Omega-6 EFAs and Human Health

The benefits associated with omega-6, an essential fatty acid (EFA), have been recently overshadowed by the abundance of research and press hyping omega-3. In addition, a Western diet rich in omega-6s but poor in omega-3s has cast a negative spotlight on this necessary nutrient. “In our society’s constant search to over simplify the complex, we often get only part of the story or jump to faulty conclusions,” said Ken Ardisson, business manager-Specialty Nutritionals, Arcadia Biosciences. “We’re told that since omega-3s are so good, then omega-6s must be bad. Following this seemingly logical thread, since linoleic acid is a major constituent of corn and soybean oils, both of which are widely used in commercial cooking, these must, therefore, also be bad.”

In fact, Ardisson noted, omega-6 and its constituents actually hold health-promoting promise for a variety of conditions ranging from skin inflammation to cholesterol control.

Omega-6’s distinctive characteristics shed light on the many avenues and possibilities of omega-6 supplementation. Omega- 6s are found in raw nuts, seeds, legumes and in unsaturated vegetable oils, such as borage, grape seed, evening primrose, sesame and soybean oils. The family of omega-6 polyunsaturated fatty acids (PUFAs) has a carbon-carbon double bond at the sixth carbon from the terminal end of the molecule. Omega-6s have complementary but notably distinct functionalities when compared to omega-3s. Linoleic acid (LA) is considered the parent of the omega-6 family and is the most abundant fatty acid seen in most seed- and vegetable-based cooking oils. It also appears LA offers significant mechanisms for the control of cholesterol. A paper published by the Endocrine Society in 2006 stated: “Linoleic acid, an omega-6 PUFA, is cardio-protective” and “remains the most potent cholesterol-lowering nutrient.”¹ In January 2008, the American Heart Association (AHA) said heart disease death rates in the United States dropped 26 percent from 1999 to 2005 due to lower cholesterol levels and a reduction of saturated fats, trans-fats and partially hydrogenated oils in the diet. Ardisson added the popularity of “heart-healthy” buttery blends, which are an assembly of oils with relatively high omega-6 content, is another indication of LA’s ability to control cholesterol.

LA can be broken down to a secondary sequential metabolite known as gamma-linolenic acid (GLA) by way of the delta-6 desaturase (D6D) enzyme. Mary Ann Siciliano, national sales manager, Arista Industries, noted pre-formed GLA can be ingested from several plant-based oils including evening primrose oil (EPO), borage and black currant seed oil. Its efficacy is based on its anti-inflammatory properties and ability to balance the ratio of saturated and unsaturated fats in cells and cell walls. “Ideally, the body produces all the GLA it needs,” Ardisson said. “However, under cer tain circumstances, the D6D enzyme becomes impaired, preventing the body from efficiently converting linoleic acid to GLA.” Factors such as stress, aging, diabetes, alcohol consumption, smoking, eczema, infection, diabetes, cancer, excessive saturated fat intake, elevated cholesterol levels, and deficiencies of vitamins B3, B6 and C, zinc and magnesium can contribute to a weakened D6D enzyme and the body’s inability to convert LA properly. Additionally, a limited delta-5 desaturase (D5D) enzyme can convert GLA metabolites into another omega-6 by-product called arachidonic acid (AA). Interestingly, AAs, which come primarily through consumption of animal products, possess a diverse duality: they are vital constituents of cell membranes but can also be converted into pro-inflammatory eicosanoids.

Step by Step

The conversion step from L A to GL A appears to play a fundamental role in the body’s ability to deal with inflammation. Dietary GLA may help reduce inflammation. “Supplementing the diet with GLA-rich oils like borage, EPO, black currant or echium seem to reduce inflammatory processes by inhibiting the conversion of arachidonic acid in the body to inflammatory products,” said David Chance, sales and marketing manager, Sanmark. He noted dietary GLA is converted to di-homo gamma-linolenic acid (DGLA), which is then converted to an anti-inflammatory eicosanoid. Siciliano added DGLA competes with AA for enzymes and prevents the negative inflammatory effect that AA would otherwise cause in the body. Further, Siciliano said, adequate amounts of certain nutrients such as magnesium, zinc and vitamins B3, B6 and C may promote the conversion of GLA to DGLA rather than AA.

The two major classes of signaling eicosanoids are prostaglandins and leukotrienes. Depending on the cell, DGLA can be converted to a prostaglandin or both prostaglandins and leukotrienes. The cyclooxygenase (COX) enzyme converts DGLA into 1-series prostaglandins (PGE1), which are the source of many healthy and beauty benefits, such as the ability to soothe skin, promote healing and regulate water loss. Its antiinflammatory properties help to distend blood vessels, aid in restraining blood clotting and abate swelling, pain and redness caused by bodily injuries.

Ann Louise Gittleman, MS, CNS, noted GLA can also help cell resilience and moisten the fatty layer beneath the skin, creating a sundry of beautifying benefits such as aiding in collagen loss; soothing dry, scaly skin; combating wrinkles; strengthening brittle nails and prevent dandruff. “The bottom line is that supplementing with GLA-rich oils provides an anti-inflammatory effect,” Chance said.

GLA is widely available from a variety of oils in softgel form or as bottled oil. Arista Industries also offers GLA in powder form from EPO and borage oil. EPO (8 to 10 percent GLA) has been used for premenstrual syndrome (PMS), menopausal symptoms and various skin conditions;^2,3 preliminary information indicates GLA from borage (20 to 24 percent GLA), black currant (14 to 17 percent GLA) or EPO may diminish joint pain, swelling and morning stiffness in arthritic conditions.4 All three are also used to address a variety of skin conditions such as eczema and dermatitis.

New GLA offerings include Arcadia Biosciences’ GLA-rich safflower plants that can produce yields of up to 40 percent GLA oil; and Sanmark’s echium, a balanced oil providing 15 percent GLA and 35 percent alpha-linolenic acid (ALA), an omega-3 EFA.

Preserving the -6s

Although commodity vegetable oils contain high levels of omega-6, there are subtle differences between such products and nutritional oils with preformed GLA. “Commodity vegetable oils are usually highly refined at extreme temperatures, which could damage the unsaturated fatty acids and also strip the oils of other beneficial components, such as vitamin E,” he said, adding to preserve vegetable oils they should not only be produced in mild conditions, but should be consumed without undergoing high temperature heating. Siciliano further noted omega-6s are not as unstable as omega-3s, “but they must be handled and packaged properly for optimal benefits and stability.”

As with all fats, production, stability and formulation can be challenging. Encapsulation of natural oil supplements into a softgel can provide protection against damage by oxygen; however, extra care during manufacturing and formulation must be followed—avoiding exposure to heat, light and oxygen during the pressing of the oil and ensuring the oil doesn’t lose its quality or become oxidized during the encapsulation process. Bottle oils must be bottled in a low-light low-oxygen atmosphere, optimally with an inert gas to protect the oils as the bottle is sealed. The bottle should be opaque to protect from light and the temperature should be controlled during storage. Finally, the customer should be educated at the store level to keep the product refrigerated and to use the product as soon as possible.

Set In Stone

The most sensitive area of discussion surrounding EFAs may well be indefining the optimal ratio of omega-6 to omega-3. Currently, the Western diet provides a ratio of omega-6 to omega-3 between 15:1 and 20:1. A 2007 study by researchers from Ohio State University reported changing the ratio of omega- 3 to omega- 6 in the diet to a more balanced intake may improve mood and reduce depression.⁵ Another study in 2005 concluded a rapid increase in omega-6 in the Western diet has caused an increase in prostate cancer.⁶

“As far as an optimal dietary ratio, there is not sufficient scientific study to justify the many prophetic statements,” Ardisson said. “ Circumstances get even cloudier when considering the pronounced benefits that linoleic acid affords for decreased serum cholesterol levels.” That said, he added ratios in the range of 4:1 to 5:1 would be a considerable improvement.

Johan Kamphuis, executive vice president-global marketing and sales, Bioriginal Food and Science, said the optimal ratio depends on age. “ For infants, the ratio is more omega-6, mostly arachidonic acid, and DHA omega-3 in the ration of 2:1; for the elderly, GLA omega-6 and omega-3 is more closely to 1:3 or 1:4,” he said.

Chance said: “Although there is some agreement that we evolved eating a diet close to a 1:1 ratio, it appears that some chronic conditions may respond better to a different ratio of omega-6 to omega-3.” He added part of the difficulty in determining a set ratio involves the form of the fatty acids used and the wide variety of different combinations, which yielded different results in testing; also, an individual’s physiology can make it impossible to pinpoint a specific ratio.

The future looks promising for omega-6s; and recent research on weight loss management,⁷ and certain types of breast cancer,⁸ could potentially bring this nutrient out of the shadows. Additionally, as consumers turn to cosmeceutical solutions to prevent aging and address skin conditions, GLA could be the next hot button in the natural beauty sector. 

References

1. Sacks, FM, et al. “Polyunsaturated Fatty Acids, Inflammation, and Cardiovascular Disease: Time to Widen Our View of the Mechanisms” (J. Clin End & Metab; 2006;91(2):398-400.)

2. Hardy ML. “Herbs of special interest to women.” (J Am Pharm Assoc (Wash). 2000; 40(2):234-42).

3. Hederos CA, et al. “ Epogam evening primrose oil treatment in atopic dermatitis and asthma.” (Arch Dis Child; 1996;75(6): 494-497).

4.Brzeski M, et al. “Evening primrose oil in patients with rheumatoid arthritis and side-effects of non-steroidal anti-inflammatory drugs.” (Br J Rheumatol; 1991 30(5): 370-2).

5. Kiecolt-Glaser JK, et al. “Depressive Symptoms, omega-6:omega-3 Fatty Acids, and Inflammation in Older Adults” (Psychosom. Med; 2006;69:217-224).

6. Hughes-Fulford M, et al. “Arachidonic acid, an omega-6 fatty acid, induces cytoplasmic phospholipase A2 in prostate carcinoma cells” (Carcinogenesis; 2005; 26(9):1520-1526).