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Examining the potential for edible sunscreen

Phytochemicals in plants are well known to have positive effects on chronic conditions, such as heart disease and cancer. But certain ones could also help you avoid ... sunburn.

Study under review: Skin photoprotective and antiageing effects of a combination of rosemary (rosemarinus officinalis) and grapefruit (citrus paradisi) polyphenols

Introduction

Common knowledge tells us that using sunscreen helps prevent sun damage, yet regular application can sometimes be cumbersome. Wouldn’t it be great if we could get similar skin protection against UV light through our diet?

UVB rays primarily produce acute effects on the skin in the form of sunburns[1] (erythema, see Figure 1), while UVA rays are primarily responsible for long term effects[2] on skin quality and appearance, producing wrinkles, dryness, and loss of skin elasticity, collectively known as ‘photoaging.’

Figure 1: The effects of ultraviolet rays A and B (UVA and UVB)

Photoaging and sunburns are both[1] caused[3], in part, by inflammation and the formation of reactive oxygen species or ‘free radicals’ generated in the skin after UV light exposure. Thus, it seems reasonable to hypothesize[4] that antioxidants could help protect against damage caused by UV radiation[5]. This study used malondialdehyde[6] (MDA) as a marker of oxidative stress in the skin, as it has been shown that MDA can be produced[7] when free radicals react with lipids in the skin.

A previous study[8] by the same group reported synergistic effects of rosemary and citrus extracts in a skin cell model, showing a decrease in reactive oxygen species and reduced DNA damage after exposure to UVB radiation. The same study included a small pilot trial in humans, showing that the combination of extracts was able to increase the dose of UV radiation necessary to cause a sunburn. The study discussed here aimed to build on those results by using living humans and different doses of the extracts. The supplement tested here was a proprietary blend of plant extracts, including rosemary and grapefruit, henceforth referred to as the R-G extract.

Reactive oxygen species have been linked to UV-induced photoaging, and it is hypothesized that antioxidants can protect against this damage. Few studies have investigated the protective properties of rosemary and citrus extracts, and most of them with limited relevance to humans. This study aimed to test the effectiveness of varying doses of extracts in a larger group of women.

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