The power of vitamin D
Vitamin D’s main claim to fame lies in supporting bone health. It’s also beneficial for strengthening immunity, necessary for muscle movement, and utilized by our nerves to carry messages between our brain and our body.
A deficiency may be difficult to recognize, says Olivia Rose, ND, clinic director of Rose Health Clinic in Scarborough, Ontario. The symptoms can be vague or overlooked and can include:
- mood changes
- brain fog
- seasonal affective disorder
- skin issues like eczema
- frequent colds or allergies
“Because vitamin D functions more like a prohormone than a typical vitamin, it’s involved in hundreds of processes in the body, from immune function and mental health to skin integrity,” says Rose. “Maintaining optimal levels is critical for overall well-being, which is why regular monitoring and appropriate supplementation are key.”
The link between vitamins D and K2
- Vitamin D keeps adequate levels of calcium in your blood.
- Vitamin K directs the calcium to your bones, thereby reducing the accumulation of calcium in soft tissues like blood vessels.
Olivia Rose, ND, says some people choose to combine the vitamins, especially when in supplement form. The combination could be advisable for someone taking higher doses of vitamin D or focused on bone health, she says, with the caveat that it’s always best to consult a healthcare professional to determine what’s appropriate for your individual needs.
How to maintain vitamin D levels as the days shorten
According to Statistics Canada, we’re four times as likely to have enough vitamin D if we’re taking supplements, and almost two times as likely to have adequate vitamin D levels if we eat fish on a weekly basis.
According to Rose, it’s essential to be mindful of maintaining healthy vitamin D levels all year round. It’s a common misconception that we don’t need to supplement in the summer because we’re getting enough sun, she says.
“In reality, many of us spend our summer days indoors or wear clothing and sunscreen that blocks vitamin D production,” says Rose. “By the time fall arrives and cold and flu viruses begin circulating, many people are already running low. This can increase our susceptibility to infections and impact immune resilience.”
What’s in a shroom?
The nutritious bounty of the mushroom doesn’t end with your garden variety button.
- Chaga is cost-efficient with antiviral and anti-inflammatory properties.
- Reishi has been used for centuries in Chinese medicine and is known to support immunity.
- Turkey tail contains antimicrobial and antiaging properties.
- Lion’s mane, known for its antioxidant and antimicrobial effects, shows promise in improving cognitive function and mood.
Vitamin D variables
When ultraviolet B rays from the sun hit your skin, it converts a chemical in your skin into vitamin D3. From there, the D3 is carried to the liver and then the kidney, where it’s converted to calcitriol, the active form of vitamin D.
Getting enough sun
The higher the latitude, the greater the risk of vitamin-D deficiency, due to the lower exposure to sunlight. Cloud cover can also interfere with the sun’s rays, as can buildings or trees.Air pollution is another factor that can interrupt UV rays and disrupt the metabolism of vitamin D in the skin.
Type of skin
Your skin type can also impact absorption. In a 2023 study based on the Canadian Health Measures Survey of 2012 to 2019, race was a prominent risk factor for inadequate vitamin D status. Another study of pregnant women in Saskatchewan (55 degrees north), found that First Nations pregnant women exhibited significantly lower levels of vitamin D than nonFirst Nations pregnant women.
Socioeconomic factors
Socioeconomic factors, such as having the opportunity to vacation in sunnier settings, preference for shade, type of diet, lighting, dress codes, sunblock use, smoking, and aging, are all thought to have an impact on the absorption of vitamin D.
When vitamin D can’t reach you
Your skin can’t produce vitamin D from sunlight streaming through a window.
Vitamin D levels across Canada
Studies indicate that 19 percent of Canadians have inadequate vitamin D status. No matter where you live in Canada, your risk of vitamin-D deficiency more than doubles during the winter months. That’s because the vast majority of the country, with the exception of the southernmost tip of Ontario, is situated above the 42nd parallel north.
That’s one of the reasons it’s mandatory in Canada for milk and margarine to be vitamin-D fortified. And if you’re not getting enough of the sunshine vitamin from these foods or others, like salmon, tuna, or eggs, it’s recommended that you consult your healthcare provider about the right supplement to meet your needs.
There are two forms of vitamin D
- D2, sourced from plants, including mushrooms
- D3, found in animal-based foods and synthesized in your skin
While both forms boost vitamin-D levels in your blood, D3 might raise it higher and longer than D2.
This article was originally published in the September 2025 issue of alive magazine.
