Since his post on vegetable oils, Caveman Doctor has received many emails (whatever an email is) asking about trans-fats, how they are made, and why they are bad for our health. As the vegetable oil article was merely an introduction, some readers also asked for some more information on their health effects. This article will hopefully answer most of these questions.
How are Hydrogenated Trans-Fats Made?
We recently discussed how vegetable oils are made. The process of creating hydrogenated trans-fats is actually not much different. However, while vegetable oils go through some hefty processing to create the final product, hydrogenation takes them one step further by changing them from liquid to solid, like Crisco. Remember the discussion of the backbone of fats and how if each one has a hydrogen atom attached it is more stable and able to fight off free-radicals? Well, the process of hydrogenation achieves this (artificially) by blasting the polyunsaturated vegetable oil with hydrogen atoms forming a trans-fat. This is what is called hydrogenation. A hydrogen atom is bound to the backbone of the fat, making it more stable and even solid at room temperature. However, this solid, creamy substance has an unnatural chemical distribution rarely found in nature. In fact, these fats are actually too stable and our body even has trouble breaking them down. Surprise, surprise; we take an artificial chemically altered substance and our body has trouble dealing with it… I like to think of these fats as “frankenfats”.
When unsure if a food contains trans-fats, simply look on the ingredients for any hydrogenated fat sources. For example, when fats or oils contain ingredients like “partially hydrogenated cottonseed oil”, you will know to avoid them.
Looking at the hydrogen atoms bound to each carbon backbone of the saturated fat above, you can see how hydrogenation artificially adds these to the backbone of a polyunsaturated fat.
Fat: The Bricks of Our Protective Cell Walls
Fat, a necessary structure in our body, is the building block of the protective walls that surround our cells. This is one of the main reasons why we need to eat fat, and lots of it. All fats we consume appear to be incorporated into our cell walls, including unhealthy trans-fats. However, while the fats in our normal cell walls can open and close to let nutrients in and waste out, trans fats are entirely too rigid and unnaturally stable and can actually block this process. It is as if the front door of our cell was replaced with a steel door, effectively keeping the bad elements in, and the nutrients out, of cells. Interestingly, animal studies show just that. This blockage in our cell wall also stops many receptors from working properly, including the all-important receptor that binds insulin1. Other studies have shown that trans-fats in our cell walls can lead to cardiovascular disease and even heart attacks2.
Just like McDonalds was forced to do in the 80s, scientists in a study exchanged palm oil, which is heavy in saturated fat, for partially hydrogenated oil in 10 normal female subjects. The diet resulted in increased total cholesterol and bad LDL cholesterol, while lowering good HDL cholesterol – all negative health effects3.
Experiment in Your Kitchen
The next time you cook with animal fat and butter, take notice of the melted oil that is left on the pan. Compare this with cooking with vegetable oils and margarine, which often leave a gummy substance that barely resembles oil. A good example of this is Crisco, or “crystallized cottonseed oil.” That gummy mess that is left on the pan is the same material that passes through your body wreaking havoc, eventually ending up in your previously healthy cells.
Also, just like the process of creating vegetable oils damages them, leaving them defenseless against oxidation, the same seems to occur with hydrogenated oils. While more structurally sound, the hydrogenation process still damages the fatty acids, resulting in oxidation and free-radical formation.
Do Experiments Actually Show The Increase in Free-Radicals in Vegetable Oil?
To test whether olive, corn, or linseed vegetable oil were oxidized differently during cooking, each was microwaved in a study. Olive oil, with its monounsaturated backbone, experienced markedly less oxidation during cooking than corn and linseed oil. Also, corn and linseed oil appear to produce more harmful chemicals and byproducts during treatment, likely due to their instability4.
After reading the process of creating vegetable oils, it is no wonder that these oils have been found to exert significant damage on the human body, causing health issues. A paramount concept of this site is reducing inflammation within the body in order to fight cancer and other insults. Vegetable oils are clearly significant sources of inflammation and should be avoided if you are attempting to maximize your health.
Just as trans-fats are incorporate into our cellular membranes, oxidized polyunsaturated fats in vegetables oils are as well, however they bring along harmful free-radicals. While antioxidant cancer fighting compounds like conjugated linoleic acid can be incorporated into our cellular membranes to fight cancer, oxidized PUFAs are incorporated as well, only this time we are inserting cancer-causing free-radicals directly in our cells5.
Do Vegetable Oils and Polyunsaturated Fats Cause Cancer?
In a very important study that, unfortunately, most people have never heard of, 846 men in a randomized controlled trial were put on a “normal” diet or one where polyunsaturated vegetable oil replaced saturated fat6. The aim of the study was to evaluate complications of atherosclerosis and mortality from the two different diets. Upon analysis of the data, it was found that almost double the amount of men died from cancer on the high vegetable oil diet. This study, which is a randomized controlled trial, the gold standard of medicine, took place all the way back in 1971. Yet, information on the connection between vegetable oils, polyunsaturated fat, and cancer not only remains hidden, but vegetable oils are still recommended as healthy by many medical professionals! Another prospective study (where they follow patients throughout the study collecting data) has shown an association between polyunsaturated fat consumption and breast cancer as well. In the same study, monounsaturated fats (like olive oil and macadamia nut oil) reduced the risk of breast cancer7.
How can Vegetable Oil and Polyunsaturated Fats Lead to Cancer?
As a radiation oncologist, my goal is to treat cancer. However, just as ionizing radiation can kill cancer cells, it can also cause cancer by damaging DNA through free radicals and oxidation. Along these lines, consuming polyunsaturated fats, with their plethora of free-radicals and oxidation, likely introduces these same cancer-causing elements into the body. One question that immediately comes to mind is whether the free radicals in PUFAs are absorbed, and animal studies have confirmed this. While animal studies are inferior to human studies, a similar experiment would be difficult and even unethical to perform in humans. Regardless, animal studies have shown that peroxidized polyunsaturated fats (which are oxidized with peroxide free radicals) were found floating in the blood of animals after consumption, along with toxic byproducts of the free-radicals8. Studies have also shown that these oxidized fats introduce free radicals directly into the walls of our blood vessels9, causing oxidation, inflammation, and atherosclerosis. This supports the thought that oxidized cholesterol, not just cholesterol is what clogs our arteries.
- The dangers of trans-fats are well known in our society and should be avoided.
- However, the issues with vegetable oils somehow fly under the radar (and they are even recommended as healthy!).
- Oxidized polyunsaturated fats and vegetable oils introduce harmful free-radicals and oxidation into our body.
- Good evidence is tough to come by in the field of nutrition, yet we actually have strong evidence that polyunsaturated fats can lead to cancer.
- Good fats include grass-fed butter and animal fat, and macadamia, avocado, coconut, palm, and olive oil.
Replace these harmful vegetable oils and trans-fats with flavorful grass-fed butter, oils with limited polyunsaturated fats like macadamia, avocado, and olive oil and healthy animal fat with cancer fighting components like CLA from sources like grass-fed beef.
1. Ibrahim A, Natrajan S, Ghafoorunissa R. Dietary trans-fatty acids alter adipocyte plasma membrane fatty acid composition and insulin sensitivity in rats. Metabolism: clinical and experimental. Feb 2005;54(2):240-246.http://www.ncbi.nlm.nih.gov/pubmed/15789505
2. Lemaitre RN, King IB, Raghunathan TE, et al. Cell Membrane Trans-Fatty Acids and the Risk of Primary Cardiac Arrest. Circulation. February 12, 2002 2002;105(6):697-701.http://circ.ahajournals.org/content/105/6/697.abstract
3. Sundram K, French M, Clandinin M. Exchanging partially hydrogenated fat for palmitic acid in the diet increases LDL-cholesterol and endogenous cholesterol synthesis in normocholesterolemic women. European Journal of Nutrition. 2003;42(4):188-194.http://dx.doi.org/10.1007/s00394-003-0411-9
4. Guillén MD, Ruiz A. Study by means of 1H nuclear magnetic resonance of the oxidation process undergone by edible oils of different natures submitted to microwave action. Food Chemistry. 2006;96(4):665-674.http://www.sciencedirect.com/science/article/pii/S0308814605003031
5. Spiteller G. The relation of lipid peroxidation processes with atherogenesis: a new theory on atherogenesis. Molecular nutrition & food research. Nov 2005;49(11):999-1013.http://www.ncbi.nlm.nih.gov/pubmed/16270286
6. Lee Pearce M, Dayton S. Incidence of Cancer in Men on a Diet High in Polyunsaturated Fat. . The Lancet. 1971;297(7697):464-467.http://linkinghub.elsevier.com/retrieve/pii/S0140673671910865
7. Wolk A, Bergstrom R, Hunter D, et al. A Prospective Study of Association of Monounsaturated Fat and Other Types of Fat With Risk of Breast Cancer. Arch Intern Med. January 12, 1998 1998;158(1):41-45.http://archinte.ama-assn.org/cgi/content/abstract/158/1/41
8. Scislowski V, Bauchart D, Gruffat D, Laplaud PM, Durand D. Effect of dietary n-6 and n-3 polyunsaturated fatty acids on peroxidizability of lipoproteins in steers. Lipids. Dec 2005;40(12):1245-1256.http://www.ncbi.nlm.nih.gov/pubmed/16477809
9. Singal PK, Petkau A, Gerrard JM, Hrushovetz S, Foerster J. Free radicals in health and disease. Molecular and Cellular Biochemistry. 1988;84(2):121-122.http://dx.doi.org/10.1007/BF00421045
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