|Some Typical Questions and Misconceptions on Fats and Oils|
|Written by Mary G. Enig, PhD|
|Wednesday, 28 February 2007 19:16|
This column is dedicated to answering some of the questions on fats and oils that we receive. They are indicative of the many unfortunate misconceptions found in the popular literature, which lead to much confusion for the consumer.
Question: I have read that carbohydrates should not be eaten with fats as this exacerbates the oxidizing problem and insulin issues of carbs and fats. Is a low-carb diet necessary to keep saturated fats from oxidizing in the body and hence becoming dangerous?
Answer: There are many misconceptions all mixed up here. First, only carbohydrates create "insulin issues." The body requires insulin to process carbohydrates, but not fats. Before the discovery of insulin, the only treatment for diabetes was a very high-fat, zero-carb diet. Because fats slow down the entry of sugar into the bloodstream, it is good for diabetics, in fact for everyone, to eat fats with carbohydrates. Dietary fats lower the glycemic index of carbohydrate foods and help stabilize the blood sugar.
Most foods and all of our meals are a mixture of carbs and fats. If it were true that we should not eat carbs and fats together, then babies would have a hard time because mother's milk is high in both carbs (in the form of milk sugar) and fats.
Regarding the "oxidizing problems," you are probably referring to the process of peroxidation, which is a type of oxidation that creates unstable moleculres, some of which can cause problems in the body. The fats most likely to peroxidize are polyunsaturated oils, especially when they are heated or processed. Saturated fats are very stable and don't develop these breakdown products even when heated to very high temperatures. Saturated fats are used in the body by muscles for the purpose of providing energy. In the muscles, they oxidize appropriately in a carefully controlled process. Oxidation is a double edged sword because you want things to be appropriately oxidized so you can get energy out of them. The different tissues, such as the muscles, use fats, especially regular saturated fats, because they don't peroxidize. It is a possibility that some carbohydrates would make unsaturated fats peroxidize more readily--that is one of many reasons not to use an excess of polyunsaturated oils.
Because you can only store a certain amount of carbohydrate, the body turns excess carbohydrates into fat, and mostly into saturated fat because that is the first thing that is made in the formation of fat.
Question: Do saturated fats cause insulin resistance?
Answer: Saturated fats have been blamed for everything that ails us, so it's not surprising that they're now being fingered for insulin resistance! There have been a few studies in the literature purporting to show that saturated fats cause insulin resistance and hence type 2 diabetes. We analyzed these studies in the Summer 2006 issue of Wise Traditions, showing that these were very poorly done studies which can hardly justify the conclusion that saturated fats cause insulin resistance. The healthy cell membrane contains at least 50 percent of its fatty acids as saturated fatty acids, so the conclusion that saturated fats cause insulin resistance is strange indeed.
What we do know is that trans fats cause insulin resistance and researchers often confuse trans with saturated fats. Unfortunately, when people are told to stop eating saturated fats, they often end up eating more trans fats.
Certain types of rare fatty acids can cause insulin resistance, but not the kinds that are found in large amounts in our food.
Question: Does a high-fat diet cause estrogen levels to be too high? I am referring to a 2003 article in the Journal of the National Cancer Institute, which indicated that when girls stopped eating animal foods, estradiol levels dropped by 30 percent.
Answer: Is it good for estrogen levels in girls to drop? Girls need estrogen for the full expression of female traits at puberty and for fertility. When estrogen drops too low, young women stop menstruating. Young girls need plenty of good fats for growth, energy and hormone production.
Question: I have seen plenty of studies indicating that butyric acid, lauric acid, myristic acid and even stearic acid are guilty of causing cholesterol issues and rises in LDL. Specifically butyric acid from butterfat is said to cause a skyrocketing effect on LDL.
Answer: Those fatty acids are all different, containing four, 12, 14, and 18 carbons respectively. Their usage in the body is totally different. Several studies have shown that stearic acid doesn't have much of an effect on LDL.
There are two kinds of LDL-cholesterol. The light, fluffy LDL is good and if these fatty acids raise light, fluffy LDL, then they are beneficial. Light fluffy LDL is a building block of lipoprotein, so the fact that it is being increased for repair is probably good.
The small dense LDL is thought to be bad. One study showed that a lowfat diet in children raises this bad kind of cholesterol Dreon, MD et al, American Journal of Clinical Nutrition 2000 71:1611-1616).
Butyric acid is found almost uniquely in butter, so it is not surprising that this innocent fatty acid is singled out for heinous crimes. Butyric acid has anti-microbial effects and feeds the good flora in the colon. Likewise lauric acid, found in large amounts in coconut oil, and myristic acid, found in butterfat and certain other animal fats, have roles to play in the body--especially lauric acid, which has antimicrobial effects and plays a role in signaling processes. Butterfat and coconut oil are competitors of the powerful vegetable oil industry, so it is wise to be very skeptical when you hear claims that these fats cause disease.
Question: Is there a proper proportion to seek these fats in? In other words, while butyric may be useful, perhaps too much is bad?
Answer: If you are eating whole, real foods, you will get fats in the right proportions. Even if you eat large amounts of butter, you still will consume only small amounts of butyric acid. The real danger is the consumption of polyunsaturated vegetable oils and trans fats, which are completely new to the human diet.
By the way, saturated fats protect against the harmful effects of trans fats. If you generally eat a lot of butter, lard, coconut oil and meat fat, you can consume industrial trans fats on occasion without problem.
Question: In regards to saturated fat, doesn't boiling oxidize the fat?
Answer: No, saturated fat is stable at cooking temperatures and can even be used for deep frying. However, boiling will certainly oxidize polyunsaturated oils and to a certain extent monounsaturated oils, creating harmful free radicals.
Restaurants and fast food establishments used highly saturated lamb or beef tallow until the early 1980s, and it would be beneficial for everybody if they returned to that practice.
Question: Is grapeseed oil a good choice? We hear so much about it. I have read that grape seed oil has a very high smoke point so it is a good oil to use for cooking.
Answer: Grapeseed oil contains phenols that raise the smoke point. However it is very high in omega-6 fatty acids, so it not a good choice for our diets--we need to avoid excess omega-6 fatty acids as much as possible. Also, grapeseed oil is industrially processed with hexane and other carcinogenic solvents, and traces will remain in the oil.
Question: I read the following statement in the Women's Health Letter: "Dietary animal fats help make hormone-like substances called prostaglandins that inhibit or block progesterone production. Not all prostaglandins inhibit progesterone, but the ones made from animal fats do." Is this true?
Answer: Where in the world do people get these ideas? Actually, saturated fats from animal foods support the body's production of prostaglandins, including those involved in hormone production. In addition, the body needs the vitamins found in animal foods, especially vitamin A, to make hormones like progesterone.
Question: I have heard that raw meat is excellent for building the body but when it is fermented, say with lemon juice, it becomes a pyruvate and thus an energy protein, not building, protein. Is there any truth to this?
Answer: This is not a question about fats and oils, but it serves as yet another example of the many misconceptions that scare us away from eating healthy food.
Pyruvic acid is one of the acids in a metabolic pathway, so in that sense it does provide energy. The body can make glucose out of pyruvic acid--so pyruvic acid would be a good and beneficial substance to eat.
During the fermentation of meat, both lactic acid and pyruvic acid are formed--the latter is formed from certain types of amino acids. But when we ferment meat, the end product is still mostly meat, not the acids formed by fermentation. Fermented meat therefore contains proteins used for building and repair, and beneficial acids used for energy. This explains why so many traditional cultures valued fermented meat!
Oxidation and Peroxidation
Oxidation of fatty acids in the body refers to a step-by-step process whereby the fats are broken down to produce energy. In the body, this proceeds as a controlled, enzymatic process whereby the fatty acid molecules lose electrons (hydrogen atoms) and the energy molecule being formed gains the electron charge. However, unsaturated fatty acids exposed to heat and oxygen, as in processing and cooking, undergo a chemical change known as auto-oxidation whereby free radicals (unpaired electrons) causing rancidity are produced. These oxidized fatty acids can cause undesirable uncontrolled reactions in the body.
Peroxidation is a process werheby oxygen is added to a molecule, resulting in unstable molecules containing extra amounts of oxygen. In the cell membranes, this can lead to uncontrolled reactions and a lot of damage. Antioxidants such as vitamin E help control the damage from peroxidation of fatty acids.
Saturated Fats Charged with New Crime!
A member in Sweden recently alerted us to articles in the Swedish newspapers describing a new study in which saturated fat is charged with impeding cognitive performance. "Saturated fat can make you stupid," said one headline.
The study was published in the European Journal of Neurology (volume 13, 2006). Male and female rats were divided into two groups, one fed a diet of 42 percent fat from a mixture of coconut oil and corn oil; the other was fed a diet of 10 percent fat. The high-fat diet had a negative effect on "hippocampal neurogenesis," that is, the generation of nerve cells in an area of the brain called the hippocampus, but only in the male rats. The authors concluded, ". . . our study provides the first compelling evidence that a high intake of dietary fat per se has a negative influence on hippocampal neurogenesis."
Note, first of all, that the authors did not single out saturated fats in their conclusion--these accusations only appeared in the media. In fact, the authors do not provide any information in the study about the precentage of fatty acids in the dietary mix. The mix could have been mostly polyunsaturated corn oil--and several studies have shown that polyunsaturated oil inhibits neurological development and function.
Nor do the researchers indicate what kind of coconut oil they were using. Most of the coconut oil used in scientific experiments is fully hydrogenated, a process that gets rid of all the essential fatty acids. Thus, the diet of corn oil and coconut oil may have induced a deficiency in omega-3 fatty acids, another likely explanation for cognitive decline.
But the interesting thing about these findings is that they only occurred in male rats, not in the females, an indication that the lack of neurogenesis was related to hormonal factors. Most rat chow is based on soy, rich in estrogenic compounds that have been shown to have deleterious effects on male rats.
There is no way to tell from this study which factors inhibited hippocampal neurogenesis but the one that is the least likely to be the culprit--the normal brain contains very high levels of saturated fat--has become the whipping boy for the others.
This article appeared in Wise Traditions in Food, Farming and the Healing Arts, the quarterly magazine of the Weston A. Price Foundation, Winter 2006.
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written by Ronny, Mar 21 2011
|Last Updated on Tuesday, 09 June 2009 19:36|