Some of our most effective nutritional oils belong to the omega-9 family and a few others belong to the omega-5 and omega-7 families. None of these fatty acids are considered essential because the human body can synthesize them. We must remember however, that non-essential does not equate with non-important. The omega 5s, 7s and 9s have unique biological properties that closely parallel those of omega-6s and omega-3s, yet are less well defined. The chief function all these fatty acids share is contributing to membrane fluidity vis-à-vis incorporation into membrane phospholipids. This means the omega 5,7,9 fatty acids share these properties with their omega-3,6 cousins:
1. Hormone responsiveness
2. Resistance to pathogenic infection
3. Nutrient transport
4. Immune competence and antibody response
Some of the properties of the omega 5,7,9s that are not necessarily shared with their essential cousins are:
1. Maintenance of cholesterol balance
6. Insulin sensitivity and responsiveness
7. Skeletal muscle growth
Let’s begin our discussion with oleic acid (18:1w-9) a mono-unsaturated 18-carbon fatty acid with a double bond at the ninth carbon. The molecule bends around the double bond and this gives it flexibility that its 18-carbon counterpart stearic acid, does not have. Thus oleic acid joins its omega-3 and 6 cousins in maintaining membrane fluidity.
Oleic acid is the most common monounsaturated fatty acid in human cells. Substitution of dietary saturated fat by oleic acid lowers cardiovascular risk by reducing blood lipids, mainly cholesterol. LDL-cholesterol, and triglycerides. This led the Food and Drug Administration (FDA) to allow the following health claim for canola oil and high oleic acid canola oil. “Canola oil (19 grams – about 1½ tablespoons per day) may reduce the risk of coronary heart disease due to its unsaturated fat content, according to supportive but not conclusive research. Canola oil should replace a similar amount of saturated fat in the diet without increasing calories.”
Besides canola oil, oleic acid is the main component of sunflower oil, olive oil, avocados and avocado oil, and almond oil. Because of the health benefits of oleic acid, sunflower, safflower and canola oils are often selectively extracted to increase their oleic acid content.
A Little Avocado with Your Hamburger?
Avocados are rich in oleic acid and antioxidants including carotenoids, tocopherols, and polyphenols. Avocados are a favorite addition to sandwiches containing hamburger or other meats. It turns out that adding avocados to a hamburger may do more than just taste good. During cooking, ground beef generates lipid peroxide free-radicals. Additional free radicals are generated during digestion of the meat. Avocados appear to reduce these effects, according to a research team at University of California Los Angeles (UCLA).
A small pilot study of eleven healthy volunteers compared their vascular and inflammatory response to eating an 8-ounce lean hamburger patty (90% meat, 10% fat) alone or topped with 2.5 ounces of avocado. Each volunteer served as his or her own control. Significant vascular effects (vasoconstriction) were noted two hours after the hamburger was eaten but this effect was not observed when the hamburger was eaten with avocado. Inflammatory response was measured in immune cells (monocytes) in the blood of the volunteers four hours after each of their two hamburger meals. Avocado also appeared to prevent the inflammatory cascade seen when the hamburger was eaten alone.
Do you feel guilty adding avocado which is high in fat and calories to meats which are already high in fat? The study found that despite the added fat (oleic acid) triglyceride levels did not rise more than when the hamburger was eaten alone. Admittedly, a hamburger is not considered a “healthy” meal for many reasons, but if you do indulge, add a little avocado.
In our next Zimmerman File, we will continue our discussion with other members of the omega 5,7and 9 families. Be sure and check out the course on nutritional oils available through NOW University.
1 Dolecek, T.A.; “Epidemiological Evidence of Relationships Between Dietary Polyunsaturated Fatty Acids and Mortality in the Multiple Risk Factor Intervention Trial” Proc Soc Exp Biol Med 1992;200:177-182.
2 Waterman, E.; et al.; “Active Components and Clinical Applications of Olive Oil” Altern Med Rev 2007;12:331-342.
3 Johnson, G.H.; “Qualified Health Claims: Letter of Enforcement Discretion – Unsaturated Fatty Acids from Canola Oil and Reduced Risk of Coronary Heart Disease” FDA Docket No. 2006Q-0091 Oct. 6, 2006.
4 Li Z.; “Hass Avocado Modulates Postrandial Vascular Reactivity and Postprandial Inflammatory responses to a Hamburger Meal in Healthy Volunteers” Food Funct 2012, Nov. 29th [Epub ahead of print].