What are Fats
Fats and oils are a chemical combination of three fatty acids joined by glycerol— hence the term triglycerides. Chemical compounds are represented by a diagram of its chemical structure. Hydrogen, oxygen, nitrogen, and carbon usually have 1, 2, 3, and 4 bonds respectively connecting them to other elements. One exception to this is when carbon forms rings as in benzene. A benzene consists molecule consists of 6 carbon and 6 hydrogen. Below is a diagram showing the structure of ethane and ethylene (ethene).
Ethane and Ethylene
A double bond between two carbon atoms is indicated by a double line.
Fatty acids consist of a chain of carbon and hydrogen atoms with a carboxyl group (-COOH) at one end.
The carboxyl group consists of two chemical groups: the carbonyl group (-C = O) and the hydroxyl group (-O-H). Most fatty acids have 4 to 28 carbon atoms with an even number of carbon atoms. The number of carbon atoms and the number and position of the double bonds define the type of fatty acid. The letters C and H representing carbon and hydrogen atoms are often omitted from the diagrams. Since carbon have four bonds and hydrogen has one bond, the presence of these atoms can be deduced. Fatty acid chains are characterised by length.
- Short-chain fatty acids are fatty acids with 6 or less carbon atoms.
- Medium-chain fatty acids are fatty acids with 7 to 12 carbons atoms.
- Long-chain fatty acids are fatty acids with tails 13 to 22 carbons.
- Very long chain fatty acids are fatty acids with tails longer than 22 carbons.
Saturated Fatty Acids
Saturated fatty acids do not have any double bonds between the carbon atoms. Saturated fats have a higher melting point and are more likely to be solid. Animal fats usually have a greater saturated fat content. They are more chemically stable and are less likely to go rancid. For example, lauric acid.
Lauric Acid
Oleic and elaidic fatty acids have the same number of atoms— both have one double bond in the same position. The carbon atoms that have the double bond have only one hydrogen atom attached. Oleic acid has the hydrogen atoms on the same side of the molecule making it a cis-fatty acid (pronounced as sis, meaning on the same side). Elaidic acid has the hydrogen atoms on the opposite side making it a trans-fatty acid (meaning on the opposite side or across).
Oleic Acid
Elaidic Acid
A cis-fatty acid is bent at the double bond, whereas a trans-fatty acid is straight. If a fatty acid has more than one double bond, then each double bond is either trans or cis. Trans-fats are primarily produced by frying or by hydrogenation. By adding hydrogen atoms to unsaturated fats to eliminate the double bonds may cause the formation of trans-fats. If all the double bonds are eliminated then a saturated fatty acid is produced. Otherwise, a trans-fatty acid may be formed.
Trans-fatty acids are detrimental to our health for the following reasons.
- Trans-fatty acids increase total cholesterol, LDL cholesterol and triglycerides.
- Trans-fatty acids also decrease HDL cholesterol.
- Note that saturated fatty acids raise total cholesterol and LDL cholesterol more than trans-fatty acids.
- Saturated fatty-acids raise HDL cholesterol. 1
- The risk of cardiovascular disease with trans-fats is greater than expected based on only changes to the lipid profile. 2
- Trans-fatty acid intake is associated with an increased level of biomarkers of inflammation and endothelial dysfunction. Endothelial cells line the surface of blood and lymphatic vessels.
- Fatty acids are components of cell membranes. Trans-fatty acids are straight molecules and cis-fatty acids are bent at the double bond. As a result, the fluidity of the cell membranes is decreased and the permeability is increased with an increase of trans-fatty acids. 3
Conjugated linoleic acids (CLAs) are found in dairy products. The unsaturated carbon atoms of CLAs are separated by one carbon atom instead of the normal two carbon atoms. Vaccenic and rumenic acids are the main trans-fatty acids found in dairy. They are both sold as health products. 4 ~ 5
According to the National Academies of Sciences: 6
Whilst suggesting that we consume no trans-fatty acids, the report deems that it is not practical.
According to Eric Rimm, the renowned Harvard nutritional epidemiologist and co-author of this report, 7
Walter Willet, the famed Harvard epidemiologist and former director of the Nurses’ Health Study II stated in a New York Times interview, 8
Most people are aware that trans-fats are really bad for you and that trans-fats are found in margarine. However, trans-fatty acids are found in all animal fats, from meat to butter. 9
Naming of Fatty Acids
There are a number of different naming conventions for fatty acids. With the omega-numbering system, the numbering of the carbon atoms commences at the opposite end to where the carboxyl group is located— omega being the last letter of the Greek alphabet. Therefore, an omega-3 fatty acid has its first double bond at the third-last carbon atom. This is denoted by n-3 or ω-3.
Other symbols used to describe fatty acids are the C:D numbers that denote the number of carbon atoms and the number of double bonds. The delta (∆) naming system describes each double bond.
Each double bond is described as cis or trans followed by ∆ with the position of the saturated carbon atom. The counting of the carbon atoms commences from the carboxyl group end, which differs from the omega-numbering system.
For example, rumenic acid is described as 18:2 cis, trans-Δ9, Δ11. Alternatively, it may be denoted by 18:2 cis-9, trans-11. Below are some examples of fatty acids.
Saturated Fats
| Name | Identifiers | Description |
|---|---|---|
| Butyric acid | 4:0 | Butyric acid is found in milk, butter and cheese. |
| Caproic acid | 6:0 | Caproic acid is found in small amounts in the milk of mammals, particularly cows, goats and sheep. |
| Caprylic acid | 8:0 | Caprylic acid is found in the milk of mammals, particularly goats and sheep. It also occurs in coconut oil. |
| Capric acid | 10:0 | Capric acid occurs in coconut oil and palm kernel oil. It also occurs in milk of mammals, particularly goats and sheep. |
| Lauric acid | 12:0 | Lauric acid is a major component of coconut oil, laurel oil (from the Mediterranean Bay Tree) and palm kernel oil. It is also found in human breast milk (6% of total fat), cow’s milk (3%) and goat’s milk (3%). |
| Myristic acid | 14:0 | Myristic acid is found in nutmeg, palm kernel oil, coconut oil, butter fat and is a minor component of many animal fats. |
| Palmitic acid | 16:0 | Palmitic acid is the most common fatty acid found in both plants and animals. It is a major component of the oil from palm trees (palm oil, palm kernel oil and coconut oil), meats, cheeses, butter, and dairy products. |
| Stearic | 18:0 | Second most common fatty acid. Occurs in animal fats up to 30% and vegetable fats is usually less than 5%. It is, however, a large component of cocoa butter and shea butter. |
Unsaturated Fats
| Name | Identifiers | Description |
|---|---|---|
| Palmitoleic acid | 16:1 n-7 cis-9 | Palmitoleic acid is found in animal tissues as well as palm oil, coconut oil, and macadamia oil. |
| Oleic acid | 18:1 n-9 cis-9 | Occurs in both animal and vegetable fats. It is a large component of olive oil. |
| Linoleic acid LA | 18:2 n-6 cis-9, cis-12 | Linoleic acid is found in many seed oils such as poppy seed, safflower, sunflower, vegetable oils, nuts, and corn. With a normal diet, more than adequate amount of linoleic acid is available. It is an omega-6 fatty acid. This is one of the two essential fatty acids for humans. |
| γ–linolenic acid GLA | 18:3 n-6 cis-6, cis-9, cis-12 | γ–linolenic found in canola, soybeans, walnuts, chia, evening primrose, and flaxseed. It is an omega-6 fatty acid. |
| Arachidonic acid AA | 20:4 n-6 cis-5, cis-8, cis-11, cis-14 | Arachidonic acid is a polyunsaturated fatty acid present in the phospholipids of membranes of the body’s cells and is abundant in the brain, muscles, and liver. Humans can synthesis AA from linoleic acid (LA). It is an omega-6 fatty acid. |
| Eicosapentaenoic acid EPA | 20:5 n-3 cis-5, cis-8, cis-11, cis-14, cis-17 | This appears to be essential for brain development in the young of mammals. It is found in fish oil and in the milk of mammals. After weaning, it is synthesised by mammals from α-linolenic acid (ALA). It is an omega-3 fatty acid. |
| Docosahexaenoic acid DHA | 22:6 n-3 cis-4, cis-7, cis-10, cis-13, cis-16, cis-19 | It is a major component of the human brain. Cold-water fish are rich in DHA, which is obtained from algae. It is found in the milk of mammals. After weaning, it is synthesised by mammals from α-linolenic acid (ALA). It is an omega-3 fatty acid. |
| Elaidic acid | 18:1 n-9 trans-9 | Elaidic acid is the major trans-fatty acid found in margarines, which are hydrogenated vegetables oils. It is the trans-fatty acid variant (isomer) of oleic acid. |
| Vaccenic acid | 18:1 n-7 trans-11 | Vaccenic acid is the main trans-fatty acid found in dairy products and the fats of ruminants. The cis-version of vaccenic acid is relatively rare and found in sea-buckthorn— a genus containing seven species of deciduous shrubs found in Europe and Asia. |
| Rumenic acid | 18:2 n-7 cis-9, trans-11 | Rumenic acid is the main conjugated linoleic acid (CLA), which is found in dairy and in the fat of cows and other ruminants. |
Omega-6 to Omega-3 Ratio
During most of human evolution, the ratio of omega-6 to omega-3 fatty acid was about 1: 1. With increase production of grains, which have a higher omega-6 fatty acid content, the ratio has increased— the ratio is now 10: 1 to 25: 1. The usual solution is to increase the intake of omega-3 by eating flaxseed oil or fish oil. A healthier alternative is to decrease the amount of fat and omega-6 intake.
Healthy Oils
There are many studies that suggest that “healthy oils” do not have any health benefits and actually increase health risks.
A review of 48 random clinical trials and 41 cohort studies was published in 2006. It showed, 10
An article published in 2007 concluded, 11
Blood thinning properties of omega-3 fats that prevent the formation of clots also increases the chance of bleeding complications such as cerebral haemorrhage. 12
There is much evidence that a whole-food, plant-based diet – that is, a diet low in fat, saturated fat and animal protein, substantially reduces the risk of not only breast cancer, but other sex-hormone related cancers as well as prostate and colon cancers.
Last updated on Sunday 5 January 2025 at 20:43 by administrators
Post Type: postFootnotes
- Brouwer, I. A. (2016). Effects of transfatty acid intake on blood lipids and lipoproteins: A systematic review and meta-regression analysis.
- Lopez-Garcia, E., Schulze, M. B., Meigs, J. B., Manson, J. E., Rifai, N., Stampfer, M. J., Willett, W. C., & Hu, F. B. (2005). Consumption of Trans Fatty Acids Is Related to Plasma Biomarkers of Inflammation and Endothelial Dysfunction. American Society for Nutritional Sciences, October 2004, 562–566.
- Ibrahim, A., & Natarajan, S. (2005). Dietary trans–fatty acids alter adipocyte plasma membrane fatty acid composition and insulin sensitivity in rats. Metabolism, 54(2), 240–246.
- Aro, A., Becker, W., & Pedersen, J. I. (2006). Trans fatty acids in the Nordic countries. Scandinavian Journal of Food and Nutrition, 50(4), 151–154.
- Zbikowska, A. (2010). Formation and properties of trans fatty acids-a review. Polish Journal of Food and Nutrition Sciences, 60(2).
- National Academy of Sciences. (2005). Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients). National Academy of Science.
- Fox, M. (2002) Trans-fat increase cholesterol levels. Jawawa – Indonesian & Financial News. 17 July. [online]. Available from: http://jawawa.id/index.php/newsitem/trans-fat-increase-cholesterol-levels-1447893297 (Accessed 30 March 2017).
- Kolata, G. (1990) Animal Fat is Tied to Colon Cancer – New York Times [online]. Available from: http://www.nytimes.com/1990/12/13/us/animal-fat-is-tied-to-colon-cancer.html (Accessed 28 January 2017).
- Ledoux, M., Juanéda, P., & Sébédio, J.-L. (2007). Trans fatty acids: Definition and occurrence in foods. European Journal of Lipid Science and Technology, 109(9), 891–900.
- Hooper, Lee, Thompson, R. L., Harrison, R. L., Summerbell, C. D., Ness, A. R., Moore, H. J., Worthington, H. V., Durrington, P. N., Higgins, J. P. T., Capps, N. E., Riemersma, R. A., Ebrahim, S. B., & Smith, G. D. (2006). Risks and benefits of omega 3 fats for mortality, cardiovascular disease, and cancer: Systematic review. British Medical Journal, 332(7544), 752–760.
- Hooper, Lee, Thompson, R. L., Harrison, R. L., Summerbell, C. D., Ness, A. R., Moore, H. J., Worthington, H. V., Durrington, P. N., Higgins, J. P. T., Capps, N. E., Riemersma, R. A., Ebrahim, S. B., & Smith, G. D. (2006). Risks and benefits of omega 3 fats for mortality, cardiovascular disease, and cancer: Systematic review. British Medical Journal, 332(7544), 752–760.
- Dyerberg, J., & Bang, H. O. (1979). Haemostatic function and platelet polyunsaturated fatty acids in Eskimos The Lancet, 2(8140)(Sep 1), 433–435
However, the study has been funded by the dairy and beef industries.
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