It’s called vitamin D, but it really isn’t a vitamin at all. Today, researchers see it as more of a hormone than a nutrient. A major source of this so-called vitamin is unique: Unlike other vitamins, we get far more vitamin D from sun exposure than from food. This compound is made in your skin, activated by your liver and kidneys, and fueled by the sun’s ultraviolet (UV) rays.
When scientists first discovered vitamin D, they saw it as a cure for a disfiguring childhood bone disease called rickets. The connection earned vitamin D a reputation for bone health, but researchers have since found many more health benefits linked to the sunshine vitamin, such as improved immune function and metabolism, as well as acting as an anti-inflammatory agent.
The most recent connection to vitamin D’s virtues may be as a treatment for COVID-19. Several observational studies conducted over the past year have revealed a striking correlation between vitamin D deficiency and COVID-19 severity. As a result, some doctors who treat COVID-19 patients often include it in their protocol.
To anyone familiar with vitamin D, the news comes as little surprise. Low vitamin D levels have previously been associated with increases in inflammatory cytokines, viral upper respiratory tract infections, and blood clots—some of COVID-19’s key characteristics.
Even Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases—who’s known more for his promotion of masks and vaccines than supplements—made one positive public nod toward vitamin D. In an Instagram Live interview with Jennifer Garner in September 2020, Fauci highlighted the need for this vitamin, particularly during a pandemic.
“If you’re deficient in vitamin D, that does have an impact on your susceptibility to infection,” Fauci said. “I would not mind recommending—and I do it myself—taking vitamin D supplements.”
Still, health officials have been very cautious regarding any claims suggesting that vitamin D can treat COVID-19. Dr. Joseph Mercola is blamed for pushing claims too far. He’s the lead author of a meta-analysis of studies correlating vitamin D levels and COVID-19 cases, and the mechanisms that may drive the protective process. The study was published in an October 2020 edition of the journal Nutrients, but Mercola was recently forced to remove the study from his website.
The issue is said to be Mercola’s peddling of an unproven remedy to treat a deadly disease. In February, the FDA sent a letter to Mercola, accusing him of selling supplements—particularly vitamin D—that are “unapproved and unauthorized products for the mitigation, prevention, treatment, diagnosis, or cure of COVID-19.”
But Mercola insists that marketing isn’t his mission. He’s more interested in getting people outside.
“I encourage people not to even take the supplements, just to go out in a bathing suit. I haven’t taken vitamin D in 12 or 13 years and have great vitamin D levels. It’s free if you go out in the sun. But most people can’t do that, so they have to resort to taking the supplement. It’s not my first recommendation, but you’ve got to give them options,” he said.
In a pandemic characterized by lockdowns, Zoom meetings, and strict stay-at-home orders, there was often less opportunity for people to soak up any share of the sunshine vitamin. And even before COVID-19, it was clear that many people already didn’t get enough of it. Fortified milk and fatty fish provide some dietary sources, but some experts say the underlying problem is that we spend our days stuck inside.
How much vitamin D we need is a matter of debate, but it’s clear that levels are often lower than they should be. Some experts contend that our body’s need for the vitamin far exceeds official recommendations, and nearly half of the planet already falls short of those suggested levels.
A 2012 study found that vitamin D insufficiency affects almost 50 percent of the population worldwide, and an estimated 1 billion people suffer from a full-blown deficiency of the vitamin. Researchers say this “pandemic of hypovitaminosis D” is mainly attributed to lifestyle. Unlike our ancestors, we spend almost all of our time indoors. And when we do go out, environmental pollution dilutes our exposure to the amount of sunlight that was once available.
A life spent primarily indoors may hardly seem like a health hazard, but researchers say that low vitamin D levels pose a legitimate public health concern, because deficiency in this compound is “an independent risk factor for total mortality in the general population.”
Nature’s Role in Medicine
Vitamins were first discovered in the early 20th century. But long before doctors ever fathomed such a thing as vitamin D, there was an understanding that fresh air and sunshine had a positive, life-giving effect on the body. For doctors of both the ancient and not-so-distant past, spending time outdoors was considered to be right up there with the other obvious tenants of good health: a balanced diet, exercise, and getting enough rest.
But doctors today have become far less likely to prescribe the great outdoors. In fact, many physicians now warn patients to avoid sun exposure to prevent skin cancer. More recently, health officials have urged the public to stay at home to avoid the spread of COVID-19.
Such advice is made with good intentions, but does it also leave us more vulnerable? For example, in 2017, researchers at Georgetown University discovered that time in the sun can rev up the immune system by activating infection-fighting T-cells. People who lack vitamin D also get sick more often. They also tend to have more back pain, depression, and fatigue.
Of course, it’s unfair to lay the blame exclusively on the medical establishment. Over the past few decades, we’ve become a culture far more interested in inhabiting cyberspace than taking a walk in the woods. Most of us make a living in climate-controlled environments, not in fields or on farms.
But even before modern technology took hold, modern medicine began distancing itself from nature. According to Cassi Vieten, a psychologist and mind-body medicine researcher with a doctorate degree in clinical psychology, science began distancing itself from the influences of the natural world as far back as 400 years ago, when it made a decisive split from the church.
“The medical system became very mechanistic. They looked at the body like a clock or a car. When something breaks, you look under the hood and have to fix it. It has nothing to do with the environment or how the person thinks or feels, believes, or imagines. And we just know that’s not true,” Vieten said.
The modern medical model has certainly made some incredible strides in treating devastating diseases, but Vieten pointed out that a solely mechanical focus can also be detrimental to people. She noted that even at top-rated mental health institutions, patients aren’t allowed to go outside, much less go into nature.
“That’s completely insane. They believe this very mechanistic brain model, where they decide that something is wrong in the brain that they’re going to fix with pills, transcranial stimulation, or implants,” she said. “We’re not against those things. But not to round it out with fresh air, sunshine, beauty, meaning, hope, love, joy, exercise, nutrition, all these things, is a very limited perspective.”
Vieten is the executive director of the John W. Brick Foundation, an organization that promotes evidence for lifestyle approaches to mental health. The foundation recently published a report examining the relationship between exercise and mental health. Researchers looked at studies published from 1990 and 2020, and examined a wide variety of activities, from team sports to yoga.
Exercise in general was found to provide a significant improvement to mental health. But the report found that the best type of exercise for improving mental health outcomes are activities that are either done outside or as part of a group.
One study in particular showed that cycling reduced the number of poor mental health days a person experiences per month more than any other type of exercise.
“They think that’s true not only because of the cycling, but also the sunshine and fresh air,” Vieten said.
The other activity found to have a big impact on mental health is team sports, which combine exercise with sunshine, fresh air, and group support.
“It’s the perfect antidepressant, if you can get yourself outside to do it. That’s the thing,” Vieten said.
Outdoor Health Benefits
Science is just beginning to tap into the psychological and biological effects the outdoors can have on our minds and bodies. For example, some studies show that just being on, in, or even near a body of water can make us happier and healthier. Other research shows that the amount of light that hits your retina results in a better mood.
In the past few years, science has also discovered that just being in the woods can lower stress hormones, pulse rate, and blood pressure. In Japan in particular, the study of forest medicine is being used as an evidence-based strategy for preventive disease.
So how do we avail ourselves of the mental and physical health benefits the outdoors have to offer?
If vitamin D is your goal, Mercola recommends getting outside on days during the warmer months, baring as much skin as you can for a small period of time.
“Get a little tan, get a little pink, but don’t get sunburned. People with light-colored skin may only be able to tolerate two minutes. Listen to your body and never get sunburned,” Mercola said. “It will give you vitamin D for free, but it also has a variety of other metabolic benefits for your health, such as nitric oxide, decreases in inflammation, and a lot of other great things.”
For mental health, Vieten recommends something as simple as a leisurely walk in a quiet place. She also urges that people seek a wide natural vista, such as a field, lake, meadow, or ocean. It may give you a sense of perspective that your smartphone never will.
“When people get depressed or anxious, they get tunnel vision—they get very myopic. They can only see what they’re worried about and they can become very self focused in a critical manner,” Vieten said. “When you look at the ocean, you have to open your peripheral vision to get it all in your eye, because it’s so big. This can really broaden your perspective, your interests, your curiosities, and your worldview. I think when people are outside, it affects their perspective on their own problems and their own life. It takes them out of their tunnel vision.”
As the world begins to emerge from quarantine, many of us have begun to appreciate the outdoors now more than ever. You don’t need a study to know that it feels good to have a gentle breeze in your hair, the warm sun on your skin, and your bare feet in the sand. But Vieten would like to see doctors contributing to the message by routinely prescribing outdoor time.