Mediterranean Diet a Potential Strategy against SARS-CoV-2 Infection: A Narrative Review

Relevance of Mediterranean diet as a nutritional strategy in diminishing COVID-19 risk: A systematic review

BACKGROUND

Mediterranean Diet has been reported to possess immunomodulatory and anti-inflammatory properties. These properties are closely associated with the immunopathogenesis of COVID-19.

OBJECTIVE

The present systematic review aimed to determine the association between Mediterranean Diet and COVID-19, COVID-19 symptoms, and COVID-19 severity.

METHODS

The protocol for this systematic review was registered in International Prospective Register of Systematic Reviews (PROSPERO) with identification number CRD42023451794. The literature search was conducted through Pubmed, Proquest, and Google Scholar on August 2023. The inclusion criteria were studies with a population of human subjects, reported the association between Mediterranean diet adherence with risk of COVID-19 infection, COVID-19 symptoms, or COVID-19 severity, and full text must be available in English. The exclusion criteria were reviews, editorials, letters, replies, systematic reviews, meta-analyses, studies on animals, and duplicates. Risk of bias in included studies was assessed using Newcastle Ottawa Scale (NOS). Data was synthesized narratively. Each study was compared and a structured summary was developed.

RESULTS

After selection process, 6 articles were included, with a sample size of 55,489 patients. All studies were observational studies and assessed Mediterranean diet adherence using food frequency questionnaires (FFQ), with scoring system varied between each study. Four studies found a significant correlation between increased adherence to Mediterranean Diet and reduced COVID-19 risk, while one study indicated non-significant association. One study reported a significant association between higher adherence to Mediterranean Diet and COVID-19 symptoms, but three studies reported non-significant association. One study found that individuals with higher adherence to Mediterranean Diet had reduced likelihood of developing severe COVID-19, however, two studies yielded inconclusive findings.

LIMITATIONS

All studies used self-administrated food frequency questionnaires (FFQs), which were prone to biased responses, such as recall and estimation bias.

DISCUSSION

Lower trends of odds ratios (ORs) were consistently observed in higher Mediterranean diet adherence. In every outcome of the included studies, ORs ranged between 0.06-0.992, however, differing levels of significance were reported in each outcome.

CONCLUSION

Overall analyses suggest that high adherence to Mediterranean Diet is a protective factor against COVID-19, with unclear benefits against COVID-19 symptoms and severity.

Mediterranean Diet Influence on SARS-CoV-2 Vaccine Adverse Reaction: Friend or Foe?

BACKGROUND

The Mediterranean Diet (MedDiet) has long been recognized for its health-promoting attributes, with proven benefits in preventing cardiovascular and metabolic diseases. During the global COVID-19 pandemic, MedDiet's potential to mitigate the impact of SARS-CoV-2 infection gained attention. This study aims to investigate the interplay among MedDiet adherence, immune system response to SARS-CoV-2 vaccines, and potential sex-related variations.

METHODS

A retrospective observational study was conducted through collecting data from a web survey for the Italian population. Adherence to the MedDiet was assessed using the Mediterranean Diet Adherence Screener (MEDAS); in addition, COVID-19 symptoms and vaccination details were also obtained.

RESULTS

Significant associations between MedDiet adherence, COVID-19 symptoms, and vaccine-related side effects were observed. Notably, females demonstrated distinct responses, reporting lymph node enlargement and a different prevalence and severity of vaccine side effects compared to males.

CONCLUSIONS

This study highlights the protective role of the MedDiet against COVID-19 and emphasizes the relevance of sex-specific responses in vaccination outcomes according to MEDAS score.

The impact of the Mediterranean diet on immune function in older adults

Diet is one of the lifestyle factors that is most amenable to intervention, and has a substantial effect on the potential for successful aging and mitigation of the risk of disease. Good nutrition is a pillar of healthy aging, and a large body of evidence attests to the benefits of the Mediterranean diet on the quality of the aging process. The Mediterranean diet comprises a wide range of nutrients which, both individually and collectively, exert positive effects on immunity, in large part mediated by the gut microbiota. In this article, we review the effect of the Mediterranean diet on immunity, and how its beneficial effects are mediated by the gut microbiota. We review the effects of certain key components of the Mediterranean dietary pattern, including vitamins, zinc, selenium, and polyphenols. Overall, the existing body of evidence convincingly demonstrates that the Mediterreanean diet affects immune health by maintaining a healthy body weight and reducing the risk of metabolic and cardiovascular diseases; by reducing inflammation and by promoting a healthy gut microbiota profile.

Clinical Evidence on the Potential Beneficial Effects of Diet and Dietary Supplements against COVID-19 Infection Risk and Symptoms' Severity

BACKGROUND

Diet and dietary supplements aim to add trace elements, vitamins, and minerals to the body to improve human health and boost the immune system. In the previous few years, the new SARS-CoV-2 coronavirus strain has been threatening the health of individuals and public health more broadly, with rates of intensive care unit cases on the rise, while long-term COVID-19 complications are persisting until today. In the peculiar circumstances of the COVID-19 pandemic, in combination with disease prevention techniques, the strengthening of the immune system is considered particularly important to enable it to effectively respond to and eliminate the SARS-CoV-2 viral pathogen in the event of infection. The purpose of the current literature review is to thoroughly summarize and critically analyze the current clinical data concerning the potential beneficial effects of diet and dietary supplements against COVID-19 infection risk and symptoms' severity. The micronutrients/supplements examined in this study in relation to COVID-19 infection are vitamins A, B, C, and D, zinc, selenium, magnesium, iron, omega-3 fatty acids, glutamine, resveratrol, beta-glucans, and probiotics. The potential effects of dietary patterns such as the Mediterranean diet against SARS-CoV-2 infection risk and symptoms' severity were also analyzed. Our literature review suggests that micro- and macronutrient supplementation and a healthy diet and lifestyle may provide support to immune system function, with beneficial effects both before and during SARS-CoV-2 infection. However, additional studies are recommended to draw safe conclusions and formulate dietary recommendations concerning dietary supplements and their possible effects on preventing and co-treating COVID-19 disease.

Association of Mediterranean Diet Adherence with Sociodemographic, Anthropometric, and Lifestyle Factors during the COVID-19 Pandemic: A Cross-Sectional Study in Greece

BACKGROUND

The COVID-19 pandemic has negatively affected several aspects of people's lifestyle worldwide. Healthy dietary patterns and their bioactive components may improve or even co-treat the negative impacts of the COVID-19 pandemic in several aspects of people's lifestyle and mental health in daily life. The aim of this survey is to evaluate the potential effect of Mediterranean diet (MD) adherence against COVID-19-induced complications.

METHODS

This is a cross-sectional survey performed on 3721 adults aged between 18 and 65 years old, which aims to evaluate the potential association of MD adherence with multiple sociodemographic, anthropometric, and lifestyle factors during the COVID-19 pandemic period.

RESULTS

This study has supported evidence that elevated MD compliance was independently related to female gender, better economic status, no smoking, increased risk of abdominal obesity, higher physical activity levels, greater prevalence of adequate sleep quality, better quality of life, and reduced probability of anxiety and depression during the COVID-19 pandemic by adjusting for multiple confounders.

CONCLUSIONS

MD compliance may improve or even co-treat the negative impacts of the COVID-19 pandemic in several aspect of people's lifestyle in daily life. Further research is strongly recommended exploring the possible beneficial effects of the MD against COVID-19 lifestyle complications in daily life.

The impact of endometriosis on dietary choices and activities of everyday life: a cross-sectional study

Introduction

Endometriosis is characterized by ectopic endometrial tissue and severe pain; frequently, women afflicted by this condition resort to non-medical interventions, such as dietary modifications. The aim of this study is to assess the impact of endometriosis on dietary patterns and quality of life.

Methods

An online survey was conducted among Italian women with endometriosis to gather self-reported demographic, clinical, dietary habit, and daily life data post-diagnosis.

Results

A total of 4,078 participants were included. Following an endometriosis diagnosis, 66% reported changes in eating habits, and 92% experienced a decline in daily life. Respondents chose dietary interventions: gluten-free (15%), anti-inflammatory (8%), Mediterranean (7.1%), or ketogenic (4%) diets, to improve health and reduce symptoms. The study revealed a shift in eating habits, with increased consumption of vegetables, fruits (10%), cereals, legumes (6.6%), and fish (4.5%), while reducing dairy products (18.4%), soy-containing foods (6.7%), and high saturated fats (8%). Eating habit changes correlated with endometriosis stages and worsened daily life. Educational level, endometriosis stages, years of symptoms, and eating habit changes linked to changes in daily life.

Conclusion

Our findings emphasize the importance of monitoring eating behaviors to prevent unhealthy habits and malnutrition in women with endometriosis. Further studies are needed to evaluate how different diets impact symptoms and enhance daily life for these individuals.

Effectiveness of Nutritional Supplements for Attenuating the Side Effects of SARS-CoV-2 Vaccines

Supplementation is known to enhance the immune response and reduce infection. Therefore, the association between immune nutrients and vaccine side effects needs to be investigated. Our aim was to analyze the relationship between vaccination side effects and supplement intake among the Italian population. The study included a questionnaire asking for personal data, anthropometric information, COVID-19 infection and immunity response, and COVID-19 vaccination and supplementation. The survey was conducted from 8 February to 15 June 2022. In the study, 776 respondents were included, aged between 18 and 86 (71.3% females). We observed a statistically significant correlation between supplement consumption and side effects at the end of the vaccination cycle (p = 0.000), which was also confirmed by logistic regression (p = 0.02). Significant associations were observed between supplement intake and side effects of diarrhea and nausea at the end of the vaccination cycle (p = 0.001; p = 0.04, respectively). Significant associations were observed between side effects and omega-3 and mineral supplementation at the start of the vaccination cycle (p = 0.02; p = 0.001, respectively), and between side effects and vitamin supplementation at the end of the vaccination cycle (p = 0.005). In conclusion, our study shows a positive impact of supplementation on vaccination response, increasing host immune defenses, and reducing side effects.

Supplementation use and diet changes during COVID-19 pandemic according to anxiety level and Mediterranean diet adherence

Aim; This study was planned and conducted to examine the change in food consumption and nutritional supplement use during the COVID-19 pandemic according to individuals' status of anxiety and Mediterranean diet adherence. Methods; This prospective, cross-sectional research was completed online with the participation of 949 people (66.4% women). The Mediterranean Diet Adherence Screener Scale (MEDAS) and Coronavirus Anxiety Scale (CAS) were applied. After this section of the questionnaire was completed, the participants were tasked with answering questions regarding changes in food consumption and use of nutritional supplements during the pandemic. Results; While 50.8% of the participants had low adherence to the Mediterranean diet, 18.2% were considered to have a high adherence. It was observed that legume (p = 0.001), milk and dairy (p = 0.01), and fruit (p < 0.001) consumption of participants with high adherence to the Mediterranean diet increased during the pandemic, and packaged food (p < 0.001) consumption decreased. The increase in the consumption of fruit (p < 0.001) and vegetables (p = 0.018) were significantly higher in the group with anxiety. Age, sex, educational status, positive COVID-19 test, place of residence, CAS score and MEDAS score affect the use of dietary supplements according to binary logistic regression (R² = 0.106 p < 0.001). The three most commonly used supplements were identified as vitamins C, D and B₁₂. Conclusions: These results can shed light on how to prepare for possible future pandemics when it comes to dealing with anxiety through diet.

Nutritional and physical activity issues in frailty syndrome during the COVID-19 pandemic

'Frailty' has been described as 'a state of increased vulnerability of the individual caused by an impairment of homeostasis as a result of endogenous or exogenous stress'. Frail individuals are depicted by a dramatic change in health status following an apparently minor insult and a higher risk of adverse health-related outcomes such as osteoporosis and sarcopenia, falls and disability, and fragility fractures. Frailty is a condition of increasing importance due to the global ageing of the population during the last decades. Central to the pathophysiology of frailty is a mechanism that is partially independent of ageing, but most likely evolves with ageing: the cumulative level of molecular and cellular damage in every subject. Furthermore, an uncorrected nutrition and a sedentary behaviour play a pivotal role in worsening the syndrome. In January 2020, a cluster of a genus of the family Coronaviridae was isolated as the pathogen of the new coronavirus disease (COVID-19). Since then, this infection has spread worldwide causing one of the most dramatic pandemics of the modern era, with more than 500 million confirmed cases all over the world. The clinical spectrum of SARS-CoV-2 severity ranges from asymptomatic conditions to mild symptoms, such as fever, cough, ageusia, anosmia and asthenia, up to most severe conditions, such as acute respiratory distress syndrome (ARDS) and multi-organ failure leading to death. Primary evidence revealed that the elderly frail subjects were more susceptible to the disease in its most intense form and were at greater risk of developing severe COVID-19. Factors contributing to the severity of COVID-19, and the higher mortality rate, are a poor immune system activity and long-standing inflammatory status of the frail subjects compared with the general population. Further recent research also suggested a potential role of sedentary behaviour, metabolic chronic disorders linked to it and uncorrected nutritional status. Thus, the aim of this review was to evaluate the different studies and evidence related to COVID-19 pandemic, both nutritional status and physical activity, and, also, to provide further information on the correct nutritional approach in this peculiar pathological condition.

Association of fruits, vegetables, and fiber intake with COVID-19 severity and symptoms in hospitalized patients: A cross-sectional study

BACKGROUND AND AIMS

Fruits and vegetables are rich in fiber and a good source of anti-inflammatory and immune-boosting vitamins, minerals, and antioxidants. We investigated the association between fruits, vegetables, and fiber intake and severity of COVID-19 and related symptoms in hospitalized patients.

METHODS

A total of 250 COVID-19 hospitalized patients aged 18 to 65 years were recruited for this cross-sectional study in Kashan, Iran, between June and September of 2021. Dietary intakes were assessed using an online validated 168-item food frequency questionnaire (FFQ). COVID-19 severity and symptoms were evaluated using the National Institutes of Health (NIH) COVID-19 Treatment Guidelines. Moreover, we examined COVID-19 symptoms, inflammatory biomarkers, and additional factors.

RESULTS

The mean age of participants was 44.2 ± 12.1 years, and 46% had severe COVID-19. Patients with higher consumption of fruits (OR: 0.28; 95% CI: 0.14-0.58, P-trend <0.001), vegetables (OR: 0.33; 95% CI: 0.16-0.69, P-trend <0.001), and dietary fiber (OR: 0.25; 95% CI: 0.12-0.53, P-trend <0.001) had lower odds of having severe COVID-19. In addition, they had shorter hospitalization and convalescence periods, lower serum C-reactive protein (CRP), and a reduced risk of developing COVID-19 symptoms such as sore throat, nausea and vomiting, dyspnea, myalgia, cough, weakness, fever, and chills.

CONCLUSION

Higher consumption of fruits, vegetables, and fiber was inversely linked with COVID-19 severity, clinical symptoms, hospitalization and convalescence duration, and CRP concentrations. The results should be interpreted with caution in light of the limitations, and prospective cohort studies are required to further evaluate these findings.

Factors Modulating COVID-19: A Mechanistic Understanding Based on the Adverse Outcome Pathway Framework

Addressing factors modulating COVID-19 is crucial since abundant clinical evidence shows that outcomes are markedly heterogeneous between patients. This requires identifying the factors and understanding how they mechanistically influence COVID-19. Here, we describe how eleven selected factors (age, sex, genetic factors, lipid disorders, heart failure, gut dysbiosis, diet, vitamin D deficiency, air pollution and exposure to chemicals) influence COVID-19 by applying the Adverse Outcome Pathway (AOP), which is well-established in regulatory toxicology. This framework aims to model the sequence of events leading to an adverse health outcome. Several linear AOPs depicting pathways from the binding of the virus to ACE2 up to clinical outcomes observed in COVID-19 have been developed and integrated into a network offering a unique overview of the mechanisms underlying the disease. As SARS-CoV-2 infectibility and ACE2 activity are the major starting points and inflammatory response is central in the development of COVID-19, we evaluated how those eleven intrinsic and extrinsic factors modulate those processes impacting clinical outcomes. Applying this AOP-aligned approach enables the identification of current knowledge gaps orientating for further research and allows to propose biomarkers to identify of high-risk patients. This approach also facilitates expertise synergy from different disciplines to address public health issues.

Higher Adherence to the Mediterranean Dietary Pattern Is Inversely Associated With Severity of COVID-19 and Related Symptoms: A Cross-Sectional Study

Background and Aims

Adherence to the Mediterranean diet (MD) has been associated with a decreased risk of developing a variety of chronic diseases that are comorbidities in COVID-19 patients. However, its association to the severity and symptoms of COVID-19 are still unknown. This study aimed to examine the association between adherence to the MD pattern and COVID-19 severity and symptoms in Iranian hospitalized patients.

Methods

In this cross-sectional study, 250 COVID-19 patients aged 18 to 65 were examined. We employed a food frequency questionnaire (FFQ) to obtain data on dietary intake of participants in the year prior to their COVID-19 diagnosis. COVID-19 severity was determined using the National Institutes of Health's Coronavirus Disease 2019 report. Additionally, symptoms associated with COVID-19, inflammatory markers, and other variables were evaluated. The scoring method proposed by Trichopoulou et al. was used to assess adherence to the MD.

Results

The participants' mean age was 44.1 ± 12.1 years, and 46% of them had severe COVID-19. Patients who adhered more closely to the MD had lower serum C-reactive protein levels (7.80 vs. 37.36 mg/l) and erythrocyte sedimentation rate (14.08 vs. 42.65 mm/h). Those with the highest MD score were 77% less likely to have severe COVID-19 after controlling for confounding variables. The MD score was also found to be inversely associated with COVID-19 symptoms, including dyspnea, cough, fever, chills, weakness, myalgia, nausea and vomiting, and sore throat.

Conclusion

Higher adherence to the MD was associated with a decreased likelihood of COVID-19 severity and symptoms, as well as a shorter duration of hospitalization and convalescence, and inflammatory biomarkers.