As an Omega-6 fatty acid, gamma linolenic acid(abbreviated to GLA (18:3)) is part of sea buckthorn oil fatty acid profile. Many studies were carried out to investigate the benefits of GLA. Oils rich in GLA have positive benefits on skin conditions such as dermatitis and eczema, pre-menstrual syndrome, rheumatoid arthritis and the prevention of heart diseases. In addition, GLA improves blood circulation, which is important for the nourishment and oxygenation of the skin, as well as to remove the excess of toxins. GLA is also a component of skin and is responsible for binds epidermis cells, being part of the intracellular cement of the skin. Furthermore, it is part of phospholipids, the major components of cell membranes. GLA is able to protect skin against infections, counteract allergies, relieve inflammations, and slow down the ageing process.

Acne and atopic dermatitis

As for skin disorders, a study was carried out to investigate if GLA could improve acne disease. Forty-five acne skin patients were divided in two different groups according to diet supplement. The supplements were omega-3 (group 1), GLA (group 2) and control group. The results showed a significant reduction of the mean of inflammatory and non-inflammatory acne lesion in the groups 1 and 2 compared to the control group. Visual analogue scale was established at the beginning of the study, and it was also reduced in these two groups.

In addition, interleukin 8 decreased significantly in the treatment groups. The study concluded by proposing two GLA possible mechanisms that may improve acne vulgaris. The first one consists in modulating the inflammatory process. GLA is converted in dihome-γ-linolenic acid (DGLA), a substrate of cyclo-oxygenase and 15-lypoxygenase. These two enzymes catalyze the production of prostaglandin E1 and 15-hydroxydihomo-γ-linolenic acid (15-OH-DGLA), which have anti-inflammatory properties. In the second one, 15-OH-DGLA can improve the hyper proliferative skin condition by the modulation of the protein kinase C.

The beneficial effects of polyunsaturated fatty acid(abbreviated to PUFA) on atopic dermatitis have been discussed for a long time. A double-blind, randomized-controlled trial investigated the effect of supplementation of borage oil (containing 100 mg of GLA) in infants with a maternal history of atopic disease. In this case, the study was not based on trying to elucidate the therapeutic effects in relation to atopic disease; instead, it focused on a possible protective role of GLA in the development of atopic dermatitis in infants with atopic mothers.

The results showed an increase of GLA and phospholipids concentration in plasma in the treatment group, which were negatively associated with the severity of atopic dermatitis when infants were 1-year-old. However, there were not significant differences in total serum IGE concentration between the two groups. The study concluded that the supplementation of GLA as a treatment seemed to be favorable but not significant.

Instead, when GLA is used as a marker of compliance, the severity of AD is strongly negatively associated with increase of GLA in infants. Finally, the authors suggested that an early supplementation with GLA in children tend to alleviate the severity of atopic dermatitis in later infancy. In accordance with these outcomes, various studies have tried to relate the effects of PUFA to atopic dermatitis as a therapeutic treatment, but their results were not conclusive.

Meibomian gland dysfunction

As for dry eye disorders, a study investigated the effect of ALA and GLA on meibomian gland dysfunction. The meibomian glands are situated inside the eyelids, and when a blockage of this gland exists, the oily part of the tears cannot be released, producing an acceleration of the drying of the eyes and generating irritation. Pinna and colleagues designed a study where subjects were divided into 3 groups. A group consumed ALA (28,5 mg) and GLA (15 mg) tablets; B group was subjected to eyelid hygiene and C group received both treatments. All treatments were once daily for 180 days. Although the three treatments presented a significant improvement in symptoms, the C group was the most efficient. The administration of GLA and LA (A group) decreased the secretion turbidity and the meibomian gland obstruction. When it was combined with eyelid hygiene (C group) it showed, in addition, a reduction in eyelid edema, foam collection in the tear meniscus and corneal staining.

The study suggested a dual effect of omega-6 fatty acids in the treatment of meibomian gland dysfunction. The anti-inflammatory activity may contribute to reducing eyelid edema. And, it may produce a less dense and turbid meibomian secretion by modifying the lipid composition. Consequently it may increase the efficacy of eyelid hygiene.

Another study carried out with a dry eye rat model revealed that dietary polyunsaturated fatty acids prevented the clinical signs of chronic corneal dryness and prevented the loss of musincs in the conjunctival epithelium. Only the rats treated with a combination of omega-6 and omega-3 decreased the expression of MHC II (inflammatory marker) on the conjunctival epithelium. The authors concluded that a combination of omega-3 and GLA fatty acids may be more successful in the treatment of dry eyes than the application of only one of them.