B vitamins are important mediators of immune function and a deficiency can increase susceptibility to infections. The severity of Covid-19 depends on the robustness of individual immune systems and it has therefore been hypothesized that an adequate intake of vitamin B could reduce the risk of the virus.
This theory is supported by a previous study which found B6 deficiency in 42.5% of Covid-19 patients and another which observed curative effects of cobalamin (B12).
“Nutrition and dietary components as modifiable factors can play a bilateral role in strengthening or weakening the immune system. Diet is also proposed as a factor potentially responsible for differences in COVID-19 death rates between and within countries,”say the authors of the current study, published in ‘The British Journal of Nutrition’.
“B vitamins are not synthesized in the human body. Thus, they should be consumed regularly in the diet. Many bodily functions, including energy production, methylation, synthesis, DNA repair, and enzyme functions, are dependent on the functions of B vitamins.”
To analyze the association between B vitamins and Covid-19, the researchers recruited 9,189 adults aged 20 to 69, 48.5% of whom were men. Dietary information was extracted from the TAMIZ study on changing consumer dietary habits and the incidence of chronic diseases and associated risk factors from the YAHS study.
The incidence of Covid-19 was determined by PCR tests and serological tests were used to estimate immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies in symptomatic or asymptomatic Covid subjects.
Food intake was assessed using a food frequency questionnaire (FFQ) covering one year and including all food groups. A questionnaire was also used to assess the level of daily physical activity.
Subjects were divided into four quartiles based on vitamin B intake, with the first comprising those with the lowest intake and used as a reference. Subjects in the second quartile reported low intake, third quartile moderate intake, and fourth quartile high intake.
Vitamin B activity
The authors note that dietary vitamin B5 intake demonstrated the highest protective association with Covid-19 and corresponded to a significant reduction in odds.
“The protective effect of vitamin B5 is partly explained by its involvement in the immune response as well as by its anti-inflammatory properties. Vitamin B5 stimulates macrophage maturation, increases macrophage phagocytosis, and promotes Th1 and Th17 cell differentiation,” they say.
Moderate vitamin B12 also reduced the risks of Covid-19, compared to the lowest quartile, but there was no significant relationship between vitamins B1, B2, B3, B9, B-complex and Covid- 19.
In the subgroup analysis by sex, the researchers noted that high vitamin B6 intake in women and moderate intake in men reduced the risk of infection after adjusting for confounding factors and relative to the lowest quartile. A high intake of B5 and B7 also reduced the odds for men.
Only subjects with a BMI of less than 25 and consuming high B7 and B12 had lower Covid-19 odds, in subgroup BMI analyses, although high B6 was effective for those with high B7 and B12. BMI was over 25.
The authors argue that altering the effects of BMI, gender and chronic disease status on the incidence of the virus offers further evidence that men with high BMIs are at greater risk of disease and mortality. and reinforce the benefits of vitamin B9 for vulnerable people with at least one chronic disease. .
Tests found low risks of virus with high vitamin B9 and B-complex content where subjects had at least one chronic disease, compared to lowest quartile, and moderate intake of B7 and B12 reduced risk in subjects without chronic disease.
The inverse association with moderate drinking in subjects without chronic disease”indicate that each micronutrient in its optimal amount may have protective effects, and not necessarily the higher the intake the lower the disease“, they comment.
This can also be explained by the influence of B vitamins on various biological functions, and in particular on the proper activation of innate and adaptive immune responses.
“Given the beneficial effects of B vitamins in reducing the risk of COVID-19 and the possibility of disruption of intestinal production of B vitamins, the dietary intake of these vitamins requires more attention,”they conclude.
Source: The British Journal of Nutrition
Published online: http://doi.org/10.1017/S0007114522003075
‘The association between B vitamins and the risk of Covid-19’
Authors: Mina Darand, Shirin Hassanizadeh, Fahime Martami, Shamim Shams-rad, Masoud Mirzaei, Mahdieh Hosseinzadeh