A new study has linked high intake vitamins A, D and E with fewer respiratory infections. The researchers are now calling for more studies to look at the nutrients’ impact on Covid-19.
According to a study published in the journal BMJ Nutrition Prevention & Health, adults who regularly took these vitamins either through food or as supplements were less likely to report respiratory complaints. The researchers suggested that since, the data represented a national analysis of a long term survey data and, as a result, there is need for further study among different ethnic groups and geographies given the current coronavirus pandemic.
The research team relied on information provided by 6115 adult participants from the 2008-2016 National Diet and Nutrition Survey Rolling Program (NDNS RP). They had completed three or more days of diet diaries. The NDNS RP is a rolling survey that collects information annually on all food and drinks consumed from around 1000 randomly selected people living in private households across the UK. The team wanted to know whether consuming these vitamins both from diet and supplements could be linked to the prevalence of respiratory complaints in a nationally representative sample of UK adults.
Potentially Influential Factors
The participants reported respiratory complaints that had not been diagnosed by a clinician. The complaints were broadly defined and included both infectious and non-infectious conditions, such as colds, chronic obstructive pulmonary disease, and asthma. 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. The results showed there were 33 cases of respiratory complaints. These respondents were generally older and less likely to say they regularly took vitamins A, E, C or D supplements. The report says:
“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 […] 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.”
Enough Vitamin D from Sunlight
Vitamin D deficiency is more common in older people, overweight people, and in black and Asian people – all groups at increased risk of becoming seriously ill with coronavirus. The researchers in the latest study, including from Imperial College London, said their work supported the hypothesis that supplementation is “critical” for some, and that diet alone is often not enough.
Vitamin A can be found in food such as whole milk, cheese, carrots and dark leafy vegetables while Vitamin E is found in nuts, seeds and vegetable oils. Meanwhile, vitamin D intake from supplements was also associated with fewer respiratory complaints, the study found.
Most people’s bodies make enough of the vitamin from sunlight, but in the winter, doctors’ advice some people to take supplements. Vitamin D can also be found in some foods such as salmon, mackerel, herring and sardines, red meat and eggs. The researchers now recommend further work “to assess the implications of the current study in the context of the current Covid-19 pandemic. Lead researcher Professor Adrian Martineau said:
“There is mounting evidence that vitamin D might reduce the risk of respiratory infections, with some recent studies suggesting that people with lower vitamin D levels may be more susceptible to coronavirus.”