|Some Recent Studies on Fats|
|Written by Mary G. Enig, PhD|
|Sunday, 22 March 2009 20:28|
While thevoices warning against saturated fats like butter, tallow and coconut oil become ever more strident, the scientific evidence for the benefits of saturated fat continues to accumulate. Here are a few recent examples:
BEEF TALLOW AND CLA
CLA is a substance that accumulates in the fat of grass-fed ruminant animals-fats like butter and tallow-that has anti-cancer effects. In a study published in the Journal of Nutrition (136 (2006) 88-93), researchers, looking into the effects of CLA on implanted and injected breast cancers cells in mice fed a control group of mice a vegetable fat blend "that approximates the fatty acid composition of the American diet." Two groups of mice were fed a diet in which half of this blend was replaced with beef tallow. Half of these mice were fed 0.1 percent fatty acids as CLA while the other received no CLA. Two other groups of mice received half of the fat ration as corn oil, one getting 0.1 percent of fatty acids as CLA and the other receiving no CLA. Another six groups were fed similarly, but the CLA groups were fed 0.5 percent CLA; another six groups were fed in a manner similar to the first six, but with the tallow or corn oil replacing only onequarter instead of one-half of the vegetable fat blend. All diets contained the same amount of fat, namely 20 percent by weight and 40 percent of calories.
In the beef tallow group that did not receive CLA, the growth and size of metastases to the lung was 2.5 times lower than in the corn oil group. In the groups receiving CLA, beef tallow reduced the ability of the breast cancer cells to metastasize to the lung and also reduced the level of CLA necessary to have an effect. CLA had no effect in the groups receiving corn oil. The researchers found that the benefits of beef tallow were due to its content of 16-carbon palmitic acid, a fatty acid singled out for opprobrium by the vegetable oil industry, probably because it is the main fatty acid in palm oil. Palm oil is the natural replacement for trans fats and hence represents a huge threat to the soy oil industry in the US-in Europe food manufacturers are replacing partially hydrogenated soybean oil with naturally saturated palm oil imported from Indonesia and Africa.
STEARIC ACID AND RISK FACTORS FOR HEART DISEASE AND STROKE
In a study carried out in Australia and published in the European Journal of Clinical Nutrition (2001 Feb;55(2):88-96), 13 healthy males consumed two experimental diets for four weeks, with a seven-week "washout" between the two dietary periods. The diet consisted of approximately 30 percent of calories as fat (a very lowfat diet). During the first phase, subjects consumed approximately 6.6 percent of calories as stearic acid (diet S), the 18-carbon saturated fatty acid found in beef fat and butter; during the second phase, the subjects consumed approximately 7.8 percent of calories as palmitic acid (diet P), the 16-carbon fatty acid found not only in butter and beef fat but also in palm oil.
The researchers took blood samples on day zero and day 28 of both diets. Markers of proneness to atherosclerosis and stroke significantly decreased on diet S and significantly increased on diet P.
This study has little significance in the world of real food as stearic acid and palmitic acid are found together in traditional animal fats and their effects would presumably cancel each other out. Also, the results were probably confounded by the very low levels of fat in both diets, levels very difficult for the ordinary person to achieve.
However, the food industry may find the results useful. Full hydrogenation of the most common vegetable oils, which contain a preponderance of 18-carbon polyunsaturated fatty acids, results in the production of saturated 18-carbon stearic acid. Fully hydrogenated oils are now showing up in the new âtrans-freeâ oil blends. The industry can argue that these industrially produced saturated fats are good for us because they lower certain risk factors for disease, but that natural saturated stearic acid in butter and beef fat should be avoided because these fats also contain that dastardly villain, palmitic acid.
NOT AS REPORTED
Researchers in the Netherlands studied the effects of different fatty acids, including saturated fatty acids and very long-chain omega-3 fatty acids, on homocysteine levels in two age groups, 47-49 years and 71-74 years old. High homocysteine levels are thought to be a marker for proneness to heart disease.
The results were published in the American Journal of Clinical Nutrition (2007 Jun;85(6):1598-1605) with the following conclusion: âHigh intakes of SFAs [saturated fatty acids] are associated with high plasma concentrations of tHcy [homocysteine]. The inverse association between dietary intakes of very long-chain n-3 FAs and plasma tHcy concentrations is apparent only at high B vitamin intakes.â
Sounds like bad news for saturated fats but if you look closely at the tables, you find no tenable or consistent relationships between consumption of various fatty acids and homocysteine levels. Among all the food evaluations, the average differences in homocysteine levels between the highest and lowest quintiles of consumption was a mere 0.33 umol/L (with a range from 0 to 0.5). And fatty acid levels were âcalculatedâ from food questionnaires, which is not a method likely to provide meaningful data.
By contrast, the difference in homocysteine levels was significantly associated with age, with levels ten times higher in the 70-year-olds compared to the 40-year-olds, but there is no mention of this important fact in the study abstract.
AHA TRANS FAT CAMPAIGN
The food industry introduced partially hydrogenated vegetable oils years ago as a substitute for liquid vegetable oils. The industrially altered but stable trans fats were the hope of the industry as evidence accumulated to show that the liquid oils were bad news indeedâcausing atherosclerosis, cancer, immune suppression, premature aging and developmental problems in children.
In what can only be described as jumping from the frying pan into the fire, industry apologists have now done an about-face and are campaigning against the trans in favor of the liquid oilsâwhile using this opportunity of heightened public interest to continue demonizing the fats we should all be using, the natural saturated animal fats in animal foods and tropical oils.
In the April 13, 2007 issue of Circulation, the American Heart Association (AHA) announced a new educational campaign to âhelp consumers limit the amounts of trans fats in their diets, while not defaulting to more saturated fats.â The campaign features an âedutainmentâ website with an interactive âfat calculatorâ and examples of products containing trans and saturated fats, all explained by two animated characters, the Bad Fat Brothers, Sat and Trans. The major priority of the campaign is âto encourage replacement of partially hydrogenated vegetable oils with oils high in unsaturated fats. . . . At the same time, the association is highlighting the negative health impacts of saturated fat.â The website warns consumers to avoid commercial baked foods, fried foods, snack foods and hard margarines, all sources of trans fats and obviously bad for us for many reasons; but consumers should also avoid natural sources of saturated fat, says the AHA, including beef, lamb, pork, poultry with skin, beef fat, lard, palm oil, coconut oil and cream, butter, cheese and other dairy products made from whole or reduced-fat milk.
FAT IS GOOD!
The movie called Beauty Shop contains a scene near and dear to our heartsâwith thanks to North Shore, Massachuestts, WAPF chapter leader Cyndy Gray for writing down this marvelous piece of dialogue.
The plot follows a character played by Andie McDowell, who starves herself in order to have a slim figure for her husband, whoâs not very nice to her. Once she acknowledges her husbandâs unsavory character, she starts living for herself.
Rita, played by Queen Latifah, has a soul-food push cart, which she brings into the beauty shop. Andie serves herself some greens and asks, âSo, if you had to take a wild guess, how many grams of fat would you say are in a plate of your greens?â
Baby, my greens is all fat,â says Rita. âMatter of fact, I found every fat you could find to put in my greens. I got fat back, salt pork, sausage, pork chop fat, pork rinds and bacon bits.â
âTalk dirty to me!â says Andie.
âThatâs right, say it with me, âFat is good!ââ
âFat is good!â says Andie.
âThatâs right now. . . Sho ânuf is!â
This article appeared in Wise Traditions in Food, Farming and the Healing Arts, the quarterly magazine of the Weston A. Price Foundation, Winter 2007.
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|Last Updated on Friday, 27 April 2012 19:58|