Vitamin D: The Sunshine Vitamin

There is a lot of scientifically-backed articles on the “sunshine” vitamin - Vitamin D3. It’s one of the most popular and important vitamins known to us, and it has a good deal of research behind it.

Even popular media pieces do a decent job of breaking down important details about D3. There’s just one issue: these articles are written for the general population. Aka, not you specifically.

Articles often overload you with D3 deficiency causes and D3 benefits without noting how lifestyle, genetics and blood levels all have a role to play. These three factors are vital for determining the correct dosages, without resorting to trial and error.

Let’s keep this in mind as we dive deeper into Vitamin D3’s role in our daily lives.


What’s it Good For?

Vitamin D3 helps improve your mood, reduces anxiety and depression, and can help with weight loss, flu resistance, healthy teeth, and range of other things. The bad stuff consists of the inverse: depression, weight gain, weaker bones (osteoporosis) and muscles, and so on.

While Rootine does the heavy lifting when it comes to determining key genetic variations and blood levels in your body, you know your lifestyle best. Below are some factors you should look out for when considering how your lifestyle affects your Vitamin D3 requirements.


Feeling Like Sunshine

Your body produces Vitamin D when sunlight hits your skin. D3 is one of six compounds in the D family, though mostly D2 and D3 are paid attention to. We’ll get into the reasons behind this by the end, but in our case, we’ll focus on D3.

Some ways you might be Vitamin D3 deficient include:

  • Living in a place with very little sun (urban environments, polluted areas)
  • Being a hermit and staying indoors
  • Being overweight
  • Not eating enough fish or dairy
  • Having darker skin

You can’t change some of these factors, but diet and exercise are mostly adjustable. Fish and shellfish are major sources of D3 - salmon, sardines, shrimp, and so on. So are dairy products like yogurt and fortified milk. Exercise has also been linked to higher levels of Vitamin D.

An easy acronym to remember is FSS - food, supplements, sunlight give you D3.

But being aware of what lifestyle aspects are affecting your Vitamin D3 levels is just one piece of the puzzle. Let’s explore what D3 actually does in your body.


Calcium <3 D3

Vitamin D3 helps the uptake of Calcium from food, which is why it’s important in maintaining strong bones and preventing osteoporosis. We take a look at Calcium and the associated LCT gene here - it’s definitely worth a read.

The body has a detector that measures if you have enough D3. The associated gene is conveniently called the Vitamin-D-Receptor-Gene, or VDR. Proper amounts of D3 activate this receptor and initiate healthy processes in your body.

If you’re part of the 48% who have a disrupted VDR gene, you likely need much higher amounts of Vitamin D3 to activate the receptor.  

There’s also a cascade effect if your VDR gene is disrupted: since your body is not getting enough D3 to activate the VDR, your Calcium absorption is affected, and you might need to take additional Calcium as well.  

Nutrients or their corresponding genes are not siloed. Don’t be stuck looking at a single domino in a domino chain: you might miss out on the bigger picture.


How Much is Enough?

There’s general disagreement among MDs on the proper daily dosage for Vitamin D3. Even the editor-in-chief at the Harvard Health Letter is basically guessing it’s 2,000 IU daily, or 50 mcg. Other sources suggest 400-800 IU, or 10-20 mcg.

Also, saying that dosages above 4,000 UI (100 mcg) are toxic isn’t exactly helpful. Which is why at Rootine, we look at blood levels and specific genes that clue us in whether you’re genetically predisposed to needing more D3.

Vitamin D3 is a crucial nutrient for the absorption of calcium, maintenance of bone mass, functioning of muscles, keeping teeth healthy and boosting the immune system, it’s not something you want to trial and error until you guess right.


What about D1, D2, D4, D5, D…?

The media focuses on two Ds - Vitamins D2 (called ergocalciferol) and D3 (called cholecalciferol), with the latter being more popular. There’s debate whether D3 is more important than D2. The Institute of Medicine, for example, says D2 is just as effective as D3. Other studies suggest that Vitamin D3 is much more effective than D2, especially for older women.

We went with D3 because it is a naturally occurring nutrient within our body. When sunlight hits our skin, we produce D3, not D2 (which naturally occurs in plants).

Here’s what Dr. John Cannell, founder of Vitamin D Council (how’s that for status) says about D2: “If you take ergocalciferol, or ‘vegetarian’ vitamin D, be warned…. It does not normally occur in the human body…. It may actually partially block vitamin D actions... All bets are off in terms of measuring blood levels.”

And the mysterious D1, D4, and D5? says D1 was discovered to be “a mixture of compounds rather than a pure Vitamin D product”, so the term is not in use anymore. Vitamins D4 and D5 are more elusive: D4 is found in certain mushrooms and D5 is man-made and was manufactured as a treatment for various cancers.

There’s also D6 and D7 (!) but we think you had your Vitamin D fill by now.



Have additional questions about how your VDR gene impacts your Vitamin D3 needs? Email our Chief Scientists and co-founder, Daniel Wallerstorfer, PhD, at