Effect of sunlight exposure on vitamin D status: A pilot randomized controlled trial

To what extent does natural sun exposure three times a week for three weeks affect vitamin D levels in fair-skinned indoor workers compared to those not receiving any extra sun exposure than the amount they receive in their day to day activity?

Status

Completed

Phases

Unknown

Study type

Interventional

Source

ANZCTR

Registry ID

ACTRN12614000863639

Acronym

D-UV

Enrollment

Registered

2014-08-12

Start date

2014-08-06

Completion date

2014-09-17

Last updated

2020-01-13

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

None listed

Brief summary

Vitamin D is essential for human well-being. Skin conversion of 7-dehydrocholesterol to previtamin D3 by UVB radiation from sun exposure remain the most abundant source of vitamin D for most humans. Available evidence suggests that relatively high proportions of people in many different countries, including in Australia and New Zealand, have low vitamin D status. However exposure to the sun causes skin cancer and it is therefore critical to develop a better understanding about possible balance between the risks and benefits of sun exposure. In particular, it is important to know how much sun exposure is needed to optimize vitamin D in different groups of people. The aim of the study is to measure the magnitude of effect of natural sun exposure three days a week for three weeks on the vitamin D level of fair-skinned indoor workers. This study will be a two-arm randomized controlled trial. Fair-skinned indoor workers aged 18 to 60 years will be randomized into two groups – control and intervention. Participants in the intervention group will be exposed to natural sunlight three days a week for three weeks while those in the control group will go about their business as usual. Blood samples will be collected from the participants pre- and post-intervention to study their levels of vitamin D. A follow up blood sample will be collected from all participants four weeks after the intervention to determine any wash-out effect. The participants’ incidental sun exposure will be monitored through UV monitors. Questionnaires will be administered to gather demographic, sun exposure and sun protection behavior as well as outdoor activity in the weekends during the intervention period. It is anticipated that this study will offer us a better understanding about the extent of effect sunlight has on vitamin D levels of people with fair skin.

Interventions

Exposure to 1 standard erythemal dose (SED) UV radiation from natural sunlight three times per week for three weeks. 1 SED, which is half the amount of UV radiation required to produce sunburn and takes about 9-12 minutes to achieve in Brisbane in the month of August and September [Samanek et al., 2006]. The dose will be monitored using a portable UV detector, which alarms when a set exposure is received.

Study design

Allocation

Randomised controlled trial

Intervention model

Parallel

Primary purpose

Treatment

Masking

Blinded (masking used) (Investigator, Outcomes Assessor)

Eligibility

Sex/Gender

All

Age

18 Years to 60 Years

Healthy volunteers

Yes

Inclusion criteria

1. Adults aged 18-60 yrs 2. Fair-skinned (Fitzpatrick skin type II-III) 3. Indoor workers (at least 80% FTE) 4. Residing in Brisbane for the duration of the study

Exclusion criteria

1. Spending more than 15 mins/day in the sun between 8 am and 4 pm 2. History of excision of keratinocytic lesions (in the last 5 years) 3. Any past history of melanoma 4. Skin photosensitivity disorder 5. Bleeding disorder (for example, haemophilia) 6. Taking vitamin D supplements and unwilling to stop taking them

Outcome results