Folate Levels and Sun Exposure - What You Need To Know.

It's the season of sunshine, which is such a welcome break from the season of snow (at least in my corner of the world). If you have methylation imbalances, folate processing issues, or MTHFR (or any other folate-related gene SNP), your level of UV exposure could change your folate needs.

Why Would Folate Levels and Sun Exposure Be Related At All?

This seems bizarrely unrelated, because why would sunshine and folate interact at all? There are two ways they interact. One is the "Vitamin D-folate hypothesis," a theory explaining how different skin pigments evolved in various populations. The other is that UV light breaks down many substances in your body by generating free radicals, because it is a harsh and surprisingly penetrative force.

UV light, which we know by different categories (like UVA or UVB light) comes in a variety of spectrums. The table below outlines the effects of each range, as well as the tissue efects.

UV Spectrum and Tissue Penetration:

Type	Wavelength	Penetration Depth	Tissue Effect
UVA (320–400 nm)	Longest wavelength	Penetrates up to 1–4 mm into the dermis	Can damage collagen and elastin; contributes to aging and cancer
UVB (280–320 nm)	Medium wavelength	Penetrates ~0.1 mm into the epidermis	Causes sunburn; strongly linked to skin cancer
UVC (100–280 nm)	Shortest wavelength	Does not penetrate past the outermost skin layer (stratum corneum)	Mostly absorbed by dead skin; germicidal

B L Diffey Solar Ultraviolet Radiation Effects on Biological Systems,1991 Phys. Med. Biol. 36 299DOI 10.1088/0031-9155/36/3/001

UVA light is able to pass deepest into your body and has been shown to penetrate through the dermis. The dermis is the main body of your skin and includes capillaries, hair follicles, and your collagen and elastin. Also, the glands that produce sweat and oil. This is where we start to get into trouble and where we see the link between folate levels and sun exposure. It's the UV effects on your red blood cells and the nutrients within them.

UV light penetrates the dermis, allowing it to reach your bloodstream.

In a study published in the American Journal of Human Biology, the red blood cell folate levels of a population were tested, and surface UV exposure was used to determine the average UV exposure for 42 and 120 days prior to the blood test. This study showed that the greater the UV exposure, the lower the red blood cell folate across all populations, but that the effect is even more significant in people with the MTHFR C677T variant.

Data provide strong evidence that surface UV-irradiance reduces long-term systemic folate levels, and that this is influenced by the C677T-MTHFR gene variant. [...] Since UV-irradiance lowers RCF in an MTHFR genotype-specific way, there are likely implications for human health and the evolution of skin pigmentation.

• Lucock M, Beckett E, Martin C, Jones P, Furst J, Yates Z, Jablonski NG, Chaplin G, Veysey M. UV-associated decline in systemic folate: implications for human nutrigenetics, health, and evolutionary processes. Am J Hum Biol. 2017 Mar;29(2). doi: 10.1002/ajhb.22929. Epub 2016 Oct 22. PMID: 27771938.

This means, the more sunlight you enjoy, the more folate you need. Especially if you have a MTHFR C677T gene variant.

Three Things You Can Do To Protect Your Folate Levels in Exposure:

• Use a barrier sunscreen, such as zinc oxide or titanium, which work by reflecting sunlight off your skin. The more UV radiation that is reflected away, the less that is penetrating your skin.

• Take riboflavin. This study demonstrates that maintaining adequate riboflavin levels enhances the stability of folate in the presence of UV radiation. (Riboflavin is also necessary to help your MTHFR enzyme work, so this is a win all around.)

• Boost your antioxidants, especially vitamin C, vitamin E, and beta carotene. The study above also shows that these antioxidants help protect folate from breakdown by UV light, which ultimately breaks things down because it causes free radicals.

Naturally, the other thing you can do is increase your dose of MTHFR-safe folate during the summer months or when you're on vacation in the sun.