Why You Need Your Vitamin D Tested After Winter

Now is the time to test your Vitamin D levels.

Vitamin D is a hot topic in much of the health and nutrition space. We see it added into many health-promoting products and readily discussed on many blogs and podcasts.

But today I want to share with you some really important considerations around Vitamin D that may have you double checking that its part of your supplement regime (especially right now).

I talk a lot about nutrients and their connection back to alcohol, and even how to properly supplement after quitting drinking. And yes, Vitamin D is one of the nutrients that can be lowered by chronic alcohol use.

But alcohol use aside, the Cleveland Clinic reports that about 50% of the population is deficient in this critical nutrient. I would guess these numbers might be even higher if we looked at how many people have optimal vitamin D levels (more about this below).

Unfortunately, vitamin D testing is still not a required nutrient screening at our regular blood work visits. So, you may need to bring it up to your doctor at your next visit.

Here's how Vitamin D deficiencies can manifest:

Low Mood

Many studies show a link between low mood, depression, and anxiety alongside Vitamin D deficiency. Therefore, optimizing levels can be an important foundational tool for warding off mood imbalances. This is also connected to why we see a rise in mood issues (aka Seasonal Depression, or Seasonal Affective Disorder [S.A.D.]) in the winter months. If you have low mood symptoms, vitamin D deficiency must be ruled out as a possible cause!

Poor Energy

A great study published in 2024 found that vitamin D can help mitigate fatigue because of its role in mitochondrial health (our energy production center of our cells), and because of its role in promoting dopamine and serotonin production.

Cravings

Low vitamin D levels have been associated with an array of cravings. Vitamin D influences leptin levels, which help us sense fullness, satiety, and proper appetite. We have also seen links between vitamin D deficiencies and cravings toward substances, like drugs and alcohol.

Lowered Stress Tolerance

Higher vitamin D levels and sun exposure have been shown to influence stress levels. A particular study in 2023 found that vitamin D was associated with perceived stress levels and stress tolerance in active adults, eluding to the fact that a deficiency could make stress seem worse.

A Weakened Immune System

One of the long-term understood mechanisms is vitamin D's role in supporting the immune system, and even how deficiencies have been linked to the development of many autoimmune conditions, including Lupus, Multiple Sclerosis, Rheumatoid Arthritis and more. Low vitamin D has been shown to lower immune function, and supplementation has been associated with promoting a stronger immune system.

So, now that we've covered the basics, let's talk about making sure you're getting enough of this critical nutrient.

"I Get A Lot of Sun!"

You've probably heard that sunlight is the best way to obtain vitamin D, and this is true... with some caveats.

Winter is a highly problematic time for Vitamin D since most of us live in regions of the country (or world!) where the sun isn't strong enough from October through May for us to produce it.

The image below shows the 37th parallel. In the winter, the sun isn't strong enough above the 37th parallel to allow for vitamin D production via the skin. Therefore, those living above the 37th parallel will be at higher risk for deficiency (I'm looking at you, most of the country). Those living below the line may still have adequate sunlight to continue production during the winter months. So, yes, take that trip to SoCal or Miami during the winter. 

Source: Harvard Health Publishing, Harvard Medical School.

So, unfortunately, getting enough sun really isn't feasible for many of us year round. 

Getting Tested: Blood Work

The best way to understand if a Vitamin D deficiency is part of the puzzle for you is by having your levels tested! While this isn't part of many standard lab testing today, most doctors are open to adding this test to your next screening if you mention it!

You can also order a Vitamin D test online through our clinic here.

Not only does this help us understand if you have a deficiency, but the exact level helps us determine a dose that can effectively restore your levels and mitigate symptoms.

Vitamin D Levels: What's the Ideal?

Standard blood labs often report anything under 30 ng/mL as a deficiency, however, many holistic or functional practitioners recommend aiming for levels closer to, or above, 50 ng/mL.

Some studies that support vitamin D and autoimmune diseases recommend levels to reach 50-70 ng/ml for optimal immune function.

Simply put:

• >30 ng/mL: Deficiency
• 30-50 ng/mL: Sub-Optimal
• 50+ ng/mL: Optimal

Sun Tips:

As mentioned above, the sun isn't strong enough for many of us year round. However, May-October is a great time to get outside and maximize our body's production of vitamin D from the sun.

15-20 minutes of sunlight on your chest, hands and face is generally enough. But be mindful: sunscreen, glass windows, and other protection blocks the UV rays that allow us to produce. So in this case, it is helpful to get a bit of sun exposure before applying protection.

Foods:

Vitamin D is not found in many foods, which is why sunlight tends to be the "go to" for getting enough. The best source is in wild-caught fish, like salmon, sardines, herring, catfish, and a few others. Small amounts can also be found in egg yolks and fortified foods (like milk with added Vitamins A and D).

Because of the lack of foods rich in vitamin D, and a generally low consumption of fish, I recommend regular supplementation (especially in the winter) to optimize levels.

Supplementation:

I am a big fan of using Vitamin D supplementation for most of my clients, and as a general recommendation for all. I suggest using a professional grade Vitamin D supplement taken with food (as vitamin D requires fat for absorption). For those concerned about bone health, try a Vitamin D + Vitamin K supplement. I use anywhere between 5,000IU - 10,000IU per day depending on blood testing and current levels.

Tips:

1. Ask for Vitamin D testing at your next blood work visit. Your doctor may or may not already test for this, but its best to ask to make sure. You can also order a Vitamin D test online through our clinic here.
2. If your levels are low, its time to supplement! 

Want to get your vitamin D levels tested alongside a complete nutrient panel? Learn more about working with Dr. Brooke for nutrient testing here.