By January, a lot of us leave home in the dark, work indoors all day, and drive home after sunset. So it’s no surprise that one of the most common nutrition questions I hear during the winter is whether people in Western Pennsylvania should be taking vitamin D. For many adults, it’s a reasonable question — because our location genuinely limits the skin’s ability to make meaningful vitamin D for much of the winter.

I’m Dr. Lauren Helf. Along with my chiropractic degree, I have a master’s in clinical nutrition, so I tend to approach supplements the way I approach everything else: what does the evidence actually support, and what makes sense for you? Let’s walk through it.

Why Vitamin D Is Different From Most Vitamins

Vitamin D behaves more like a hormone than a traditional vitamin. It helps regulate bone health, calcium absorption, muscle function, and normal immune function, and tissues throughout the body have receptors for it. That broad role is part of why it gets so much attention — and also why it’s worth understanding rather than guessing about.

Why Where You Live Matters

Here’s the fact that really drives this article. Above roughly 37° latitude, the sun’s UVB rays during much of late fall and winter are simply too weak for significant vitamin D production in the skin. Pittsburgh sits at about 40.4° N — comfortably north of that line. It’s why someone who spends plenty of time outdoors in July may still run low in January: it isn’t about how much you go outside in winter, it’s that the winter sun here can’t do the job even if you do.

Food Should Always Come First

Before I recommend any supplement, I encourage patients to build a healthy foundation. That means vegetables, fruit, lean proteins, healthy fats, and whole grains, along with good hydration, regular activity, and adequate sleep. Supplements are meant to support a healthy lifestyle — they don’t replace one. You can read more about our approach to nutrition and recovery if you want the bigger picture.

Foods That Naturally Contain Vitamin D

A handful of foods are good sources: fatty fish like salmon and sardines, egg yolks, and fortified foods such as dairy, plant milks, and some cereals. The honest catch is that even with a healthy diet, many people struggle to reach recommended intake from food alone, especially in winter. The NIH Office of Dietary Supplements is a good, plain-language reference on food sources and how much different people need.

Who May Be More Likely to Have Low Vitamin D?

Some people are more likely than others to run low: older adults, people with darker skin, those who spend most of the day indoors, people living in northern climates, people with certain digestive disorders, and those who avoid fortified foods. I’ll add a caution here — this is about who’s more likely to be low, not a way to diagnose yourself. Only testing can tell you your actual level.

Vitamin D and the Immune System

This is where the old version of this article overreached, so let me be careful. Vitamin D does play an important role in helping the immune system function normally, and researchers continue to study how vitamin D status relates to things like respiratory infections. Some studies suggest that correcting a true deficiency may benefit certain individuals. But vitamin D should not be viewed as a guaranteed way to prevent illness, and I won’t tell you it “boosts your immunity.” The honest position is that maintaining a healthy level supports normal function — not that a supplement will keep you from getting sick.

Should Everyone Take Vitamin D?

Not necessarily. Some people get adequate vitamin D; others clearly benefit from supplementation; and some are best served by discussing testing with their healthcare provider. I prefer recommendations based on the individual rather than assuming every patient needs the same supplement at the same dose. That’s true for vitamin D and for just about everything else.

What About Other Supplements?

Most people don’t need dozens of supplements. The foundation is always the same — healthy food, movement, sleep, and hydration. From there, depending on the individual, a healthcare professional might recommend one or two specific supplements to fill a genuine gap. The goal is targeted and thoughtful, not a cabinet full of bottles.

Why Our Office Carries Nutritional Frontiers

When we do recommend a supplement, we want products from companies that emphasize quality, sound manufacturing standards, and ingredient transparency — which is why we keep Nutritional Frontiers products available. I want to be clear about something, though: patients are never expected to buy supplements through our office. We simply like having access to products we feel comfortable recommending when they’re appropriate. Where you purchase a supplement matters far less to me than whether you actually need it.

Supplements I Discuss Most Often

Rather than name specific products, it’s more useful to talk in categories. The ones that come up most in my conversations are vitamin D, omega-3 fatty acids, magnesium, and — only when it’s appropriate for the person — probiotics. I don’t recommend all of these universally; which, if any, make sense depends entirely on the individual, their diet, and their goals.

Small Habits Make a Bigger Difference Than One Supplement

If you take one thing from this, let it be this: eat mostly whole foods, drink plenty of water, stay physically active, prioritize sleep, and manage stress. Use supplements to fill real nutritional gaps — not to compensate for habits that aren’t serving you. No single pill outperforms the basics done consistently.

My Advice for Patients During a Pennsylvania Winter

Winter is actually a great time to pay attention to the fundamentals. A balanced diet, regular movement, good sleep, hydration, and — when appropriate — carefully chosen supplements all support your overall health, and comfortable movement through drug-free chiropractic care fits right alongside them. If you have questions about whether vitamin D or another supplement makes sense for you, I’d be glad to talk it through at your visit. Request an appointment anytime. — Dr. Lauren Helf, DC