Palmitoleic acid (16:1) is an omega-7 monounsaturated fatty acid uncommon within the plant kingdom. Sea buckthorn is one of the few plants that present this fatty acid. Sea buckthorn oil extracted from the pulp and peel contains high levels of palmitoleic acid –up to 42%. On the contrary, sea buckthorn seed oil presents extremely low levels of palmitoleic acid (< 0.5% of palmitoleic acid in triacilglicerol). The composition of the fatty acid may be different according to its origin, subspecies or harvesting time.

Skin and mucous disorders

Several scientists conclude that palmitoleic acid plays a role in different mechanisms that improve skin and mucous disorders. Some studies emphasize the beneficial effects of palmitoleic acid for vaginal inflammatory atrophy treatment. Although an extensive range of treatments exist for this disorder –such as systemic and local estrogens, local testosterone, retinoid and anti-inflammatory ointment, these treatments are frequently inefficient.

Because of this reason, more researches are needed, a study focuses on the oral administration of 3 capsules of omega-7 sea buckthorn to 5 patients twice a day during 12 weeks. The results show an obvious improvement of chronic vaginal inflammatory atrophy in three cases. But the improvement was less considerable. The mechanisms of omega-7 did not take place through an increase of circulating estrogen level, therefore it is an alternative to this treatment.

Another study focusing on the vaginal inflammatory atrophy suggested a daily oral intake of 3 g of sea buckthorn oil, where the main fatty acid was palmitoleic acid (28%) . A total of 126 postmenopausal women were randomized into two groups: in the first one they were administered sea buckthorn oil, while in the second one administered placebo. The results of the study indicate a positive increasing trend of the vaginal health index for the sea buckthorn oil group. The ability of palmitoleic acid is to inhibit melanogenesis. The melanogenesis is the synthesis of melanocyts, cells that produce the melanin pigment.

The inhibition activity of the palmitoleic acid was determined versus three melanogenic keys enzymes in murine B16 melanoma cells. These enzymes were tyrosinase, tyrosinase-related protein-1, tyrosinase-related protein-2 and microphtalmina-associated transcription factor. The results showed an inhibition of tyrosinase and the others. Palmitoleic acid is proposed as a potential anti-melanogenic agent and effective in hyperpigmentation disorders.

Another effect of palmitoleic acid in skin and mucous is related to the human sebum. Human sebum consists mostly of triglycerides, wax esters and squalene, and its composition is unique to sebaceous cells. Sebum does account for the self-disinfecting activity at the skin surface, and palmitoleic acid accounts for most of this activity. An in vitro study was carried out based on collected skin surface lipids and investigated its antimicrobial activity. The results revealed that the palmitoleic acid at concentrations below 0.5 mg/ml had little effect on the growth of C. albicans and at concentrations above 1.0 mg/ml were effective in preventing the attachment of pathogenic yeast cells to isolated sheets of mammalian stratum corneum.

Due to its potential activity against the adhesion of C. albicans to the skin, palmitoleic acid is included as a medical preventive treatment for wound infections. However, palmitoleic acid is not effective in gram-negative bacteria. Palmitoleic acid may be a natural antimicrobial gram-positive bacteria of the skin. The bactericidal activity of palmitoleic acid calcium salt has also been investigated. By means of an in vitro study it was demonstrated the activity of palmitoleic acid against Staphylococcus aureus and Propionibacterium acnes.

Cholesterol levels

Palmitoleic acid also helps lowering cholesterol levels. A study compares the effects of diet in regard to hypercholesterolemia in rats. The rats were distributed in six groups with different diets rich in either palmitate, stearate, palmitoleate, oleate, linoleate or α-linoleate. The palmitoleate was found to be as effective as linoleate in lowering the plasma cholesterol level. And when it was compared to oleate and to other saturated acids, the palmitoleate was clearly more hypercholesterolemic.

Insulin resistance and liver dysfunction

The possible relation between palmitoleic acid and hepatic insulin sensitivity was also investigated. The study consists in two groups of mice, one of them were fed a high-fat diet and the other a standard diet for 12 weeks. In the last 2 weeks, the high-fat diet mice were treated daily with oleic acid or palmitic acid. After 12 weeks, the mice were injected with insulin or vehicle and various parameters were analyzed. The study concluded that palmitoleic acid supplementation in mice fed with high-fat diet stimulated the uptake of glucose and impaired the lipogenesis in liver by activation of AMPk and FGF-21, dependent on PPAR-α.

All these effects are essential to control insulin resistance and to reduce the ectopic deposition of lipids in the liver. The study also suggested that palmitoleic acid plays an important role as a non-pharmacological treatment for diabetes and liver dysfunctions. Moreover, it highlighted an increased lipolysis and a decreased lipogenesis in adipocytes.

In Addition, the immunity system could be affected by palmitoleic acid, which lowered NF-kB p65 phosphorylation and proinflammatory cytokine expression in macrophages. Another study demonstrated that there is an increased insulin sensitivity in the liver and muscle, which improved hypertriglyceridemia and hyperglycemia in diabetic rats when they were fed 300 mg/kg of palmitoleic acid daily for 4 weeks. More studies show a relation between the palmitoleic acid and the immunity system. This fatty acid promoted a suppressive effect in isolated human lymphocyte proliferation characterized by a decrease of Th1 and Th17 response, and co-stimulatory molecule (CD28).