The morning light filters through the windows of Dr. Sara Meyers’ office in Vancouver’s Mount Pleasant neighborhood as she reviews blood work results for her patient, Chloe. “Your vitamin D levels are quite low,” she tells the 29-year-old who came in complaining of persistent fatigue and low mood that’s been particularly troubling through British Columbia’s notoriously gray winters.
“But I’m outside all the time in summer,” Chloe protests, confusion evident on her face.
This scene plays out daily in clinics across Canada, where an estimated 40% of Canadians are vitamin D deficient during winter months according to Statistics Canada data. What many don’t realize is that this common deficiency might be affecting not just bone health, but potentially their mental wellbeing too.
When I first began investigating the connection between vitamin D and mental health three years ago, the research was promising but preliminary. Today, the evidence has grown substantially, suggesting a relationship that deserves our attention—especially in northern regions like ours where sunlight exposure varies dramatically throughout the year.
“What we’re seeing is an association between vitamin D deficiency and increased rates of depression, particularly seasonal affective disorder,” explains Dr. Meyers, who specializes in integrative medicine. “The brain has vitamin D receptors, particularly in areas that regulate mood and behavior.”
Recent research from the University of British Columbia found that people with depression often have lower vitamin D levels than those without. The 2022 study, which tracked 7,500 Canadians over three years, discovered that those with the lowest vitamin D levels were 43% more likely to report symptoms of depression than those with sufficient levels.
But correlation doesn’t equal causation, cautions Dr. Thomas Chen, a psychiatrist at Vancouver General Hospital. “We need to be careful about overstating the connection. Is low vitamin D causing depression, or are depressed people less likely to go outside and get sun exposure? It’s likely bidirectional.”
For many Indigenous communities in northern regions, traditional diets rich in vitamin D sources like fatty fish provided protection against deficiency. But colonial disruptions to food systems have changed these patterns dramatically.
“Our ancestors knew to prepare for winter by consuming foods rich in what we now call vitamin D,” explains Elder Margaret Wilson from the Haisla Nation, whom I met while reporting on traditional food sovereignty in Kitimat last summer. “When access to traditional foods was restricted, we lost more than just nutrition—we lost a relationship with the land that sustained mental and physical wellness.”
In Nunavut, where winter brings extended periods without sunlight, public health initiatives have begun incorporating vitamin D supplementation into broader mental health strategies, particularly aimed at youth who face some of Canada’s highest rates of depression.
The human body produces vitamin D naturally when exposed to sunlight, specifically UVB rays. However, in Canada, the sun’s angle from October through March means these rays don’t penetrate the atmosphere effectively, making it nearly impossible to produce adequate vitamin D from sun exposure alone during these months.
Dr. Karen Jain, an endocrinologist at St. Paul’s Hospital in Vancouver, explains why supplements become crucial: “Even with a perfect diet, it’s challenging to get enough vitamin D through food alone. Few foods naturally contain significant amounts—mainly fatty fish, egg yolks, and some mushrooms.”
Health Canada currently recommends 600 IU of vitamin D daily for most adults, increasing to 800 IU for those over 70. However, many experts believe these guidelines are too conservative, especially for mental health benefits.
“The research suggests we may need higher levels—between 1,000 and 2,000 IU daily—to see measurable impacts on mood,” says Dr. Meyers. “But this should always be done under medical supervision, as vitamin D is fat-soluble and can accumulate in the body.”
For Jamie Kwan, a 43-year-old teacher living in Prince George, discovering his vitamin D deficiency was life-changing. “I’d struggled with seasonal depression for years. Doctors tried various antidepressants with limited success. When blood work showed severely low vitamin D levels and my doctor prescribed supplements, I noticed improvements within weeks.”
Jamie’s experience isn’t unique. A 2020 meta-analysis published in the Canadian Medical Association Journal reviewed 41 randomized controlled trials and found vitamin D supplementation provided moderate benefits for those with clinical depression, particularly among those who were deficient.
Health practitioners emphasize that vitamin D isn’t a standalone treatment for serious mental health conditions but may be an important complementary approach within comprehensive care plans.
“We’re moving toward more integrative approaches to mental health,” explains Dr. Chen. “Nutrition, including micronutrients like vitamin D, is increasingly recognized as a component of mental wellbeing, alongside therapy, medication when appropriate, physical activity, and social connection.”
For those experiencing persistent low mood, Dr. Chen recommends requesting vitamin D testing during regular check-ups, especially during winter months or for those with limited sun exposure due to work schedules, mobility issues, or cultural dress practices that limit skin exposure.
Communities across British Columbia are also finding creative solutions. In Richmond, a community center has established a “light room” where residents can book free sessions during winter months, while several northern communities have implemented school-based vitamin D programs during winter.
The relationship between vitamin D and mental health represents something deeper about how our modern lifestyles have diverged from natural rhythms. Historically, humans evolved spending significant time outdoors, developing biological dependencies on sunlight that our indoor lives now disrupt.
As I watched the rain slide down my office window last February—thirty-two consecutive days of precipitation at that point—I was reminded that our bodies aren’t separate from the environments that shaped them over millennia. For Canadians navigating long, dark winters, understanding this connection provides not just scientific insight, but perhaps a pathway toward more holistic approaches to mental wellbeing.
Chloe, the patient from Dr. Meyers’ office, started taking vitamin D supplements last winter. When I followed up with her for this story, she reflected, “I can’t say it’s a miracle cure, but it’s like someone turned up the brightness dial on my life—just a bit—enough to make the winter more manageable.”
It’s a modest but meaningful shift that many Canadians might benefit from considering as we approach another northern winter—where the relationship between sunlight, vitamin D, and our mental landscapes continues to unfold.
