It may seem as though headlines touting the importance of vitamin D are everywhere these days. From minimizing the negative impacts of Covid-19 to combating seasonal affective disorder (SAD), vitamin D is proving critical to our health in many ways. As Toronto-based certified nutrition practitioner Marina Kaplan explains, “vitamin D is such a huge topic because it touches so many systems.”
Kaplan also notes that a lot of the world is vitamin D deficient and, since our healthcare system no longer funds vitamin D deficiency tests, it can be tricky to know when we’re short on this essential nutrient. The average person between the ages of 14-70 need 600 IU (international units) of vitamin D per day. For this reason, it may be helpful to understand the role and function of vitamin D, as well as to learn to recognize what those deficiency symptoms can look (and feel) like and what we can do about it.
What is vitamin D?
While vitamin D is a nutrient, Kaplan says it may also be helpful to think of it as a hormone. “It has signaling capacity,” she says, adding, “Our body has many cells that have vitamin D receptors that are triggered when vitamin D attaches itself to them.”
Think: lung disease outcomes are typically better for people who are not deficient in the vitamin. “We’ve heard of this with Covid,” Kaplan adds. The vitamin’s other primary role is in calcium absorption from our small intestine and bone development, but it also plays a role in immune function, the recovery of muscles and even heart health, she explains.
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Where you can find vitamin D in food
Vitamin D is a fat-soluble vitamin, meaning it’s absorbed with fats and is drawn to the body’s fatty tissue and liver.
Kaplan also clarifies that there are two main forms of the vitamin: D3, which is animal-based, and D2, which is plant-based. For vitamin D3, “You can find it in fatty fish and fish oils.
- oily fish, such as wild-caught salmon, tuna, sardines and mackerel
- cod liver oil
- beef liver
- pasture-raised eggs and egg yolk, specifically
- sunflower sprouts
- even some mushrooms contain vitamin D due to their exposure to ultraviolet light
For a more affordable option, you can also find it in dairy and vitamin D-fortified products, such as orange juice and cereals, or take vitamin D2 in supplement form. Kaplan points that products that are fortified rely on the plant-based vitamin D2 form, so vegans and vegetarians need not worry.
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What can happen when we are chronically vitamin D-deficient
“Vitamin D impacts every single system of the body, like the circulatory system and our respiratory system,” Kaplan says. So over time, if someone is chronically vitamin D-deficient, it could be a contributing factor to chronic health conditions. For example, it plays a part in osteoporosis, arthritis and bone fractures. Kaplan also adds that it can also contribute to “inflammation, diabetes, hypertension, cardiovascular disease — a lot of these diseases are related to an inflammatory state, which vitamin D affects.”
While the reverse (having too much vitamin D) is possible, it’s very rare, says Kaplan. “It’s more likely that people are vitamin D-deficient than that they have too much vitamin D, and that often happens only through excessive supplementation.”
How BIPOC are impacted by vitamin D deficiency
“[They] have more melanin — a pigment that’s present in skin,” Kaplan explains. “And this pigment can impact absorption of vitamin D through UVB radiation, which activates vitamin D. This pigment can compete with UVB absorption and if you live in northern climates, you don’t get as much UVB exposure to begin with.” One 2017 study concluded that, of the study sample of pregnant women in Switzerland, “women with dark skin colour were statistically significantly more often vitamin D-deficient compared to women with light skin colour.”
For this reason, Kaplan says, “it’s a good rule of thumb to supplement for vitamin D, especially if you have darker skin and lack sun exposure.”
Signs you may be vitamin D-deficient
As for how to recognize symptoms of vitamin D deficiency? Kaplan cautions, “It can be difficult to talk about vitamin D deficiency symptoms because its impacts are so wide-reaching.” These symptoms are also attributed to other causes. But if you notice you’re experiencing these, it may be a good idea to consult your primary healthcare provider to see if you may benefit from upping your vitamin D intake.
Sign 1: You experience bone fractures often
Because one of vitamin D’s primary functions is to help with the absorption of calcium, it plays a key role in bone health, density and development. One key outcome of this is bone fractures. So if you notice you break bones often, take note. And even if you don’t get fractures, bone pain can be another indication.
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Sign 2: You come down with colds and other illnesses a lot
As Kaplan mentions, because it plays a role in our immune system function, a lack of vitamin D impacts our ability to fight invading bugs and viruses. For example, some studies suggest that low levels of vitamin D contribute to bronchitis and pneumonia. And, as noted, this deficiency has even been linked to Covid-19.
Sign 3: Your wounds and muscles are slow to heal
If you notice it takes you longer than average for your cuts and abrasions to heal, this may be one indication you’re low on vitamin D. Similarly, slow muscle recovery and frequent muscle pain are also linked to low levels.
Sign 4: You experience chronic fatigue
If you notice that you’re constantly lethargic, burnout may be one possible reason. But studies also suggest that even a slight vitamin D deficiency can impact our energy levels and lead to fatigue. This may be helped with supplementation. (Talk to your healthcare professional before taking supplements.)
Sign 5: You have difficulty concentrating
While there can certainly be many reasons for why you may have a hard time staying focused, vitamin D could be a factor as it plays a part in executive function. One meta-analysis (a study of other studies) found that low vitamin D is associated with mental shifting, informational updating and processing speed. The same meta-analysis noted other studies that found it could impact memory too, and further research noted it’s linked to cognitive decline.
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