The omega group of fatty acids have caused quite the nutritionally rave over the past decade. However, among them, omega-7 seems to go unnoticed. 

Omega-7 fatty acids are monounsaturated fatty acids primarily found in the form of palmitoleic acid (16:1 n-7) and vaccenic acid (18:1 n-7). Palmitoleic acid is a common omega-7 monounstaurated fatty acid that is present in adipose tissues with high concentrations in the liver (4). Vaccenic acid is a naturally occurring trans-fatty acid found in primarily dairy products such as milk, butter and yogurt. Cis-vaccenic acid, the steroisomer of this form, is found in sea buckthorn oil (3). Additionally, omega-7 fatty acids are found in smaller amounts within other animal, marine, and vegetable oils. The two most common botanical sources with the highest sources of omega-7 are macadamia nuts and macadamia oil, along with sea buckthorn oil. Raw macadamia nuts contain 58.877 grams of monounsaturated fats per 100 g serving where approximately 13 grams are palmitoleic acid (16:1 n-7) and 43.75 grams are vaccenic acid (18:1 n-7) forms (1). Sea buckthorn oil has two forms: seed oil and pulp oil. The seed oil contains a fatty acid weight percentage of under 0.5, whereas, the pulp oil contains 15-50% of palmitoleic acid. Additionally, seed oil percentage of vaccenic is 2-4 and pulp oil percentage is 5-15 (3).

The applicability of omega-7 supplementation on human health is undetermined due to the mass research conducted in animal models and the inconsistent results in human trials. Within a large prospective cohort study in four US communities, anthropometric characteristics were measured. It was discovered that whole-fat diary consumption was significantly linked to higher trans-palmitoleate levels. High phospholipid trans-palmitoleate levels were correlated to lower metabolic risk, reduced inflammation, triglyceride levels and adiposity, as well as higher HDL-cholesterol levels in study participants (5). This study supports that circulating omega-7 through dairy consumption improves cardiovascular health and reduces diabetes incidence. However, in a study conducted in a middle-aged Chinese population, adverse effects were found with circulating palmitoleic acid. In fact, it was discovered that high erythrocyte palmitoleic acid levels were associated with adverse profiles of adipokines and inflammatory markers and ultimately, an increased risk of metabolic syndrome (7).

Results in animal models are generally more consistent for therapeutic applications. In an animal study using mice, 400 fatty acid profiles were analyzed and compared for the relationship between metabolic alterations in adipose tissue and whole-body metabolism through lipid signals. It was discovered that the omega-7 fatty acid, palmitoleate, is the main lipid component contributing to the regulation of SCD-1 expression; which significantly translates to insulin action and inhibition of hepatic steatosis (2). Most recently, omega-7 palmitoleic acid has been proposed as an aid in satiety. In an animal model using food-deprived rats, palmitoleic acid supplementation suppressed food consumption in a dose-dependent manner and effected plasma satiety related hormone levels; with a drastic increase of CCK over controls when subjected to a 500 mg/kg dose. It is possible that palmitoleic acid stimulates oleoylethanolamide, a fat-induced bioactive that affects vagus nerve activity through PPARa, to suppress appetite through inducing satiety and decreasing meal frequency (6).

To date there is very little consistency in omega-7 research in human health. Within the food matrix, consuming dietary dairy sources has shown to yield therapeutic results; however, the lack of human intervention trials using sea buckthorn oil or macademia oil makes it difficult to conclusively recommend a daily regimen. As omega-7 fatty acids are found in smaller amounts in other animal, fish, and vegetable oils, the inclusion of these supplements into a daily regimen may be feasible when considering the holistic effects of other omega polyunsaturated fatty acids. The most recent research, within animal models, demonstrating a link between omega-7 supplementation and satiety is a promising area for penetration into the dietary supplement market but human health applications have yet to be explored.

References

1. http://ndb.nal.usda.gov/ndb/foods/show/3717?fg=Nut+and+Seed+Products&man=&lfacet=&format=&count=&max=25&offset=50&sort=&qlookup=.
2. Cao, H., Gerhold, K., Mayers, J. R., Wiest, M. M., Watkins, S. M., & Hotamisligil, G. S. Identification of a lipokine, a lipid hormone linking adipose tissue to systemic metabolism. . Cell. 2008;134(6):933-44. 

3. Erkkola, R., & Yang, B. Sea buckthorn oils: Towards healthy mucous membranes. AGRO FOOD INDUSTRY HI TECH. 2003;14(3):53-9. 

4. Knothe G. Biodiesel derived from a model oil enriched in palmitoleic acid, macadamia nut oil. Energy & Fuels. 2010;24(3):2098-103. 

5. Mozaffarian, D., Cao, H., King, I. B., Lemaitre, R. N., Song, X., Siscovick, D. S., & Hotamisligil, G. S. Trans-palmitoleic acid, metabolic risk factors, and new-onset diabetes in US adults: A cohort study. Annals of internal medicine. 2010;153(12):790-9. 

6. Yang, Z. H., Takeo, J., & Katayama, M. Oral administration of omega-7 palmitoleic acid induces satiety and the release of appetite-related hormones in male rats. Appetite. 2013;67:1-7. 

7. Zong, G., Ye, X., Sun, L., Li, H., Yu, Z., Hu, F. B., Lin, X. Associations of erythrocyte palmitoleic acid with adipokines, inflammatory markers, and the metabolic syndrome in middle-aged and older chinese.  The American journal of clinical nutrition. 2012;96(5):970-6.