Keeping Bones Strong — Focus on Vitamin D Supplements

Betty Chaffee/ May 11, 2020/ Dietary Supplements, Self management/ 2 comments

Vitamin D is one of the most commonly used dietary supplements. But what does it do? And who really needs to take supplements? Let's talk about how vitamin D works, how much you need to stay healthy, and whether dietary sources can meet your daily needs.

Functions of vitamin D

The main function of vitamin D is to help the body absorb dietary calcium and to regulate the levels of calcium and phosphorus in the blood. By doing this, it plays a major role in maintaining bone strength and preventing osteoporosis. Vitamin D also plays a role in the life cycle of cells in the body, and has an effect on the immune system. Over the years, claims have been made that vitamin D can prevent certain types of cancer, improve balance and help prevent falls, and generally improve health and lengthen life. But most of those claims havn't been proven. The only thing we know for sure is that vitamin D is essential to keep bones strong.

Where can you get your vitamin D?

You've heard me say on many occasions that it's best to get nutrients from the diet instead of supplements. Here is that exception to the rule! There are very few foods that naturally contain vitamin D. In fact, vitamin D is the one of the only nutrients your body makes on its own. When skin is exposed to sunlight it starts making vitamin D. It turns out that fifteen minutes of full sunshine can provide enough vitamin D to carry you through several days. Skin type makes a big difference, though. Aging and dark skin are less efficient than young and light skin at producing vitamin D. Not only that, but the sunscreen and protective clothing we use to prevent skin cancer also prevents skin from making vitamin D . And some regions of the world just don't get enough sunlight year-round (like Michigan, where I live). So if you live in an area with less sunlight, consistently cover sun-exposed skin with clothing or sunscreen, have dark or aging skin, or rarely get outdoors, it may be time to consider taking vitamin D supplements.

Daily requirements of vitamin D

Most people need between 400 and 1000 units (10 - 25 mcg) of vitamin D daily to keep bones healthy. If your blood level of vitamin D is low, you may need higher doses for a while to replenish your body's stores. But even if you have a normal blood level you still need to get enough vitamin D to keep it that way. Side effects and drug interactions are uncommon at recommended doses.

Which supplement should you choose?

There's a wide variety of vitamin D supplements. Here are some things to think about when choosing the product that's right for you.

Vitamins D2 (ergocalciferol) and D3 (cholecalciferol) are both available over the counter.  They have slightly different chemical structures, but they're equally effective. And there's no difference in the recommended daily dose. People with low blood levels of vitamin D are often prescribed vitamin D2 initially, followed by a daily dose of vitamin D3. But you may find that vitamin D3 is much easier to find on the pharmacy shelf. In reality, either one can be used safely to maintain bone health. 

Some of the same things we said about calcium supplements apply to vitamin D supplements, too. An important one -- if you already take a daily multivitamin, you may be getting all the vitamin D you need. If the label says there's between 400 and 1000 units (or 10 to 25 mcg), you're getting the amount most people need.

If you plan to take both calcium and vitamin D, consider a product that has both. That'll decrease your cost as well as the number of tablets you have to take. It'll take a bit of time to look through all the products on the shelf to find one that's right for you. Review our last article if you need a refresher on how much calcium to take. 

Here's another thing you've heard me say many times - read labels carefully! Vitamin D tablets are available in many different doses, so be sure you're getting the dose that's right for you. And be sure the product has been checked for potency and purity by looking for a brand name you trust or a product that has a Seal of Approval.

Keep your bones healthy and strong by getting enough vitamin D!

Bones are one of the body's organs that allow us to stay active and healthy as we age. Make sure you're getting the right nutrients to keep your bones as strong as possible. If you have a health concern that has you wondering if you should take vitamin D, ask your doctor's advice or leave a comment here. You can also send a secure message to BetterMyMeds by contacting us directly.



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About Betty Chaffee

Betty Chaffee, PharmD, is owner and sole proprietor of BetterMyMeds, a Medication Management service devoted to helping people get the maximum benefit from their medications.


  1. Great post that got me thinking. Do you know if your skin reacts the same, as far as its production of vitamin D, by using tanning booths? I’ve never been in favor of tanning booths, but maybe this is one benefit that should be considered.

  2. A great question, Tony!

    It turns out that tanning beds use the same light rays (UVA and UVB) that are in sunlight. UVB light is what allows the skin to make vitamin D. Problem is that UVB light is also what increases the risk of skin cancer. So in the end, it appears that tanning beds aren’t a safe way to get vitamin D..

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