Vitamin D: Why Is It Important?

What Is Vitamin D?

Vitamin D is a fat soluble vitamin, like Vit A, E & K.
Although it is present in foods, it is not present in many foods, nor is it in abundant supply. We can get Vit D from the sun, and this is certainly a good idea, but we will touch on why this is often not enough, especially in colder climates like most of Canada. Supplementing and fortifying foods with Vitamin D is also something that helps, but again the question we should ask ourselves is, are we getting enough?

Inactive vs Active Vitamin D
Vitamin D collected from the sun, diet and some supplements are in the inactive form, which means it needs to be converted by the body to its active form.
- Liver --> Vitamin D --> 25 hydroxyvitamin [25 (OH)D] or calcidiol (D2).
- Kidneys --> physiologically active 1,25 dihydroxyvitamin [1,25 (OH)2D] also known as calcitriol (D3).

 What Does Vit D Do in the Body?

There are a number of important jobs that Vit D does:

• Promotes calcium absorption in the gut
• Maintains appropriate calcium and phosphate levels in the blood
• Normal bone mineralization
• Ensures that muscles contract properly
• Monitor cell growth
• Modulate cell differentiation and death
• Neuromuscular and immune function
  
• Activation of various genes and their associated proteins

Measuring Vitamin D status
Generally the next question I get from a lot of people is how do I know if I'm getting enough Vit D. Currently the best way to do this is to measure it in the blood by look at the blood or serum concentration of calcidiol (D2). Wait, didn't I say that the active form is calctriol (D3)?  The reason is the 1/2 life of D3 is too short to make it a good indicator as well as it being regulated highly regulated by parathyroid hormone, calcium and phosphate. D3 levels also do not normally decrease significantly until Vit D deficiency is severe. 

How Much Vit D is Needed?
If we understand how important Vit D is, the next thing my patients often ask is how much do I need?
As we mentioned above, to know if you personally are getting enough, getting your levels checked is going to be the best option. However, there are general recommendations made by the government which are based on what is called the RDA or Required Daily Allowance.  This depends on the average of what works best for a healthy population and maintaining basic requirements for health. In the case of Vit D that's enough to bone health and calcium metabolism, and then in addition the RDA is set based on minimal sun exposure as well. All of this combined, the current daily recommendation for adults and children over 4 years is 400 IU.

If we're trying to raise our levels of Vit D, 400 IU is definitely not going to be enough.

Food Sources: Can I get Enough?
There are a few sources of dietary Vit D:
- Fatty fish such as salmon, makerel, and tuna or good quality fish oil products
-  Beef liver, egg yolks, and cheese will have small amounts
- Some mushrooms provide D2 in variable amounts

The good news is the body is primed to absorb food dietary Vit D, as it is often in the active form (D3) and this appears to be 5 times more potent that the parent vitamin based on some studies.

Fortification
I know there's lots of foods that have Vit D on the label, doesn't that mean there's Vit D in it? It's true, that in Canada we have been fortifying foods with Vit D since the 1930s. The main sources are milk (35-40 IU/100ml) and margarine (equal to or more than 530 IU/100g). Many other dairy products do not fortify (cheeses and ice cream), while others food products like orange juice, yogurt, and breakfast cereals do. Manufacturers are also not always required to list Vit D or how much, so that makes it challenging to estimate as well.

Can I Get Enough from the Sun?

Most people meet at least some of their Vit D requirements from the sun. However, what most people don't realize is that this depends. You need to be outside at the right time of day, and depending on where you live, time of year as well. We need to be exposed to UVB rays at wavelengths of 290-320 nanometers. Other factors that can affect this are: cloud cover, smog, melanin content of your skin (the darker your skin the more difficult it is to 'absorb' enough sun).

Optimal Sun Exposure
The factors previously mentioned and current research that's been done still makes it challenging to know exactly what the right amount of sun exposure is for each person. However, these guidelines are helpful to get some helpful exposure:
- In general, approx 5-30 mins of sun exposure between 10am -3 pm twice a week to arms, face, neck. legs or back without sunscreen [NOTE: if you are monitoring risk for skin cancer, than keep in mind any recommendations from your healthcare provider]
- Spring, Summer and Fall are the optimal times of year, particularly those who live in more northern latitudes

Can I Take Too Much?
Generally speaking you would need to be taking a lot of Vit D to cause harm. The general thought currently is taking 10,000 to 40,000 IU a day consistently for a prolonged length of time. The blood level would be more than 500 nm/L that would be considered toxic. The research is still determining what that exact level would be. The symptoms of Vit D toxicity are not very specific: anorexia, weight loss, polyuria (aka peeing a lot), and heart arrhythmias. If you are at all concerned, please do speak to your health care provider.

Take Home Message
- Vit D is important for our overall health, and we're still figuring out the full extent of what this entails
- Vit D is present in the diet, and through exposure to the sun we are able to synthesize Vit D
- The drawback is it's tough to determine how much we're getting, so many of us will need to supplement with it at times
- There are safe and unsafe levels of Vit D, and finding out what works best for us personally is likely going to require getting our levels checked periodically.



Have questions about Vitamin D or making sure you're getting what you need to live your best life? Connect with me and we can get a personalized plan together that takes your individual needs into account.




Note: Talk to your Naturopathic Doctor today about getting assessed and treated if needed, and as always talk to your health care provider before beginning any new medication or supplement. This information is not meant to replace the advice/guidance of a medical professional, nor should it be acted upon by individuals unsupervised by the appropriate healthcare provider.