Vitamin D in Sudbury: What Northern Ontario Winters Mean for You

Sudbury winters are long, dark and cold, and that affects more than your mood. Your skin makes vitamin D when sunlight hits it, but at our latitude (about 46° north) the sun sits too low from roughly late fall to early spring for your body to make much. Add bundled-up clothing and more time indoors, and many Northern Ontarians come up short over the winter.

Why vitamin D matters

• Bones and teeth: vitamin D helps your body absorb calcium.
• Muscle function: it supports normal muscle function, which matters if you train.
• Immune function: vitamin D helps maintain normal immune function.

How much do adults need?

Canadian guidance for healthy people is:

• Ages 9 to 70: aim for 600 IU a day
• Over 70: aim for 800 IU a day
• Upper limit for adults: stay below 4,000 IU a day unless your doctor tells you otherwise

Some people need more, for example if your blood levels are low. That's a conversation for your doctor, who can test you.

Can I get it from food?

Some, but it's hard to reach your target from food alone in winter. Good sources include:

• Salmon, trout, sardines and canned tuna
• Eggs (the yolk)
• Milk and fortified plant beverages (in Canada, milk is fortified with vitamin D)
• Fortified yogurt and some orange juices

How to choose a supplement

• Pick D3 (cholecalciferol). It's the same form your skin makes and the most common form in supplements.
• Check the dose per serving so you know exactly how many IU you're taking.
• Take it with a meal that has some fat, because vitamin D is fat-soluble.
• Make it a habit. Keep it next to your coffee maker or protein tub so you don't forget.

We carry HD Muscle Vitamin D3. Many people also pair winter vitamin D with magnesium or a daily multivitamin. See our full Health & Wellness collection.

Quick FAQ

Should I take vitamin D all year? Many Canadians focus on fall through spring, when sunlight is weakest. Ask your doctor what makes sense for you.

Can I take too much? Yes. Vitamin D builds up in the body, so stay under 4,000 IU a day unless your doctor advises otherwise.

Does a sunny winter day help? Not much. In winter, the sun's angle at our latitude is too low for your skin to make meaningful vitamin D.

Stock up without leaving the house

When it's -25°C outside, let us come to you. Get free local delivery in Sudbury on orders over $75, or pick up at MOTIV, 1755 Lasalle Blvd.

This article is general information, not medical advice. Talk to your doctor or pharmacist before starting a supplement, especially if you're pregnant, take medication or have a health condition. Always follow the product label.

Source: Northwest Territories Health and Social Services, 2025 vitamin D guidelines (based on Health Canada's dietary reference intakes).