Antioxidants Protect Your Skin From Air Pollution

How Antioxidants Protect the Skin Against Air Pollution

Summary

• Air pollutants that cause oxidative stress and inflammation to the skin include ultraviolet radiation, polycyclic aromatic hydrocarbons, volatile organic compounds, nitrogen oxides, sulfur dioxide, particulate matter, ozone, heavy metals, and cigarette smoke.
• We discuss the evidence for using vitamin C, vitamin E, vitamin A, resveratrol, tea polyphenols, or soy topically or systemically to protect the skin.

The Effect of Pollution on the Skin

The skin is continuously exposed to several air pollutants shown to increase inflammatory and oxidative stress responses.¹ Some of these harmful pollutants include:

• Ultraviolet radiation^2,3
• Polycyclic aromatic hydrocarbons^3,4
• Volatile organic compounds^3,4
• Nitrogen oxides³
• Sulfur dioxide³
• Particulate matter^3-5
• Ozone^3,4
• Heavy metals⁴
• Cigarette smoke³

Ultraviolet radiation can cause DNA damage which can lead to the development of skin cancer.^2,4

Polycyclic aromatic hydrocarbons are one of the major organic pollutants implicated in causing cancer and acne by altering DNA expression and interfering with intracellular receptors.³

Volatile organic compounds are thought to cause atopic dermatitis by inducing the production of pro-inflammatory cytokines.³ Exposure to areas of high air pollution containing oxides has been associated with increased prevalence of eczema.³

Particulate matter is another one of the most common air pollutants that induces oxidative stress and inflammation.^3,5 This may lead to pigment spots, wrinkles, eczema, and skin aging.^3,5 Diesel exhaust emissions have been shown to increase the expression of protein NRF2 (which is involved in the oxidative stress response) in primary keratinocytes.⁶

Previous research has shown that ozone reduces the level of antioxidants, vitamin E and vitamin C, on the skin.^3,4 Ozone disturbs the activity of matrix metalloproteinases and reduces the skin’s microflora as well.⁴

Cigarette smoking is associated with several health conditions including psoriasis and periorbital wrinkling.³ Environmental cigarette smoke contains many carcinogens and a large amount of oxygen radical forming substances known to interact with skin, such as catechol.³ The reactive oxidants and free radicals from cigarette smoke have been associated with oxidative stress and lipid peroxidation.³

The Skins’ Natural Defense Mechanisms

The body has antioxidant enzymatic and non-enzymatic mechanisms to counter act the effects of pollution.² Some of the enzymes activated as a result of reactive oxygen species emission include glutathione peroxidase, glutathione reductase, superoxide dismutase, and catalase.² Some of the non-enzymatic antioxidants include ascorbic acid, α-tocopherol, uric acid and glutathione.²

Topical & Systemic Use of Antioxidants

Topical and systemic antioxidants have been studied for their protective effects to the skin. Specifically, vitamin C, vitamin E, vitamin A, resveratrol, tea polyphenols, and soy have been utilized in topical and systemic forms to protect the skin. One study using an oral antioxidant alongside a topical combination of vitamin E, vitamin C, carotenoids, and plant extracts from green tea, green coffee, pongamia, pinnata seed and angelica found increased epidermal thickness and reduced wrinkle volume in participants after eight weeks.⁷

Vitamin C

Topical Use

Vitamin C is one of the main antioxidants used topically to protect the skin. It can neutralize free radicals in aqueous compartments of the skin, replenish vitamin E levels, and aids in collagen synthesis.^8-10 It has been indicated to be used topically to prevent ozone induced damage, UVB-induced erythema, and apoptotic sunburn cell formation.^9,11,12

Some topical antioxidant products may be unstable. However, formulations containing red plum, high in vitamin C, have been shown to remain stable after undergoing several tests.¹³ Other stable forms of vitamin C include ascorbyl-6-palmitate, magnesium ascorbyl phosphate, disodium isostearyl 2-0 L-ascorbyl phosphate, ascorbic acid sulphate, and tetraisopalmitoyl ascorbic acid.⁹

Systemic Use

Oral intake of 100mg of vitamin C daily for four weeks was found to increase radical-scavenging activity on the skin by 22%.¹⁴ An almost doubled dose of 180mg of vitamin C over four weeks was found to increase antioxidant activity by 37%.¹⁴ Another study found oral intake of a combination of vitamin C and vitamin E to significantly reduce thymine dimer induction after ultraviolet radiation exposure.¹⁵

Vitamin E

Topical Use

The main role of vitamin E is to protect cell membranes from oxidative stress.⁸ However, vitamin E in the superficial layers of the stratum corneum is rapidly depleted when exposed to the slightest sunlight.¹⁶ Use of a vitamin E body wash has been shown to substantially increase the vitamin E in the skin more effectively than dietary supplementation.¹⁶ Multiple studies have shown topical vitamin E to reduce lipid peroxidation, photoaging, immunosuppression, and photocarcinogenesis.⁸ Topical vitamin E combined with vitamin C has a synergistic effect on the skin as well.^8,10

Systemic Use

No clinical or histologic difference were seen in a study that gave patients 400 IU of oral alpha-tocopherol daily for six months.¹⁷ Another study also found oral vitamin E supplementation unable to provide photoprotection under ultraviolet radiation induced oxidative stress.¹⁸ However, it was found to significantly reduce skin malondialdehyde concentrations which is an indicator of oxidative stress.¹⁸

Vitamin A

Topical Use

Vitamin A is commonly used in anti-aging products.¹⁰ Vitamin A can come in retinoid or carotenoid form with several derivatives.^8,10 Retinoids have antioxidant effects that induce the synthesis of collagen and reduce the expression of collagenase 1.¹⁰ Carotenoids on the skin are able to neutralize free radicals and stop lipid peroxidation as well.⁸ Retinal should be used at night because it will breakdown when exposed to light or when used with benzoyl peroxide.

Systemic Use

Dietary intervention of tomato paste, which contains high amounts of carotenoid lycopene, was found to increase the total number of carotenoids on the skin that protect against ultra violet radiation induced erythema.¹⁹ Another study found positive results on the skin with the supplementation of a synthetic lycopene, tomato extract, and a carotenoid enriched drink as well.¹⁹

Resveratrol

Topical Use

Resveratrol may help counteract the effects of pollution due to its ability to neutralize free radicals, increase intrinsic antioxidant capacity, increase mitochondrial biogenesis and its anti-inflammatory, anti-diabetic, and anti-cancer activity.^8,17 One study found a nighttime cream containing resveratrol, baicalin, and vitamin E to improve dermal thickness after twelve weeks of application.¹⁷

Systemic Use

There have been limited research studies investigating the effect of oral supplementation of resveratrol on skin protection in humans. However, a mice study found that oral administration of resveratrol delayed the progression of ultraviolet radiation induced skin tumors and reduced the conversion of benign papillomas to malignant squamous cell carcinomas.²⁰

Tea Polyphenols

Topical Use

Unfermented tea extracts have very high antioxidant activity, however, this property is removed during the production of commercialized green, black, and oolong tea.⁸ Tea polyphenols are quite unstable but have been stabilized in topical formulations by using butylated hydroxytoluene to reduce its susceptibility to oxidation.⁸ Topical application of green and white teas have been found to protect against ultraviolet radiation.^21-23

Systemic Use

Oral intake of green tea catechin extracts have been found to target the skin and have a direct effect on 12-LOX and possibly cytochrome P450 isoforms to suppress the biosynthesis of eicosanoid 12-HETE after exposure to ultraviolet radiation.²⁴ A different study found the opposite; oral intake of green tea catechins with vitamin C was unable to significantly reduce skin erythema, leukocyte infiltration, or eicosanoid response to UVR inflammatory when taken over three months.²⁵ Another study in which mice were given a polyphenolic green tea extract found greater antioxidant and phase II enzymatic activities in the lungs and small bowel rather than the liver and skin.²⁶

Soy

Topical Use

Genistein is one of the major antioxidant compounds in soy.²⁷ Topical application of this isoflavone has been shown to decrease immunosuppression and inflammation caused by ultraviolet induced oxidative damage.^8,27

Systemic Use

There is insufficient evidence available to comment on the oral supplementation of genistein and other soy derived antioxidants’ role in skin protection.