Australian researchers conducted a study monitoring vitamin D levels in the blood of people who regularly used sunscreen with SPF 50+ throughout the year. This type of sunscreen can block up to 98% of ultraviolet rays.

The Impact of Sunscreens on Vitamin D Synthesis

Dermatologists recommend the consistent use of sunscreen to protect against harmful ultraviolet radiation, which increases the risk of skin cancer. However, there have been concerns that using such creams might interfere with the production of vitamin D, which is synthesized in the skin under the influence of sunlight. Many of these studies were conducted in laboratory settings using UV lamps, so their results are not always directly applicable to real-life situations.

Study Design

A group of Australian medical professionals set out to determine how regular use of high-SPF sunscreen affects vitamin D levels in real-world conditions. The study involved 639 men and women aged 40 to 64 who had not previously used sunscreen regularly and did not take vitamin D supplements.

The participants were divided into two groups. One half received instructions to systematically apply SPF 50+ sunscreen on days when the UV index was forecasted to be 3 or higher. The second group (the control group) used sunscreen at their own discretion.

Blood samples were taken from all participants before the start of the study and again one year later to measure vitamin D levels (25-hydroxycalciferol, 25(OH)D). The final analysis included data from 628 people—11 were excluded due to missing follow-up samples.

Results and Conclusions

At the beginning of the study, the average 25(OH)D level was similar in both groups: 63.5 nanomoles per liter in the main group and 62.1 nanomoles per liter in the control group. The researchers compared these values with the results after one year, taking into account initial vitamin D levels, regional UV intensity, and individual sun exposure (time spent outdoors and type of clothing).

It was found that among those who regularly used high-SPF sunscreen, vitamin D deficiency (levels below 50 nanomoles per liter) was observed in 46% of participants, compared to 37% in the control group.

The authors concluded that consistent use of high-SPF sunscreen can indeed lower vitamin D levels compared to irregular use of such products. However, this does not mean that skin protection should be abandoned: sunscreens remain a crucial element in skin cancer prevention, as confirmed by numerous studies.

Recommendations

Australian experts note that people who regularly use high-SPF sunscreens may need to take additional vitamin D supplements to maintain healthy levels in the body.