Vitamin supplements could cut women’s risk of catching Covid-19, study claims

Vitamin supplements could reduce the risk of women getting Covid-19, a study has claimed.

King’s College London researchers used data from their Covid Symptom Study app and found taking the daily pills may reduce the virus risk by up to 14 per cent.

But the results were surprisingly specific – vitamin C and zinc, usually associated with the immune system, didn’t help and men didn’t get the same benefit as women.

Women taking vitamin D, multi-vitamins, omega-3 or probiotics appeared to be between nine and 14 per cent less likely to get Covid-19. 

This means that, if the average risk of getting Covid was one in 10, those taking supplements could see their risk fall to around one in 12.

But scientists were very unsure of the results and said the study did not prove that the pills actually protected women, but may have been a sign of generally healthier lifestyles. The expert who led the study said people shouldn’t start trying to protect themselves with vitamins. 

If women genuinely do get more protection, they suggested, it may be because they have generally tougher immune systems that respond better to supplements. 

It comes after the Department of Health last week announced the Government would send out free vitamin D supplements to people at high risk from Covid-19.

Overwhelming scientific evidence suggests the ‘sunshine vitamin’ may offer some protection against severe Covid-19, but some studies have claimed the proof isn’t strong enough.

Some types of vitamin supplements could protect women from developing Covid-19, according to a King’s College London study (stock image) 

The study was done on 372,720 users of the Covid Symptom Study app in the UK, who had reported what supplements they were taking at the start of the epidemic.

Around half of the group (175,652) said they regularly took supplements while the rest of the participants did not. 

Tracking the volunteers over the course of Britain’s crisis, the researchers found that fewer women in the supplement were testing positive than would have been expected.

They wrote in the study: ‘We observed a modest but significant association between use of probiotics, omega-3 fatty acid, multivitamin or vitamin D supplements and lower risk of testing positive for SARS-CoV-2 in women. 

‘No clear benefits for men were observed nor any effect of vitamin C, garlic or zinc for men or women.’

The study suggested that probiotics offered the biggest protection, with a 14 per cent lower risk of testing positive.

The percentage risk change does not mean that 14 per cent of women taking the supplement would test positive, but that if a group of them were compared to a group of similar women not taking the supplement, the number of positive tests would only be 86 per cent as high. 

Multi-vitamins, the researchers found, reduced the positive test rate by 13 per cent, while Omega-3 lowered it by 12 per cent. 


Nearly three million people in England will be offered free Vitamin D supplements this winter in an attempt to boost their immune systems.

The Government will deliver doses of the ‘sunshine vitamin’ to all care home residents as well as people classified as ‘clinically extremely vulnerable’.

Deliveries will be free of charge, starting in January, providing four months’ worth of supplements to last 2.7million people through the winter months.

The supplements support general health, in particular bone and muscle health, but around one in five Britons have Vitamin D deficiencies. 

There is some evidence suggesting that it may help people fight coronavirus, and the link between the two is still being researched with larger-scale trials needed.

The NHS recommends taking 10 micrograms of vitamin D – the amount found in one salmon fillet – each day to keep bones and muscles healthy in the winter. But health chiefs have this year advised Britons take the supplement all year because lockdowns are driving people indoors.

Health Secretary Matt Hancock said: ‘Because of the incredible sacrifices made by the British people to control the virus, many of us have spent more time indoors this year and could be deficient in Vitamin D. 

‘The Government is taking action to ensure vulnerable individuals can access a free supply to last them through the darker winter months.’

Vitamin D led to a nine per cent lower risk of testing positive for coronavirus. 

The researchers suggested that women taking vitamins may have stronger immune systems and therefore be less likely to get sick with Covid-19.

They said: ‘Biological explanations include the well documented discordant immune systems between sexes that could respond differently to supplements. 

‘Research indicates that females typically possess a more resilient immune system than males with higher numbers of circulating B cells when matched for age, BMI and clinical parameters, as well as a slower age related decline in circulating T- and B-cells.’ 

T cells and B cells are white blood cells that attack invading viruses and bacteria. 

The study was based on positive test results reported by app users, meaning most of the people testing positive would have done so because they got symptoms.

Women may have differences in their immune systems that meant supplements benefitted them more than they did men, the experts said, or they may simply have reported them more accurately.

They tried to rule out the fact that those taking supplements were likely to be healthier overall, but found that the positive effect was still there even when other aspects of their lives were taken out of the equation.

And if it was a simple link to a healthier lifestyle, the researchers said, they would have expected a benefit from vitamin C, zinc or garlic supplements as well.  

Professor Tim Spector, an epidemiologist who worked on the study, said: ‘Many people think that taking vitamins and other supplements can help maintain a healthy immune system, but spending your money on supplements in the hope of trying to avoid getting Covid-19 is largely unjustified. 

‘You’re better off focusing on getting a healthy diet with diverse fresh vegetables and fruits, which should give you all the nutrients you need for a healthy immune system.

‘Over the weekend, the government announced it would be providing 2.7 million vulnerable individuals in England to be offered free winter supply of Vitamin D. 

‘Based on our research, we cannot tell whether vitamin D supplements will have any real impact on these high risk groups.’ 

Professor Naveed Sattar, a metabolic medicine expert at the University of Glasgow, was not involved with the study but said: ‘These are interesting results but due to the way the study has been conducted, these data absolutely cannot tell us that taking such supplements “protects” against infection from Covid-19. 

‘It may be that by being more health conscious, some women are less likely to become infected, so that it’s the behaviours that explain these results not the supplements. 

‘The lack of any association in men also suggests the results may be confounded in ways not measured since there is no biological reason to think some supplements should work in women but not men. So, lets await the results of randomised trials.

‘In the meantime, as taking supplements can sometimes provide people with false reassurance, people should be advised that to lessen infection risk, continue to do the things proven to work, especially social distancing until the pandemic passes. 

‘Also, keeping active and watching ones weight has more evidence to suggest it may protect against more severe COVID-19, and other chronic diseases. Supplements have no such evidence.’

The King’s research has not yet been reviewed and published in a journal, but was posted online by the scientists who did it. 

One study found that 72 per cent of NHS workers in Birmingham who were lacking in the 'sunshine vitamin' (left column) tested positive for coronavirus antibodies in the blood — a sign of previous infection. This compared to just 51 per cent for those who had a healthy amount of the vitamin (right column)

One study found that 72 per cent of NHS workers in Birmingham who were lacking in the ‘sunshine vitamin’ (left column) tested positive for coronavirus antibodies in the blood — a sign of previous infection. This compared to just 51 per cent for those who had a healthy amount of the vitamin (right column)

What have studies into vitamin D and Covid-19 shown?

When? September.

By who? Cordoba University in Spain.

What did scientists study? 50 Covid-19 hospital patients with Covid-19 were given vitamin D. Their health outcomes were compared with 26 volunteers in a control group who were not given the tablets.

What did they find? Only one of the 50 patients needed intensive care and none died. Half of 26 virus sufferers who did not take vitamin D were later admitted to intensive care and two died.

What were the study’s limitations? Small pool of volunteers. Patients’ vitamin D levels were not checked before admission. Comorbidities were not taken into consideration.

When? September.

By Who? University of Chicago.

What did scientists study? 500 Americans’ vitamin D levels were tested. Researchers then compared volunteers’ levels with how many caught coronavirus.

What did they find? 60 per cent higher rates of Covid-19 among people with low levels of the ‘sunshine vitamin’.

What were the study’s limitations?  

Researchers did not check for other compounding factors. Unclear whether or not volunteers were vitamin D deficient at the time of their coronavirus tests. People’s age, job and where they lived – factors which greatly increase the chance of contracting the virus – were not considered.

When? September.

By Who? Tehran University, in Iran, and Boston University.

What did scientists study? Analysed data from 235 hospitalized patients with Covid-19.

What did they find? Patients who had sufficient vitamin D – of at least 30 ng/mL— were 51.5 per cent less likely to die from the disease. They also had a significantly lower risk of falling seriously ill or needing ventilation. Patients who had plenty of the nutrient also had less inflammation – often a deadly side effect of Covid-19. 

What were the study’s limitations? Confounding factors, such as smoking, and social economic status were not recorded for all patients and could have an impact on illness severity.  

When? July.

By Who? Tel Aviv University, Israel.

What did scientists study? 782 people who tested positive for coronavirus had their vitamin d levels prior to infection assessed retrospectively and compared to healthy people.

What did they find? People with vitamin D levels below 30 ng/ml – optimal – were 45 per cent more likely to test positive and 95 per cent more likely to be hospitalised.

What were the study’s limitations?  Did not look at underlying health conditions and did not check vitamin D levels at the time of infection.

When? June.

By Who? Brussels Free University.

What did scientists study? Compared vitamin D levels in almost 200 Covid-19 hospital patients with a control group of more than 2,000 healthy people.

What did they find? Men who were hospitalised with the infection were significantly more likely to have a vitamin D deficiency than healthy men of the same age. Deficiency rates were 67 per cent in the COVID-19 patient group, and 49 per cent in the control group. The same was not found for women.

What were the study’s limitations?  Independent scientists say blood vitamin D levels go down when people develop serious illness, which the study did not take into consideration. This suggests that it is the illness that is leading to lower blood vitamin D levels in this study, and not the other way around.

When? June.

By who? Inha University in Incheon, South Korea.

What did scientists study? 50 hospital patients with Covid-19 were checked for levels of all vital vitamins and compared to a control group.

What did they find? 76 per cent of them were deficient in vitamin D, and a severe vitamin D deficiency (<10 ng/dl) was found in 24 per cent of Covid-19 patients and just 7 per cent in the control group.

What were the study’s limitations?  

Small sample size and researchers never accounted for vitamin levels dropping when they fall ill.

When? June.

By Who?. Independent scientists in Indonesia.

What did scientists study? Checked vitamin D levels in 780 Covid-19 hospital patients.

What did they find? Almost 99% of patients who died had vitamin D deficiency. Of patients with vitamin D levels higher than 30 ng/ml  – considered optimal – only  per cent died.

What were the study’s limitations?  It was not peer-reviewed by fellow scientists, a process that often uncovers flaws in studies.

When? May.

By Who? University of Glasgow.

What did scientists study? Vitamin D levels in 449 people from the UK Biobank who had confirmed Covid-19 infection. 

What did they find? Vitamin D deficiency was associated with an increased risk in infection – but not after adjustment for con-founders such as ethnicity. It led to the team to conclude their ‘findings do not support a potential link between vitamin D concentrations and risk of Covid-19 infection.’

What were the study’s limitations?  Vitamin D levels were taken 10 to 14 years beforehand. 

When? May.

By Who? University of East Anglia.

What did scientists study? Average levels of vitamin D in populations of 20 European countries were compared with Covid-19 infection and death rates at the time.

What did they find? The mean level of vitamin D in each country was ‘strongly associated’ with higher levels of Covid-19 cases and deaths. The authors said at the time: ‘The most vulnerable group of population for Covid-19 is also the one that has the most deficit in vitamin D.’

What were the study’s limitations?  The number of cases in each country was affected by the number of tests performed, as well as the different measures taken by each country to prevent the spread of infection. And it only looked at correlation, not causation.

When? May.

By Who? Northwestern University.

What did scientists study? Crunched data from dozens of studies around the world that included vitamin D levels among Covid-19 patients. 

What did they find? Patients with a severe deficiency are twice as likely to experience major complications and die.

What were the study’s limitations?  Cases and deaths in each country was affected by the number of tests performed.