Vitamin D: The Unsung Hero in Cancer Prevention, Immunity, and Hormonal Health

Written By Ryan McWhorter

When you think of vitamin D, what comes to mind? Sunshine, bone strength, maybe immune support?

While it’s true that vitamin D helps with those things, what most people don’t realize is just how far its benefits reach especially when it comes to cancer prevention, autoimmune support, and hormone health.

At Alabama Functional Medicine, Dr. Ryan McWhorter has been recommending vitamin D to his patients for more than 20 years. And after decades of observation, research, and real-world outcomes, he believes it’s one of the most powerful tools in our functional toolkit, especially for women looking to feel safe and strong in their own bodies again.

Let’s break it down.

What Does Vitamin D Actually Do?

Vitamin D plays a surprisingly complex role in your body. Here are a few key functions:

  • Helps regulate cell growth: One of the most striking benefits of vitamin D is its role in preventing abnormal or uncontrolled cell growth (i.e. cancer).

  • Supports your immune system: It helps your body see what doesn’t belong, including mutated or abnormal cells that could become problematic.

  • Prevents new blood vessels from feeding young cancers: Vitamin D blocks the “call for help” that abnormal cells send when they try to create their own blood supply. Without that supply, they wither.

  • Reduces inflammation: Which is foundational for healing everything from joint pain to hormone imbalances and even autoimmune flares.

Why D3 with K2 (and a Boost of Iodine)

The form of vitamin D you take matters. At Alabama Functional Medicine, we recommend a highly bioavailable Vitamin D3 with K2 and Sea Iodine—and here’s why:

  • K2 ensures calcium goes where it belongs—into your bones, not your arteries. It also supports healthy teeth and cardiovascular function.

  • Iodine supports healthy thyroid function and reproductive organ health (think breast, prostate, uterus, ovaries), and may provide additional protection against hormone-related cancers.

  • Together, they form a trio that supports immunity, hormone balance, and long-term cellular health.

This is why we offer this exact combo through our Saluxis Essentials Vitamin D3 + K2 + Iodine formula. It’s a powerful, once-a-day supplement designed to do more than just "cover your bases."

Who’s at Risk for Low Vitamin D?

Almost everyone. But especially those who:

  • Spend most of their day indoors

  • Wear sunscreen daily (important, but it blocks vitamin D production)

  • Have darker skin tones (melanin reduces synthesis)

  • Live in cloudy or northern climates

  • Have absorption issues (like IBS, Crohn’s, or a history of gallbladder issues)

In Alabama, Dr. McWhorter routinely sees vitamin D levels in the 20s or 30s in patients who aren’t supplementing, which is far below optimal.

How Much is Enough?

The commonly recommended range for vitamin D is 50–80 ng/mL. But after decades of clinical experience and research review, Dr. McWhorter prefers 90 ng/mL. In fact, he maintains this level in his own bloodwork.

Not every doctor agrees on that target, but for his patients, he’s seen the outcomes: better immune resilience, fewer hormone crashes, less cancer recurrence, and stronger bones.

That said, you should always test your levels before supplementing aggressively. We offer in-house testing and help patients dial in the exact dose their body needs.

What Else Can Vitamin D Support?

Besides cancer prevention and immune strength, Vitamin D may also help with:

  • Autoimmune conditions like lupus and rheumatoid arthritis

  • Metabolic issues such as insulin resistance or blood sugar imbalance

  • Mood disorders including seasonal depression and anxiety

  • Osteoporosis prevention

  • Hormonal balance across the menstrual cycle and into menopause

  • Blood pressure regulation

It’s a humble supplement with outsized impact.

Final Word from Dr. McWhorter

“I don’t guess. I test. And what I’ve seen, over and over, is that vitamin D done right changes lives. We check it at least once a year for all patients—and when it’s low, we correct it. It’s one of the simplest, most effective steps you can take toward long-term wellness.”

Ready to Check Your Levels or Start Supplementing?

Ask us about adding a vitamin D test at your next appointment or shop the exact supplement we recommend from Saluxis Essentials.

Your future self and your immune system will thank you.

Email info@drmcwhorter.com for references.

Ryan McWhorter