GS-Fitness/CORE Boot Camp: Sun Exposure and The Vitamin D-ilemma.

Vitamin D deficiency has become the most common health condition worldwide. It is associated with the cause of rickets in children, decreased bone health in adults and decreased cognitive function in the elderly. Every tissue in the human body has a vitamin D receptor because vitamin D plays a major role in so many physiological functions that aid in the prevention of common diseases such as cancer, diabetes, hypertension and many illnesses that effect the elderly. Here are ten things to know about vitamin D and how to obtain the recommended daily allowance (RDA).

How does body make D from sun? Let’s start by having a better understanding of the science behind how the body obtains vitamin D from the sun. When the ultra violet radiation (UVB) rays hit your skin it sets off a chemical reaction that converts a prohormone in the skin into vitamin D. Once you make vitamin D in your skin it goes to the liver and then the kidneys to get activated.

How much vitamin D is necessary on a daily basis? 600 IU per day for humans aged 1 year up to age 70. 700-800 IU for people 70 years of age and over.

Vitamin D is rare in foods. Dairy contains 100 IU per serving, which means an adult would need to drink six glasses of milk per day. Cod liver oil by far has the highest vitamin D content. Salmon, mackerel, and herring are close seconds. Farm raised fish has next to no vitamin D content at all. Wild caught fish is a much richer source of vitamin D. Mushrooms that have been exposed to UVB rays are also a great source.

You can never make too much D from sun exposure. If you’re exposed to sunlight, your body will make vitamin D and it will stay with you 2x longer than any diet source.

When is best time to be out in sun? 10am-3pm is best time to absorb vitamin d. Almost all vitamin D rays are being absorbed by the ozone layer before the hours of 10 Am and after the hours of 3 pm.

How great is the risk of melanoma from sun exposure? Most melanomas occur on the least sun exposed areas. Occupational sun exposure reduces risk for melanoma. In 1915 research found that indoor workers had eight times more chance of dying from cancer. 1941 people living in the northeast had a higher risk of cancer death than people living in Florida or Georgia. Activated vitamin D inhibits cancer cell growth.

How does the use of sunscreen impact vitamin D production? Sunscreen with SPF 30 reduces ability make vitamin D from sun exposure by 95-98%. Going out into to sun to the extent of skin obtaining a light pink tint = 20,000 IU vitamin D
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Does skin color impact how much vitamin D is or can be made? African Americans need 4-10X the sun exposure than a Caucasian to produce the right amount of vitamin D for their bodies. It’s known that African Americans have a higher incidence of heart disease, diabetes, cancers, and infectious diseases. A conclusion can be drawn that vitamin D deficiency is at least a factor in the cause.

How much exposure is a healthy amount to promote vitamin D production? 5 to 15 minutes 2-3x/week. Protect the face. Get the 5-15 minutes of exposure on arms and legs to elicit vitamin D production in skin and body, then apply sunscreen.

Does a person’s body size impact how much vitamin D is needed? Obese people need 2-5x more vitamin D in order to prevent vitamin D deficiency and any disease related to D deficiency.

How can you tell how much vitamin D you are making from the sun? There is a mobile application. http://dminder.info. This app will tell you how much vitamin D can be made from your location at the current time. Enter in your skin type and the app can tell you how much can be made.


Resources:
1. Michael F. Holick –“ The D-Lightful Vitamin D for Good Health.” https://www.youtube.com/watch?v=Lvogqa3BWVE.
2. U.S. Department of Health and Human Services. National Institute of Health. “ Vitamin D Fact Sheet for Health Professionals.” Ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/

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