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Is the Sun the Best Source of Vitamin D? Why Your Skin Beats a Pill (and How to Do It Safely)

Reading time: about 6 minutes

Every summer the same argument flares up. One side treats the sun as pure medicine, the other treats it as the enemy, and most of us end up in the middle, unsure whether to step outside or hide from it. The honest answer is more interesting than either camp lets on, and it starts with a fact that rarely makes the headlines: your skin is the best place to make vitamin D, and sunlight does a few things a supplement simply can't. Here's what the science shows, and a practical routine you can tailor to your skin.

Your skin is the better factory

A vitamin D capsule does one job: it raises your vitamin D. Sunlight on skin does that and more.

The standout is what happens to your blood vessels. When ultraviolet light hits your skin, it releases a small store of nitric oxide into your circulation. Nitric oxide relaxes blood vessels, and researchers at the Universities of Southampton and Edinburgh found that short UV exposure lowers blood pressure independently of vitamin D, an effect traced to nitric oxide released from the skin. The American Heart Association has covered the same line of research.

It doesn't stop at your heart. Experts gathered by the University of Edinburgh's Institute for Regeneration and Repair concluded that regular sun exposure is linked to lower blood pressure and reduced risk of heart disease, type 2 diabetes and obesity, with benefits that reach into immunity and mood and appear to be driven by more than vitamin D alone. That is the part the supplement aisle can't bottle.

None of this means the sun is risk-free. UV is still the main cause of skin cancer, and the goal is never to bake. The takeaway is gentler: total sun avoidance has its own costs, and a sensible relationship with the sun beats both extremes.

Timing matters more than you think

Here's where most people, and a lot of old advice, get it backwards. Your skin makes vitamin D only from UVB rays, and UVB behaves very differently from the soft light of early morning.

UVB is strongest when the sun is highest, around the middle of the day. When the sun sits low at dawn or dusk, its UVB is filtered through far more atmosphere, so the same time outdoors early or late yields a fraction of the vitamin D you'd make at midday. That golden-hour light is wonderful for your mood and sleep, but it makes almost no vitamin D.

A quick field test: look at your shadow. If it's shorter than you are tall, the sun is high enough for UVB to reach you. As a rule of thumb, the UV Index in Canada is 3 or higher from roughly 11 a.m. to 3 p.m. between April and September, even on cloudy days, and a UV Index around 3 is about the threshold where vitamin D production becomes possible.

The Canadian winter catch

There's a long stretch of the year when none of this applies here, no matter how bright the day looks.

Classic research on latitude found that winter sun in northern cities is too low in the sky to make any vitamin D, with the dead zone in Edmonton running October through March. Toronto, around 43.7 degrees north, sits in a similar gap. A Canadian study put it plainly: in fall and winter, UV levels are too low for any skin type to get enough vitamin D from sun alone, so Canadians should rely on food and supplements, and tanning beds are not a safe alternative according to the Canadian Dermatology Association, Health Canada and the WHO. For roughly half the year, your vitamin D plan here lives on your plate and in the supplement bottle.

How much sun, by skin type

Less than you'd guess, and it depends on how easily your skin burns. The window is brief, taken at midday, with arms and legs exposed, and always stopped well before any pink. These are general starting points, not prescriptions.

There's reassuring evidence behind keeping it short. A study tracking both sides of the ledger found that brief, low-dose summer sunlight kept lighter-skinned people vitamin D sufficient while causing only low-level, non-accumulating DNA damage. One honest caveat: for the very fairest skin, the gap between making vitamin D and starting to burn is slim, so if you burn in minutes, have had skin cancer, or are immunosuppressed, a supplement is the safer default.

A simple, no-guilt routine

• Mornings, for energy: get outside into natural light soon after waking. Low UV, no vitamin D, but lovely for mood and sleep.

• Midday, for vitamin D: when the UV Index is 3 or higher and your shadow is short, take a brief, skin-type-appropriate window with arms and legs bare, never to the point of pink. Then cover up or apply SPF 30 or higher, and reapply after swimming or sweating.

• Winter, and the rule that overrides everything: from late fall through early spring, rely on food and a supplement. And never burn, since one intense exposure does far more harm than steady, moderate sun.

One more reassurance: your body quietly caps its own production, so once your skin has made its fill, more sun adds no extra vitamin D, only more risk. That's the case for keeping each session short. And if you're unsure where your levels stand, ask your doctor about a simple blood test.

Want the whole system in one place? The full routine, tuned to your skin and the season, lives in my new Sun Health Guide. Get the Sun Health Guide →

The glow without the ageing

Here's the part that tends to land harder than the cancer talk, especially in midlife. The sun is the single biggest reason skin looks older than its years. The Skin Cancer Foundation pins around 90 percent of visible skin changes on photoaging, the slow build-up of UV damage over a lifetime. UVA in particular reaches deep into the skin and breaks down the collagen and elastin that keep it firm, which over time surfaces as fine lines, sagging, rough texture and dark spots. A deep tan today is really a loan against your skin's future.

The good news is you can have the bronzed look without making that trade, which is exactly what self-tanners are for.

A self-tanner works on the surface and nowhere else. Its active ingredient, DHA, is a sugar-derived colour agent that reacts with the outermost, already-dead layer of your skin and turns it temporarily brown. No melanin, no UV, no deeper damage, and it fades over a few days as those surface cells shed. Dermatology groups point to sunless tanners as the only safe way to look tan.

What makes a good one:

• DHA as the active, ideally plant-derived from sugar beets or sugarcane.

• A gradual, buildable formula, so you can sneak up on the shade instead of overshooting into orange.

• Fragrance-free if your skin runs sensitive, since added scent is a common irritant.

• A foam, water or lotion rather than an inhalable spray. If you do use a spray, protect your eyes, nose and mouth.

The one thing a self-tanner will not do is protect you from the sun. It is colour, not sunscreen, with no meaningful SPF. So treat them as two jobs: fake the colour, and still wear SPF 30 whenever you are out.

Don't forget the plate

Sunlight is the best source, but for half the Canadian year it's barely a source at all, so food earns its place. Fatty fish like salmon, egg yolks and fortified milk carry meaningful vitamin D, and a daily supplement fills the gap through the darker months.

Summer also makes eating well easy, and June tends to be one long string of weddings, barbecues and last-minute get-togethers. My fancy appetizer platter is built for exactly those days, whether you're hosting or showing up with something in hand. Prosciutto, burrata, eggs, olives, cucumber and melon with good bread and a drizzle of olive oil and balsamic. Ten minutes, no real cooking, and it lands looking like you fussed for an hour, with real protein and colour so you're not running on crackers at your own party. If you'd like a whole season of simple, impressive food like it, that's exactly what my cookbook, Love What's On Your Plate, was built for.

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Frequently asked questions

Is sunlight better than a vitamin D supplement? For vitamin D itself, both work. But sunlight on skin also triggers nitric oxide, which lowers blood pressure independently of vitamin D, along with emerging benefits for mood and immunity that a pill doesn't replicate. A supplement is the safer choice when you can't get sun safely.

What's the best time of day to make vitamin D? The middle of the day, roughly late morning to mid-afternoon, when the sun is highest and UVB is strongest. Early and late sun produces very little.

Can you get vitamin D through a window? No. Glass blocks almost all UVB, so a sunny window or a drive in the sun won't raise your vitamin D. You need direct outdoor exposure.

Does a self-tanner protect you from the sun? No. A self-tan is colour, not sunscreen, and it carries no meaningful SPF. You still need broad-spectrum SPF 30 or higher whenever you are outside, exactly as you would without it.

How do I get enough vitamin D in a Canadian winter? You mostly can't from the sun at our latitude from late fall through early spring. Rely on vitamin D rich foods and a supplement, and ask your doctor about testing.

Ready to do summer sun well?

You don't have to piece this together from a dozen conflicting articles. My new Sun Health Guide puts the whole system in one place, tuned to your skin and your season, so you can soak up the good and protect your glow without the guesswork.

Get the Sun Health Guide →