QUICKLINKS AND VIEW OPITONS
Stearic Acid and other fatty acids
Sunday, November 16, 2003 6:01 am Email this article
An interview with Artemis Simopoulos, M.D., author of "The Omega Diet".
Artemis P. Simopoulos, M.D. is the president of The Center for Genetics, Nutrition and Health in Washington, D.C., a member of the International Society for the Study of Fatty Acids and Lipids and the author of a wonderful book titled The Omega Diet (Harper Collins, 1999). Dr. Simopoulos is the lead author on a summary statement of new Recommended Dietary Intakes for Omega-6 and Omega-3 Fatty Acids. These recommendations were formed by consensus during a workshop that was held at The National Institutes of Health (NIH) in Bethesda, Maryland, April 7-9, 1999. The workshop was sponsored by the National Institute on Alcohol Abuse and Alcoholism-NIH, the Office of Dietary Supplements-NIH, The Center for Genetics, Nutrition and Health, and the International Society for the Study of Fatty Acids and Lipids, and cosponsored by several industry groups.
Larry Hobbs interviewed Dr. Simopoulos first about stearic acid and later about the new recommendations on fatty acid intake.
Hobbs: Is it common knowledge that stearic acid suppresses weight gain?
Simopoulos: Yes. It is almost an axiom among nutritionists that stearic acid leads to less weight gain than other forms of saturated fat or linoleic acid.
Hobbs: Why haven’t obesity researchers studied stearic acid as a means of preventing/treating obesity? Has this been overlooked?
Simopoulos: A study published several years ago reported that stearic acid has thrombogenic properties?increasing the tendency for clot formation and clumping of platelets. Renaud (1979) in a study of French men from two areas of France found that saturated fat intake?mostly stearic acid?was correlated with platelet clotting and platelet aggregation. Therefore this aspect of stearic acid needs to be studied further. If this is confirmed then stearic acid should not be used in the prevention or management of obesity.
Renaud S; Dumont E; Godsey F; Suplisson A; Thevenon C. Platelet functions in relation to dietary fats in farmers from two regions of France. Thromb Haemost 1979 Feb 15;40(3):518-31.
Renaud S. [Thrombogenic and atherogenic effects of dietary fats]. Ann Nutr Aliment 1976;30(2-3):235-41.
Hobbs: Do you think that the decrease in stearic acid intake and the increase in linoleic acid intake may help to explain the nation’s ever increasing weight?
Simopoulos: It seems possible. Over the last 40 years animal fat intake has been decreasing, while vegetable fat intake has been increasing in the U.S.
Hobbs: What are the new recommendations for intake of omega-6 and omega-3 fatty acids?
Simopoulos: 1. Intake of the omega-6 fatty acid linoleic acid?which are found abundantly in corn oil, safflower oil and soybean oil?should not exceed 6.67 grams per day based on a 2000 kcal diet or 3 percent of calories.
2. The intake of the omega-3 fatty acid alpha-linoleic acid?which are found abundantly in flaxseed oil, flaxseeds, canola oil, walnuts and walnut oil, and green leafy vegetables especially purslane?should be 2.22 grams per day based on a 2000 kcal diet or 1 percent of calories.
3. Pregnant and lactating women should ensure an intake of 300 mg per day of docosahexaenoic acid (DHA) which is found abundantly in fish oil.
4. Intake of trans fatty acids should be avoided. Trans fatty acids are found in hydrogenated and partially hydrogenated oils such as margarine and in high temperature cooking such as reused frying oils. Except for dairy products, trans fatty acids are not naturally found in foods.
5. Intake of saturated fats?which are found abundantly in foods such as beef, pork and butter?should not exceed 8 percent of calories.
6. The majority of fatty acids should be obtained from monounsaturates which are found abundantly in olive oil and canola oil.
Hobbs: Was stearic acid separated from other saturated fatty acids as far as recommended intake?
Simopoulos: No, it was not. Stearic acid tends to be found in foods along with the other saturated fatty acids?palmitic acid, lauric acid and myristic acid. Therefore one recommendation was made for all of the saturated fatty acids combined?that they should not exceed 8 percent of calories.
Hobbs: What are the effects of omega-3 fatty acids found in fish oil and flax oil that you have written so much about?
Simopoulos: Animal and human studies show that omega-3 fatty acids lead to decreases in body fat and eventually weight loss. The ratio of omega-6 fatty acids to omega-3 fatty acids is also very important.
Hobbs: How so?
Simopoulos: There is an increase in insulin resistance and the prevalence of diabetes as the ratio of omega-6-to-omega-3 increases above 4-to-1.
Hobbs: What is the ratio in the typical American diet?
Hobbs: Is this why insulin resistance is a problem in America?
Simopoulos: Yes. Approximately 25 percent of the non-obese population is insulin resistant.
Hobbs: What is the connection between insulin resistance and obesity?
Simopoulos: All obese individuals are insulin resistant and all diabetics are insulin resistant. But a certain portion of the population, about 25 percent, are insulin resistant before they become diabetic or obese.
Hobbs: Are you saying that insulin resistance may contribute to obesity rather than being caused by obesity?
Simopoulos: Yes. It was recently found that insulin resistance precedes obesity, diabetes and hypertension in some individuals.
Hobbs: What causes insulin resistance?
Simopoulos: About 25 percent of the non-obese population has a genetic predisposition to insulin resistance. A sedentary life-style also increases insulin resistance, and the ratio of omega-6-to-omega-3 fatty acids correlates with insulin resistance. Saturated fat may also increase insulin resistance by reducing the number of insulin receptors and the action of insulin. However in rats, omega-3 fatty acids, and especially DHA, which is found in fish oil, prevents the saturated fat-induced increase in insulin resistance. Omega-6 linoleic acid found in corn oil correlates with hyperinsulinemia.
Hobbs: What is the best way to improve insulin sensitivity?
Simopoulos: Exercise, weight loss and omega-3 fatty acids.
Hobbs: What do you think about the recommendation a decade or so ago recommending to replace saturated fat with polyunsaturated fats like corn oil?
Simopoulos: This indiscriminate replacement of saturated fats with corn oil led to huge amounts of omega-6 linoleic acid into the food supply and threw the ratio of omega-6-to-omega-3 further out of balance. Corn oil contains omega-6 fatty acids, but no omega-3 fatty acids. Humans are being exposed to pharmacological doses of omega-6 linoleic acid for the first time in history. One of the main recommendations that came out of the workshop is the importance of reducing the omega-6 polyunsaturated fatty acids found abundantly in corn oil, safflower oil and soybean oil. A reduction in intake of these oils which contain a large amount of linoleic acid?corn oil, safflower oil and soybean oil?as well as an increase of alpha-linolenic acid found abundantly in flax oil, hemp oil and green leafy vegetables, and an increase in EPA and DHA?found in fish oil?is necessary to achieve a healthier diet.
Hobbs: Is this omega-3 fatty acid deficiency or ratio imbalance implicated in diseases?
Simopoulos: Yes. Many chronic diseases such as coronary heart disease, hypertension, aging, obesity, and diabetes are characterized by the omega-6-rich/omega-3-poor type of physiology. That is, pro-inflammatory, pro-thrombotic, and pro-constrictive. So if you have a genetic disposition for one of these diseases, the typical American diet increases the chances of getting the disease.
(Editor?s Note: See ORU March 1998 for a summary of the health effects of the various fats and fatty acids.)
Hobbs: How do omega-6 and omega-3 fatty acids affect cancer and tumors?
Simopoulos: Omega-6 linoleic acid found abundantly in corn oil, safflower oil and soybean oil increases tumor growth, whereas the omega-3 fatty acids found in fish oil suppress them.
Hobbs: Do obese people suffer from deficiencies of EPA and DHA, the omega-3 fatty acids found in fish oil?
Simopoulos: Maybe. Low levels of DHA are associated with increases in body weight. A study in Pima Indians found that the lower the DHA content of muscle cell membrane phospholipids the higher the body weight. They also found that the lower the DHA the higher the insulin resistance.
Hobbs: Although the omega-3 alpha-linolenic acid can be converted to EPA and DHA, are there people who need to take EPA and DHA-containing fish oil supplements?
Simopoulos: Yes. Hypertensives, some diabetics and premature babies are limited in the ability to convert omega-3 alpha-linolenic acid to EPA and DHA. They need to supplement with fish oils as well as eating alpha-linolenic acid. This means either eating cold water fish, like salmon, mackerel or sardines packed in sardine oil or olive oil but not soybean oil, or taking a fish oil supplement.
Hobbs: How much fish oil do you recommend as a supplement?
Simopoulos: One gram per day for health or 3 grams per day for people with diseases.
Hobbs: Do trans fatty acids found in hydrogenated and partially hydrogenated oils affect body weight?
Simopoulos: Maybe. Women who ate margarine, which is made from hydogenated oil, at least four times per week gained 5 pounds in six weeks compared to those who consumed it less frequently even though both groups consumed and expended the same number of calories according to one clinical trial. It has also been shown that animals that are fed trans fatty acids have larger fat cells than those who don?t although their overall body weight is the same.
There are no beneficial effects of trans fatty acids. Trans fatty acids found in hydrogenated oils such as margarine raise triglycerides, raise LDL cholesterol and lower HDL cholesterol. Trans fatty acids found in hydrogenated oils have also been shown to increase the risk of heart disease. Partially hydrogenated oils?which contain trans fatty acids?inhibit the metabolism of omega-6 and omega-3 fatty acids at many steps and induce partial deficiencies of these essential fatty acids.
Hobbs: Do you think an elevated intake of trans fatty acids also helps explain America’s weight gain?
Simopoulos: Yes. Trans fats now make up 5 to 7 percent of our diet, so it seems likely that the combination of a high intake of trans fats as well as a high intake of omega-6-rich, omega-3-deficient corn oil may be part of the reason Americans are gaining weight. It’s also likely that this is contributing to chronic diseases like hypertension and diabetes.
Hobbs: Are omega-3 fatty acids found in flax oil and fish oil useful in preventing weight gain?
Simopoulos: Yes. Fish oil has been shown to reduce body fat and stimulate fat oxidation in humans according to a small study by Couet (1997). Body fat decreased by an average of -1.9 pounds after three weeks when six grams of dietary fat was replaced with six grams of fish oil compared to a decrease of -0.7 pounds during a control period. Fish oil also decreased insulin levels by approximately 50 percent?from 10.5 to 5.3 uU/ml. Six grams of fish oil is the amount of oil found in 4 to 7 ounces of fish depending on the species. Fat oxidation was also increased 20 percent, although the total calories burned was unchanged. Omega-3 fatty acids also protect against weight gain in animals.
The American diet has an absolute and a relative deficiency of omega-3 fatty acids. That is, we don’t consume enough omega-3’s to start with and our over-consumption of omega-6’s from corn oil puts the ratio out of balance and also causes a relative deficiency.
Couet C, Delarue J, Ritz P, Antoine JM, Lamisse F. Effect of dietary fish oil on body fat mass and basal fat oxidation in healthy adults. International Journal of Obesity, 1997 Sep, 21(9):637-43.
Hobbs: What should we use instead of corn oil?
Simopoulos: Oils that are high in monounsaturates, like olive oil or canola oil or a combination of the two. Canola oil also contains omega-3 alpha-linolenic acid. The ratio of omega-6-to-omega-3 is 2-to-1. This compares to soybean oil which has a ratio of 7-to-1, and you don’t want that. And corn oil doesn’t contain any omega-3’s.
It?s also worth noting that replacing polyunsaturated fat with monounsaturated fat?extra-virgin olive oil in this case?reduced the dose of antihypertensive medicine by 48 percent according to a new study by Ferrara et al (2000). Hypertensive men and women were told to use 3 to 4 spoonfuls per day?30 to 40 grams?of olive oil as added fat after cooking for six months. When they used polyunsaturated fat?sunflower oil?instead, the reduction was only 4 percent. The mechanism of action of the olive oil was thought to be enhanced nitric oxide levels stimulated by polyphenols found in the olive oil.
Ferrara LA; Raimondi AS; d’Episcopo L; Guida L; Russo AD, MS; Marotta T. Olive Oil and Reduced Need for Antihypertensive Medications. Archives of Internal Medicine 2000 Mar 27;160(6):837-842.
Hobbs: What are your personal recommendations for weight loss and good health?
Simopoulos: 1. Increase protein intake to 20 percent of calories.
2. Decrease saturated fat intake and replace with monounsaturated fat found abundantly in olive oil and canola oil. These first two recommendations can be achieved by eating lean meat, fish, legumes, skim milk, low fat cheese, and omega-3-rich eggs that are balanced in omega-6 and omega-3 fatty acids. These eggs are still hard to find in stores.
3. Eliminate hydrogenated and partially hydrogenated oils?such as those found in margarine and many baked goods?in order to reduce the intake of trans fats.
4. Decrease intake of omega-6 fatty acids?linoleic acid which is found abundantly in corn oil, soybean oil and safflower oil?and increase intake of omega-3 fatty acids found in fish oil, flax oil and green leafy vegetables in order to get a balance of omega-6 and omega-3.
5. Increase the intake of fruits and vegetables.
6. Reduce the intake of carbohydrates from cereal and grains and especially from high-fructose corn syrup found in most soft drinks and many sweetened fruit juices.
7. And get 30 minutes of moderate exercise each day.
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