Huiles végétales comme écrans solaires.

Vegetable oils against the sun's UV rays, good or bad idea?

Considered simple and natural, the act of setting aside conventional sunscreens in favor of plant-based oils is increasingly recommended for peaceful sunbathing, to the detriment of traditional sun filters that are criticized due to their potential impact on health and/or the environment. In addition to their protective, nourishing, and repairing virtues, these oils also offer sun protection that varies from one oil to another. But do they truly protect the epidermis from the harmful effects of UV rays?

Our range of sun care products for optimal skin protection against UV rays.

Substituting traditional sun protection with a vegetable oil: a misguided good idea.

While the sun is essential to our well-being due to its vital contribution of vitamin D, it is also known to cause several damages to the epidermis: skin conditions, sunburns, photoaging (sun spots, wrinkles, skin dryness...), skin cancer, etc. It has been demonstrated that the use of sunscreens significantly reduces the risk of many of these conditions. However, with the controversy surrounding sun filters as they are believed to diffuse into the body through the skin, their use raises many concerns.

To mitigate the risks associated with this absorption, vegetable oils have emerged as a viable alternative in the realm of "natural" health due to their purported photoprotective benefits. They have been reported to contain UV filters and would thus contribute to protecting the skin from the sun. Indeed, certain vegetable oils have demonstrated their absorptive power within the UVA and UVB ranges, thereby indicating potential for use as broad-spectrum UV protectors.

Several studies have been conducted to assess the actual UV protection value provided by vegetable oils. However, opinions vary with different results. An initial study conducted in 2000 revealed that raspberry seed oil would have a sun protection factor for UVB (SPF) and for UVA (PFA) of 28 ± 50 and 6.75 ± 7.5, respectively. This broad-spectrum UV protection would even be comparable to that of a sunscreen containing titanium dioxide. It would thus protect the skin against damage induced both by UVA (320 ± 400 nm) and UVB (290 ± 320 nm) due to their diffusing and absorbing capabilities.

In 2016, another study demonstrated that the SPF values for other vegetable oils range between 2 and 8, determined by the UV spectrophotometric method in the 290 - 320 nm range. As a result, they obtain the following values:

Name of the Vegetable OilINCI NameSPF Value Determined In Vitro
Olive OilOlea Europaea Fruit Oil7,549
Coconut OilCoconut Oil7,119
Castor OilCastor Seed Oil5,687
Sweet Almond OilSweet Almond Oil4,659
Mustard OilBrassica Nigra Seed Oil2,105
Chaulmoogra OilTaraktogenos Kurzii Seed Oil2,019
Sesame OilSesamum Indicum Seed Oil1,771

According to MARTINIAKOVA, in a study conducted in 2021, the SPF values of vegetable oils would be even lower than those reported so far, even for raspberry oil. The protection index against UVA and UVB of 14 virgin vegetable oils next to actual sunscreens for reference was measured, using conventional SPF tests in vitro and in vivo . The in vivo tests were carried out in the accredited laboratory of the National Institute of Public Health in Prague using the ISO 24444 method, an international standard for SPF tests.

Indeed, to assert that a skincare product provides protection from UV-related damage, European regulations require a guarantee of a minimum level of protection. The SPF must be measured using standardized methods that are internationally recognized. The majority of the tested vegetable oils would thus have values between 2.5 and 4.5 in vivo, and between 0.01 and 0.6 in vitro, with the exception of tamanu oil, which has a value of approximately 11, likely due to its high proportion of calophyllolides.

Name of the Vegetable OilINCI NameIn vivo determined SPF valueSPF Value Determined In Vitro
Argan OilArgania Spinosa Kernel Oil3.2 ± 0.70.097 ± 0.001
Avocado OilPersea Gratissima Oil2.7 ± 0.40.081 ± 0.002
Black Cumin OilNigella Sativa Seed Oil2.7 ± 0.60.072 ± 0.001
Carrot OilDaucus Carota Sativa Seed Oil2.5 ± 0.60.087 ± 0.002
Chaulmoogra OilTaraktogenos Kurzii Seed Oil3.0 ± 0.40.023 ± 0.002
Coconut OilCoconut Oil1.2 ± 0.10.004 ± 0.001
Hazelnut OilGevuina Avellana Kernel Oil2.5 ± 0.60.017 ± 0.003
Hemp OilCannabis Sativa Seed Oil2.5 ± 0.60.052 ± 0.003
Moringa OilMoringa Oleifera Seed Oil2.9 ± 0.60.071 ± 0.002
Raspberry OilRubus Idaeus Seed Oil2.6 ± 0.50.384 ± 0.016
Rosehip OilRosa Canina Seed Oil2.6 ± 0.60.215 ± 0.014
Shea ButterShea Butter4.5 ± 1.00.580 ± 0.036
Tamanu OilCalophyllum Inophyllum Seed Oil4.1 ± 1.011,170 ± 0.429
Wheat Germ OilWheat Germ Oil2.8 ± 0.60.199 ± 0.002

Reminder : Based on regulated tests, an SPF 2 can allow approximately 50% of UVB rays to pass through, an SPF 15 allows 7%, an SPF 20 allows 5%, an SPF 30 allows 3%, an SPF 50 allows 2%, and an SPF 100 only allows 1% to pass through.

Vegetable Oils: Are they effective in protecting the skin from the sun?

While these vegetable oils indeed have recorded an SPF, none appear to be high enough to provide adequate and useful protection against harmful UV rays on their own, making claims that vegetable oils can be used as sunscreen incorrect and harmful. The risk of sunburn is thus very high, especially when considering people's application habits.

However, the antioxidant and reparative effects of plant oils may play a role in supporting the skin's ability to reduce the harmful impacts of UV rays. Moreover, all these studies have evaluated the level of protection different plant oils provide against UVB rays, not UVA rays. UVA rays penetrate deeper into the skin and are responsible for premature aging and, more seriously, certain types of skin cancer, even though they account for 95% of the UV rays that reach the skin.

It is globally recommended to favor high SPF of 30 or more to help prevent cellular damage caused by the sun and reduce the risk of skin cancer in sensitive populations. Therefore, the only way to preserve one's sun capital is to apply a daily sun care product with higher protection combining mineral and organic filters, in addition to limiting sun exposure, seeking shade, and wearing protective clothing.

Note : Thanks to its high content of antioxidant flavonoids, which make it a natural sun protector (an in vivo SPF of about 20, evaluated and proven by the Hélioscience Laboratory), we have incorporated karanja oil(INCI: Pongamia Glabra Seed Oil) into the composition of our face sun creams , in addition to conventional UV filters, to benefit from the photoprotective properties of both.

Sources

  • GIRARD B. & al. Characteristics of raspberry (Rubus idaeus L.) seed oil. Food Chemistry (2000).

  • SWARNLATA S. & al. In vitro sun protection factor determination of herbal oils used in cosmetics. Pharmacognosy Research (2010).

  • CHAUHAN A. & al. UV-blocking potential of oils and juices. International Journal of Cosmetic Science (2016).

  • MARTINIAKOVÁ S & al. The real UVB photoprotective efficacy of vegetable oils: in vitro and in vivo studies. Photochemical & Photobiological Sciences (2021).

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