52 ANTI-POLLUTION Control■ 10 µmol ■ 20 µmol ■ 20,000 15,000 10,000 5,000 0 LTB4
Tissue alone Marine oil Borage oil
Blackcurrant seed oil Trichodesma oil Echium oil
0 LTB4 (A isomer) LTB4 (B isomer) Figure 2: Leukotriene B4 synthesis inhibition from SDA
Studies around the world in urban-dwelling humans, in places like Mexico, southwest China, Germany, and Korea, have shown that elevated air pollution sets the stage for higher incidences of atopic dermatitis, acne, eczema, ageing spots, melanoma, and hypersebborhea (excessive sebum gland output), and further accelerates the visible signs of ageing. One 2019 literature study found that, overall, the symptoms of chronic inflammatory skin diseases seem exacerbated when adult and pediatric subjects are exposed to high pollution levels.5 Adding to the worry for young parents
is evidence of a strong correlation between maternal exposure to high particulate matter (PM) air pollution and newborn children’s prevalence for atopic eczema, associated with higher trans-epidermal water loss (TEWL), a basic hallmark of skin becoming more dysfunctional. The reviewing authors noted that PM-
induced oxidative stress could induce epigenetic changes in fundamental DNA repair genes in the placenta, which could affect fetal immune development.6
So, in pregnant women exposed
to higher air pollution, not only is their own skin affected adversely, but likely too is their children’s future capacity of the skin to function properly – against air pollution but also any number of environmental, microbial, immune, UV, and allergic insults — for the rest of their lives.7
Anti-inflammatory omega-3 and omega-6 polyunsaturated fatty acids One of the earliest recognized signs of dietary deficiency in dietary fatty acids was through skin dysfunction. Two landmark publications nearly a century ago (Burr and Burr 1929, 1930)8
led to the early recognition that some
plant-based lipids are biologically essential for healthy skin. They showed that inducing fatty acid deficiency in rats — i.e. by rigorously excluding all fat from the diet, caused a number of deficiency symptoms including a dermopathy characterized by scaly skin (epidermal hyper-proliferation) and rapid water loss via accelerated TEWL. However, the symptoms could be easily
reversed by adding linoleic acid (LA, C18:2n-6) back into the diet. This mimics the effect noted for typical vitamin deficiencies which are readily reversed by adding the missing
PERSONAL CARE May 2023 5 10 15 Figure 3: Prostaglandin E2 inhibition from omega-3 oils
vitamin back into diet. Indeed, early after this discovery, plant-based alpha-linolenic acid (ALA, C18:3n-3) was, for a while, called ‘Vitamin F’. Since LA and ALA are necessary for animal
health but cannot be made de novo in the body, they must come from the diet. Hence both these fatty acids are called ‘essential’ fatty acids (EFAs). By the 1970s, skin care products companies like Unilever were investigating topically applied EFAs. They found that EFA-deficient animal
skin could be normalized by topical application of EFAs and identified the skin lipids that constitute the epidermal moisture barrier. These were, in the main, LA fatty acid derivatives, namely ceramides and its related lipids. By the early 1990s, researchers at Nestlé were investigating topical applications of naturally occurring plant- based polyunsaturated fatty acids stearidonic acid (C18:4n-3) and gamma-linolenic acid (C18:3n-6). In one pivotal study (Guichardant 1993)9
,
Nestlé published a paper detailing the effect of SDA, EPA (C20:5n-3), and di-homo-γ-linolenic acid (DGLA, C20:3n-6), GLA’s recognized anti-inflammatory metabolite, on cultured human leukocytes. These experiments showed that topical SDA reduced the amount of an inflammatory metabolite (LTB4, leukotriene B4) on the same order as EPA (Figure 2). Significantly DGLA was superior to either EPA or SDA. At the time, Nestlé’s interest in SDA was based on the availability of a byproduct from their blackcurrant juice production, namely blackcurrant seed oil. Blackcurrant seed oil contains SDA ~3% and GLA ~14% and this oil became a key ingredient in a number of cosmetics marketed by Vichy (a Nestlé company). Soon, other cosmetics industry
suppliers including Croda and Scotia in the UK investigated other plant-based polyunsaturated fatty acid sources containing either SDA, GLA, or both. These were conducted to determine if topically applied natural plant-based lipids could mitigate epidermal inflammation. The model chosen was an engineered human skin suspended at the air/culture- medium or water interface and the test substances were applied at the skin surface.
Inflammation — similar to some effects from higher chemical and particulate air pollution exposure — was induced using UV-irradiation and the tissue analyzed for inflammatory mediators.
The earliest experiments simply compared
a number of omega fatty acid sources: marine oil (EPA, DHA), borage oil (LA, GLA), blackcurrant seed oil, Trichodesma seed oil, and Echium oil (all containing ALA, SDA, LA, GLA), on the release of prostaglandin E2 (PGE2). PGE2 is an inflammatory metabolite produced from arachidonic acid (AA, C20:4n-6) by the enzyme cyclooxygenase (COX1/2). These results are shown in Figure 3. The test oils containing SDA—borage <0.2%,
blackcurrant seed oil ~3%, Trichodesma ~6%, and Echium ~13%—all inhibited PGE2 release from irradiated skin. The higher the SDA content, the greater the effect. Surprisingly, the high EPA marine omega-3 oil showed no effect. This gave further support to a 1989 industry study carried out by Scotia which treated both normal and atopic eczema (AE) children with topical evening primrose oil capsules containing ~8% GLA. While the normal children experienced
only a 5% reduction in skin roughness, the AE children’s skin roughness improved significantly by 15%. Subsequent experiments led by Croda in the late 1990s using topical Echium oil demonstrated the primary activities found were anti-inflammatory, retained dermal moisture, and endogenous collagen synthesis via upregulation of fibrillin-1, procollagen-1, and decorin.10
Ahiflower® oil — the richest combined SDA/GLA source for skin health Plant-based Ahiflower (Buglossoides arvensis) seed oil was not an available option for investigating topical skin inflammatory and moisture protection/TEWL responses until 2013. This novel regeneratively-grown oil launched commercially in 2015 in the EU and North America, initially in dietary applications. It is notable for having the highest overall
omega-3-6-9 content (>90%) and for having the highest combined SDA (20%) and GLA (6%) content versus any other omega-3 polyunsaturated fatty acid source. This on top of having approximately 80% of the ALA
www.personalcaremagazine.com 20 Prostaglandin E2 release (pg/g tissue) x 1000 ZK1301n skin model-prostaglandin release
metabolite (picomol/108
leukocytes)
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