(The Times of Israel) Good levels of vitamin D, the so-called sunshine vitamin, help people to fight the coronavirus more quickly and effectively and reduce chances of hospitalization, Israeli researchers have concluded.

However, others are cautioning broad conclusions, saying other factors may be involved.

Milana Frenkel-Morgenstern of Bar Ilan University told The Times of Israel on Sunday that vitamin D is “like a steroid,” after publishing what she says is the world’s largest population-based study of its kind.

She embarked on the joint study with Leumit Health Services to probe whether there is a basis to suggestions — heard throughout the pandemic — that vitamin D may prove helpful.

Her team studied a 7,807-strong sample of Israelis who were tested for the coronavirus. It found that the average vitamin D level for people who screened negative was in the internationally-accepted “adequate” range, while the average for those who tested positive fell in the “inadequate” category.

Vitamin D levels of less than 20 nanograms per milliliter of blood are considered inadequate.

Frenkel-Morgenstern said that people in her sample who tested negative were, on average, within the adequate range, showing a mean vitamin D count of 21 nanograms per milliliter. Those who tested positive were, on average, under the adequate level, with a mean vitamin D count of 19 nanograms per milliliter.

People who went on to be hospitalized after their test had a lower mean vitamin D count: 17 nanograms per milliliter.

The study, newly peer-reviewed and published in The FEBS Journal, compared people who got a negative result to those who ended up both testing positive and being hospitalized, and reported a stark difference in vitamin D levels.

Frenkel-Morgenstern said the people she studied aged 50 and over were twice as likely to find themselves hospitalized with COVID-19 if they had low vitamin D levels compared to people of a similar age with good vitamin D levels.

People aged 25 to 49 with low vitamin D levels were 1.45 times more likely to be hospitalized with COVID-19 than others their age, she said.

Vitamin D levels below the recommended level — classed as deficiency or, less seriously, insufficiency — are very common, and it is estimated that a billion people worldwide have vitamin D deficiency and 50 percent of the population has an insufficiency. Frenkel-Morgenstern said that her research suggests that some 70 percent of Israelis have low vitamin D levels.

Frenkel-Morgenstern, head of Bar Ilan University’s Lab for the BioComputing of Complex Diseases, does not think that vitamin D stops people from catching coronavirus, but she believes that it boosts the body’s ability to fight it once infected. She said that her results reflect vitamin D helping some people to experience the virus relatively lightly and stay out of hospital, and others ridding themselves of the virus before they get tested.

Frenkel-Morgenstern said it is urgent, mid-pandemic, that people boost their vitamin D levels, as the prevalence of low levels is widespread.

She claimed her findings should guide public policy. She said that, ironically, coronavirus lockdowns and a culture of people avoiding unnecessary outings, has actually contributed to low vitamin D levels that are putting people at risk.

Normally, most vitamin D is absorbed through the skin, from sunlight. “The problem now is people stay indoors or in cars all day, not going to beaches, do not have the sun exposure,” she said, adding that she believed the best action people can take is ensuring they are spending time outside.

She argued that authorities must factor vitamin D needs into future restrictions, and avoid closing public outdoor spaces, like nature reserves and beaches, as happened during the March-April lockdown. “This is why it’s so important to not close the beaches in any future lockdown,” she said. “People should go to the sun, to the sea.”

There are growing suggestions internationally that good vitamin D levels — long thought to have a range of health benefits — help people to deal with the coronavirus. A recent German study concluded that “much more attention should be paid to the importance of vitamin D status for the development and course of the disease.”

The Israeli study’s research sample consisted of 782 COVID-19 positive patients and 7,025 COVID-19 negative patients, who are members of Leumit Health Services, an Israeli HMO.

Leumit was involved in the research process, and its head of managed care, Eugene Merzon, said that it stands up to scrutiny “even after adjustment for age, gender, socio-economic status and chronic, mental and physical disorders.”

But Ella Sklan, head of a molecular virology lab at Tel Aviv University, who is unconnected to the study, told The Times of Israel that she thinks people should keep results of vitamin D research in perspective.

She said that the vitamin is good for the immune system, and that she urges her mother to take it, but thinks that studies that herald its benefits for the coronavirus may be reflecting other variables. Sklan gave the example of physical activity, saying that a person with high vitamin D levels may well exercise more, and the exercise could be impacting health.

“People want to find something magic that will change everyone’s life now, but I wouldn’t rely on this thinking,” Sklan said.

Besides taking Vitamin D as a supplement and getting more sunlight, here are a few other Vitamin D supplements to consider.