According to the European Union, Vitamins A, E, C and D aid the normal functioning of the immune system and the American Nutrition Association suggests these vitamins may also help fight off respiratory infections.
Nutrition plays a critical role in the prevention of a number of infectious diseases, while malnutrition is known to contribute to increased morbidity and mortality from such diseases. According to a new report, nutrition has never been more crucial:
“Globally, there has been an emerging trend of pandemics affecting the respiratory system, which has culminated most recently in the severe acute respiratory syndrome coronavirus 2019 outbreak. Current efforts to tackle the pandemic rely on managing associated symptoms and providing standard supportive nutritional care, with a substantial burden on the National Health Service.”
The research team, comprised of multiple institutions mostly based in London, noted that there is an urgent need to expand their understanding of how vitamin intake could influence the incidence and severity of respiratory complaints. “This understanding is critical to developing short-term and long-term public health nutrition recommendations to help tackle respiratory complaints and reduce burden on healthcare systems.”
To do so, the research team investigated whether these vitamins could be linked to the prevalence of respiratory complaints in a nationally representative sample of UK adults. The research team looked at the intake of vitamins A, E, C and D from both diet and supplements.
The study, published in the journal BMJ Nutrition Prevention & Health, used information provided by 6,115 adult participants from the 2008-2016 National Diet and Nutrition Survey Rolling Programme (NDNS RP) who had completed three or more days of diet diaries. The NDNS RP is a rolling survey that collects information annually on all food and drink consumed from about a thousand randomly selected people living in private households across the UK.
The researchers looked at dietary intake only (continuous exposure) and that from diet and supplements (binary exposure), accounting for potentially influential factors, such as age, sex, weight (BMI), smoking, household income and total energy intake.
Respiratory complaints reported by the participants had not been diagnosed by a clinician. Such complaints were defined as the self-reported presence of a number of conditions, such as weak chest, breathlessness, bronchial trouble, collapsed lung, lung damage by viral pneumonia, throat infection and others.
In total, 33 cases of respiratory complaints were reported. These respondents were generally older and less likely to say they regularly took vitamins A, E, C or D supplements.
The researchers note that it wasn't possible to determine any associations with vitamin C supplements, as none of the adults with respiratory complaints reported taking them.
A & E
Vitamin A and E intake from both diet and supplements was associated with a lower prevalence of respiratory complaints in UK adults.
Vitamin D intake from supplements, but not from diet, was associated with fewer respiratory complaints, prompting the researchers to suggest that the findings add to the current scientific debate on the value of vitamin D supplementation.
"It is estimated that around a fifth of the general population in the UK have low vitamin D, and over 30% of older adults aged 65 years and above do not achieve the recommended nutrient intake," noted the researchers.
"Our findings are consistent with the hypothesis that supplementation is critical to ensuring adequate vitamin D status is maintained and potentially indicate that intake of vitamin D from diet alone cannot help maintain adequate vitamin D status."
Overall, the researchers conclude, “Intake of vitamin A and E from diet and supplements, and vitamin D from supplements is associated with lower self-reported prevalence of respiratory complaints.”
There was no obvious association between BMI and vitamin intake, or between BMI and respiratory complaints.
Further research needed
The findings warrant further study among different ethnic groups and geographies in view of the current coronavirus pandemic, the researchers suggest.
“Our study also highlights the need for further data collection on nutrition and respiratory disorders to cover wider geographical areas and high-risk groups, including a focus on other ethnicities.”
Because this is an observational study, cause cannot be can't established. Additionally, the number of respiratory complaints was small, so no inferences can be made with respect to the pandemic, the researchers cautioned.
"Further research is required to assess the implications of the current study in the context of the current coronavirus disease 2019 pandemic using data from longitudinal cohorts," the research team suggested.
"While acknowledging the limitations of this data, it does add further to a growing body of interest and evidence for the role of vitamin D in respiratory health,” said Shane McAuliffe, Science Communications Lead for the NNEdPro Nutrition & COVID-19 Taskforce. “Given our knowledge of the extent of vitamin D deficiency in the population, balanced with the low cost and low risk of adverse events, it seems sensible to provide supplementation of this key vitamin, particularly to those most likely to be deficient."
Professor Sumantra Ray, Executive Director of the NNEdPro Global Centre for Nutrition & Health in Cambridge and Visiting Professor of Public Health at Imperial College London, said that data is a continuous reminder that micronutrient deficiencies exist. "Despite this, micronutrient deficiencies are often overlooked as a key contributor to the burden of malnutrition and poor health, presenting an additional layer of challenge during the COVID-19 pandemic."
The report noted that the next steps include longitudinal studies on vitamin intake and respiratory infections to disentangle the direction of causality.
Future studies on the relationship between vitamin intake and immunity to COVID-19, including diverse ethnic groups, are also planned.
Source: BMJ Nutrition Prevention & Health
bmjnph-2020-000150. doi: 10.1136/bmjnph-2020-000150
“Association between vitamin intake and respiratory complaints in adults from the UK National Diet and Nutrition Survey years"
Authors: S. Almoosawi et al.