Flyer Health: Vitamin D

You may have heard of rickets before, but it’s not likely that you’ve had it. It’s also unlikely that you even know anyone who has had it. That’s kind of amazing, considering that only about 100 years ago, rickets was nearly universal in certain populations, even in America.

As you may know, rickets is a disease characterized by weak, unmineralized bones owing to a severe Vitamin D deficiency. When a Vitamin D deficiency gets to the point that your bones are literally bending under the weight of your body, you know it’s bad news. Fortunately, the incidence of rickets has fallen dramatically from what it was a century ago, but the bad news is that many people still may not get enough Vitamin D.

What is Vitamin D?

Vitamin D is an essential nutrient that we cannot make ourselves, at least not without some help. But unlike the other vitamins like A, B, C, and E, which we must get from our diet, we can actually get Vitamin D from a couple different places. Like the other vitamins, we can get it from certain foods, but we can also make it in our skin when we get enough sunlight.

Vitamin D is needed by your body in order to absorb calcium from your intestinal tract–without Vitamin D, calcium that you eat cannot be absorbed from your gut. Calcium is needed at all times by every cell in the body, however, and when you don’t absorb enough calcium from the gut, your body will “borrow” some from your bones to keep up with basic cellular functions. This is why Vitamin D deficiency can lead to weakened bones.

When you play with your dogs at Wilson Park on a spring afternoon, when you’re out on Beaver Lake in the summer, and even when you’re walking to lunch up and down Dickson Street, the UV rays from direct sunlight are converting a chemical in your skin called 7-dehydrocholesterol into a form of Vitamin D. It is thought that it only takes about 20 minutes of direct sunlight on your face or arms (without sunscreen) to make enough Vitamin D for the day. The body is pretty darn efficient at making Vitamin D, probably because it’s a pretty darn important nutrient.

Well, if it’s so easy to make Vitamin D, then why don’t people get enough?

Be honest–when was the last time you actually sat out in the direct sun for 20 minutes without any sunscreen? If you’re like me, the answer might be, “I don’t even know.” During the winter, I’m lucky if I see the sun at all, as I’m typically inside from sun up till sun down. In the summer, I’m lucky if I get 20 minutes of sun on a random Saturday or Sunday afternoon. Let’s face it, getting enough sunlight can be tough. And to get enough Vitamin D, you need 5-30 minutes of direct sunlight every day. And that’s not even recommended! Because as we all know, even though UV rays help us make Vitamin D, they can also just as easily damage your skin. After all, who hasn’t had a sunburn? You have to be able to find a balance between getting enough and getting too much. And that can be difficult.

Given that the many people work inside during the day, it should come as no surprise that a lot of people don’t get enough sunlight to meet their daily needs of Vitamin D. This is especially true if you have darker skin, because the pigments in dark skin actually compete with Vitamin D’s precursor for all the sun’s rays. This means that if you’re dark-skinned, you’re at an elevated risk of being Vitamin D deficient. Complicating things further is the well-established link between too much sun exposure and certain kinds of skin cancer, especially in fair-skinned individuals.

The bottom line is this: it may not always be possible, or advisable, for a person to get all their Vitamin D from the sun.

If you can’t get enough sunlight, there are still plenty of ways to get Vitamin D, however. Certain foods, such as cold water fish like Tuna, Mackerel, and Salmon, are all naturally rich in Vitamin D. Also, most milk products nowadays are fortified with Vitamin D. So if you don’t get enough sunlight, especially in the winter months when the sunlight is less intense, it’s a good idea to try and incorporate extra fish or dairy into your diet. Cod Liver oil is especially abundant in Vitamin D–one tablespoon has over 300% of your daily need!

The current recommendation is that all adults get at least 400IU of Vitamin D per day. (If you’re lactating, you need more!) To give that some context, it takes about four glasses of fortified milk to give you that much Vitamin D. That’s a lot of milk. And milk ain’t cheap. Fortunately, Vitamin D supplements are also available, and they can be an economical way to get your Vitamin D when you aren’t able, for whatever reason, to get Vitamin D from other sources.

Some studies have suggested that the recommended daily allowance for Vitamin D should be higher than it currently is by twice the current amount or more. While slightly more than 400IU of Vitamin D per day has been shown to be beneficial, it is difficult to say for sure what level of dietary Vitamin D should be suggested, because too much Vitamin D can be toxic. Vitamin D is dissolved in fat in the body, and because of this, it can be stored for long periods of time. Taking too much Vitamin D over long periods of time can potentially lead to levels of Vitamin D that are unsafe. While doctors will sometimes prescribe doses of 50,000IU to be taken once a week for people who are Vitamin D deficient, it is not safe to take extremely high levels of Vitamin D every day. Right now the best data available suggests that adults should take no more than 2,000IU of Vitamin D per day, if taken every day. If you are concerned about Vitamin D intake, and how much is right for you, it’s best to talk to your doctor about it.

Why Should I Care About My Vitamin D Levels?

There are plenty of reasons to make sure you get enough Vitamin D. This is especially true if you are dark-skinned, elderly, lactating, obese, or have limited sun exposure, because you will be at a higher risk of developing a deficiency. While the kind of extreme deficiency that leads to rickets is fairly rare, having chronically low Vitamin D levels can lead to low bone density, and potentially, osteoporosis. In this case, an ounce of prevention is worth a pound of cure indeed.

But enough with the doom and gloom–it’s a bit depressing to read about all the bad things that can happen if you don’t get enough Vitamin D. Fortunately, there are also plenty of positive benefits of making sure you get enough. For instance, Vitamin D may actually play a role in the prevention of certain cancers. Vitamin D has been shown to be protective against colon cancer, and it is thought to be protective against breast and prostate cancers as well. Finally, Vitamin D is now thought to aid in prevention of several other conditions, including diabetes, hypertension, and multiple sclerosis, but the research on this is still inconclusive.

At any rate, Vitamin D is absolutely essential to good health, and the easiest way to get it will always be from sunlight. That means you now have a legitimate medical excuse to pack a lunch basket and head out to Gulley park this weekend, or go to the lake at the next available opportunity. Any excuse to get away from the glow of your computer monitor and get a little outdoor recreation is pretty awesome, if you ask me.

For much more info on Vitamin D, go here.

[Original photo before remix: virgomerry via Flickr, Creative Commons 2.0]