by by Vreni Gurd | Fri, 04/06/2007 - 11:15pm
We are told that saturated fat and trans fat are terrible for us. The distinction must be made. Saturated fats are healthy, trans fats are not.
Saturated fats have been vilified as being the cause of heart disease, some cancers, and the obesity epidemic. Although heart disease and cancer were rare before 1920, the incidences of these diseases have increased dramatically since then. By as early as 1950, heart disease was the leading killer of Americans. However, contrary to what one would expect if the saturated fat/heart disease hypothesis were true, the consumption of animal fat between 1910 and 1970 DECREASED by 21% and the consumption of butter DECREASED from eighteen pounds per person per year to only four, according to the research of Sally Fallon and Mary Enig. Furthermore, over that same time span the consumption of refined vegetable oils much of it consumed as partially hydrogenated or trans fat, INCREASED by 400%, and the consumption of sugar and processed foods INCREASED by 60%. Current Canadian 2006 data (thank you Chris Williams!) suggest that those trends are continuing, with a continued decrease in the consumption of high saturated- fat foods like full-fat milks, eggs and red meat between 1970 and 2006. Since 1981, butter consumption (a saturated fat) has decreased by a third, while the consumption of salad oil (refined and therefore rancid polyunsaturated vegetable oils) has more than tripled. Shortening consumption (a trans fat) has remained relatively constant. So considering the continued decline in saturated fat consumption, blaming heart disease on saturated fat makes no sense (see this study published in the Lancet). To fully understand how it is possible that we find ourselves in this position where we are being told to eat refined polyunsaturated vegetable oils which are disease-causing and avoid saturated fats which are health promoting, read The Oiling of America by Mary Enig, PhD, fats and oils researcher, and Sally Fallon. The insight into the politics of food is scary.
All fats and oils are made up of a mixture of saturated, mono and polyunsaturated fatty acids. Calling animal fats "saturated fats" is very misleading, as many animal fats are actually more than 50% unsaturated, and chicken fat is actually 70% unsaturated. If a fat were completely saturated it would be very solid with the consistency of hard wax. For example, beef fat or tallow is made up of about 50% saturated fatty acids (25% palmitic acid, 22% stearic acid and others), 40% monounsaturated fatty acids (oleic acid, the main fatty acid in olive oil), and the balance polyunsaturated fatty acids (linoleic and linolenic, the ratio depending on the diet of the cattle).
Saturated fatty acids are critical to maintaining the structure and rigidity of our cells by making cell membranes out of phospholipids and cholesterol, and they act as enzyme and hormone regulators thereby playing an integral role in cell messaging. When the body is fooled and incorporates trans fats into the cell membrane instead of saturated fats, cell messaging no longer works, which is one of the reasons trans fats are so dangerous.
Saturated fats are necessary for calcium to be incorporated into our bones, so no-fat or skim milk won't work as a calcium source, unless you eat some saturated fat in your meal. Saturated fats are needed to boost immune function, and to build a healthy nervous system and digestive tract. Saturated fats are the base material out of which the body makes cholesterol, which is the precursor to such critical hormones as vitamin D, cortisol, testosterone, estrogen and progesterone, as well as bile acids which are necessary for the digestion of fats. Fats also are needed as carriers for the fat soluble vitamins (the antioxidant vitamins), like vitamin A, E, D, K, and a low fat diet can lead to deficiencies in these nutrients. Saturated fats are also needed to be able to utilize omega 3 fatty acids easily. Breast milk is high in saturated fat for a reason - it is vital for the healthy development of the baby! Does it make sense that saturated fats which are vital for a baby are suddenly poison for an adult?
Fat is also needed to feel satisfied after a meal. Mary Enig says in her book Know Your Fats: The Complete Primer For Understanding the Nutrition of Fats, Oils, and Cholesterol that "as a result of the presence of fat in the small intestine, special hormones are produced that prevent hunger contractions. ... Too much fat in the diet and the loss of weight is thwarted; too little and the hunger pangs play havoc with good intentions and usually lead to overeating carbohydrates."
Saturated fatty acids can be broken down into three groups - short chain, medium chain and long chain. The short and medium chain saturated fatty acids don't turn into body fat unless consumed in very large quantities, but rather are utilized immediately by the body for energy. Therefore fats that contain more short to medium chain fatty acids have less calories than the same amount of longer chain fatty acids. According to Mary Enig, in her book Know Your Fats: the Complete Primer for Understanding the Nutrition of Fats, Oils and Cholesterol, a pound of coconut oil has 100 kilocalories less than a pound of soybean oil. And yes, butter has less calories than margarine, although not much less.
If you are eating high quality fats, such as pasture fed, non-medicated, organic eggs, dairy, poultry, and meat, you are doing your body good. If you are eating conventionally raised poultry and meat, it is a good idea to cut off the fat, as the medications, hormones and pesticides consumed by the animal will be concentrated in the fat, which will in turn be concentrated in your fat. Cook only with pasture-fed organic butter, ghee, tallow or chicken fat, or organic coconut oil, or unrefined or cold pressed extra virgin olive oil (low to medium temperatures only), as these fats are stable and won't oxidize and go rancid when heated. To find out what ratio of fat, protein and carbohydrates are appropriate for you according to your own personal biochemistry, get yourself metabolically typed at Healthexcel, and receive a food list of appropriate foods for you. Some people require more quality fats to be healthy than others.
Showing posts with label Transfats are Bad. Show all posts
Showing posts with label Transfats are Bad. Show all posts
Saturday, September 12, 2009
Wednesday, December 12, 2007
Higher Trans Fat Levels In Blood Associated With Elevated Risk Of Heart Disease
ScienceDaily (Mar. 28, 2007) — High consumption of trans fat, found mainly in partially hydrogenated vegetable oils and widely used by the food industry, has been linked to an increased risk of coronary heart disease (CHD).
“The strength of this study is that the amount of trans fatty acid levels was measured in blood samples from the study population. Because humans cannot synthesize trans fatty acids, the amount of trans fat in red blood cells is an excellent biomarker of trans fat intake,” said senior author Frank Hu, associate professor of nutrition and epidemiology at HSPH.
Clinical trials have shown that trans fatty acids increase LDL cholesterol and lower HDL cholesterol, making them the only class of fatty acids, which includes saturated fat, to have this dual effect. HDL (high-density lipoprotein) is considered a “good” cholesterol; LDL (low-density lipoprotein) a “bad” cholesterol.
The researchers, led by Hu and lead author Qi Sun, a graduate research assistant at HSPH, set out to test the assumption that higher trans fatty acid levels in erythrocytes—red blood cells—were associated with a higher risk of heart disease among U.S. women. Blood samples collected in 1989 and 1990 from 32,826 participants in the Brigham and Women’s Hospital-based Nurses’ Health Study were examined. During six years of follow-up, 166 cases of CHD were diagnosed and matched with 327 controls for age, smoking status, fasting status and date of blood drawing.
After adjusting for age, smoking status and other dietary and lifestyle cardiovascular risk factors, the researchers found that a higher level of trans fatty acids in red blood cells was associated with an elevated risk of CHD. The risk among women in the top quartile of trans fat levels was triple that of the lowest quartile. “Positive associations have been shown in earlier studies based on dietary data provided by the participants, but the use of biomarkers of trans fatty acids is believed to be more reliable than self-reports. This is probably the reason why we see an even stronger association between blood levels of trans fat and risk of CHD in this study,” said Sun.
“These data provide further justifications for current efforts to remove trans fat from foods and restaurant meals,” said Hu. “Trans fat intake in the
The study was supported by the National Institutes of Health.
“A Prospective Study of Trans Fatty Acids in Erythrocytes and Risk of Coronary Heart Disease,” Qi Sun, Jing Ma, Hannia Campos, Susan E. Hankinson, JoAnn E. Manson, Meir J. Stampfer, Kathryn M. Rexrode, Walter C. Willett, Frank B. Hu, Circulation, April 10, 2007.
Adapted from materials provided by Harvard School of Public Health.
Trans Fat Leads To Weight Gain Even On Same Total Calories, Animal Study Shows
ScienceDaily (Jun. 19, 2006) — The "apple" body shape that increases the risk of diabetes and heart disease may be accelerated by eating trans fat such as partially hydrogenated vegetable oil, according to new animal research at Wake Forest University School of Medicine.
"Diets rich in trans fat cause a redistribution of fat tissue into the abdomen and lead to a higher body weight even when the total dietary calories are controlled," said Lawrence L. Rudel, Ph.D., professor of pathology and biochemistry and head of the Lipid Sciences Research Program.
"What it says is that trans fat is worse than anticipated," Rudel said. "I was surprised."
According to the U.S. Food and Drug Administration (FDA), consumption of saturated fat, trans fat, and dietary cholesterol raises low-density lipoprotein (LDL), or "bad" cholesterol, levels, which increases the risk of coronary artery disease.
Kylie Kavanagh, D.V.M., presented the findings today at the 66th annual Scientific Sessions of the American Diabetes Association in
All that extra weight went to the abdomen, and some other body fat was redistributed to the abdomen. Computed tomography (CT) scans showed that the monkeys on the diet containing trans fats had dramatically more abdominal fat than the monkeys on the monounsaturated fat. "We measured the volume of fat using CT," Kavanagh said. "They deposited 30 percent more fat in their abdomen."
The monkeys all were given the same amount of daily calories, with 35 percent of the calories coming from fat. The amount of calories they got should only have been enough to maintain their weight, not increase it, Rudel said. "We believed they couldn't get obese because we did not give them enough calories to get fat."
One group of monkeys got 8 percent of their calories from trans fat while the other group received those calories as monounsaturated fat. The researchers said that this amount of trans fat is comparable to people who eat a lot of fried food.
"We conclude that in equivalent diets, trans fatty acid consumption increases weight gain," said Kavanagh.
Over the entire course of the study, there was a small but significant difference in weight between the two groups. "In the world of diabetes, everybody knows that just 5 percent weight loss makes enormous difference," Kavanagh said. "This little difference was biologically quite significant."
Rudel said, "The study was specifically funded to look at the role of trans fatty acids in atherosclerosis."
He said that at the time he got a grant from the National Heart, Lung and Blood Institute, there was not much evidence in the literature and no animal models that documented the hazards of trans fats, though there are data showing it was a risk factor for atherosclerosis.
Kavanagh said the six-year length of the study was equivalent to 20 years in people.
According to the FDA, trans fat is found in vegetable shortenings, some margarines, crackers, cookies, snack foods, and other foods made with or fried in partially hydrogenated oils. Unlike other fats, the majority of trans fat is formed when food manufacturers turn liquid oils into solid fats like shortening and hard margarine by adding hydrogen.
Since Jan. 1, the FDA has required the amount of trans fat to be listed in the nutrition facts panel on all foods. But the restaurant industry is exempt.
Other researchers on the American Diabetes Society report include Janice D. Wagner, Ph.D., D.V.M., John Jeffrey Carr, M.D., Kate Jones, B.S., Janet Sawyer, M.S., and Kathryn Kelly., B.S., all from Wake Forest University School of Medicine.
Adapted from materials provided by Wake Forest University Baptist Medical Center.
Trans Fatty Acids: What Are They And Why Shouldn't You Eat Them?
ScienceDaily (
Chemical &Engineering News, in its Sept. 22 issue, describes the chemistry of these culprits. C&EN is the newsmagazine of the American Chemical Society, the world's largest scientific society.
In issuing its order, the FDA relied mainly on an
What are trans fatty acids?
Unsaturated fats, found in such foods as avocados and olive and corn oils are heart healthy, but in the air they can go rancid by absorbing oxygen and then decompose, C&EN explains. Manufacturers can stop this process by bubbling hydrogen (hydrogenation) through the fat at a high temperature in the presence of a catalyst like nickel and in the absence of oxygen.
The process raises a fat's melting point, turning liquid vegetable oil into products ranging from soft margarine to solid shortening, according to the newsmagazine. When the healthful unsaturated fats are partially hydrogenated, the double bonds are rearranged, converting some to the trans configuration and shifting the double bonds along the chain. Unfortunately, this newly created trans fatty acid is an artery-clogger.
Amid the criticism of cookies, chips and other products containing trans fat, a number of companies have either developed foods without partially hydrogenated oils or have pledged to explore ways of replacing the fat. PepsiCo's Frito Lay, for example, has already eliminated trans fats from some of its products.
To access the C&EN article on trans fats, go to: http://pubs.acs.org/cen/science/8138/8138sci4.html
Adapted from materials provided by American Chemical Society.
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