Cutaneous defence mechanisms are impaired by chronic exposure to environmental stressors, such as noxious air pollutants, ozone, and UV radiation, which compromise skin integrity, the Italian authors explain in 'Antioxidants'.
Environmental stressors stimulate excessive production of reactive oxygen species (ROS) that overwhelm skin defences causing oxidative stress and resulting in premature aging.
However, natural compounds like blueberries (that contain high levels of potent anthocyanins) elicit a protective response and prevent skin damage, they write. Bioactive polyphenols, such as anthocyanins, have strong antioxidant, anti-inflammatory, immunomodulatory, and antimicrobial properties, among others.
A typical serving of blueberries contains a large quantity of major antioxidants crucial for cutaneous systems, including anthocyanins (the most abundant and potent compound). Blueberries are also rich in retinol and vitamin A, beneficial for skin health.
The recent report states: “In vitro studies exhibit anthocyanin’s significant antioxidative ability to scavenge ROS and have beneficial biological functions such as enzyme inhibition, as well as anti-inflammatory and antibacterial effects.”
Cutaneous mechanisms
Human skin is composed of several layers - the outer stratum corneum (the principal barrier), the dermis (comprised of collagen fibres), and the hypodermis or subcutaneous layer of adipose tissue - and is essential for protection, thermoregulation, sensation, water storage, absorption, expression, and vitamin D3 synthesis.
Skin stimulates several enzymatic and non-enzymatic defensive mechanisms that impede the harmful build-up of ROS, such as the superoxide anion (O-2), hydroxyl radical (HO), alkoxy radical (RO), and peroxyl radical (ROO).
While ROS is naturally produced in skin cell mitochondria, excessive exposure to UV light, pollution, and cigarette smoke causes oxidative damage and contributes to extrinsic premature aging.
“Catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPX) are three enzymes present in the skin which are responsible for preventing cutaneous oxidative damage,” the authors explain.
“This physiological mechanism can handle moderate levels of ROS; however, exposure to environmental pollutants can result in an excessive and chronic increase in ROS which overwhelms the antioxidant defences of the skin.”
Environmental stressors
Pollution is responsible for depletion of the ozone layer and increased ultra-violet B (UVB) radiation, which is highly mutagenic and cytotoxic to the skin. Moreover, toxins like carbon monoxide have increased ground level ozone (O3), associated with higher incidence of respiratory and cardiorespiratory mortality.
The authors’ comment: “Unlike UV light, O3 is unable to penetrate the cutaneous tissues, and its effect is mainly mediated by a cascade of bioactive reactions, leading to increased lipid peroxidation and ROS formation, which modulate key physiological inflammatory pathways and exhaust cutaneous antioxidants, causing adverse skin conditions.”
Furthermore, particulate matter (PM) provokes skin barrier dysfunction and exacerbates skin ailments, including atopic dermatitis, as they circumvent physiological barriers.
Polyphenol activity
The authors cite findings from recent studies on blueberry metabolism that found consistent consumption increased total anthocyanin-derived metabolites in blood serum.
“When the three phases of polyphenol digestion (salivary, gastric, and intestinal) are complete, 169 polyphenolic metabolites can be found in measurable amounts in blood plasma. Among these, 58 blueberry-derived metabolites significantly change in concentration following blueberry consumption.”
Furthermore, the prebiotic efficiency of parent blueberry polyphenols such as anthocyanins can be maximized through microencapsulation, consequently thwarting degradation from the upper gastrointestinal tract, they add.
Topical application
“Rigorous” application of natural bioactives demonstrated “their ability to supplement depleted levels of skin micronutrients” from environmental stressors, the authors say.
“Application of compounds containing vitamin E and C successfully replenished the depleted cutaneous antioxidants stores due to O3 and UV exposure. The topical application of resveratrol, from the stilbenoid group of polyphenols found in blueberries, can protect against UV- and H2O2-induced cell apoptosis via SIRT1 activation.”
Studies also show that pre-treatment with blueberry extract mitigates the harmful effects on keratinocyte proliferation and migration from O3 exposure and revealed improvements in human dermal fibroblasts when treated with blueberry anthocyanins.
“Blueberry extract was able to reduce the increase in 4-HNE (lipid peroxidation product) and NLRP1, an inflammasome isoform that regulates the activation of caspase-1 which induces an inflammatory response in the epidermis, proven to increase in response to O3 exposure,” they write.
Dietary supplementation
Conflicting evidence on the ability of dietary supplementation to reduce inflammation and oxidative stress and limited clinical studies of effects on skin health, demonstrate the need for further studies on the link between skin health and blueberry consumption, the authors comment.
Nevertheless, data did reveal a positive correlation between supplementation and improved overall vascular function.
“Psoriasis and hidradenitis suppurativa are directly associated with metabolic syndrome and cardiovascular disease, suggesting blueberry supplementation could attenuate these skin conditions,” the authors say.
“Dietary consumption of blueberries can also modulate the gut microbiome, which plays an important role in a variety of skin disorders (gut–skin axis).”
They conclude that despite positive the health benefits identified, more research is needed to examine the role of blueberry-derived metabolites in blood plasma and their ability to modulate cutaneous mechanisms.
Source: Antioxidants
Published online, June 12, 2023: https://doi.org/10.3390/antiox12061261
‘Blueberry Supplementation and Skin Health’
Authors: John Ivarsson, Jr., Alessandra Pecorelli, Mary Ann Lila and Giuseppe Valacchi