How much of the sunshine vitamin are you getting? One way to meet your body’s vitamin D requirements is to get sun exposure for at least 10 minutes most days of the week. But that doesn’t always work out. You may work a full-time job that keeps you indoors most of the time or live in an area that gets little direct sunlight.
You might also have higher vitamin D requirements because of the color of your skin. If you have darker skin, your skin contains more melanin. Melanin absorbs some of the UV rays that tell your body to make vitamin D. Therefore, you need more sunlight to get the same amount of vitamin D that person with lighter skin gets during the same time period.
Some people need more sun exposure to get enough vitamin D because they’re obese, over the age of 60, or have medical problems that lead to greater loss of vitamin D, such as inflammatory bowel disease. Then there’s also the problem of location.
If you live in a Northern latitude where you get little direct sunlight in the winter, you need more time outdoors to meet your body’s vitamin D needs. If it’s cold, it’s not practical to go outside with short sleeves either, so you spend more time inside under artificial lights. That won’t boost your vitamin D level!
Food as a Source of Vitamin D
Since sun exposure isn’t always a reliable source, you might turn to food to meet your vitamin D requirement. Don’t count on it! Most foods are not a good source of vitamin D, although manufacturers of some packaged and processed foods add vitamin D to their offerings. Examples are makers of some brands of breakfast cereal, yogurt, plant-based milk, dairy milk, and orange juice.
There are some natural food sources of vitamin D, but you have to eat a lot of these foods to achieve a healthy vitamin D level. For example, salmon, sardines, egg yolks, and cod liver oil contain vitamin D. Plus, if you expose mushrooms to ultraviolet light, they supply vitamin D too. When you eat these foods, you absorb some of that vitamin D.
Here’s another question. Does it matter where you get your vitamin D from–food or sun or is it all the same, assuming you get enough of it?
Vitamin D from Food versus the Sun
The form of vitamin D you get when you expose your skin to sunlight is vitamin D3 or cholecalciferol and it’s produced by a series of chemical reactions brought on by sun exposure. When the sun hits your skin, a compound on your skin called dehydrocholesterol gets converted to a vitamin D precursor. From there, this pre-vitamin D travels to your kidneys and liver where they modify it to become active vitamin D3 (cholecalciferol).
What about food? When you get vitamin D from natural food sources, such as salmon or egg yolks, it’s also in the form of vitamin D3. In contrast, foods fortified with vitamin D contain another form of vitamin D called vitamin D2 (ergocalciferol). For example, the vitamin D you get from plant-based milk or orange juice is likely vitamin D2. Does it matter whether you’re getting vitamin D3 from animal-based foods and sunlight or vitamin D2 from some fortified foods, like plant-based milk?
According to some studies, vitamin D2 is not as potent as vitamin D3. In one study, researchers gave 335 healthy women foods fortified with vitamin D2 or vitamin D3 from animal sources, like salmon. The vitamin D3 was twice as effective at boosting blood levels of vitamin D. So, vitamin D2 may be less efficient at getting your vitamin D level up relative to vitamin D3.
Another study published in the Journal of Clinical Endocrinology and Metabolism found that vitamin D3 is 87% more effective at boosting vitamin D concentrations than is vitamin D2. Furthermore, you store up to 3-fold more vitamin D when you get it in the D3 form. That’s a substantial difference!
What can you learn from this? It’s best to get vitamin D from sun exposure or a vitamin D3 supplement rather than fortified foods since some fortified foods contain vitamin D2.
What about Vitamin D Supplements?
You can buy vitamin D supplements in both the D2 and D3 form at most health food stores. Before taking one, know why you’re taking it. If you’re deficient in vitamin D, that’s a legitimate reason. However, if you’re taking high doses to ward off health problems, the evidence is still lacking.
In fact, a 2019 study in The New England Journal of Medicine found supplementing with vitamin D didn’t reduce the risk of cardiovascular disease, stroke, or cancer but it did show that participants who took vitamin D had a lower risk of dying of cancer if they developed it.
Even the bone health benefits of vitamin D aren’t set in stone. You need a certain amount of vitamin D in your body to prevent bone loss but raising your level beyond what you need to avoid deficiency won’t necessarily offer more benefits and getting too much vitamin D can be harmful.
What’s the solution? Check your vitamin D level through a blood test and if you’re deficient, your doctor may recommend a supplement. If that’s the case, look for one that contains vitamin D3 since it is more efficient at increasing body stores of vitamin D.
The Bottom Line
A healthy vitamin D level is critical for healthy bones and immune system. Sun can be an unreliable source, especially if you live far from the equator. Plus, most foods are a poor source of vitamin D too.
Start by checking your vitamin D level. If it’s low, you’ll need a supplement and your level will determine how much you take per day. If you’re not sure what your level is, it’s safe to take 800 IU to 2,000 IU per day. Buy vitamin D supplements from a reliable supplier and choose the vitamin D3 form since some research suggests it’s better for raising your vitamin D level.
References:
- Harvard T.H. Chan School of Public Health. “Vitamin D”
- 2018 Oct; 10(10): 1498. Published online 2018 Oct 13. doi: 10.3390/nu10101498.
- com. “People Have Been Taking Vitamin D All Wrong, Study Shows”
- J Clin Endocrinol Metab. 2011 Mar;96(3):E447-52. doi: 10.1210/jc.2010-2230. Epub 2010 Dec 22.
- N Engl J Med 2019; 380:33-44. DOI: 10.1056/NEJMoa1809944. January 3, 2019.
- The Lancet Diabetes and Endocrinology. Volume 6, Issue 11, P847-858, November 1, 2018.
- J Investig Med. 2011 Aug; 59(6): 881–886.doi: 10.231/JIM.0b013e31821b8755.
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