At the present time, there is no Rec- ommended Dietary Allowance (RDA) for EFAs in the U.S. However, the National Academy of Sciences’ Institute of Medi- cine (IOM) recommends 1.6g/day of ALA for men and 1.1g/day for women.4 The American Heart Association (AHA) and the Heart and Stroke Foundation in Canada recommend that fatty fish be consumed twice a week.5 THE IMPORTANCE OF THE OMEGA 6-3 RATIO Omega-6 fatty acids, specifically linoleic acid (LA) and arachidonic acid (AA), are also essential. However, in many ways they act opposite to the anti-inflamma- tory and “blood thinning” actions of the omega-3 fatty acids. Specifically, they tend to promote infl ammation and clot- ting. They also compete with enzymes that help short chain ALA be converted to long chain EPA and DHA.6,7 Therefore, the consensus recommendation is to eat more “anti-infl ammatory” omega-3 fats and fewer pro-inflammatory omega-6 fats and saturated fats.8 DO ALL OMEGA-3 FATS HAVE THE SAME HEALTH BENEFITS? Omega-3 fats are alike in some ways and different in others. Chronic diseases like heart dis- ease, diabetes, cancer and arthritis are marked by inflammation. Therefore, all omega-3 fats help reduce chronic disease risk by blocking inflammation.10,11 Still, it is generally recognized that the long chain omega-3 EPA/DHA intake is more powerful in relation to cardiovas- cular disease and inflammatory joint dis- ease.12,13,14 acid, EPA and DHA all act in support of keeping cell membranes flexible and elastic, and block the actions of some compounds that cause inflammation and clotting.9 Even more important to ap- preciate are DHA’s unique health effects. Because it helps the eye, brain and ner- vous systems develop properly, infants have a special need for DHA. 15,16,17,18,19 Aging adults may need DHA, too, as it grants the most protection against Alzheimer’s disease.20 A FISH STORY Multiple clinical studies have shown the oils of fatty fi sh, EPA and DHA, to be of benefi t to the cardiovascular sys- tem, brain and visual function, immune www.canadianchiropractor.ca Alpha-linolenic function, skin health, inflammatory modulation and joint health.21,22 As ALA conversion to EPA is moderate at best, depending on many variables, and con- version to DHA is minimal, it is generally thought that regular, twice-weekly fatty fi sh oil consumption, or fi sh oil supple- mentation, are the best ways to enhance EPA/DHA status.23,24 However, the AHA warns that “some species of fi sh may contain significant levels of methylmercury, polychlorinated biphenyls (PCBs), dioxins, and other en- vironmental contaminants. These sub- stances are present at low levels in fresh waters and oceans, … generally highest in older, larger, predatory fi sh and marine mammals.”25 Protection Agency actually posts an advi- sory of fish consumption!26 and Canada advise pregnant and nursing women, women who may become preg- nant and young children to avoid eating certain fish.27,28 Fish oil capsules are the most concen- trated form of omega-3 fats. Fortunately, few contain mercury. However, some may contain carcinogenic polychlorinated bi- phenyls (PCBs). Consumers who follow the label recommendation on some fish oil supplements can take in up to 43 per cent of the daily upper limit of PCBs!29 The biggest problem with deteriora- tion in the quality of fi sh oil is rancidity from oxidation. Analytical assessments of oxidation are provided in terms of Perox- ide Value (PV), Anisidine Value (AV), and Totox Value. However, the easiest test is the “taste test.” If the oil tastes or smells bad, it probably is bad, regardless of what the tests say.30 Because of the lipid per- oxidation, it is generally recommended to take physiological doses of vitamin E when supplementing with fish oils.31,32 According to AHA guidelines, supple- menting more than two grams of fish a day should be under a health profession- al’s guidance as it may lead to too much blood thinning and subsequent internal bleeding.33 We should not forget that fi sh is the major dietary source of vitamin D and yet is absent from most fi sh oils. As re- cent studies suggest that consuming more Vitamin D may lower the risk of death from any common disease of ag- ing, especially colon and breast cancer, this is not an unimportant omission.34,35 Those fi sh oils, like cod liver oil, may The U.S. Environmental Both the U.S. have some vitamin D but may also have concomitantly high doses of vitamin A which may be contraindicated.36 Both the U.S. and Canada advise pregnant and nursing women, women who may become pregnant and young children to avoid eating certain fish. Swallowing large or numerous fish oil pills and taste, texture and swallow- ing issues with fi sh oils, both including fi shy aftertaste and “fi sh burps”, can be a compliance hurdle. FACTORS IN FAVOUR OF FLAX Flaxseed is much more than just the richest source of ALA. Flaxseed is ap- proximately 38 per cent oil, which is comprised mainly of alpha-linolenic acid, with lesser amounts of the omega-6 and omega-9 fatty acids. Not to be overlooked, is that flaxseed’s dietary fi bre content of about 28 per cent grants added health benefi ts. The Ameri- can Dietetic Association has cited fibre’s “signifi cant impact” on obesity, cardio- vascular disease and Type 2 diabetes pre- vention and management.37 Flax has a ratio of soluble-to-insoluble fi bre that can vary in a ratio of between one part to four parts soluble-to-insoluble and four parts to six parts, respectively.38 Insoluble dietary fi bre supports healthy elimination and colon health, and may even have protective effects against colon cancer.39 The soluble dietary fibrefraction of fl ax is found primarily as mucilage gums, which have been shown to play a role in lowering serum cholesterol levels and glycemic control.40 Flax’s other very beneficial compound is its lignans and fi bre. Lignans are a subclass of polyphenols known as phy- toestrogens – plant compounds that can have estrogen-like actions.41 Through the actions of the lignans and ALA, flax may block tumour growth in animals and may help reduce breast, prostate and colon cancer risk in humans, likely by competing with toxic endogenous and xenogenous estrogens.42,43,44,45,46 CANADIAN CHIROPRACTOR | MAY 2008 • 17
Chiropractic + Naturopathic Doctor May 08: Page 17
