Polyunsaturated fat
In nutrition, polyunsaturated fat, or polyunsaturated fatty acid (PUFA), are fatty acids in which more than one carbon–carbon double bond exists within the representative molecule.[1] That is, the molecule has two or more points on its structure capable of supporting hydrogen atoms not currently part of the structure. Polyunsaturated fatty acids can assume a cis or trans conformation depending on the geometry of the double bond.
The lack of the extra hydrogen atoms on the molecule's surface typically reduces the strength of the compound's intermolecular forces, thus causing the melting point of the compound to be significantly lower. This property can be observed by comparing predominately unsaturated vegetable oils, which remain liquid even at relatively low temperatures, to much more saturated fats such as butter or lard which are mainly solid at room temperature. Trans fats are more similar to saturated fat than are cis fats in many respects, including the fact that they solidify at a lower temperature than cis fats.
A fatty acid has a carboxylic acid at one end and a methyl group at the other end. Carbon atoms in a fatty acid are identified by Greek letters on the basis of their distance from the carboxylic acid. The carbon atom closest to the carboxylic acid is the alpha carbon, the next adjacent carbon is the beta carbon, etc. In a long-chain fatty acid the carbon atom in the methyl group is called the omega carbon because omega is the last letter of the Greek alphabet.
Omega-3 fatty acids have a double bond three carbons away from the methyl carbon, whereas omega-6 fatty acids have a double bond six carbons away from the methyl carbon. The illustration below shows the omega-6 fatty acid, linoleic acid.
Dietary Sources
Polyunsaturated fat can be found mostly in Nuts, Seeds, Fish, Algae, Leafy Greens, and Krill. Whole food sources are always best, as processing and heating may damage polyunsaturated fats.
Health
Benefits
Omega-3 fatty acids in algal oil, fish oil, fish and seafood have been shown to lower the risk of heart attacks.[2] Omega-6 fatty acids in sunflower oil and safflower oil may also reduce the risk of cardiovascular disease.[3]
Among n-3 fatty acids [Omega-3], neither long-chain nor short-chain forms were consistently associated with breast cancer risk. High levels of docosahexaenoic acid (DHA), however, the most abundant n-3 PUFA [Omega-3] in erythrocyte (red blood cell) membranes, were associated with a reduced risk of breast cancer.[4] The DHA obtained through the consumption of polyunsaturated fatty acids is positively associated with cognitive and behavioral performance.[5] In addition DHA is vital for the grey matter structure of the human brain, as well as retinal stimulation and neurotransmission.[6]
Dietary intake of polyunsaturated fatty acids has been shown in several studies to decrease the risk of developing amyotrophic lateral sclerosis (ALS, a.k.a. Lou Gehrig's Disease).[7][8] Essential fatty acids (EFA) are shown to decrease the risk of depression, hypertension, and attention deficit hyperactivity disorder.[9]
There exist conflicting associations between dietary factors and incident atrial fibrillation (AF). A 2010 study published in AJCN suggested that polyunsaturated fats were found to have no significant association with AF.[10]
Consumption during pregnancy
Consumption of omega-3 fatty acids during pregnancy is critical to fetal development. They are required during the prenatal period for the formation of synapses and cell membranes. These processes are also essential in postnatal human development for injury response of the central nervous system and retinal stimulation.[9]
A study published in The Journal of Nutrition in 2007 found that the maternal diet of rats affects the brain DHA status of offspring. It suggests that a maternal diet containing insufficient amounts of omega-3 polyunsaturated fatty acid can lead to greater risk of decreased accretion of brain DHA in offspring.[11]
Relation to cancer
A 2010 study of 3,081 women suffering from breast cancer was done to research the effects of polyunsaturated fats on breast cancer. It demonstrated that the consumption of high amounts of long chain omega-3 polyunsaturated fats from food produced a 25% reduced risk of additional breast cancer events. These women were also shown to have reduced risk of “all-cause mortality.” Consumption of polyunsaturated fats through fish oil supplements was not shown to decrease risk of recurring breast cancer events.[12]
At least one study in mice has shown that consuming high amounts of polyunsaturated fat (but not monounsaturated fat) may increase the risk of metastasis in cancer patients.[13] The researchers found that linoleic acid in polyunsaturated fats produced increasing membrane phase separation, and thereby increased adherence of circulating tumor cells to blood vessel walls and remote organs. According to the report 'The new findings support earlier evidence from other research that consuming high amounts of polyunsaturated fat may increase the risk of cancer spreading'.The propensity for polyunsaturated fats to oxidize is another possible risk factor.[14][15] This leads to the generation of free radicals and eventually to rancidity. Studies have shown that low dosages of Coenzyme Q10 reduce this oxidation, and a combination of a diet rich in polyunsaturated fatty acids and Coenzyme Q10 supplementation leads to a longer lifespan in rats.[16] Studies on animals have shown a link between polyunsaturated fat and the incidence of tumours. In some of these studies the incidence of tumours increased with increasing intake of polyunsaturated fat, up to about 5% of total energy, near to the middle of the current dietary intake in humans. It is advised that the level of polyunsaturated fats in the diet be regulated if Coenzyme Q10 supplements are not being taken. However, even without Coenzyme Q10 supplementation, the effect on health might be considered by some to be more beneficial than harmful, due to the supposed cholesterol lowering effects of unsaturated fats compared to saturated fats; however, (a) monounsaturated fats have also been posited to lead to lower cholesterol levels; (and (b) it is no longer clear that saturated fats actually cause elevated blood cholesterol levels.[17]
Food sources of polyunsaturated fat
[18]
| Food source (100g) |
Polyunsaturated fat (g) |
| Walnuts |
47 |
| Sunflower Seeds |
33 |
| Sesame Seeds |
26 |
| Unsalted Peanuts |
16 |
| Peanut Butter |
14.2 |
| Olive Oil |
11 |
| Seaweed |
11 |
| Sardines |
5 |
| Soybeans |
5 |
| Tuna |
3 |
| Wild Salmon |
2.5 |
| Whole Grain Wheat |
0.8 |
10% of a person’s daily caloric intake should be consumed from polyunsaturated fats.[19]
Fat composition in different foods (click at right to hide or show)
| Food |
Saturated |
Monounsaturated |
Polyunsaturated |
| As weight percent (%) of total fat |
| Cooking oils |
| Canola oil |
7 |
59 |
29 |
| Corn oil |
13 |
24 |
59 |
| Olive oil |
13 |
74 |
8 |
| Sunflower oil |
10.3[20] |
19.5[20] |
65.7[20] |
| Soybean oil |
15 |
24 |
58 |
| Coconut oil |
92 |
6 |
2 |
| Dairy Products |
| Cheese,regular |
64 |
29 |
3 |
| Cheese,light |
60 |
30 |
0 |
| Milk, whole |
62 |
28 |
4 |
| Milk, 2% |
62 |
30 |
0 |
| Ice cream, gourmet |
62 |
29 |
4 |
| Ice cream, light |
62 |
29 |
4 |
| Meats |
| Beef |
33 |
38 |
5 |
| Ground sirloin |
38 |
44 |
4 |
| Pork chop |
35 |
44 |
8 |
| Ham |
35 |
49 |
16 |
| Chicken breast |
29 |
34 |
21 |
| Chicken |
34 |
23 |
30 |
| Turkey breast |
30 |
20 |
30 |
| Turkey drumstick |
32 |
22 |
30 |
| Fish,orange roughy |
23 |
15 |
46 |
| Salmon |
28 |
33 |
28 |
| Hot dog, beef |
42 |
48 |
5 |
| Hot dog, turkey |
28 |
40 |
22 |
| Burger, fast food |
36 |
44 |
6 |
| Cheeseburger, fast food |
43 |
40 |
7 |
| Breaded chicken sandwich |
20 |
39 |
32 |
| Grilled chicken sandwich |
26 |
42 |
20 |
| Sausage, Polish |
37 |
46 |
11 |
| Sausage, turkey |
28 |
40 |
22 |
| Pizza, sausage |
41 |
32 |
20 |
| Pizza, cheese |
60 |
28 |
5 |
| Nuts |
| Almonds dry roasted |
9 |
65 |
21 |
| Cashews dry roasted |
20 |
59 |
17 |
| Macadamia dry roasted |
15 |
79 |
2 |
| Peanut dry roasted |
14 |
50 |
31 |
| Pecans dry roasted |
8 |
62 |
25 |
| Flaxseeds, ground |
8 |
23 |
65 |
| Sesame seeds |
14 |
38 |
44 |
| Soybeans |
14 |
22 |
57 |
| Sunflower seeds |
11 |
19 |
66 |
| Walnuts dry roasted |
9 |
23 |
63 |
| Sweets and baked goods |
| Candy, chocolate bar |
59 |
33 |
3 |
| Candy, fruit chews |
14 |
44 |
38 |
| Cookie, oatmeal raisin |
22 |
47 |
27 |
| Cookie, chocolate chip |
35 |
42 |
18 |
| Cake, yellow |
60 |
25 |
10 |
| Pastry, Danish |
50 |
31 |
14 |
| Fats added during cooking or at the table |
| Butter, stick |
63 |
29 |
3 |
| Butter, whipped |
62 |
29 |
4 |
| Margarine, stick |
18 |
39 |
39 |
| Margarine, tub |
16 |
33 |
49 |
| Margarine, light tub |
19 |
46 |
33 |
| Lard |
39 |
45 |
11 |
| Shortening |
25 |
45 |
26 |
| Chicken fat |
30 |
45 |
21 |
| Beef fat |
41 |
43 |
3 |
| Dressing, blue cheese |
16 |
54 |
25 |
| Dressing, light Italian |
14 |
24 |
58 |
| Other |
| Egg yolk fat |
36[21] |
44[21] |
16[21] |
| Unless else specified in boxes, then reference is: [22] |
See also
References
- ^ Ordman, R. (2011). "Introduction to fats. Unpublished manuscript". Beloit, WI: Biochemistry Program, Beloit College. http://chemistry.beloit.edu/Ordman/nutrition/essays/essayfats.htm.
- ^ National Institute of Health (August 1, 2005). "Omega-3 fatty acids, fish oil, alpha-linolenic acid". Archived from the original on 3 May 2006. http://web.archive.org/web/20060503222604/http://www.nlm.nih.gov/medlineplus/print/druginfo/natural/patient-fishoil.html. Retrieved 26 March 2006.
- ^ Willett, Walter C (September 2007). "The role of dietary n-6 fatty acids in the prevention of cardiovascular disease". Journal of Cardiovascular Medicine 8: S42–5. doi:10.2459/01.JCM.0000289275.72556.13. PMID 17876199.
- ^ Pala, V.; Krogh, V; Muti, P; Chajès, V; Riboli, E; Micheli, A; Saadatian, M; Sieri, S et al. (July 2001). "Erythrocyte membrane fatty acids and subsequent breast cancer: a prospective Italian study". Journal of the National Cancer Institute 93 (14): 1088–95. doi:10.1093/jnci/93.14.1088. PMID 11459870.
- ^ Van De Rest, O.; Geleijnse, J. M.; Kok, F. J.; Van Staveren, W. A.; Dullemeijer, C.; Olderikkert, M.G.M.; Beekman, A. T.F.; De Groot, C. P.G.M. (August 2008). "Effects of Fish Oil on cognitive performance in older subjects". Neurology 71 (6): 430–38. doi:10.1212/01.wnl.0000324268.45138.86. PMID 18678826.
- ^ Bain, S. (2010). "Achieving optimal omega-3 atty actid status in the vegan population". Beloit, WI: Biochemistry Program. http://chemistry.beloit.edu/Ordman/posters/posttexts/prefa07/bain06.jpg.
- ^ Veldink, J H; Kalmijn, S; Groeneveld, G-J; Wunderink, W; Koster, A; De Vries, J H M; Van Der Luyt, J; Wokke, J H J et al. (April 2007). "Intake of polyunsaturated fatty acids and vitamin E reduces the risk of developing amyotrophic lateral sclerosis". Journal of Neurology, Neurosurgery, and Psychiatry 78 (4): 367–71. doi:10.1136/jnnp.2005.083378. PMC 2077791. PMID 16648143. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2077791.
- ^ Okamoto, Kazushi; Kihira, Tameko; Kondo, Tomoyoshi; Kobashi, Gen; Washio, Masakazu; Sasaki, Satoshi; Yokoyama, Tetsuji; Miyake, Yoshihiro et al. (October 2007). "Nutritional status and risk of amyotrophic lateral sclerosis in Japan". Amyotrophic Lateral Sclerosis 8 (5): 300–4. doi:10.1080/17482960701472249. PMID 17852010.
- ^ a b Bain, S. (2010). "Achieving optimal omega-3 fatty acid status in the vegan population". Beloit, WI: Biochemistry Program. http://chemistry.beloit.edu/Ordman/posters/posttexts/prefa07/bain06.jpg.
- ^ Shen, J.; Johnson, V. M.; Sullivan, L. M.; Jacques, P. F.; Magnani, J. W.; Lubitz, S. A.; Pandey, S.; Levy, D. et al. (2010). "Dietary factors and incident atrial fibrillation: The Framingham Heart Study". American Journal of Clinical Nutrition 93 (2): 261–6. doi:10.3945/ajcn.110.001305. PMC 3021424. PMID 21106919. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3021424.
- ^ Ozias, MK; Carlson, SE; Levant, B (2007). "Maternal Parity and Diet (n-3) Polyunsaturated Fatty Acid Concentration Influence Accretion of Brain Phospholipid Docosahexaenoic Acid in Developing Rats". The Journal of Nutrition 137 (1): 125–9. PMID 17182812. http://jn.nutrition.org/content/137/1/125.abstract.
- ^ Patterson, R. E.; Flatt, S. W.; Newman, V. A.; Natarajan, L.; Rock, C. L.; Thomson, C. A.; Caan, B. J.; Parker, B. A. et al. (2010). "Marine Fatty Acid Intake is Associated with Breast Cancer Prognosis". The Journal of Nutrition 141 (2): 201–206. doi:10.3945/jn.110.128777. PMC 3021439. PMID 21178081. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3021439.
- ^ "New findings measure precise impact of fat on cancer spread". 2009. http://www.eurekalert.org/pub_releases/2009-02/pu-nfm022509.php.
- ^ Scislowski, Valérie; Bauchart, Dominique; Gruffat, Dominique; Laplaud, Paul-Michel; Durand, Denys (2005). "Effect of dietary n-6 and n-3 polyunsaturated fatty acids on peroxidizability of lipoproteins in steers". Lipids 40 (12): 1245–56. doi:10.1007/s11745-005-1492-z. PMID 16477809.
- ^ Diniz, Yeda Sant'Ana; Cicogna, Antonio C; Padovani, Carlos R; Santana, Lea S; Faine, Luciane A; Novelli, Ethel L.B (2004). "Diets rich in saturated and polyunsaturated fatty acids: metabolic shifting and cardiac health". Nutrition 20 (2): 230–4. doi:10.1016/j.nut.2003.10.012. PMID 14962692.
- ^ Quiles, José L; Ochoa, Julio J; Huertas, Jesús R; Mataix, José (2004). "Coenzyme Q supplementation protects from age-related DNA double-strand breaks and increases lifespan in rats fed on a PUFA-rich diet". Exp Gerontol. 39 (2): 189–94. doi:10.1016/j.exger.2003.10.002. PMID 15036411.
- ^ Guyenet, Stephen. "does dietary saturated fat increase blood cholesterol?". http://wholehealthsource.blogspot.com/2011/01/does-dietary-saturated-fat-increase.html. Retrieved 13 November 2011.
- ^ "National nutrient database for standard reference, release 23". United States Department of Agriculture, Agricultural Research Service. 2011. http://www.nal.usda.gov/fnic/foodcomp/search/.
- ^ Ordman, R. (2011). "Dietary recommendations from the national cholesterol education program expert panel on detection, evaluation, and treatment of high blood cholesterol in adults. Unpublished manuscript". Beloit, WI: Biochemistry Program, Beloit College. http://chemistry.beloit.edu/Ordman/nutrition/ald/0804.htm.
- ^ a b c .nutritiondata.com --> Oil, vegetable, sunflower Retrieved on September 27, 2010
- ^ a b c .nutritiondata.com --> Egg, yolk, raw, fresh Retrieved on August 24, 2009
- ^ Feinberg School > Nutrition > Nutrition Fact Sheet: Lipids Northwestern University. Retrieved on August 24, 2009
External links
