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 IU 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 IU 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.*
Nutrition scientist Ashley Jordan Ferira, Ph.D., RDN shared these additional insights: “This study is valuable for two reasons. First, it demonstrates the efficacy of vitamin D supplementation in positively affecting vitamin D status. Second, it confirms the pharmacokinetic research-backed phenomenon that predicts 1,000 IU of vitamin D3 will move the 25(OH)D ‘needle’ by about 10 ng/ml in normal-weight adults. That predictable math is the reason why we actually need much more vitamin D, around 5,000 IU or more, to achieve and maintain vitamin D sufficiency throughout life.”*