The skin is the human body’s largest organ, covering an area of nearly 1.8 m2. It functions as a metabolically active biological barrier by separating internal homeostasis from the external environment. Aside from providing cover, the skin also prevents water loss, regulates the body’s temperature, absorbs mechanical energy, protects against UV light and acts as an antimicrobial defense system. Therefore, maintenance of the skin is critical for normal homeostasis.
A series of publications in the 1920s and 30s discussed a new disease caused by the prolonged exclusion of fat from the diet, which resulted in epidermal hyperplasia, scaly skin and an increase in transepidermal water loss (TEWL).1 Interestingly, upon consumption of linoleic acid (LA), all the characteristics of this deficiency could be alleviated.2, 3 It was therefore recognized that LA was an essential fatty acid (EFA) required for normal bodily function. In addition, a pioneering link was made between the importance of EFAs and cutaneous skin biology.
Since that time, it has been established that the skin requires fatty acids to synthesize cell membranes and the lipid-enriched extracellular membranes of the stratum corneum (SC). These structures are vital in maintaining the epidermal water barrier and thus the hydration of the skin.4 When the barrier is disrupted, a three-fold increase in de novo fatty acid synthesis is observed. If this increase is inhibited, a delay in skin barrier recovery is seen.5 This further signifies the importance of fatty acids within the skin.
LA and α-linolenic acid (ALA) are essential polyunsaturated fatty acids (PUFAs) that can be further grouped depending on the position of the carbon-carbon double bond (see Figure 1). If this occurs on the n-6 position, it is regarded as an omega-6 fatty acid (LA), and if this occurs on the n-3 position, it is regarded as an omega-3 fatty acid (ALA).
EFAs cannot be synthesized by mammalian cells and therefore must be acquired from dietary sources.4 The modern Western diet incorporates more omega-6 than omega-3 fatty acids6 and this lack of omega-3 fatty acids has contributed to the recent surge in cardiovascular diseases, certain types of cancer, and inflammatory and auto-immune disorders.6
To counteract these disorders, researchers have examined oral supplementation with omega-3 fatty acids. The most studied are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Large population-based clinical studies have demonstrated that oral supplementation with these acids benefits human health.7 These studies have resulted in recognition of EPA and DHA by the US Food and Drug Administration (FDA), which gave them a “qualified health claim” in 2004.8
Research recently has shifted to determining whether other fatty acids have potential health benefits to humans. Of the other PUFAs, stearidonic acid (SDA) has emerged as a potential candidate. Researchers have observed that SDA is a precursor of EPA and DHA, and it is able to bypass the rate-limiting step in omega-3 PUFA biosynthesis.9 This ability is important since it has been shown that the bioconversion of the rate-limiting substrate ALA to EPA and DHA is only 6% and 3.8% respectively.6 Therefore, if SDA bypasses this step, there is a potential for higher EPA/DHA bioavailability.
A number of plant derived oils on the market boost PUFA enrichment. Echium plantagineum (echium) seed oil contains 14% SDA, which could be considered a high proportion. In addition, it contains ALA, LA and γ-linolenic acid (GLA) in approximate concentrations of 30%, 20% and 10% respectively. Since PUFAs have been shown to play a major role in epidermal homeostasis, the aim of the present study was to determine whether oral supplementation with echium oil could produce skin benefits. Further, this investigation aimed to see whether echium’s PUFA blend could offer advantages when applied topically.
A blind oral supplementation study was carried out for 12 weeks in which panelists were administered either 2 g of encapsulated echium oil per day or a medium chain triglyceride placebo. Panelists’ skin was assessed for its collagen levels, barrier performance and hydration.
Collagen measurements were taken at week 0, 6 and 12 with a skin imaging devicea.9 After 6 weeks, an increase in collagen levels in the skin was recorded with echium oil supplementation. This increase was maintained at 5% on average throughout the remainder of the study. The increases observed were significant when compared with the week 0 value.
When these values were compared with the placebo group, the increase observed with the echium oil was significantly higher (see Figure 2). It was therefore concluded that orally administered echium oil imparted a positive effect on the levels of collagen within the skin.
To demonstrate skin barrier performance, a sodium lauryl sulfate (SLS) challenge was conducted. SLS severely disrupts the skin barrier and leads to a detectable increase in water loss through the skin.10 The SLS challenge was carried out at the start of the study and after 12 weeks of supplementation with echium oil. Two groups of panelists with dry skin were enlisted for this experiment since dry skin sufferers already have a compromised barrier and therefore any benefits provided via supplementation are easier to identify.12
One group of 15 panelists was given a placebo and another group of 9 panelists received the echium oil. Panelists were instructed to cease using any moisturizers or topical medications for one week prior to the baseline and all subsequent readings. Panelists showered with a standardized bathing product throughout the study and were directed to avoid sunburn, tanning and excessive sun exposure. In addition, panelists were asked to not change their diet, to keep alcohol consumption within normal levels, and to avoid taking high doses of supplements such as fish oil, omega 3 or omega 6.
All major variables were controlled as best as possible including diet so that any change in the panelists could be attributed to the supplementation of their diet with the placebo or echium oil. Figure 3 demonstrates that both groups of panelists saw a decrease in barrier performance after 12 weeks of supplementation. This was shown by an increase in TEWL of approximately 140% in the placebo group and 30% in the echium group.
The overall decrease in barrier performance was attributed to the seasonal change from fall to winter, which makes the skin more prone to damage. However, it can be seen that the increase in TEWL in the placebo group is significantly higher than the echium group. It was therefore concluded that echium oil improved the barrier performance of panelists with dry skin, leading to less damage. While the placebo group experienced a significant (p = 0.003) increase in TEWL after 12 weeks, the group taking echium oil saw no significant change (p = 0.077). This demonstrates that echium oil can provide barrier protection benefits to individuals afflicted with dry skin.
While the mechanism of action of the echium oil is unknown, it could be postulated that oil increases the synthesis of the skin lipids, reinforcing the barrier to better withstand environmental insults. Moreover, with its high proportion of LA, it is possible that this fatty acid contributed to the esterified ceramides 1 and 4. These ceramides are located in the lamellar bilayers in the SC and are essential for normal barrier function.13
In addition to barrier function, an increase in skin hydration was shown by skin conductance measurements. These values significantly increased between weeks 6 and 12 by approximately 20% in the echium group, compared with the placebo group (Figure 4). The same proposed mechanism for improving barrier function could also explain improvements in skin hydration.
Expression of Dermal Structural Proteins
Aging of the skin is both an intrinsic and extrinsic process. Intrinsic aging can be attributed to many factors, including cumulative endogenous damage due to the continuous formation of reactive oxygen species generated by oxidative cellular metabolism. Extrinsic aging develops from several factors including severe physical and psychological stress, alcohol intake, poor nutrition, environmental pollution and exposure to UV radiation. Of these extrinsic factors, UV radiation contributes up to 80% of the effects of aging.
UV radiation can be broken down into UVA, UVB and UVC. UVC does not contribute to skin photoaging, since it is filtered out by the earth’s atmosphere. UVB mainly induces alterations at the epidermal level, whereas UVA penetrates more deeply into the dermis. It is therefore widely accepted that UVA plays an important role in the pathogenesis of skin photoaging.
A blind study was carried outb on 14 healthy but clinically photoaged volunteers, ages 41–78. The volunteers topically applied 5% echium oil under occlusion to their forearm on days 1, 4 and 8 of the study, with an untreated occluded site serving as the control. The solvent for the echium oil was isopropyl myristatec. On day 12, randomized punch biopsies were taken of the treated and untreated sites, cryo-sectioned and stained for specific dermal markers. The degree of staining was graded on a five point scale where 0 was no staining and 4 was maximum staining.
The results demonstrated that fibrillin-1, pro-collagen-1 and decorin levels, which are integral to providing the skin with strength and support to maintain a youthful appearance, increased significantly compared with the untreated site (Figure 5). In photoaged skin, collagen fibers are disorganized, collagen precursors are reduced, and cross-linking of collagen fibers is decreased.15 This study established that echium oil has potential as an antiaging ingredient to slow the signs of aging and reverse the signs of photoaging skin.
Reducing Fine Lines and Wrinkles
Skin damage is visually expressed as coarse and fine wrinkling.14 Thus, a study of 10 volunteers examined the topical application of an emulsion containing either 5% echium oil or a control emulsion onto wrinkled skin. The study aimed to confirm whether the increases observed in fibrillin-1, pro-collagen-1 and decorin produced visually perceivable benefits. Results showed that echium oil significantly decreased the mean depth of one identified main wrinkle by an average of 30.63% (see Figures 6 and 7). The overall roughness of the skin also decreased significantly, by 23.59%. This reduction could be attributed to the echium oil’s ability to induce dermal structural proteins, resulting in smoother skin and a reduced wrinkle depth.
Arachidonic acid (AA) is an omega-6 PUFA and is the second most prominent PUFA in the skin, accounting for approximately 9% of total fatty acids. It is integrated in the cell’s plasma membrane and released by catalytic hydrolysis by epidermal cytosolic phospholipase A2. This can occur, for example, when the skin is exposed to UV light. The result is the generation of prostaglandins and hydroxyl fatty acids via the cyclooxygenase or lipoxygenase pathways, respectively.16 The main function of these metabolites is to regulate proliferation and differentiation processes within the epidermis. However, if the levels become elevated, inflammation can be triggered.4
Full skin substitutes containing human fibroblasts and keratinocytes were produced. Within these substitutes, the levels of prostaglandin E2 (PGE2), a metabolite of AA with inflammatory properties, were determined. To these substitutes, 3 µl each of echium oil, blackcurrant oil, borage oil and marine oil were topically applied for 24 hr; one control sample was left untreated for comparison. Subsequently, the skin substitutes were exposed to UVB light at a dose of 4 J/cm2. After further incubation for 24 hr, the media were removed and PGE2 levels were determined. The PGE2 release was calculated as a percentage of the control.
The results demonstrated that echium oil decreased PGE2 levels after UV exposure more than the other oils applied (see Figure 8). This anti-inflammatory potential of echium oil is attributed to its levels of SDA. It is believed that SDA has the ability to inhibit cyclooxygenase activity and thereby block the conversion of arachidonic acid to PGE2. Echium oil has a higher amount of SDA than the other oils tested, which is likely why it lowered PGE2 release more effectively. This decrease is enhanced synergistically by ALA and LA. Both of these PUFAs have been shown to have cyclooxygenase-inhibiting activity, ALA being the stronger of the two.17 ALA is present in echium oil at a concentration of 30% and could further boost the anti-inflammatory activity of echium oil.14
Due to these benefits, echium oil could be of interest for skin smoothing, calming and after sun products and for the treatment of inflammatory skin disorders. The author notes, however, that echium oil does not provide anti-inflammatory benefits by acting as a sunscreen. Rather, it reduces inflammation by partially inhibiting the downstream mechanism of UV-induced inflammation.
Based on the described studies, the author concludes that, in addition to PUFA supplementation, echium oil can increase skin collagen levels, barrier function and skin conductance when administrated orally. When topically applied, echium oil can increase dermal structural proteins, resulting in a reduction in fine lines and wrinkles. Due to its unique blend of fatty acids, echium oil is also able to perform as an anti-inflammatory agent by blocking PGE2 formation after UVB exposure. This suggests the use of echium oil for a multitude of personal care applications. Formulators can utilize echium oil systemically and topically to target beauty from the inside and outside to create the next generation of skin care regimens.
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