COVID-19 Nutrition: European Study Claims Eating Certain Vegetables Could Lower COVID-19 Mortality Risks.Cabbage, Cucumbers Good While Lettuce Bad
: A study by researchers in Europe claims that COVID-19 mortality rates may be lower in countries where individuals consume high amounts of cabbage and cucumber.
Increasing average daily consumption of the vegetables by 1 gram may cut mortality rate, according to research, which has not been peer-reviewed. The research findings are published on a preprint server. https://www.medrxiv.org/content/10.1101/2020.07.17.20155846v1
The research findings lend support to two other studies published earlier this year that were headed by the same lead researcher, Dr Jean Bousquet, from Charité, Universitätsmedizin Berlin. Dr Bousquet is the former chairman of the WHO Global Alliance against Chronic Respiratory Diseases,
The initial study reported that COVID-19 mortality rates seemed to be low in countries with high consumption of traditional fermented foods. At the same time, the second narrowed down the beneficial food type to fermented vegetables. https://www.thailandmedical.news/news/must-read-covid-19-nutrition-european-study-links-consumption-of-fermented-and-pickled-vegetables-to-low-study-covid-19-mortality
The researchers had proposed that this protective effect may be associated with the antioxidant activity of the foods acting on insulin resistance since many vegetables have been shown to have antioxidative effects against diabetes and cardiovascular disease.
In this new study, the team hypothesized that a high intake of antioxidant-rich Brassica vegetables such as broccoli, cauliflower, and head cabbage (white, red, and savoy cabbage) might be associated with the low COVID-19 mortality seen in some countries.
Dr Bousquet and colleagues say the “the negative ecological association between COVID-19 mortality and the consumption of cabbage and cucumber supports the a priori hypothesis previously reported.”
The study team recommends testing the hypothesis further by conducting individual studies in countries where a high vegetable intake is typical.
Interestingly since the COVID-19 outbreak began in Wuhan, China, late last year, one striking finding has been the highly variable death rate between and within countries, say Dr Bousquet and team.
While many factors may be involved, diet is one potentially relevant factor that has been largely overlooked, they add.
In the current study, the researchers proposed that “vegetables such as Brassica that possess an antioxidant activity reducing insulin resistance may also be associated with low COVID-19 mortality in countries.”
In order to investigate, the team used data extracted from the European Food Safety Authority (EFSA) Comprehensive European Food Consumption Database to compare the consumption of Brassica vegetables including broccoli, cauliflower, head cabbage (white, red and savoy cabbage) and leafy brassica with the consumption of spinach, cucumber, courgette, let
tuce, and tomato.
Relevant data on COVID-19 mortality were downloaded from the Johns Hopkins Coronavirus Resource Center, and the mortality per number of inhabitants was used to estimate death rates. Data downloaded from EuroStat were used to adjust for potential confounders by country, including gross domestic product, population density, the proportion of people older than 64 years, unemployment rate, and obesity prevalence.
The study team reports that of all the variables and confounders considered, only the consumption of head cabbage and cucumber had any significant impact on the COVID-19 mortality rate by country.
Significantly it was observed that for each gram per day increase in the amount of head cabbage consumed, the risk of dying from COVID-19 decreased by 13.6 %. For each gram per day increase in the amount of cucumber consumed, this death risk fell by 15.7%.
Numerous natural compounds derived from vegetables are potent activators of the transcription factors related to antioxidant effects such as Nrf2.
Dr Bousquet told Thailand Medical news, “Cruciferous vegetables such as Brassicaceae contain high amounts of sulforaphane, a potent activator of Nfr2.”
While cucumber does not belong to the Brassicaceae family, it is rich in a compound called Cucurbitacin B that exerts anti-inflammatory and hypoglycemic effects through the activation of Nrf2, says the team.
However lettuce could potentially have the opposite effect. Lettuce was another puzzle, and one the researchers had no explanation for yet. They found countries where more lettuce was eaten like Spain and Italy had considerably higher Covid-19 death rates than those where it was eaten less, such as Germany. The difference was not statistically significant for some countries, but the pattern was clear even after adjusting for factors such as GDP, population density, obesity prevalence and age distribution.
Dr Bousquet added, “These results and those of the recent study on fermented foods suggest a strong link between Nrf2 and the protection against severe forms of COVID-19.”
The researchers however caution: “Thus, although this study is only indicative of the role of diet in COVID-19, it is however, another piece of the hypothesis proposing that some vegetables with antioxidant properties may be involved in the prevention of severe COVID-19 at a country level.”
The study team also acknowledges that since the study was restricted to European counties, the findings cannot be extrapolated to other regions.
They said, “The hypothesis needs to be tested in individual studies performed in countries where the consumption of vegetables is common.”
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