Vitamin D - The Sunshine Vitamin
Vitamin D is often called the “sunshine vitamin” because the body produces it when the skin is exposed to sunlight. It is also an essential nutrient with several important functions in the body. Getting enough vitamin D can be difficult, particularly for people living in northern climates such as Canada. There are only a limited number of foods that naturally contain significant amounts of vitamin D, and sunlight is not a reliable source throughout the entire year.
During the fall and winter months, the angle of the sun and shorter days greatly reduce the body's ability to produce vitamin D from sunlight. For many Canadians, food and supplements become more important sources during this time.
Why Vitamin D Matters
Vitamin D is involved in several important processes throughout the body, from maintaining strong bones to supporting normal immune and muscle function.
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Bone and teeth health: Helps the body absorb calcium and phosphorus, which are essential for maintaining strong bones and teeth.
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Muscle function: Supports normal muscle function and strength.
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Immune function: Helps regulate immune system activity and plays a role in the body’s defense against infection.
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Mood and brain health: Vitamin D receptors are found throughout the brain, and adequate levels are important for normal neurological function. Low vitamin D status has also been associated with mood changes.
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Cell growth and function: Vitamin D helps regulate processes involved in cell growth, development, and normal cellular function.
How to Get Enough Vitamin D From Sunlight in Canada?
Sunlight is the most natural way for the body to make vitamin D. When UVB rays reach the skin, they start a process that leads to vitamin D production.
The amount your body can make depends on several things. The season, your geographical location, the time of day, skin tone, age and how much skin is exposed can all make a difference.
Living farther north is particularly important. In Canada and other northern parts of the Northern Hemisphere, the sun sits lower in the sky during much of the fall and winter. Even when the day looks bright and sunny, there may not be enough UVB radiation reaching the skin for significant vitamin D production.
That means spending time outside in winter does not necessarily mean you are making enough vitamin D. Outdoor activity is still good for many reasons, but sunlight cannot always be relied upon as a year-round source of vitamin D in northern climates.
Food Sources of Vitamin D
Vitamin D is found naturally in a limited number of foods. Fatty fish are among the best dietary sources, including:
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Salmon
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Sardines
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Trout
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Mackerel
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Egg yolks
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Cod liver oil
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Liver and other organ meats
Many commonly consumed foods contain vitamin D because it has been added during manufacturing. These include certain types of milk, plant-based beverages, breakfast cereals, and other fortified products.
Checking the nutrition label is the easiest way to know whether a particular product contains added vitamin D and how much it provides.
Vitamin D for Vegetarians and Vegans
Getting vitamin D from food can be more difficult for people who avoid animal products. Most natural food sources of vitamin D come from animal foods, particularly fish and egg yolks.
Some mushrooms contain vitamin D2 when they have been exposed to UV light, and fortified plant-based foods can also contribute to vitamin D intake.
Supplements are another option. Vegan Vitamin D products are available in both D2 and D3 forms, depending on the source and product.
Vitamin D2 vs. Vitamin D3
If you’ve looked at vitamin D supplements, you’ve probably noticed two forms: D2 and D3.
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Vitamin D2 (ergocalciferol): Usually comes from plant and fungal sources, including mushrooms and yeast.
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Vitamin D3 (cholecalciferol): The form produced by the skin in response to sunlight. Most traditional D3 supplements are made from lanolin, which comes from sheep’s wool.
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Vegan D3: Made from lichen, providing a plant-based alternative to lanolin-derived D3.
Both D2 and D3 can increase vitamin D levels, but D3 is generally more effective at raising and maintaining blood levels.
When and How Should Vitamin D Be Taken?
Vitamin D can be taken at any time of day. There is no strong reason that it has to be taken in the morning or at night.
Because it is fat-soluble, taking vitamin D with a meal that contains some fat can help with absorption. This does not require a particularly high-fat meal. Eggs, nuts, seeds, avocado, olive oil, dairy products or fish are examples of foods that contain fat.
For people taking several supplements, it can also make sense to check labels for vitamin D in multivitamins, calcium products and other supplements. Adding the amounts together gives a more accurate picture of total daily intake.
Can You Take Too Much Vitamin D?
Vitamin D toxicity is uncommon and is generally caused by taking excessive amounts of supplements rather than from food or sunlight. Too much vitamin D increases calcium levels in the blood, which can cause nausea, vomiting, weakness, excessive thirst and urination, dehydration, and kidney stones. Severe toxicity can cause kidney problems and abnormal heart rhythms.
For most people, the tolerable upper intake level is 4,000 IU (100 mcg) per day for ages 9 and older. The upper limit is lower for younger children. These limits include vitamin D from food, beverages, and supplements.
A healthcare professional may sometimes recommend a higher dose for a limited period to correct a deficiency. That is different from taking a high dose on a long-term basis without monitoring.
How Long Does It Take to Raise Vitamin D Levels?
Vitamin D levels do not usually change overnight. The time needed to raise a blood level depends on how low it is to begin with, the dose being used, absorption, body size and other individual factors.
With consistent supplementation, blood levels can begin to rise within weeks, but it may take several months to reach a new steady level. For someone being treated for a documented deficiency, a healthcare professional may repeat bloodwork after a period of supplementation to see how well the level has responded.
Should You Take Vitamin D All Year?
There is no single answer that applies to everyone. Some people get regular sun exposure and consume foods containing vitamin D, while others have very limited exposure throughout the year.
Age, diet, lifestyle, geographic location, and individual health factors can all affect vitamin D needs.
A blood test measuring vitamin D levels can provide useful information if there is concern about low levels. This can also help when deciding whether supplementation may be appropriate and how much may be needed.
Choosing a Vitamin D Supplement
Vitamin D supplements are available in several forms, including capsules, softgels, liquid drops, oral sprays, and emulsified or water-miscible formulas.
Because vitamin D is fat-soluble, taking a standard vitamin D supplement with a meal containing some healthy fat may support absorption. Foods such as eggs, avocados, nuts, seeds, olive oil, and fatty fish can provide dietary fat.
However, some people have difficulty digesting or absorbing fats, which can affect the absorption of fat-soluble vitamins such as vitamin D. This may occur with certain digestive or gallbladder conditions, or when fat absorption is impaired. In these cases, an emulsified or water-miscible form of vitamin D may be worth considering, as it is formulated to make the vitamin easier to disperse and may be better tolerated or absorbed. These are some great D-mulsion options:
Whether through food, sunlight, or supplementation, getting enough vitamin D is an important part of year-round nutrition. Understanding where your vitamin D comes from and choosing a supplement that suits your needs can help you maintain adequate levels throughout the year.