Journal Name:
J. Am. Diet Assoc.
Article Title:
Dietary Modeling Shows that the Substitution of Canola Oil for Fats Commonly Used in the United States Would Increase Compliance with Dietary Recommendations for Fatty Acids
Date Written:
2007
Volume:
107
Number:
0
Page:
1726
Author(s):
Johnson, G.H.; Keast, D.R.; Kris-Etherton, P.M.
Article:
Statistics compiled by the American Heart Association (AHA) show that there are approximately 1.4 million deaths due to this cause each year (an average of one death every 34 seconds). Cardiovascular disease claims about as many lives as the next five leading causes of death combined (those being cancer, chronic lower respiratory diseases, accidents, diabetes mellitus, and influenza/pneumonia).
Canola oil has the potential to help consumers achieve dietary goals because it has the lowest concentration of saturated fatty acids (SFAs - 7.1% of total fatty acids) of all oils commonly consumed in the United States, including (presented in decreasing order by usage): soybean oil (14.4%), corn oil (12.9%), cottonseed oil (25.9%), palm oil (49.3%), olive oil (13.5%), peanut oil (16.9%), and sunflower oil (9.7%) (6). In addition, canola oil is composed predominantly of monounsaturated fatty acids (MUFAs)—58.9% of total fatty acids—and is the richest source of the n-3 essential fatty acid, ALA (9.3% of total fatty acids), of the edible oils widely available in the United States noted above.
Canola oil has been shown to reduce serum total cholesterol and/or low-density lipoprotein (LDL) cholesterol when fed in place of higher SFA-containing fats in most controlled intervention studies. The majority of these studies also reported that canola oil had no effect or a beneficial effect on serum high-density lipoprotein cholesterol and/or triglycerides. Numerous government and public health organizations, including the Dietary Guidelines for Americans 2005, the National Cholesterol Education Program, and the AHA have advised Americans to limit intake of fats and oils high in SFAs and/or TFAs, and to choose products low in such fats and oils. Specifically, the maximum recommended intakes of SFAs range from 7% to 10% of energy and those for TFAs range from the lowest possible amount to no more than 1% of energy. One strategy to achieve this recommendation is to replace foods that are high in SFAs with those that are higher in unsaturated fatty acids when making dietary selections. The purpose of this study was to estimate the changes in energy, fatty acid, and cholesterol intake that would occur if such recommendations were implemented using an oil with a very favorable fatty acid profile.
Thus, this study was designed to examine the effect of substituting canola oil for selected vegetable oils and canola oil–based margarine for other spreads on energy, fatty acid, and cholesterol intakes among US adults. Twenty-four–hour food recall data from the 19992002 National Health and Nutrition Examination Survey (NHANES) were used to calculate the effect of substituting canola oil for dietary corn, cottonseed, safflower, soybean, and vegetable oils described as “not further specified” and of canola oil–based margarine for other spreads at 25%, 50%, and 100% replacement levels. Adult participants aged ≥20 years (n=8,983) of the 1999-2002 NHANES were included. Sample-weighted mean daily intake values and the percentage of subjects meeting dietary recommendations were estimated at the various replacement levels. Standard errors of the means and percentages were estimated by the linearization method of SUDAAN.
Significant changes compared to estimated actual intakes were found and included: saturated fatty acid intake decreased by 4.7% and 9.4% with 50% and 100% substitution, respectively. Complete substitution increased monounsaturated fatty acid and ALA intakes by 27.6% and 73.0%, respectively, and decreased n-6 polyunsaturated fatty acid and linoleic acid intakes by 32.4% and 44.9%, respectively. The ratio of n-6 to n-3 fatty acids decreased from 9.8:1 to 3.1:1 with 100% replacement. Energy, total fat, and cholesterol intakes did not change.
The increased intake of MUFAs at the expense of PUFAs that would result from greater use of canola oil is also consistent with most current dietary benchmarks. The National Cholesterol Education Program concluded that MUFAs lower serum LDL cholesterol levels compared to SFAs and do not lower high-density lipoprotein cholesterol levels or raise triglyceride levels. In addition, a meta-analysis of 14 studies found that the cholesterolemic effects of MUFAs and PUFAs are comparable when used as a replacement for dietary SFAs, and the AHA endorsed this conclusion. MUFAs might also be advantageous because they do not increase the susceptibility of LDL cholesterol to oxidation as can be the case with diets high in PUFAs. Oxidation of LDL cholesterol particles in the arterial intima is believed to be an early insult that contributes to inflammation, foam-cell formation, and ultimately the development of atherosclerotic plaques. These observations, in part, contributed to the recommendation made by the National Cholesterol Education Program and the IOM that PUFA intake not exceed 10% of energy. Substitution of canola oil for other fats would substantially increase the intake of ALA and reduce the ratio of n-6 to n-3 fatty acids. Considerable data suggest that the long-chain n-3 PUFAs are cardioprotective and emerging evidence suggests that ALA—the only n-3 fatty acid found in appreciable amounts in some vegetable oils—might also be effective in this regard. ALA might have beneficial effects on cardiac arrhythmia, inflammation, and thrombosis. Furthermore, considerable epidemiologic evidence shows that ALA intake is associated with decreased morbidity and mortality from coronary heart disease.
Substitution of canola oil and canola oil–based margarine for most other vegetable oils and spreads increases compliance with dietary recommendations for saturated fatty acid, monounsaturated fatty acid, and ALA, but not for linoleic acid, among US adults. The results of this study show that fatty acid intake can be influenced substantially through a simple recommendation to change the type of vegetable oil used at the table and in cooking. The lack of consumer barriers to such a change with respect to cost, taste, convenience, and availability makes canola oil attractive from a practical perspective. In addition, a qualified health claim on the ability of canola oil and eligible canola oil–containing foods to reduce the risk of coronary heart disease was authorized by the Food and Drug Administration on October 6, 2006. The availability of this claim may increase consumer awareness of the potential health benefits of canola oil.
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