Vitamin D

Written by Maria Di Iorio, RD, CD

When you hear someone say Vitamin D, what is the first thing that comes to mind? Is it sunshine, or perhaps bone health? Both would be exactly right. Vitamin D is strongly associated with sunshine and bone health but that’s not all! Let’s dive into Vitamin D to see how impactful it can be to our overall health and the benefits it can provide for athletes.

The Sun, Food, and Supplementation: How we get Vitamin D!

1. Sun Exposure:

Sunshine (UVB) + exposed skin = Vitamin D Production

Sunshine, specifically ultra violet B radiation (UVB), penetrates the skin's outer layer and after a series of different reactions within the body Vitamin D is created. Just by sitting in the warm sun with face, arms and legs exposed, your body is able to produce Vitamin D. Pretty amazing!

Although it sounds easy to walk outside and get your Vitamin D from the sun, there are a few barriers to obtaining an adequate amount of Vitamin D from sun exposure alone.

Your Skin Pigmentation: People with a darker skin pigmentation require a longer time in the sun to make Vitamin D1. Research suggests that those with a darker skin tone would need to stay in the sun up to 3-5 times longer, compared to a lighter-skinned individual, in order to produce the same amount of Vitamin D. Due to current research regarding increased sun exposure and skin cancer, it may be safer for those with darker skin tones to get their Vitamin D orally, via food and/or supplementation.

Where You Live: Those who live at a latitude above 37⁰ North or below 37⁰ South of the Equator will not be able to make enough Vitamin D via the skin during winter months due to decreased UVB exposure from the sun2. Salt Lake City, UT lies at the 40.7⁰ North latitude which falls within this range. During the winter months Utes, it will be important to focus on getting enough Vitamin D via food and/or a supplement.

SMART Sun Exposure: Let’s revisit the current research regarding sun exposure and skin cancer. It’s important to note that UVB radiation has been linked to causing skin cancer3, resulting in the increased uses of sunscreen now-a-days. The advantage of sunscreen is it blocks the absorption of UVB radiation to protect the skin… BUT WAIT… isn’t that the radiation we need from the sun to make Vitamin D? Well gosh, what is one to do? It is recommended that individuals be smart about getting their Vitamin D from the sun.

• Some experts suggest the use of sunscreen and protective clothing OVER getting one’s Vitamin D from the sun through unprotected exposure3. Instead they suggest individuals get their Vitamin D orally, via food and/or supplementation.

• Other experts suggest, no more than 10-15 minutes of unprotected sun exposure between the daytime of 10:00 am-3:00 pm4. Once those minutes are up, apply sun protection of 30 SPF or above.

• Whether you choose to follow the first or second suggestion, either way, an oral route of Vitamin D will need to be considered.

Food:

Vitamin D is not widely found within food sources but there are a few that will provide the body with Vitamin D. Egg yolks, tuna, and salmon are natural sources of Vitamin D. Other food items like milk, cereals and orange juice have been fortified with Vitamin D, meaning they do not naturally contain the vitamin but it has been added during the manufacturing process. Something to keep in mind though is that these food items, both natural and fortified, do not provide a significant amount of Vitamin D. Check out the table below to see how many International Unites (IU) of Vitamin D each food item contains.

Table 1: IU of Vitamin D per Food Item5

You may be thinking, “Well that’s great, but how much Vitamin D do I need daily to then figure out what foods or food combinations to eat?”

Excellent thought!

The Recommended Dietary Allowance (RDA) for young adults is 600 IU of Vitamin D per day. Other research suggests daily Vitamin D intakes should be greater. This is where consulting with your physician or registered dietitian is important to help you determine your specific Vitamin D needs.

Supplementation:

Supplementation with a Vitamin D3 pill, capsule, or gummy is another route to assist those in reaching adequate levels of Vitamin D in the body.

If you think you are not getting enough Vitamin D from the sun and/or your diet, supplementation can be an appropriate route to explore. It is important to first talk with your physician or registered dietitian before beginning a Vitamin D supplement. Your Vitamin D levels should first be checked via a blood draw. Once your levels are known, your health care professional can assist with determining the proper supplement and dose.

Vitamin D and It’s Role in Athletic Performance

Vitamin D and Muscle Health:

Athletes, do you know Vitamin D’s super power? Vitamin D’s super power is it’s actually a hormone that aids in processes that positively affect muscle!

Research shows that peak neuromuscular performance is associated with above adequate levels of Vitamin D in the body6. Vitamin D plays an important role in the health of Type II fast-twitch muscle fibers. Think a minute, in your sport, is it necessary for you to make quick sudden movements? If so, you are definitely utilizing these fast-twitch muscles fibers. Inadequate levels of Vitamin D in the body can negatively affect these fast-twitch muscle fibers from working at their most optimal level to provide you with the best athletic performance.

Adequate levels of Vitamin D also play a positive role in:

- Increased muscle protein synthesis

- ATP concentration

- Strength

- Jump Height

- Jump Velocity

- Jump Power

- Exercise Capacity

- Physical Performance

It can also decrease muscle breakdown and reverse muscle weakness.

Vitamin D and Bone Health:

In addition to muscle health, Vitamin D plays a vital role in bone health. You may be familiar with the importance of Calcium for bone health but where does Vitamin D come in?

Think of Vitamin D as Calcium’s BFF. If Vitamin D isn’t present, the body is unable to absorb an adequate amount of Calcium. If Vitamin D is present with Calcium, then it is able to be absorbed and utilized in building and maintaining strong healthy bones.

Additionally, adequate levels of Vitamin D in the body assists in the prevention of developing stress fractures and reducing inflammation.

Wow, all that from one tiny Vitamin… I mean hormone? Awesome!

Citations

1. Nair R, Maseeh A. Vitamin D: The "sunshine" vitamin. Journal of pharmacology & pharmacotherapeutics. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3356951/?report=printable. Published April 2012. Accessed April 23, 2020.

2. Harvard Health Publishing. Vitamin D and your health: Breaking old rules, raising new hopes. Harvard Health. https://www.health.harvard.edu/staying-healthy/vitamin-d-and-your-health-breaking-old-rules-raising-new-hopes. Published May 17, 2019. Accessed April 23, 2020.

3. Moriarty C. Vitamin D Myths 'D'-bunked. Yale Medicine. https://www.yalemedicine.org/stories/vitamin-d-myths-debunked/. Published March 15, 2018. Accessed April 23, 2020.

4. Esposito L, Kotz D. How Much Time in the Sun Do You Need for Vitamin D? U.S. News & World Report. https://health.usnews.com/wellness/articles/2018-07-18/how-much-time-in-the-sun-do-you-need-for-vitamin-d. Published July 18, 2018. Accessed April 23, 2020.

5. How to Get More Vitamin D From Your Food. Health Essentials from Cleveland Clinic. https://health.clevelandclinic.org/how-to-get-more-vitamin-d-from-your-food/. Published January 27, 2020. Accessed April 23, 2020.

6. Shuler FD, Wingate MK, Moore GH, Giangarra C. Sports Health Benefits of Vitamin D. Sports Health: A Multidisciplinary Approach. 2012;4(6):496-501. doi:10.1177/1941738112461621.