From the Guidelines
Sunlight exposure is the most effective natural way to increase vitamin D levels without supplementation. According to a study published in the Annals of Internal Medicine 1, ultraviolet B exposure can increase vitamin D levels, although several variables such as time of day, season, cloud cover, skin pigmentation, and sunscreen use can affect the length of exposure needed.
Key Considerations
- Spending time outdoors during midday with arms and legs exposed can trigger vitamin D synthesis in the skin
- Diet can also contribute to vitamin D levels through foods like fatty fish, egg yolks, mushrooms exposed to UV light, and fortified products
- The body's ability to produce vitamin D from sunlight decreases with darker skin pigmentation, age, sunscreen use, and in northern latitudes, especially during winter months
- Regular moderate exercise may also help maintain vitamin D levels by improving metabolism and reducing body fat
Important Factors
- Include healthy fats in meals to optimize absorption from food sources since vitamin D is fat-soluble
- Be aware that sun exposure to prevent vitamin D deficiency is not generally recommended due to the increased risk for skin cancer associated with UVB radiation, as noted in the study 1
- Consider individual factors that may affect vitamin D production, such as skin pigmentation and geographic location, to determine the best approach for increasing vitamin D levels without supplementation.
From the Research
Factors that Increase Vitamin D Levels without Supplementation
- Sun exposure: UV exposure is the primary method of boosting serum vitamin D levels, which accounts for numerous health benefits 2
- Latitude, season, skin color, and sun protection determine UV absorption and vitamin D production 2
- A "little and often" exposure regime is often suggested to produce naturally recommended vitamin D levels, being essential for skeletal health 3
- In summer and spring, 1000 IU vitamin D doses are synthesized in 10-15 minutes of sun exposure for adults with 22% of uncovered skin 3
Sun Exposure Guidelines
- Public health sun protection guidelines decrease the incidence of skin cancer, but sun avoidance can cause hypovitaminosis D 2
- Sun protection strategies should still be implemented to reduce skin cancer, and sunscreen only minimally lowers vitamin D production 2
- Increasing UV exposure without causing sunburn maximizes vitamin D production 2
- Daily solar UV exposure durations needed to produce vitamin D with limited sunburn risk were estimated to be between 9 and 46 minutes in Switzerland 3
Comparison with Other Methods
- Sunlight exposure was not sufficient to overcome vitamin D insufficiency or deficiency in a clinical study, with the largest change in serum 25(OH)D observed among the vitamin D supplementation group 4
- Narrowband ultraviolet B three times per week is more effective in treating vitamin D deficiency than 1600 IU oral vitamin D₃ per day 5
- Vitamin D deficiency can increase chronic diseases and cancer, while adequate vitamin D levels can help prevent them 2