride glucose-waist circumference index (TyG-WC index) were calculated. The analyzed anthropometric measurements/indices and atherogenic indices demonstrated significant correlations in PCOS women. T A strong relationship was found between fasting glucose, fasting insulin, glucose after 60 min, HOMA-IR index in the patients with PCOS. There was no significant relationship between HbA1c and other analyzed parameters and indices. Most of the analyzed anthropometric and atherogenic indices may be useful tools in evaluating metabolic disorders, and, in particular, glucose and insulin abnormalities in PCOS women.