Vitamin D is a fat-soluble vitamin crucial for many bodily processes. Unlike most vitamins, it can be synthesized in the skin when exposed to sunlight (UVB rays). But you should also know vitamin D is technically considered a prohormone (often simply referred to as a hormone) rather than a traditional vitamin.
Vitamin D has hormone-like behavior. Once your skin produces vitamin D (or you obtain it from your diet), it undergoes transformations in the liver and then the kidneys to become activated.
We call it a vitamin because vitamin D was first discovered in the context of nutritional deficiency (rickets in children and osteomalacia in adults). And because it can also be obtained through the diet, it was classified as a vitamin.
In modern nutrition and medicine, we continue to label it as a “vitamin” for consistency and because many people do not get enough sun exposure to synthesize adequate amounts naturally, making dietary intake or supplementation essential.
There are two primary dietary forms:
– Vitamin D2 (ergocalciferol): Found mainly in plant sources like mushrooms.
– Vitamin D3 (cholecalciferol): Found in animal sources such as fatty fish (salmon, mackerel, sardines), and egg yolks to name a few.
Why is Vitamin D important:
There are several role’s that vitamin D has in our bodies. From bone and muscle health to immune function there’s a big reason to prioritize getting enough of it.
– Bone Health: Helps the body absorb calcium and maintain proper bone density.
– Immune Function: Plays a role in immune system regulation; certain immune cells have vitamin D receptors.
– Mood Regulation: Some studies suggest a correlation between low vitamin D levels and mood disorders.
– Muscle Function: Contributes to muscle strength and coordination.
Why are we Low in Vitamin D?
In today’s modern world, there are several reasons we become low in vitamin D. Here are a few:
Reduced Sun Exposure
– Many jobs require people to be indoors for extended periods.
– Screen time (computers, smartphones) leads to less time outdoors.
– Use of sunscreen (while beneficial for skin health) can reduce vitamin D synthesis.
Geographic and Seasonal Factors
– People living far from the equator have limited UVB intensity in winter months.
– Cloud cover, pollution, or wearing protective clothing can lower UV exposure.
Lifestyle Changes
– Urban living often means less access to outdoor spaces.
– Fear of sun damage leads many to cover up or avoid direct sunlight altogether.
Who Typically Has an Issue with Low Vitamin D
Certain groups are more prone to deficiency and there are reasons why that is. There are also lifestyle factors that contribute. Here are
1. Older Adults
– The skin’s ability to synthesize vitamin D decreases with age.
– Limited mobility can reduce outdoor activity.
2. People with Darker Skin
– Higher melanin content in the skin reduces the rate of vitamin D production.
– This can require longer sun exposure to produce the same amount of vitamin D as someone with lighter skin.
3. Individuals Who Cover Their Skin for Cultural or Religious Reasons
– Wearing clothing that covers most of the body can limit UVB exposure.
4. Those with Malabsorption Issues
– Conditions like celiac disease, Crohn’s disease or other gut health issues may reduce vitamin D absorption from food and supplements.
5. Obesity
– Vitamin D is fat-soluble and may become sequestered in fat tissue, making it less available for the body to use.
6. Diet
– Inadequate intake of vitamin D–rich foods (fish, egg yolks, fortified milk).
– Strict vegan diets without supplementation.
7. Certain Medications
– Long-term use of steroids, some weight-loss drugs, and seizure medications can interfere with vitamin D metabolism.
8. Kidney or Liver Disorders
– Vitamin D needs to be converted into its active form in the liver and kidneys.
– If these organs are not functioning optimally, vitamin D levels can drop.
Best Practices for Vitamin D Absorption
If you’re going to focus on getting enough Vitamin D in your life for optimal health, here are a few methods to consider.
a. Balanced Approach to Sun Exposure
– Aim for moderate sun exposure (about 10–30 minutes, depending on skin type and UV intensity) on arms and legs a few times a week.
– Always be mindful of sun safety—avoid long, unprotected UV exposure. And be mindful of sunscreen ingredients. There has begun to be more awareness about the harmful effects that some sunscreens have on our skin.
- And eliminate seed oils from your diet. See the work of Cate Shanahan MD and learn all about how seed oils are connected to skin cancer.
b. Pair with Dietary Fats
– Since vitamin D is fat-soluble, taking supplements with a meal that contains healthy fats (e.g., avocado, nuts, or olive oil) can improve absorption.
c. Use of Supplements
– Vitamin D3 (cholecalciferol) is often considered more effective at raising and maintaining vitamin D levels compared to D2 (ergocalciferol).
– For some individuals, especially those with absorption issues, sublingual or liquid vitamin D formulations may be better absorbed.
The Relationship Between Vitamin D and Vitamin K
Vitamin D and vitamin K2 work together in a complementary way to ensure that calcium is utilized effectively throughout the body. Vitamin D enhances the absorption of calcium from the diet, helping to raise overall calcium levels in the bloodstream. However, without adequate vitamin K2, much of this calcium could end up being deposited in soft tissues, such as the arteries, rather than in the bones where it is needed.
Vitamin K2 activates proteins that direct calcium into the skeletal system and away from areas where it can lead to harmful calcification. In this way, the two are collaborators… I like to see them as “buddies.” By combining vitamin D’s role in boosting calcium absorption with vitamin K2’s function in calcium distribution, these two nutrients support optimal bone strength while helping to protect cardiovascular health.
The highlights:
Why Vitamin K Matters:
– Vitamin K1 (phylloquinone): Primarily involved in blood clotting, found in leafy greens like spinach and kale.
– Vitamin K2 (menaquinone): Plays a crucial role in bone and cardiovascular health by directing calcium to bones and teeth rather than soft tissues like arteries.
Synergy Between Vitamin D and K
– Vitamin D3: Increases calcium absorption from the gut.
– Vitamin K2: Guides that calcium to bones and away from arteries, helping to prevent calcification in arteries and other soft tissues.
Together, vitamins D3 and K2 can help optimize bone strength and reduce the risk of abnormal calcium deposits in the body. Some supplements even combine both to enhance these synergistic benefits.
Key Takeaways:
– Know Your Risk Factors: Age, skin tone, geographic location, and health conditions can affect vitamin D status.
– Embrace Balanced Sunlight: Safe sun exposure supports natural vitamin D production.
– Don’t Forget Vitamin K2: It works hand-in-hand with vitamin D3 to ensure calcium goes to the right places.
– Avoid Overdoing It: Work with a healthcare provider to understand your specific levels.
With the proper approach—safe sun exposure, a balanced diet, and possibly the right supplements—most people can achieve healthy vitamin D levels, supporting stronger bones and overall well-being.
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Disclaimer
This blog post is for general informational purposes and should not be taken as medical advice. Always consult a qualified healthcare professional before making changes to your diet or supplement routine, especially if you have pre-existing health conditions or take prescription medications.