Winter in the Pacific Northwest is a time for grey cloud cover and drizzle. A fairly well-known side effect of the season is a common health challenge: vitamin D deficiency. Here in the PNW, the lack of sunlight during the colder months leaves many of us vulnerable to low levels of this essential nutrient.
While a sunny winter getaway might feel like a temporary fix (and one of my favorite interventions), it’s not enough to sustain your body’s needs. And it’s not just PNW residents at risk—indoor lifestyles, sunscreen use, and outdated medical guidelines have left many people deficient, regardless of their geography.
Vitamin D isn’t just another nutrient on a checklist—it’s a cornerstone for whole-person health. Here’s what you need to know to optimize your levels and why functional nurses can lead the charge in addressing this overlooked epidemic.
Vitamin D’s Vital Role
Vitamin D is more than just the “sunshine vitamin.” It is actually a steroid hormone, influencing countless processes in the body. Here’s what it does:
Immune Regulation: Balances immune activity to prevent overreactions (like autoimmune conditions) while boosting your ability to fight infections.
Mood and Mental Health: Deficiency is linked to depression, anxiety, and seasonal affective disorder (SAD), particularly in darker months.
Bone and Muscle Health: Enhances calcium absorption, maintaining strong bones and reducing fracture risk, while supporting muscle strength to prevent falls.
Chronic Disease Prevention: Optimal levels are associated with reduced risks of diabetes, cardiovascular disease, and certain cancers.
Why Vitamin D Deficiency is Common—Even in Sunny Places
Interestingly, areas that experience less sunshine such as the PNW tend to have a higher prevalence of conditions associated with vitamin D deficiency including autoimmune conditions and brain health concerns. That said- it’s easy to assume that only those of us enduring gray winters are at risk, but that’s far from the truth. Even in sunny climates, many people are deficient due to:
Indoor Lifestyles: Spending hours in front of computers or working indoors limits exposure to UVB rays.
Sunscreen Use: While critical for skin cancer prevention, sunscreen blocks the UVB rays needed to produce vitamin D.
Outdated Guidelines: The “replace and move on” model many of us were taught has created a system where providers often neglect long-term monitoring or supplementation for optimal levels.
Current guidelines still don't recommend regular monitoring of vitamin D levels, but I can say that from testing and replacing vitamin D in my own patient population for years that- YES, most people are deficient, and YES, those people have more of the associated health conditions. And when we replace and optimize vitamin D levels, they feel better! Unfortunately, most healthcare providers are trained to limit screening for vitamin D deficiency, and to only replace when it’s flagged as dangerously low (typically below 20 ng/mL), not to aim for the optimal ranges that prevent disease and promote wellness (typically identified as 40-60 ng/mL). This gap has left countless patients without the ongoing support they need and many more patients completely unaware of their vitamin D deficiency.
Signs You Might Be Deficient
Vitamin D deficiency is often subtle, with symptoms mistaken for other conditions. Watch for:
Persistent fatigue or low energy
Frequent colds or infections
Muscle weakness, cramps, or joint pain
Depressed mood or irritability
Slow wound healing
Bone or back pain
A diagnosis of any number of autoimmune or brain health concerns (among numerous other chronic health conditions associated with vitamin D deficiency).
If these resonate with you or your patients, it’s time to evaluate vitamin D levels.
Testing, Dosing, and Guidelines
Testing:
The gold standard for assessment is a 25-hydroxy vitamin D blood test.
Optimal levels range from 40–60 ng/mL, with some individuals thriving closer to 80 ng/mL.
Dosing:
Adults: 2,000–5,000 IU daily is common, but doses may vary based on initial lab results.
Children: 400–1,000 IU per day, depending on age and size.
High-Dose Therapy: Some patients with severe deficiency may need short-term higher doses under medical supervision.
Guidelines vs. Functional Practice:Many conventional guidelines focus on treating deficiency as a short-term issue: replace, recheck (maybe), and move on. This approach often neglects to monitor levels long-term or ensure they’re maintained in the optimal range. It also doesn't account for variations in sunlight exposure that may cause fluctuations through the year. A vitamin D level monitored annually in August may look optimal, but might actually be quite low each year in February. Functional nurses, however, understand the importance of ongoing testing and dosing adjustments to keep levels steady for lifelong health.
Reassessment: Retest after 3–4 months of supplementation and adjust dosing as needed. This is a critical factor. There is not a one-size-fits-all dose, and we can't just recommend an "average" dose for our patients and have them continue this long term. Monitoring vitamin D levels is important, and getting those repeat labs can often be a challenge for nurses AND their patients.
Choosing the Right Supplement
Not all vitamin D supplements are created equal. Here’s how to choose the best option for your needs:
D3 vs. D2: Vitamin D3 (cholecalciferol) is far more effective than D2 (ergocalciferol) at raising and maintaining levels.
Pair with K2: Adding K2 directs calcium to your bones and teeth, reducing the risk of calcification in arteries.
Don't forget the magnesium: Take with a quality magnesium formulation to support bone health. They work synergistically!
Common Formulations:
Capsules or Tablets: Convenient and widely available.
Liquid Drops: Ideal for individuals with digestive issues or those needing precise dosing.
Absorption Matters
Vitamin D is fat-soluble, so it’s best absorbed when taken with a meal containing healthy fats. Pairing your dose with foods like avocado, nuts, seeds, or olive oil can significantly improve effectiveness.
Can You Take Too Much?
Yes, but it’s rare when supplementation is monitored properly. Toxicity occurs when levels exceed 100 ng/mL, often due to prolonged high dosing. Symptoms of toxicity include:
Nausea or vomiting
Kidney stones
Hypercalcemia (too much calcium in the blood)
Beyond toxicity, higher levels of vitamin D actually have an immunosuppressive effect. This can be useful short term in some cases, but long term could have harmful effects. Regular testing ensures your dosing remains safe and effective!
Why Winter Vacations Aren’t Enough
A sunny getaway might feel like the perfect remedy for PNW winters, but it’s not a long-term solution. While your body can store vitamin D in fat tissue, levels deplete quickly without consistent exposure or supplementation. Daily dosing throughout the winter is essential for maintaining optimal health.
The Call for a Paradigm Shift
Outdated “replace and move on” protocols are no longer enough. As functional nurses, we have the training to see beyond the minimum thresholds and aim for optimal wellness. By educating patients and advocating for better testing and monitoring practices, we can address this silent epidemic and improve lives.
Empowering Nurses to Lead the Way
Vitamin D deficiency isn’t just a patient problem—it’s a systemic issue rooted in gaps in education and care. What's more, research around nutrition interventions is often lacking, poorly funded, and poorly designed (such as using an ineffective dosage, poor quality supplement, not timing with fatty meals, etc.). Nurses are uniquely positioned to lead the charge, offering holistic, evidence-based strategies to ensure better outcomes for patients. We can educate and empower our patients to take their health into their own hands!
If you’re ready to transform your practice and dive deeper into functional medicine, explore my current and upcoming offerings including the Holistic Nursing Entrepreneur Program™. Together, we can reshape healthcare—one empowered nurse at a time.
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