Vitamin D has been nicknamed the “Sunshine Vitamin” because it is produced by your skin cells when exposed to sunlight. So, it should be easy enough to get all the vitamin D you need during the summer, right? Wrong! It is estimated that 42% of the US population is deficient in vitamin D and the number is probably worst during the colder months. Let’s try to understand the importance of this molecule and learn how to avoid a vitamin D deficiency.
What is vitamin D and why is it important?
Vitamin D is a fat-soluble vitamin that acts more like a hormone than a vitamin. Most vitamins, like the B family, for example, act as a cofactor for your enzymes, which means they are essentials to metabolize certain molecules, like carbohydrates and fats. Vitamin D on the other hand helps to promote and regulate certain functions in the body.
Here are some important roles associated with the sunshine vitamin:
- It promotes calcium absorption in the gut;
- It helps maintain an adequate concentration of calcium and phosphate in the blood by promoting their reabsorption by our kidneys;
- It promotes bone resorption (the process by which the bones are broken down by the body to release calcium and phosphate in the blood), therefore it helps to maintain the calcium and phosphate concentration in the bloodstream.
Vitamin D has other important roles in the body, including immune functions, reduction of inflammation, and the modulation of cell growth.
So, a vitamin D deficiency can lead to soft or fragile bones as you get older, which means you can be at risk of breaking a bone from a fall that would normally only lead to a small injury.
Where to get your vitamin D?
The first and most obvious is sun exposure.
With adequate sunlight exposure, your skin can produce between 10 000 and 25 000 IU per day. That would be sufficient to cover your vitamin D needs, but that means you have to go out in the sun every day of the year for a period of 10 to 30 minutes during midday. Of course, vitamin D production is affected by sunscreen, the amount of skin exposed (think winter), and the presence of clouds blocking the sun.
Then comes the food.
There is not a lot of food that provides vitamin D and when it does the numbers are not that impressive. Here are a couple of examples: salmon, trout, swordfish (yes fish got it!), mushrooms exposed to UV light (what does that even mean, do I have to take them out in the sun before I cook them??), fortified foods (which means that vitamin D has been added to) like cows milk, soy milk, and orange juice. To get a complete and detailed list you can check out this list. But who really wants to measure what they eat to make sure they get enough vitamin D? I have better things to do and I hope you do too!
Finally, the dietary supplements.
Vitamin D supplements come in two forms: D2 and D3. The latter is considered superior at high doses, so I would suggest looking for vitamin D3 supplements (which is the most common form available anyway). This, in my opinion, is the easiest way to get your daily dose of vitamin D and it is one of the cheapest supplements you will come across. If you are interested, you can always check out our vitamins and minerals section.
How to avoid a vitamin D deficiency?
First things first, how do you know if you have a vitamin D deficiency? You don’t! Unless you want to get a blood test and make sure your numbers are correct. But that means taking the time to go to the doctor and maybe pay for the test. Nobody really wants to go through all that hassle every now and then to make sure that their vitamin D level is right all the time.
So, your options are pretty simple:
- Go out in the sun every day and make sure you get enough sun exposure (but how do you really know what is enough?)
- Take the time to measure and consume enough food that contains vitamin D by consulting the table every day.
- Or just pop a pill out of a bottle to make sure you get the right dose every day in less than a couple of seconds!
How much vitamin D is enough?
The amount of vitamin D needed each day to be in an optimal concentration in the body depends on a multitude of factors. Here are a couple of examples: age, BMI, sun exposure, latitude, season, amount of skin exposed to the sun, etc. That being said, the recommended daily dose is between 1000-4000 IU. This should bring most people in the ideal range for optimal body functions.
Do I run the risk of a vitamin D overdose?
4000 IU per day is the upper safe limit fixed by the Institute of Medicine (IOM), but there are many studies that used doses up to 10 000 IU/day without any negative effects. Here’s an example.
Toxicity in humans has been observed when taking massive doses ranging from 60 000-300 000 IU per day for several months before showing signs of hypercalcemia. As you can see these numbers are way above what is recommended and cannot be attained by accident.
In conclusion, if you are considering taking vitamin D supplements to avoid a deficiency, you should follow the guideline of 1000-4000 IU per day (yes even during summer, you won’t overdose promise!). If you think that you have a vitamin D deficiency and are considering taking more than 4000 IU, I strongly recommend that you talk to your doctor before doing so! Be smart, stay healthy!