Zinc oxide is a mineral (physical/inorganic) sunscreen, which means it protects the skin from UVA and UVB rays by reflecting and scattering light. It is increasingly being used as an alternative to chemical sunscreens (also known as organic), some of which are recognised endocrine disruptors.
Iron oxide is not an approved sunscreen, but it is often added to mineral sunscreens to reduce the white cast. The addition of iron oxide to sunscreens also broadens the UV protection of mineral sun protection agents to the longer spectra of UVA and visible light. More specifically, when iron oxide is combined with zinc oxide, it can reduce the amount of UVA rays capable of penetrating the skin to 1.5%.
Visible light, particularly high-energy visible light (HEV), accounts for approximately 39 to 44% of total solar radiation and penetrates the skin in the same way as UV radiation. Like UV radiation, visible light can also lead to the production of free radicals, which accelerate skin ageing and the appearance of brown spots. A study has shown that, during sun exposure, visible light accounted for 33% of free radical production, while UV radiation accounted for 67%.
Some research suggests that iron oxide can enhance the overall sun protection provided by zinc oxide sunscreens by absorbing all wavelengths of visible light. This is particularly significant for individuals suffering from hyperpigmentation and melasma, as visible light can increase melanin production.
In a study, individuals undergoing a hydroquinone treatment were given a standard broad-spectrum SPF50 sunscreen containing zinc oxide or a similar sunscreen also containing iron oxide. They were instructed to apply it daily. While all patients saw their hyperpigmentation decrease, those who used the iron oxide sunscreen experienced significantly greater improvements.
This suggests that the combination of zinc oxide and iron oxide in a sunscreen is particularly beneficial for individuals suffering from melasma and other pigmentation disorders.
Our SPF50 face sunscreen with aloe vera contains non-nanometric zinc oxide.