A Lexicon on Lipids
Essential Fatty Acids (EFAs). The EFAs are certainly not entirely new. It seems that most everyone has heard of flaxseed oil and the benefits of omega-3 EFAs in the diet. What many don't realize is that other options exist for obtaining EFAs. There are also new products that have a similar fatty acid profile to flax, such as chia seed oil.
Much like a vitamin, two fatty acids are truly "essential": linoleic acid (LA) and alpha-linolenic acid (ALA). These fatty acids are the "source material" for the metabolism of other fatty acids which, in turn, produce prostaglandins and eicosanoids.
The recommended ratio for omega-6 to omega-3 in our diets is in the range of 4:1 to 6:1. However, there is a tendency for excess consumption of the omega-6 fatty acid, linoleic acid. One disadvantage is that the omega-6s compete for the delta-6-desaturase enzyme that is also needed for omega-3 fatty acid metabolism. Thus, it is thought that, in some cases, a person may benefit from dietary supplementation of GLA because this avoids the use of delta-6-desaturase.
On the Web: NUTRITIONAL FATS
- www.supplementwatch.com Online "encyclopedia" of supplements with associated claims and supporting theories.
- www.eatright.org/pr/1999/0921f.html American Dietetic Assoc. press release with information on DHA
Council for Responsible Nutrition page on global standards for DHA and EPA
Type "A Question of Balance" into the keyword search field on the home page for more information on dietary ratios of omega-3 to omega-6.
Flaxseed oil (Omega-3 source). Flaxseed oil is a great source of omega-3 fatty acids, and it is one of the more popular ways to get omega-3s into the diet among health-conscious consumers. Flaxseed oil in the diet has been shown to improve the ratio of omega-3 to omega-6 EFAs in the body, andâ€”againâ€”is thought to offer protection against inflammatory conditions. Flaxseed has been clinically studied in several areas. Research results indicate that flaxseed oil produces significant protective effects against both breast and colon cancers; significant evidence exists for the consumption of flaxseed and flaxseed oil and decreased pro-inflammatory prostaglandins. Also, 40g of flaxseed oil daily reduced blood clotting, an issue in cardiovascular disease.
Borage oil (high in GLA). Borage is noted for is its natural 1:1 ratio of omega-6 and omega-3 fatty acids. The clinical benefits of borage oil have been associated with the high amount of GLA present in borage seeds. Therefore, the clinical benefits of borage are similar to those of evening primrose oil and black currant oil. Studies that specifically focused on GLA from borage oil targeted such conditions such as rheumatoid arthritis and eczema, and found beneficial results.
Evening primrose oil (high in GLA). Evening primrose oil (EPO) is primarily known for its clinically studied effect on PMS. It also has been found efficacious in studies for reducing "bad" or LDL cholesterol and reducing the risk of heart disease. EPO has been tudied with mixed results for a number of other conditions. A stronger relationship appears to exist between its consumption and reduced risks of cancer, decreased Sjogren's syndrome symptoms and improved immune function; more equivocal results exist for dermatitis, eczema, and asthma.
Black currant oil (Omega-3 source). Black currant oil has high levels of GLA and, therefore, its benefits are related to those that have been studied for GLA sourcesâ€”such as borage oil and EPO.
Hemp seed oil (Omega-3 source + GLA). Hemp seed oil is interesting because it contains both omega-3 fatty acids, and GLA (and just in case you were wondering, it does not contain the non-essential substance THC, the psychoactive compound in marijuana). Although hemp is gaining popularity, its long-term legal status in the U.S. remains to be seen.
Chia seed oil (Omega-3 source). Chia seed oil is a relatively new supplement source for the omega-3 fatty acids. Its chemical composition and characteristics are similar to flax, but it also has an unusually high protein content and good amino acid profile. Chia seed is an ancient staple grain to the indigenous people of parts of Latin America and Mexico; it is also reputed to be an energy enhancerâ€”among other unconfirmed benefits.
Conjugated linoleic acid (CLA). CLA is touted for many health benefits, including fat loss, muscle gain and increased calorie expenditure. Also, it is an antioxidant and may help reduce risk of cancer. The studies on its cancer-fighting properties have been promising, but its reputed effects on body composition attract most.
CLA has performed very well in animal studies in producing leaner, more muscular experimental animals, but how does it fare in humans? So far, the evidence is inconclusive, although two recent studies have shown good results. CLA (3-4g daily) was given to obese men and found to produce a reduction of two to four pounds in body fat over 12 weeks, and a 1 inch difference in abdominal fat.
Medium chain triglycerides (MCT). MCTs seem too good to be true! They are fats that generally are not metabolized like fat. The theory is that MCT oil can be used to replace certain food oils, such as salad dressing, while avoiding some of the disadvantages associated with fat consumption. (Since MCTs are not stable to heat, they cannot be used as cooking oil.) MCT supplementation commonly is claimed to improve endurance, promote fat loss, spare muscle glycogen, increase the metabolic rate, and maintain muscle massâ€¦how much of this is true?
MCTs are fats of 6, 8, 10, or 12 carbons, giving them their name medium-chain triglycerides. Due to their length, they are treated differently than the more prevalent types of fats in the body (the long-chain fats), and they are transported to the liver directly during metabolism, where they are quickly used. MCTs behave more like carbohydrates in the body, where they can provide a quick source of energy. However, they also tend to produce ketone bodies, which, in large amounts, may be an issue for diabetics. For non-diabetics, MCTs have been shown safe in quantities up to 1g/kg of bodyweight.
Guggulipids. Guggulipids are made from the gum resin of a tree from India called Commiphora mukal. Guggulipids have been used for centuries in Ayurvedic medicine, and many of their uses are now being confirmed by science. They have been shown to decrease LDL and total serum cholesterol, cholesterol synthesis, and platelet aggregation, but raise HDL cholesterol and increase bile secretion and fibrinolytic activity.
Although nutritionists advise us not to categorize fats as "good" or "bad," certain lipids will be increasingly sought after for the health benefits they provide.
References:Ghorai M,, et. al., 2000. A comparative study on hypocholesterolaemic effect of allicin, whole germinated seeds of bengal gram and guggulipid of gum gugglu. Phytother Res May;14 (3):200-2.
Mc. Kenna, D.; K. Hughes; and K. Jones. (In Press) The Natural Dietary Supplement Desktop Reference. Haworth Press.
Singh RB, et. al., 1994. Hypolipidemic and antioxidant effects of Commiphora mukul as an adjunct to dietary therapy in patients with hypercholesterolemia. Cardiovasc Drugs Ther Aug;8 (4):659-64.