What’s the hype about Vitamin D?

As we enter into our fall and winter months, it is a great time to discuss our “sunshine” vitamin - vitamin D! Vitamin D is one of our four fat-soluble vitamins. There are two forms of vitamin D - ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). Vitamin D2 is about one-third less potent when compared to vitamin D3, which is why we see much higher doses in vitamin D2 supplements. In the United States, it is estimated that almost one in four individuals have deficient vitamin D levels (<20 ng/mL). In functional medicine, we find optimal vitamin D levels to be 60-100 ng/mL. Thus as we can see, there are likely more than just one in four individuals in the United States that are deficient in vitamin D. Now you may wonder - why are so many individuals deficient in vitamin D and where do we get it from?

We can get vitamin D from food, sun, and supplements. There is very little vitamin D found in our food naturally and in fortified foods. Despite our best efforts eating foods with vitamin D, we typically cannot meet our daily needs. 

• Vitamin D is found naturally in:

  • Fatty fish such as salmon, mackerel, trout, herrings, sardines, and tuna 

  • Fish liver oils 

  • Very small amount of vitamin D:

    • Beef liver

    • Egg yolks

    • Cheese

    • Mushrooms

• Vitamin D is found to be fortified in (may vary from brand to brand): 

  • Milk: cow’s, almond, oat, soy, and almond 

  • Breakfast cereals 

  • Orange Juice 

  • Yogurt

  • Other food products indicated as “fortified with vitamin D”

Since most food sources of vitamin D do not contain adequate levels of vitamin D to meet our vitamin D requirements, can sunshine meet our vitamin D requirements? 

The most efficient way to get vitamin D, besides a supplement, is through sunlight. Just brief exposure to sunlight (expose their face, legs, arms, and hands to sunlight 2-3 times per week for about 25% of the time it would take to cause mild sunburn) can provide our bodies with 80-90% of the vitamin D we need. It is estimated that a full day of full body sun exposure may provide the body with 10,000IU of vitamin D daily. So here is your excuse to stay outside all day! However, vitamin D production from sunline can be hindered by sunscreen, season, time of day, clouds, age, higher latitudes, and skin type. For example, in Boston there are 4 months out of the year that there is insufficient UV-B energy to produce vitamin D in the skin. Thus, vitamin D supplements will likely be necessary for individuals living in northern latitudes. 

So what about Vitamin D supplements? How much do you need? 

The amount of vitamin D we need varies depending on individuals age and can also vary based on our genetics. Because vitamin D is a fat-soluble vitamin, it is best absorbed (up to 20% higher absorption) if taken with a high fat meal or snack. The upper limit established is 4000IU per day. However, some individuals do have a genetic mutation that may require your body to need more vitamin D to meet adequate levels. 

Now that we know vitamin D deficiency is common and that it may be hard to get naturally, what is the importance of this fat-soluble vitamin? 

Probably the most known role of vitamin D is its role in bone metabolism and calcium absorption. Not only does vitamin D help with absorption of calcium, but it also helps with the absorption of phosphorus and magnesium. Calcium and phosphorus together are important for maintaining our bone health. In regards to magnesium, did you know that for every process in our body that requires energy (APT) magnesium is needed? 

Vitamin D also plays an important role in our immune health. Specifically, vitamin D down regulates IL-12 (leading to a Th1 response) and IL-23 (leading to a Th17 response). Those cytokines promote autoimmune responses when not regulated. Thus, adequate vitamin D plays a role in prevention of an autoimmune disease developing. Vitamin D also helps promote our T-regulatory immune response that directly helps prevent autoimmune, allergy, and other bacterial and viral infections from developing in our bodies.

Vitamin D may also be protective for our heart health through decreasing blood cholesterol levels, decreasing inflammatory markers (TNF-alpha) and improving blood pressure in those with vitamin D deficiency. 

A deficiency in vitamin D has been linked to an increased risk for multiple sclerosis. Through different research studies, it has been found that individuals who live closer to the equator have lower occurrences of multiple sclerosis compared to those living further away from the equator.

If we haven’t convinced you of the importance of vitamin D yet, here are a few other reasons to ensure you have adequate vitamin D levels! Deficiency of vitamin D may also increase the risk of developing Type 2 Diabetes, may lead to an increased risk of cancer (colon, prostate, and breast), and has been linked to depression.

Wondering how you can optimize your health? Consider working 1:1 with one of our Registered Dietitians for individualized, functional support!