In a recent review article published within the journal Antioxidants, scientists in the USA and South Korea discuss the advantages of topical and dietary blueberry supplementation in stopping environmental stressor-mediated skin damage and preserving skin health.

Study: Blueberry Supplementation and Skin Health. Image Credit: Subbotina Anna / Shutterstock.com

Background

Environmental stressors, including air pollutants, ozone (O₃), and ultraviolet (UV) radiation, are known to wreck skin and induce premature skin aging. Excessive exposure to those stressors can result in the chronic production of reactive oxygen species (ROS), which might suppress the cutaneous defense system, in addition to induce oxidative stress and premature aging.

Physiology of human skin

Human skin consists of three most important layers, including the epidermis, dermis, and hypodermis. The epidermis is the outermost layer of the skin and acts as the primary line of defense against environmental stressors, microorganisms, and physical trauma.

The dermis, which is situated directly beneath the epidermis, accommodates blood vessels, lymphatic vessels, nerves, and several other immune cells, including fibroblasts. The hypodermis, which can also be generally known as the subcutaneous layer, is a thick adipose tissue layer that has many essential functions, including water storage, absorption of lipophilic compounds, and protection.

The cutaneous defense system consists of several enzymatic and non-enzymatic antioxidants that act in synergy to scavenge ROS, prevent lipid peroxidation, and suppress inflammation.

Catalase, superoxide dismutase, and glutathione peroxidase are the most important enzymatic antioxidants which can be present at higher concentrations within the epidermis than within the dermis. Non-enzymatic antioxidants mainly include vitamin C, vitamin E, glutathione, uric acid, and ubiquinol, all of that are also present at higher concentrations within the epidermis than within the dermis. 

Environmental stressors

A certain level of UV light exposure to the skin is important to provide vitamin D. Nonetheless, prolonged exposure to UV light can result in severe skin complications, including skin cancer.

Pollutants emitted from power plants, chemical plants, and cars are major sources of O₃. Each day exposure to high levels of O₃ can result in cardiorespiratory complications and skin adversities.

Particulate matter (PM) is the foremost air pollutant produced by industrial waste products, the burning of fossil fuels, volcanoes, dust storms, and forest fires. Ultrafine PM is thought to cause skin barrier dysfunction and atopic dermatitis.

The first mechanisms involved in environmental stressor-mediated skin damage include chronic production of ROS, suppression of cellular antioxidants, induction of oxidative stress, and DNA damage.

Bioactive compounds in blueberry

Blueberries are a wealthy source of many bioactive compounds with antioxidant, anti-inflammatory, immunomodulatory, and antimicrobial properties, including flavonoids and other polyphenolic compounds.

Anthocyanin is the foremost polyphenol in blueberry, which is chargeable for its blue color. This compound has strong antioxidant, anti-inflammatory, and antibacterial properties.

Other polyphenolic compounds in blueberries include flavonols, ellagitannins, proanthocyanidins, hydroxycinnamic acids, gallotannins, and hydroxybenzoic acids. Upon consuming blueberries, these compounds undergo significant modifications during metabolism, thereby resulting in the generation of several polyphenolic metabolites that could be detected within the blood.

Catabolism of blueberry-derived metabolites by gut microbiota can provide protection against several health complications, including gastrointestinal problems, diabetes, cardiovascular and neurodegenerative diseases, in addition to cancers.

Along with polyphenols, blueberries are a wealthy source of vitamins A, C, and E, which have well-established helpful effects on the skin.

Topical application of blueberry

Studies investigating the topical application of phytochemicals have indicated that bioactive compounds present in blueberries, resembling vitamin C, vitamin E, and resveratrol, provide protection against common environmental stressors.

In accordance with available literature, direct topical application of blueberry-derived phytonutrients and extracts reduces O₃– and UV radiation-induced skin inflammation. O₃-induced proliferation and migration of keratinocytes can be prevented by blueberry extract pretreatment.

The treatment of human dermal fibroblasts by blueberry anthocyanin has been found to cut back nuclear factor kappa B (NFkB) activation and forestall collagen degradation. Blueberry extracts also appear to guard the epidermis from O₃– and UV radiation-mediated damage by inhibiting inflammation and oxidative stress.

Mechanistically, blueberry extracts have been shown to modulate NFkB and nuclear factor erythroid 2-related factor 2 (Nrf2) pathways to cut back UV radiation-induced inflammation and increase antioxidant defense, respectively.

One other health good thing about topical blueberry extract application is the advance of the skin barrier function. The UV radiation-mediated degradation of skin proteins filaggrin and involucrin is chargeable for the lack of barrier function and induction of chronic skin inflammation. Blueberry topical application has been found to extend the degrees of those proteins to guard against UV radiation.

The topical application of blueberry extract on the skin of female diabetic patients appears to enhance skin smoothness and moisturization, in addition to prevent skin wrinkle formation.      

Blueberry dietary supplementation    

Studies directly investigating the effect of blueberry dietary supplementation on skin health are scarce. This could possibly be as a consequence of the low bioavailability of bioactive compounds within the blood upon ingestion of blueberries. Nonetheless, there may be evidence suggesting that blueberry dietary supplementation may improve skin vascular functions.

A study conducted on UVB-irradiated hairless mice has indicated that dietary supplementation with fermented black rice and blueberry with Lactobacillus plantarum improves skin hydration and barrier function.

Dietary supplementation with blueberry bioactive compounds also appears to cut back skin roughness and increase elasticity. Furthermore, oral supplementation with blueberry-derived epigallocatechin-3-gallate (EGCG) prevents UV radiation-mediated lack of epidermal barrier function in hairless rats.  

An imbalance in skin and gut microbiota is related to a wide range of skin complications, including atopic dermatitis, psoriasis, pimples vulgaris, dandruff, and skin cancer. Skin and gut microbiota compositions are maintained through bidirectional mechanisms.

Blueberry dietary supplementation appears to extend certain gut microbial species, which may need helpful effects in patients with psoriasis. Blueberry dietary supplementation has also been found to extend the degrees of gut microbiota-derived helpful metabolites, including short-chain fatty acids and butyrate, which could improve skin health by reducing oxidative stress and inflammation.