Don’t Guess Your Vitamin D Levels—Here’s How to Get It Right
Vitamin D is often called the “sunshine vitamin,” but it’s so much more than that. Technically, it’s a hormone that influences almost every system in your body—from supporting your immune system to balancing your hormones and even regulating your mood.
Unfortunately, Vitamin D deficiency is incredibly common, with research suggesting that more than 40% of adults in the U.S. have insufficient levels. This number is even higher for people with darker skin tones, those living in less sunny climates, and anyone who spends most of their time indoors.
In this post, we’ll dive deep into why Vitamin D matters, debunk common myths, and offer practical tips on testing and supplementation to help you take control of your health.
Why Testing Your Vitamin D Levels is So Important
You might be thinking, “I’m getting plenty of sunshine!” or “I’m already taking a Vitamin D supplement—so I’m fine, right?” Not necessarily. Vitamin D levels can vary greatly depending on individual factors like lifestyle, genetics, and overall health. Here’s why testing is crucial:
Everyone Processes Vitamin D Differently
Even if you’re spending time outdoors, the amount of Vitamin D your body makes depends on:
Skin tone: Darker skin produces less Vitamin D.
Location: If you live in northern regions or areas with lots of cloud cover, UVB rays may not be strong enough.
Sunscreen use: While sunscreen is essential for skin protection, it reduces Vitamin D production.
Vitamin D Builds Up in Your Body
Unlike some vitamins that are water-soluble (like Vitamin C), Vitamin D is fat-soluble. This means your body stores any extra Vitamin D in your fat cells. While this is great for maintaining levels over time, it also means you can take too much and risk toxicity.
You Might Be Taking the Wrong Dose
It’s common for people to guess their Vitamin D needs, but here’s the issue:
Some people are taking far too little, thinking that what’s in a basic multivitamin or 400 IU a day is enough.
Others take megadoses, believing it’s harmless, only to find their levels are dangerously high.
Symptoms Can Be Sneaky
Vitamin D deficiency often doesn’t show clear signs until it’s advanced. Symptoms like fatigue, low mood, or bone aches are easy to miss—or blame on something else. On the flip side, high levels (toxicity) can cause symptoms like nausea, confusion, or kidney issues.
Testing is the Only Way to Know Your Optimal Level
Optimal Vitamin D levels vary depending on the individual, but a range of 40–60 ng/mL is ideal for most people. Testing gives you a clear picture of where you stand so you can supplement (or adjust your dose) accordingly.
Who Should Test Their Vitamin D Levels?
Anyone experiencing fatigue, depression, or frequent colds.
People with autoimmune conditions like Hashimoto’s or lupus.
Those with limited sun exposure (e.g., office workers, people in northern climates).
Pregnant or breastfeeding individuals, as Vitamin D supports both maternal and baby’s health.
People with darker skin tones or those using sunscreen regularly, as these factors reduce natural Vitamin D synthesis.
Testing is simple, and knowing your levels can help prevent health issues before they start.
Don’t Guess, Test!
I’m so excited to offer you a simple and convenient way to prioritize your health with direct access to Vitamin D testing!
Skip the wait times and referrals, and take control of your health with ease.
Convenient testing options—visit a Labcorp location or schedule a home blood draw.
Accurate and reliable results from top-tier labs.
The ability to tailor your Vitamin D supplementation based on real data.
Vitamin D’s Role in Hormone Health
Vitamin D is unique because it functions more like a hormone than a vitamin. Here are a few ways it impacts your hormones and overall health:
Reproductive Health:
Vitamin D is essential for healthy ovulation and menstrual cycles.
It also improves sperm quality, making it important for anyone trying to conceive.
Thyroid Function:
Low Vitamin D has been linked to an increased risk of autoimmune thyroid diseases like Hashimoto’s and Graves’ disease.
Stress and Cortisol Regulation:
Chronic stress can deplete your Vitamin D levels. At the same time, Vitamin D helps balance cortisol (your body’s stress hormone), creating a healthier stress response.
Mental Health:
Studies have shown that Vitamin D deficiency is linked to depression and anxiety, particularly in women.
Myths About Vitamin D and Skin Absorption
Understanding how your body produces Vitamin D can help you make better choices for your health. Let’s debunk a few misconceptions:
Myth #1: Everyone Gets Enough Vitamin D from the Sun
While the sun is a natural source, factors like skin tone, time of year, and even age influence how much Vitamin D your body can produce.
Darker skin tones have more melanin, which reduces the skin’s ability to make Vitamin D. This means someone with darker skin may need significantly more sun exposure to produce the same amount of Vitamin D as someone with lighter skin.
If you live above the 37th parallel (think northern U.S. states or Europe), the angle of the sun in winter months isn’t strong enough for Vitamin D production.
Myth #2: Sunscreen Completely Blocks Vitamin D Synthesis.
Research shows that even with sunscreen, the skin still synthesizes some Vitamin D—just less than without it. This means it’s still possible to get some benefits while protecting your skin from UV damage.
How Your Body Makes Vitamin D (and Why Sunlight Isn’t Always Enough)
The process of making Vitamin D in your body is like baking a cake—you need the right ingredients, the perfect conditions, and enough time. Here’s how it works, step by step, in simple terms:
Step 1: Sunlight Hits Your Skin
When sunlight, specifically UVB rays, touches your skin, it starts a reaction. Your skin uses a form of cholesterol to create pre-vitamin D3—the raw ingredient for Vitamin D.
Why it’s tricky:
UVB rays don’t penetrate glass, so sitting by a sunny window doesn’t count.
If you live far from the equator, UVB rays are weaker, especially in the winter.
Sunscreen and clothing block UVB rays (and rightly so—they protect your skin from harmful burns).
People with darker skin have more melanin, which blocks UVB rays, making it harder to produce Vitamin D.
Step 2: Your Liver Gets to Work
Once pre-vitamin D3 is made in your skin, your liver steps in and converts it into a usable form called 25-hydroxyvitamin D (25(OH)D)—think of this as the cake batter.
Why it’s tricky:
If your liver isn’t working well (due to health conditions or nutrient deficiencies), this step might not happen efficiently.
Step 3: The Kidneys Finish the Job
Finally, your kidneys convert 25(OH)D into active Vitamin D (called calcitriol). This is the form your body uses to strengthen your bones, support your immune system, and balance your hormones.
Why it’s tricky:
Kidney health is crucial for this step, so if your kidneys are overworked or unhealthy, your body might struggle to activate Vitamin D.
Certain chronic illnesses or medications can slow this process.
Why Sunlight Alone Isn’t Enough for Most People
Modern Lifestyles:
Most of us spend a lot of time indoors at work, school, or home, limiting our exposure to sunlight.
Geography:
If you live far from the equator (e.g., the northern U.S., Canada, or northern Europe), the sun’s rays aren’t strong enough to help your body produce Vitamin D, especially in fall and winter.
Age:
As you age, your skin becomes less efficient at making Vitamin D.
Skin Tone:
People with darker skin tones have more melanin, which protects against UV damage but also reduces Vitamin D production.
Sunscreen and Sun Safety:
Using sunscreen is essential to protect your skin from UV damage, but it can reduce the amount of Vitamin D your body makes.
The Bottom Line: Why Supplementation is Often Necessary
While sunlight is the natural way to make Vitamin D, most of us face barriers that make it difficult to get enough. That’s where testing your levels and supplementing comes in—it fills the gap when sunlight can’t.
Pro Tip: If you do get sun exposure, aim for 10–30 minutes on bare skin (without sunscreen) a few times a week, depending on your skin tone and location. Always protect your skin if you’ll be outside longer.
So How Much Vitamin D Should You Really Take?
The amount of Vitamin D you need depends on several factors, including your current levels, age, skin tone, and where you live.
General Guidelines:
For maintenance: 1,000–2,000 IU/day is a safe range for most adults.
To correct deficiency: 5,000–10,000 IU/day may be recommended short-term under the guidance of a healthcare provider.
Why Supplementation Matters
While sunlight is an ideal source, modern lifestyles often make it hard to get enough. Vitamin D-rich foods like fatty fish, egg yolks, and fortified milk are helpful but unlikely to meet your body’s needs alone.
Choosing the Right Vitamin D Supplement
Not all supplements are created equal. Here’s what to look for:
Vitamin D3 (Cholecalciferol):
This is the natural form your body produces from sunlight and is better absorbed than D2.
Combined with K2:
Vitamin K2 helps direct calcium to the bones (where it belongs) and away from arteries (where it doesn’t).
Oil-Based or Liposomal Forms:
Vitamin D is fat-soluble, meaning it absorbs better when taken with dietary fat or in an oil-based formula.
Third-Party Tested:
Look for brands that test for purity and potency to ensure you’re getting what’s on the label.
Product Highlights
Ensuring optimal Vitamin D levels is crucial for overall health, and selecting a high-quality supplement can make a significant difference. Here are some of my top recommendations from reputable brands:
Thorne Vitamin D/K2 Liquid
This liquid supplement combines Vitamin D3 and K2 to support bone, cardiovascular, and immune health. Each two-drop serving provides 1,000 IU of Vitamin D3 and 200 mcg of Vitamin K2. The liquid form allows for flexible dosing and is ideal for those who prefer not to swallow pills.
Genestra D3 K2 Mulsion
This emulsified formula offers enhanced bioavailability of Vitamins D3 and K2. Each five-drop serving delivers 1,000 IU of Vitamin D3 and 90 mcg of Vitamin K2. The citrus-flavored liquid can be taken directly or mixed into beverages, making it a convenient option for daily supplementation.
Seeking Health Optimal Vitamin D3 + K2 Drops
This product provides a synergistic blend of Vitamin D3 and K2 in a convenient liquid form. Each drop contains 2,000 IU of Vitamin D3 and 100 mcg of Vitamin K2, allowing for easy adjustment of dosage to meet individual needs. The formula is free from common allergens and artificial additives.
Thorne Vitamin D-5000
For those needing a higher dose, this supplement offers 5,000 IU of Vitamin D3 per capsule. It's designed to support bone, immune, and cardiovascular health, and is free from gluten, dairy, and soy. This option is suitable for individuals with significant deficiencies or higher Vitamin D requirements.
Nordic Naturals Kids Vitamin D3 Gummies
These gummies provide 400 IU of Vitamin D3 per serving, supporting bone development and immune function. They are gelatin-free, gluten-free, and dairy-free, making them suitable for various dietary needs. My kids are huge fans of the wild watermelon splash flavor!
Your Next Step to Optimal Vitamin D Levels
I’ve partnered with Rupa Health, my trusted testing platform that handles all of my patients' lab needs, to bring you something truly empowering: Direct access to ordering your own Vitamin D test!
This means you can skip the wait times and referrals, and take control of your health with ease. Vitamin D is a cornerstone of wellness, influencing everything from your energy and mood to your immune system and hormone balance. Testing your levels is the first step to understanding your body’s needs and ensuring you’re staying in a healthy range.
With this service, you’ll have access to:
Convenient testing options—visit a Labcorp location or schedule a home blood draw.
Accurate and reliable results from top-tier labs.
The ability to tailor your Vitamin D supplementation based on real data.
I’ve seen how life-changing it can be for my patients to optimize their Vitamin D levels, and I want to make that same opportunity available to you. I am so excited to extend this service to my community, giving you a simple, affordable, and accessible way to prioritize your well-being!
