Sunlight & Supplements: Do You Still Need Vitamin D in the Summer?

Sunlight & Supplements: Do You Still Need Vitamin D in the Summer?

Vitamin D is an essential nutrient involved in bone health, immune regulation, and mood stability.

Often referred to as the “sunshine vitamin,” it’s produced in the skin in response to ultraviolet B (UVB) radiation from the sun. During the winter months, when sunlight exposure is limited, vitamin D supplementation becomes a common recommendation.

But once summer arrives and people spend more time outdoors, the question arises: is continued supplementation necessary?

Theoretically, summer sun exposure should be enough for most people to maintain healthy vitamin D levels. When skin is exposed to direct sunlight, it can synthesize adequate amounts of vitamin D, particularly between 10 a.m. and 3 p.m.

However, several variables can impact this natural process, including geographic location, time spent outdoors, skin tone, sunscreen use, and even age.

For instance, individuals living in northern latitudes or those who regularly wear protective clothing may still struggle to reach optimal levels through sun exposure alone.

It's also important to consider that excessive sun exposure carries its own risks, such as sunburn and long-term skin damage. Many individuals use sunscreen to protect themselves, which, while beneficial for skin cancer prevention, can significantly reduce the skin’s ability to produce vitamin D.

According to some studies, it has been said that sunscreen with SPF 30 can decrease vitamin D synthesis by more than 95%. This presents a unique dilemma—protecting skin health while trying to maintain adequate vitamin D levels.

Routine blood testing is the most reliable way to determine whether an individual is getting enough vitamin D, regardless of the season.

For patients with autoimmune disorders, low immunity, or bone density concerns, maintaining levels on the higher end of the range may be particularly beneficial. Integrative Medicine of Idaho often encourages personalized lab testing to inform these decisions.

Supplementation during the summer may still be appropriate for certain individuals, especially those with limited sun exposure, darker skin tones, or medical conditions that affect vitamin D metabolism.

Even in sunny seasons, daily routines—such as working indoors, avoiding peak sunlight hours, or living in shaded areas—can reduce effective UVB exposure.

Additionally, older adults and individuals with gastrointestinal absorption issues may not efficiently convert or absorb vitamin D from sunlight or food alone.

Therefore, while summer increases the opportunity for natural vitamin D production, it doesn’t automatically eliminate the need for supplementation. An individualized approach, guided by lab testing and lifestyle factors, is the best way to determine whether continuing vitamin D supplementation during the warmer months is appropriate.

At Integrative Medicine of Idaho, we emphasize personalized care and data-driven decisions to support year-round health and wellness.