There’s a common misconception that if individuals live in sunny places, they must also make plenty of vitamin D from the sun. However, people fail to acknowledge that there are a wide variety of factors that affect the body’s vitamin D production, including (but not limited to):
- Skin pigmentation: A person of darker skin pigmentation has more melanin in their skin. Melanin blocks UVB from penetrating the skin, slowing the production of vitamin D. Therefore, if you have a darker complexion, you will require more time in the sun before acquiring the necessary vitamin D for your body.
- Sunscreen: Sunscreen blocks UVB from reaching your skin, meaning if you’re wearing sunscreen properly, you will not receive much vitamin D from the sun.
- Clothing: The amount of clothing you wear is directly related to the amount of vitamin D your body will produce when exposed to the sun. The more clothing you wear, the less skin exposed to the sun, leading to less vitamin D production.
- Your body stops making vitamin D: After your body has made anywhere from 25,000 to 50,000 IU of vitamin D, the body halts its production of vitamin D to avoid reaching toxic levels. This means that if you spend a full day out in the sun, you likely won’t get enough vitamin D to last the week. Instead, you may end up with an awful sunburn. Therefore, the Vitamin D Council recommends spending about half the time it takes for your skin to begin to burn in order to receive the maximal benefits and minimal risks from the sun.
A recent study tested the theory that individuals who live in sunny places also receive more vitamin D. The researchers measured the vitamin D status of 254 Moroccan adults. All adults were above the age of 50 years and were considered healthy. Vitamin D deficiency was defined as levels below 10 ng/ml, and vitamin D insufficiency was defined as levels below 30 ng/ml Here are the results from their analysis:
- The prevalence of vitamin D deficiency was 4.4% and 8.6% among men and women, respectively.
- A total of 85.2% and 77.4% of men and women, respectively, were considered vitamin D insufficient.
The researchers concluded,
“If the location of Morocco is theoretically between latitudes of 32° 0’ N and longitudes of 5° 00’ W, then it gets plenty of sunlight throughout the year and should not experience poor vitamin D status…Despite a sunny environment, we found in this study a high prevalence of hypovitaminosis D in Moroccan men over 50 years old and postmenopausal women.”
The researchers explained the possible reasons why Moroccan individuals have such a high prevalence of low vitamin D levels,
“Many factors can contribute to poor vitamin D status in Moroccan men and women…Indeed, Moroccan people avoid the sun and have a more pigmented skin, also their clothing style prevents exposure of the body to direct sunlight…”
The study illustrates the need to make a conscious effort to achieve a healthy vitamin D status. Unfortunately, even if we live in a location with an abundance of sun exposure, we are not guaranteed an adequate amount of vitamin D. The Vitamin D Council recommends that individuals sunbathe when their shadow is shorter than they are tall, and as mentioned before, only for about half the time it takes for your skin to begin to burn. Going out in your swimsuit will allow the UVB to reach most of your skin, increasing the amount of vitamin D your body makes. On days you cannot receive safe sun-exposure, we recommend that you supplement with 5000 IU vitamin D3.
Tovey, A. & Cannell, JJ. Nearly 90% of older Moroccan men and women have low vitamin D levels. The Vitamin D Council Blog & Newsletter, 2016.