Quick answer: For most people, vitamin D supplements are the safer, more reliable choice. Sunshine triggers natural vitamin D production, but the amount your body makes varies widely based on skin tone, season, location, and sunscreen use—and unprotected UV exposure raises skin cancer risk. A quality supplement delivers a consistent, measurable dose without those downsides.
I get asked about vitamin D constantly in my practice. Especially in Seattle! Vitamin D deficiency is incredibly common. So when patients ask me, “Dr. McCarty, should I just go outside more instead of taking a supplement?” I love that question, because the answer is more nuanced than you’d expect.
Why Does Vitamin D Matter So Much?
Vitamin D does a lot more than most people realize. It supports your immune system, your mood, your bone density, and even your hormonal health. Low levels have been linked to fatigue, depression, and increased susceptibility to illness. As a naturopathic doctor, this is one of the first things I check—because when your vitamin D is low, you feel it.
The tricky part? Your body doesn’t make vitamin D on its own. It needs a trigger. And that trigger is either sunlight hitting your skin, or a supplement you take daily.
What Happens When You Get Vitamin D From Sunshine?
When UVB rays from the sun hit your bare skin, your body converts a cholesterol compound in your skin into vitamin D3. It’s a beautiful, natural process—and yes, it works. But here’s what most people don’t realize: getting a reliable dose from sunshine alone is surprisingly difficult.
Why sunshine isn’t as consistent as you think
How much vitamin D your skin makes depends on a long list of variables:
- Your skin tone. Melanin (the pigment that gives skin its color) acts as a natural sunscreen. Darker skin tones require significantly more sun exposure to produce the same amount of vitamin D as lighter skin tones.
- Sunscreen use. Applying SPF 30 blocks roughly 95–98% of UVB rays—which is great for your skin, but it dramatically reduces vitamin D production.
- Time of day. UVB rays are only strong enough to trigger vitamin D synthesis between about 10am and 3pm.
- Season and geography. If you live above 37° latitude (which includes most of Washington State), UVB rays from October through March are too weak to produce meaningful vitamin D—no matter how long you stand outside.
- Cloud cover and air pollution. Both filter out UVB rays, further reducing what reaches your skin.
So even on a sunny day, the amount of vitamin D your body actually produces can vary wildly. And chasing enough sun to meet your daily needs comes with a real cost.
The skin cancer risk is real
Here’s where I have to be honest with you: there is no “safe” level of UV exposure that reliably produces vitamin D without also damaging your skin cells. The American Academy of Dermatology confirms that UV radiation—even without burning—causes cumulative DNA damage that raises your risk of skin cancer over time. Melanoma is the deadliest form, and rates have been rising for decades.
I’m not saying never go outside. Please go outside! Fresh air and nature are genuinely good for you. But intentionally skipping sunscreen or prolonging unprotected sun exposure to boost your vitamin D levels? That’s a trade-off I can’t recommend when there’s a safer option available.
Why Vitamin D Supplements Are the Better Choice
A high-quality vitamin D supplement cuts through all of that variability. You take it, you absorb it, and you know exactly how much you’re getting. No guessing.
The benefits that make supplements the smarter pick
Precise, controlled dosing. A supplement gives you an exact, measurable amount—whether that’s 1,000 IU, 2,000 IU, or whatever your provider recommends based on your labs. No estimating.
Year-round reliability. Supplements work in January just as well as they do in July. Your vitamin D levels don’t have to drop every winter just because the sun does.
No UV damage. You get all the benefits of vitamin D without any of the skin cancer risk that comes with unprotected sun exposure.
Easy absorption—with one small tip. Vitamin D is a fat-soluble vitamin, which means it absorbs best when taken with a meal that contains some healthy fat. Think avocado, olive oil, nuts, or eggs. A simple habit that makes a real difference.
What form of vitamin D supplement should you take?
Look for vitamin D3 (cholecalciferol) rather than D2. Vitamin D3 is the same form your skin produces naturally and is more effective at raising and maintaining blood levels. Pairing it with vitamin K2 is even better—K2 helps direct calcium to your bones rather than your arteries, making the combination a smart choice for long-term bone and cardiovascular health.
How Do You Know If You’re Actually Deficient?
The only way to know for certain is to test. I run a simple 25-hydroxyvitamin D blood test on almost every new patient at my clinic, because deficiency is so common—especially in the Pacific Northwest. Optimal levels generally fall between 60–80 ng/mL, though this can vary based on your individual health picture.
If your levels are low, I’ll work with you to find the right dose to bring them up safely. And if you’re not sure where to start, that’s exactly what we’re here for.
The Bottom Line on Vitamin D Supplements vs. Sunshine
Sunshine is wonderful. But as a source of vitamin D? It’s unreliable, inconsistent, and comes with a meaningful skin cancer risk when used without protection. A vitamin D3 supplement gives you a safe, predictable, and effective way to support your health—every single day, regardless of the weather outside.
This is one of the simplest, most impactful things I recommend to new patients. And the best part? It’s easy.
If you’ve never had your vitamin D levels tested, or if you’re curious whether naturopathic care might be a good fit for you, I’d love to connect. Book a consultation at Roots of Health and let’s take a look at the full picture of your health together.
Frequently Asked Questions About Vitamin D Supplements and Sun Exposure
How much vitamin D do adults need per day?
The Recommended Dietary Allowance (RDA) set by the National Institutes of Health is 600–800 IU per day for most adults. However, many integrative and naturopathic practitioners find that higher doses—typically between 1,000 and 5,000 IU daily—are needed to bring deficient individuals into an optimal range. Always get your levels tested before significantly increasing your dose.
Can you get enough vitamin D from food alone?
Very few foods contain meaningful amounts of vitamin D naturally. Fatty fish (like salmon and mackerel), egg yolks, and fortified foods like milk or orange juice contain small amounts, but not nearly enough to meet daily needs for most people. Supplementation is almost always necessary.
Is it possible to take too much vitamin D from supplements?
Yes. Vitamin D toxicity is rare but possible, typically from very high doses taken over extended periods. Symptoms can include nausea, weakness, and elevated calcium levels. This is why testing your blood levels and working with a healthcare provider to determine your dose is important rather than guessing.
Who is most at risk for vitamin D deficiency?
People with darker skin tones, those who live in northern latitudes (like the Pacific Northwest), individuals who spend most of their time indoors, older adults, and people who consistently use sunscreen are all at higher risk for deficiency. Obesity and certain gut conditions that affect fat absorption can also reduce vitamin D levels.
Does vitamin D help with mood and depression?
Research suggests a connection between low vitamin D levels and depression, particularly seasonal affective disorder (SAD). While vitamin D supplementation is not a standalone treatment for depression, correcting a deficiency may support mood, energy, and overall wellbeing as part of a broader care plan.
