Why Vitamin D Matters More Than Ever

By Christine Sagan, MSN, APRN, FNP-BC

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As we step into viral season, many of us are thinking about ways to keep our immune systems strong. COVID-19 is still circulating, and we’re seeing an uptick in cases. One nutrient that has been in the spotlight for years—and deserves to stay there—is Vitamin D.

Contrary to popular belief, this isn’t just a “winter vitamin.” Even in summer months, most people don’t make enough Vitamin D from sunlight alone. That’s why it should be considered the number one vitamin to take long-term, year-round.

Beyond “The Sunshine Vitamin”

Vitamin D isn’t just a vitamin—it’s technically a secosteroid hormone. That means it acts more like a hormone than a simple nutrient, influencing multiple systems in your body:

• Bone & muscle health – supports calcium balance and prevents fractures.

• Immune defense – enhances the body’s ability to fight infections.

• Metabolic health – helps regulate blood sugar and weight.

• Inflammation control – reduces chronic inflammation, a driver of aging and chronic disease.

One exciting area of research looks at Vitamin D’s role in neuroprotection and brain performance. Vitamin D is a  brain longevity strategy. Vitamin D’s impact on brain-derived neurotrophic factor (BDNF):

• BDNF is like “fertilizer” for your brain — it helps neurons grow, repair, and form new connections. Higher BDNF is linked to better memory, learning, and resilience against depression and neurodegenerative diseases.

• Vitamin D influences neurotrophic factors, including BDNF, which may explain part of its role in supporting mood, cognitive function, and protecting against age-related decline.

• People with low Vitamin D often show lower BDNF and higher rates of depression, while supplementation has been linked in some studies to improved mood and cognition.

Vitamin D & Viral Illnesses

Recent systematic reviews and meta-analyses have shown a consistent pattern:

• People with low Vitamin D levels have higher risk of infection, more severe disease, and increased risk of ICU admission or death when hospitalized with COVID-19.

• Supplementation—especially for those who are deficient—has been associated with lower ICU admission rates and reduced mortality.

• The greatest benefit is seen when Vitamin D levels are maintained in the 40–60 ng/mL range.

How Vitamin D Protects You

Vitamin D helps the immune system fight viruses in several powerful ways:

• Stimulates production of antimicrobial peptides like cathelicidin, which directly kill viruses and bacteria.

• Modulates the adaptive immune system to balance over- and under-reaction.

• Helps calm the release of pro-inflammatory cytokines, lowering risk of the “cytokine storm” that can cause lung and organ damage in severe infections.

• Supports lung health by maintaining the integrity of airway and alveolar cells.

Anti-Aging & Longevity Benefits

While the COVID connection is what made headlines, Vitamin D’s benefits extend far beyond. Research suggests it may:

• Lower chronic inflammation, a root cause of aging.

• Protect muscles and bones, reducing falls and frailty with age.

• Potentially reduce risk of age-related conditions like diabetes, heart disease, and even neurodegenerative illness.

How Much Should You Take?

• Up to 5,000 IU/day+ is considered safe and often necessary.

• Take your Vitamin D consistently, all year long.

  
  

The best way to know your needs is through a simple blood test for 25-hydroxyvitamin D.

Bottom Line

Vitamin D is safe, affordable, and powerful. Maintaining healthy levels—especially as we enter viral season—may lower your risk of infection, reduce disease severity, and support whole-body health.

This Month’s Featured Supplement

At Vitae, we source and carry only high-quality supplements, and this month’s featured product is BioTech’s Vitamin D3-5. Each capsule delivers 5,000 IU of highly absorbable Vitamin D3 to help you maintain optimal levels year-round. Our 250-capsule bottle is on special this month for just $17.60, making it an affordable and reliable way to support immunity, mood, and overall longevity.