Recent articles have highlighted the horrible irony of chemicals present in sunscreens that cause the skin to become more sensitive to the sun, leading some to wonder if natural sunscreens are, indeed, better for naturally healthy skin.

Take coconut oil, for example. Is it a safe sunscreen? Could you really sidestep all of the problems inherent in choosing a commercially produced sunblock that isn’t full of parabens, phthalates, bisphenol-A, and retinyl palmitate just by greasing yourself up with some basic kitchen staples?A number of natural sunscreens have been proposed over the years, and many older sunbathers continue to affirm olive oil as the only sun protection anyone needs. But how much protection does olive oil, sesame oil, or even lavender oil really provide? Is this just a way of marinating yourself and smelling great as you cook on the beach?

Testing Natural Sunscreens

A pretty thorough answer to these questions can be found courtesy of study carried out by Chanchal Deep Kaur and Swarnlata Saraf in 2010. They looked at the sun protection factor of herbal oils commonly used in cosmetics, by evaluating their ultraviolet (UV) absorption ability.

Volatile and nonvolatile herbal oils were included in the study, such as coconut and sesame oil, and peppermint and tea tree oil. Many of these oils are included in commercial sunscreens to make them smell good or to provide a purported benefit such as antibacterial activity or added moisturising capacity and the researchers were interested to see how much protection the oils themselves added to such formulas.

What is SPF?

Sun protection factor (SPF) is a standardised way of measuring how effectively a sunscreen (or specific ingredient) absorbs the ultraviolet radiation that causes sunburn. The minimal erythema dose (MED) is what determines the SPF given to a chemical or formula; this basically describes how long it takes for skin to show signs of burning.

To test this in the laboratory (rather than signing up volunteers to get sunburn) researchers use a spectrophotometric method designed by Mansur et al. The oils were diluted in hydroalcoholic solution and light at the wavelength of 290-320 nm (UVB) was applied to each oil sample. The results might surprise you…

Olive oil came out top of the list of those oils tested, with an SPF of 7.5, followed closely by coconut oil at just over 7. Peppermint oil, tulsi oil, and lemongrass oil were also quite protective with an SPF over 6.

All of the nonvolatile oils tested had an SPF between 2 and 8, and volatile oils had an SPF between 1 and 7. The researchers noted that oily substances are helpful in sunscreens because they more effectively spread on the skin to provide more uniform protection as well as helping protect the skin against moisture loss from heat and wind.

Simply smothering yourself in a mix of coconut oil and peppermint oil is unlikely to offer you significant sun protection however, although you might attract some complimentary olfactory attention.

UVA, UVB, and… UVC?

If you’re unsure as to how SPFs are calculated then take look at this quick primer. What you might quickly realise is that the protection afforded by these natural oils is somewhat limited. There is no clear evidence of absorption of UVA radiation (320-400 nm), or UVC radiation (200-280 nm) which is the most biologically damaging kind. UVC radiation is usually filtered by the ozone layer but this is little help for those living underneath the gaping hole in the Earth’s protective shield.

Both UVA and UVB can cause skin cancer, with the latter thought most responsible, and commercial sunscreens are required to filter out both types of rays. The lower the SPF of a sunscreen the less of these rays it screens, with a low SPF 2 product only filtering about half of the sun’s rays, and an SPF 30 screening about 97%.

Can I Use Coconut Oil as a Sunscreen?

Those who burn pretty quickly are not likely to be able to use olive oil or coconut oil as an effective natural sunscreen, needing to reapply it at least every couple of hours in order to avoid burning. Those who burn less quickly may feel a false sense of confidence in using such pantry ingredients prevent burning as the other harmful rays continue to sneak through and cause cumulative damage to cells that can turn them cancerous.

The merit, then, of coconut oil as a natural sunscreen is that it may help provide a more natural base for commercially produced sunscreens with a higher SPF that spread well, contain fewer chemicals of concern and have the added bonus of themselves providing some protection in contrast to the petrochemicals usually forming a sunscreen base.

Making Better Sunscreens Using Natural Ingredients

Natural liquid oils such as sesame, almond, coconut, and olive oil contain vitamins and polyphenols that can support skin health, such as vitamin E, carotenoids, and other antioxidants. Making a sunscreen smell nice and feel good on the skin is also helpful in that it will encourage more people to use sun protection when the alternative is an unpleasant chemical formula that is hard to rub in and that leaves skin feeling tacky.

Volatile oils such as lavender, orange, and peppermint are also helpful in that they provide physiological, psychological, and cosmetic benefits by reducing inflammation, influencing mood, and exerting an antibacterial and antioxidant effect in some cases.

What Affects the Sun Protection Factor?

Formulating a sunscreen is a complicated business as it may be that a single ingredient confers very good protection from a wide range of wavelengths but that it is adversely affected by being combined with a solvent, emulsifier, or other component in the final product.

The pH of sunscreen, it’s viscosity and ability to be effectively rubbed into the skin, and even the packaging in which the product is sold can all affect how much protection it confers. A hydroalcoholic solution evaporates quickly after application, leaving a film on the skin that sticks closely to the skin’s surface for better protection.

Why I Won’t be Relying on Coconut Oil Sunscreen

Simply slapping on some coconut oil as you sunbathe is unlikely to give you significant protection from sunburn or skin cancer but in the absence of a better option, or the ability to stay in the shade, it is likely better than nothing.

I, for one, will not be relying on coconut oil or olive oil as natural sunscreen as I burn too quickly and would need to reapply every hour or so, making it not only excessively expensive but also meaning that my skin would likely become too coated in grease to be healthy in other respects. The use of coconut oil as a natural sunscreen base seem sensible however, and it could offer a good option for people with allergies to common sunscreen ingredients.

References

Chanchal Deep Kaur and Swarnlata Saraf, In vitro sun protection factor determination of herbal oils used in cosmetics, Pharmacognosy Res. 2010 Jan-Feb; 2(1): 22–25. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3140123/

Mansur JS, Breder MNR, Mansur MCA, Azulay RD. Determinação Do Fator De Proteção Solar Por Espectrofotometria. An Bras Dermatol Rio De Janeiro. 1986;61:121–4. http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-93322004000300014

Ferrero L, Pissavini S, Marguerite, Zastrow L. Sunscreen in vitro spectroscopy: Application to UV A protection assessment and correlation with invivo persistent pigment darkening. Int J Cos Sci. 2002;24:63–70. https://www.ncbi.nlm.nih.gov/pubmed/18498497

Afaq F, Mukhtar H. Botanical antioxidants in the prevention of photocarcinogenesis and photoaging. Exp Dermatol. 2006;15:678–84. https://www.ncbi.nlm.nih.gov/pubmed/16881964

Bendová H, Akrman J, Krejcí A, Kubác L, Jírová D, Kejlová K, et al. in vitro approaches to evaluation of Sun Protection Factor. Toxicol in vitro. 2007;21:1268–75. https://www.ncbi.nlm.nih.gov/pubmed/17945463

Wood C, Murphy E. Sunscreens Efficacy. Glob Cosmet Ind Duluth. 2000;167:38–44.

Riegelman S, Penna RP. Effect of vehicle components on the absorption characteristics of sunscreens compounds. J Soc Cosmet Chem. 1960;11:280–91.