How To Strengthen Your Immune System with Vitamin D

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Remember sick days? Laying in bed, watching daytime game shows, and drinking orange juice. Your mom pumped you with vitamin C, maybe even zinc, to help you kick whatever you had. Well what if I told you that what you really should have been taking was vitamin D?

You may have heard that you need to spend 15 minutes in the sun to get your daily dose of vitamin D. And maybe you know that it is especially good for your bones. But did you know that vitamin D helps regulate your immune system?

My “Ah-ha” Moment

I thought getting sick 4-5 times per year was completely normal. In fact, when I was in college at the University of Florida, I was constantly catching colds. I would always chalk it up to “I just have a really weak immune system”. Fast forward about 5 years: I’m in physical therapy school, living back at home, and as stressed as ever adjusting to the craziness that is graduate school. My mom got on a “natural kick” and began changing her lifestyle. One of her changes was that she began seeing a physician who was board certified in functional medicine.

After a few months of seeing the positive changes in my mom’s health, I called and made an appointment. It was as easy as a blood draw and a follow up appointment and boy, was I impressed. Among other things, I found out that my vitamin D blood value was way below the minimum for optimal functioning.

Before I tell you how this story ends, I want you to understand more about this powerhouse vitamin that does so much, yet is so under appreciated. The 5 questions I’m going to address today include:

Fast Facts

• Vitamin D is involved in hormone and chemical messenger balance, insulin sensitivity, and the immune system (Amrein et al, 2020).

• 35% of adults in the United States are vitamin D deficient (Sizar et al, 2020).

• Optimal levels in the blood are 40-80 ng/mL (Harrington, 2020).
  • A deficiency is any value below 20 ng/mL i (Harrington, 2020).

• The two main forms of vitamin D are D2 and D3 (Tripkovic et al, 2012).
  • Vitamin D2 (ergocalciferol) is plant-based.
  • Vitamin D3 (cholecalciferol) is animal-based.

Sources

• Main sources of Vitamin D in our diet include salmon, egg yolk, and fortified milk (Tripkovic et al, 2012). 

• Other sources include the sun and supplementation.

• Vitamin D is stored in our fat and is not excreted daily like water-soluble vitamins (think vitamin C and B vitamins) (Zadka, 2018).
  • This makes it ideal for taking weekly!

Immune System Bodyguard

There are two forms of vitamin D that we can supplement with: vitamin D2 and D3. Unfortunately for my vegan friends, vitamin D3 has been shown to increase blood levels of vitamin D more efficiently (Tripkovic et al, 2012). Most fortified foods contain D2, so your best bet is supplementation with D3 in addition to getting much needed sunshine.

Vitamin D helps to decrease inflammation from acute respiratory tract infections (like the flu) and talks to cells that turn on our immune defenses (Bivona et al, 2018). One study that looked at data from over 11,000 subjects found:

• People who supplemented got sick less than those who didn’t (Martineau et al, 2017).
• For those with deficiencies below 10 ng/mL, supplementing cut their risk of getting a respiratory infection in half (Martineau et al, 2017).
  • “Vitamin D supplementation was 10 times more effective than the flu shot at preventing the flu.”
• The risk of getting the flu was the same for those with high vitamin D levels as those who received a flu shot (about 10%) (Martineau et al, 2017).

Vitamin D supplementation was 10 times more effective than the flu shot at preventing the flu.

Martineau et al, 2017

How Did Vitamin D Help Me?

I consistently began taking a weekly, high dose of vitamin D about 1 year and a half ago. In this time, I have not been sick. Through flu season and COVID, working with children in an outpatient clinic, and even being around a sick husband/son, I have not been sick ONCE. You have to understand that this is shocking for me for two reasons.

First, in the last 10+ years I have easily gotten sick 4 dozen times so to experience a sniffle-free year seems like a miracle. Second, it really is as easy as taking one pill once per week. I’ve found vitamin D as cheap as 10 cents per pill, and even if you can’t afford that, I’m sure you can get it through your doctor if your levels are low enough.

I have been taking a weekly dose of vitamin D3 of 50,000 IU and have not had any related adverse reactions. I get my vitamin D3 through my physician; one bottle contains 15 pills and costs about $15. These results are my own and you should always consult your physician to determine where your vitamin D levels are at and what dosing would be right for you.

Supplementation should be paired with a nutritious diet low in processed and high-sugar foods. If your vitamin D is very low, taking an average dose of 600 IU may not be enough to raise your levels significantly. To get the biggest bang out of your oral vitamin D, taking magnesium and vitamin K2 could boost its effects. As always, you should consult your physician before taking any supplementation.

Too Long, Didn’t Read

If you find yourself constantly run down and sick (insert your toddler sneezing in your face), ask your doctor to check your vitamin D levels and talk to them about supplementation. I highly recommend searching for a physician certified in functional medicine near you. They look at you holistically and strive to make improvements in your health by making sure your blood levels (and hormones!) are all where they are supposed to be. You can find one through a simple google search including your area code. As my doctor would say, our immune system is supposed to be hard at work fighting off cancer, NOT being knocked out by the common cold.