Borage, a plant with ferny leaves, electric blue flowers, and cucumberlike fruit, is becoming known in the culinary world as a tasty herb and condiment. But research on the medicinal properties of borage is still in the early stages, despite some promising work showing anti-inflammatory and antierythemic properties. The herb is worth investigating, as it may have dermatologic applications.
Borago officinalis is an annual herb native to Syria and now grown throughout the Mediterranean, Middle East, North Africa, Europe, and South America. Derived from the seeds of the plant, borage seed oil is used in medical practice for its anti-inflammatory activity in the treatment of atopic dermatitis, arthritis, and other conditions. In fact, the use of borage oil has demonstrated efficacy as a topical therapeutic approach to childhood eczema in small studies in which, for example, the symptoms of childhood atopic dermatitis were relieved by undershirts coated with borage oil (Eur. J. Dermatol. 2007;17:448-9; J. Dermatol. 2007;34:811-5; J. Fam. Pract. 2009;58:280-1).
Significantly, borage seed oil is also the best plant source of the omega-6 essential fatty acid gamma-linolenic acid (GLA), with GLA accounting for about a quarter of the oil and some extraction processes yielding products with over 50% GLA. Human skin cannot synthesize GLA from the precursor linoleic acid, which is notable because GLA is believed to contribute to skin hydration. As an oral supplement, borage seed oil is believed to be useful in reducing skin inflammation and erythema. As an ingredient in topical applications, it is thought to moisturize and strengthen the skin barrier. This column will discuss recent research on the role of borage seed oil and GLA in modern dermatologic care.
Some 20 years ago, in response to reports that GLA-containing vegetable oils contributed to reducing the symptoms of inflammatory skin conditions, Miller et al. fed guinea pigs borage oil, containing 25% GLA, or a control diet containing safflower oil (less than 0.5% GLA) for 8 weeks to establish whether GLA could modulate cutaneous eicosanoids. Examination of epidermal samples, including neutral lipids and phospholipids, revealed a significant increase in GLA and dihomo-gamma-linolenic acid (DGLA), its elongase product. Analysis of epidermal eicosanoids showed substantial rises in 15-hydroxy fatty acid (15-OH-20:3n-6) and prostaglandin PGE1, both metabolites of DGLA (and both of which display anti-inflammatory potential), in the borage oil–fed guinea pigs. The authors concluded that increased dietary GLA has the potential to produce local anti-inflammatory metabolites, thus representing a nontoxic approach to treating inflammatory skin disorders (Biochem. Biophys. Res. Commun. 1988;154:967-74).
In a study 3 years later, Miller et al. supplemented the diets of normal guinea pigs with various polyunsaturated fatty acids, ethyl esters of either fish oil (rich in the omega-3 fatty acids eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) or gamma-linolenic acid–rich borage oil, to determine the epidermal effects. The researchers found that guinea pigs that were administered borage oil preferentially incorporated DGLA, the epidermal elongase product of GLA, into epidermal phospholipids. EPA and DHA were also incorporated into epidermal phospholipids in the group that was fed fish oil. The investigators then considered the epidermal levels of the 15-lipoxygenase products and their relative inhibitory strengths to develop a method to quantify the overall potential of the dietary oils to yield local anti-inflammatory results.
Consequently, they noted that fish oil and borage oil leukotriene inhibition potentials greatly surpassed that of controls. The investigators concluded that the reported beneficial effects of fish and borage oils in the treatment of chronic inflammatory skin disorders may be at least partly attributed to the effects on the epidermal 15-lipoxygenase products engendered by the dietary oils (J. Invest. Dermatol. 1991;96:98-103).
Transepidermal Water Loss Impact
In 1993, Tollefson and Frithz studied the significance of transepidermal water loss (TEWL) and stratum corneum water content in disease and recovery in 37 patients with clinically diagnosed infantile seborrheic dermatitis. Within 3-4 weeks of a daily regimen of topically applied borage oil containing 24% GLA, all patients were symptom free. In the assessment of TEWL and stratum corneum water content, 25 healthy, age-matched children served as controls. Although there were no significant differences between the groups in terms of stratum corneum water content, significant pretreatment differences in TEWL were found between patients and controls. There were no significant differences after treatment, however. The investigators concluded that GLA is key to maintaining normal TEWL and as a treatment for infantile seborrheic dermatitis (Acta Derm. Venereol. 1993;73:18-20; Br. J. Dermatol. 1993;129:95).