Vitamin D Supplementation & Sunshine Went Head To Head In This Study

Despite its key role in bone, muscle, and immune health, half of the U.S. population is not getting the vitamin D it needs to support whole-body health.* To be specific, 29% of American adults are deficient in vitamin D, while 41% are insufficient1.

A 2021 study conducted in Korea put these two methods of getting vitamin D to the test. Vitamin-D-deficient participants were given the choice between sunlight exposure and a modest level of oral vitamin D supplementation (1,000 I.U. of D3 taken daily, to be exact). 

Serum 25(OH)D levels (i.e., the blood biomarker for vitamin D status) were evaluated at the beginning and end of the three-month study to document changes. The sunlight exposure group had no significant increase in average serum 25(OH)D levels, while the oral supplementation group saw an average serum increase of 11 ng/ml at the end of the three months. 

In other words, vitamin D levels increased in participants that took 1,000 I.U. of vitamin D3, while those exposed to the sun experienced no significant changes. This confirmed what mindbodygreen has known all along: Vitamin D supplementation is the most effective and efficient method of raising vitamin D to levels of sufficiency.* 

With the many factors that affect our exposure to sunshine and ability to convert it into this essential vitamin—such as geographic location, season, climate, UV levels, pollution, clothing, sunscreen, age, and skin tone—we simply can't rely on sunlight when it comes to getting enough vitamin D.

While it's clear vitamin D supplementation is an effective way to promote sufficient D levels, there are a lot of inefficient supplements out there that might not do the trick due to their subpotent or ineffective formulas. As Ferira expounded, this study confirms that taking 1,000 I.U. is the rule-of-thumb to raise vitamin D serum levels approximately 10 ng/ml in healthy adults. That's why we recommend an even higher daily dose of 5,000 I.U. for adults (3,000 I.U. at the absolute minimum to avoid clinical insufficiency cutoff of 30 ng/ml).