The debate over daily sunscreen use has intensified, with conflicting advice about whether SPF creams are necessary in winter and whether they might contribute to vitamin D deficiency. According to Professor Helen MacDonald of the University of Aberdeen, an expert in sunlight and health, both arguments miss the mark.
Professor MacDonald explains that standard SPF only blocks UVB radiation, which is responsible for sunburn and skin cancer risk, but does not cause the visible signs of ageing. That damage comes from longer-wavelength UVA radiation, which requires a broad spectrum sunscreen with a four- or five-star UVA rating. A moisturiser labelled only with an SPF number is unlikely to offer adequate UVA protection.
In the UK, winter sun is too low in the sky for most UVB rays to reach the ground. The period from mid-October to mid-March carries the lowest risk of sunburn, while April to September is the key time for vitamin D synthesis. UVA, however, is present year-round and is less affected by season, weather, or location.
Using a broad spectrum sunscreen in winter is therefore advisable to protect skin from UVA-driven ageing, and it will not reduce vitamin D production because the body does not synthesise vitamin D from sunlight during the winter months anyway. To maintain adequate vitamin D levels, Professor MacDonald suggests skipping sunscreen for short summer exposures of ten minutes or less, and taking supplements during winter.
