Before I went to nutrition school and became a nutritionist, I went to see a naturopathic doctor for my hormone issues. She started by running a lot of labs, one was my blood levels of vitamin D. They were below range low, so she had me start taking 10,000 IU of a D3 supplement for 3-6 months, until I tested in the optimal range.

That was over seven years ago. Since then I have taken 2,000-3,000 IU in the summer months and 5,000 IU in the winter months for maintenance.

A few weeks ago I went and got my annual physical and blood work. I usually ask for my vitamin D to be measured because you never know exactly what they will run. I love my doctor, and she warned me that while she would run it, she couldn’t guarantee that insurance would cover it. And if they didn’t it could be $250 or more!

So you can see how I was surprised that my vitamin D came back low this time.

A few problems with this:

Why are we not testing D levels anyways! Especially with all the knowledge we know about it and the last 2 years!
Thankfully I did ask for it to be tested, otherwise how would I have known it was low!

WHAT IS VITAMIN D?

Vitamin D is an essential fat-soluble vitamin. This means we can’t make it in our body and must get it from outside sources like food, sunlight, and supplements. And we need to consume fats with it for us to absorb and use it.

One of the main ways we get vitamin D is from the sun. Once the sun hits our skin, it gets converted in the liver where it’s stored and then sent to the kidney’s and convert into the active form D3. It’s also a prohormone, it’s got a cholesterol-like structure and the body has receptors for it throughout.

BENEFITS OF VITAMIN D

Vitamin D helps with

Bone health
Immune health
Healthy cells and cell growth
Mood and mental health
Blood pressure regulation
Hot flashes in menopause
Works in synergy with vitamin K, boron mand calcium

DEFECIENCIES

A 2010 study estimated 42%, and other studies show as high as 80% of American adults are deficient, 70% of children are D deficient.

While another study showed 80% of those who got Covid -19 were deficient in vitamin D! The Journal of American Medical Association found that those deficient in vitamin D were 1.77 times greater of contracting COVID-19!

If you have any of the symptoms or conditions below you might want to consider vitamin D

Fatigue
Hair loss
Insomnia or trouble sleeping
Weakness
Osteoporosis or any bone health issues
Heart disease
Autoimmunity
Cancer
Immune related illnesses
Mood disorders, especially depression
Blood sugar issues

However, if you have kidney stones or excess calcium levels you might not want to supplement, talk to your doctor.

THE BEST WAYS TO GET VITAMIN D

1. SUNLIGHT

Vitamin D is called the sunshine vitamin because this is the best way to get our vitamin D levels met. But what many don’t realize is that sun can only be absorbed at:

A specific angle - when the sun is above 50 degrees from the horizon or 90% directly overhead, or your shadow should be shorter than you are tall
A certain time of day - generally 10am-2pm (mostly in spring and summer)
Direct contact to skin, meaning no clothing, no sunscreen, and no clouds in front of it

During winter months from November to March when less daylight is out this means less time for vitamin D. This can also mean colder weather, rain or snow, when we wear long layers and covering up and less time outside, which means less absorption of D. Many studies published in the Journal of Nutrition show people living in northern latitudes and those in the northern part of the US are more likely to have lower D levels.

Latitude and vitamin D production in the skin

Except during the summer months, the skin makes little if any vitamin D from the sun at latitudes above 37 degrees north (in the United States, the shaded region in the map) or below 37 degrees south of the equator. People who live in these areas are at relatively greater risk for vitamin D deficiency.

If you sit in the sun unexposed, without sunscreen, for roughly 10 minutes, you likely absorb about 10,000 units of natural vitamin D. However, keep in mind that this amount differs by location, person to person, and dependent on skin tone. The darker skin tone also has a harder time getting D from vitamin, and may need up to 2 hours daily. Some with light skin only need 10-15 minutes daily.

Additionally, with age our skin is less able to take in and convert the D in the body.

The take away here, if you are over 70, have darker skin, and live in the northern latitude you might want to get your vitamin D levels tested, and get more intentional about your sources of vitamin D.

2. FOOD SOURCES

Only 25-30 % of our vitamin D needs are met through food!

In a recent study of over 116,000 female nurses showed that in 7-days the median daily intake of vitamin D was 372 IU, well short of even the low end of 2,000 IU for maintenance! Results of this study also showed higher levels of D were associated with lower risks of cancer, as well as positively-correlated with drinking less alcohol, not smoking, being more active and eating less red meat, and more protective behaviors like high fiber intake, folate and calcium intake.*

Food Sources of Vitamin D (natural not fortified):

Raw oysters (794 IU per cup)
Fatty fish, like sardines, mackerel, wild caught salmon (up to 526 IU per 3.5 oz.)
Wild mushrooms, like maitake (393 per half cup)
Pork (120 IU per 4 oz.)
Egg yolks (44 IU per egg)
Beef liver (36 IU per 2.5 oz.)
Select Cheeses, like fontina, muenster, Monterey (up to 15 IU per half cup)

3. SUPPLEMENTATION

RDA (Recommended Dietary Allowances) is only 400 -800 IU (International Units). Most RDAs are the bare minimum needed to survive not to thrive.

You know I follow food first (they’re called supplements for a reason). HOWEVER, as you can see, vitamin D3 is one of those vitamins that we need in larger quantities than food and the sun (for most) can provide.

And because vitamin D is fat-soluble, I always advise regular blood level testing and talk to a functional medicine practitioner, like myself, about what levels are best for you to talk. Blood levels, measured as 25-OH Vitamin D, in range is 30-100 ng/mL, optimal levels are 40-80 mg/mL.

For Supplementation:

D3 form supplementation is the best for absorption
2,000-5,000 IU daily for maintenance (generally safe for most)
Buy and use quality professional brands like Thorne Research, Xymogen and MegaFoods (not sponsored, but Wellevate offers free accounts for these brands and more)

I hope you enjoyed learning all about vitamin D. If you are interested in some fun graphics, I posted a whole vitamin D series on Instagram: post 1, post 2, post 3 and post 4. Hit me up with any vitamin D questions you got below.

Reference:

US Map Image Via Harvard Medical

Map Image via: Grass Roots Health

*https://www.gastrojournal.org/action/showPdf?pii=S0016-5085%2821%2903235-2

Additional information on sun exposure per area here