Conjugated linoleic acid

Jump to: navigation, search

Conjugated linoleic acid (CLA) refers to a family of many isomers of linoleic acid (at least 13 are reported), which are found primarily in the meat and dairy products of ruminants. As implied by the name, the double bonds of CLAs are conjugated.

Conjugated linoleic acid is a trans fat, though some researchers claim that it is not harmful in the same fashion as other trans fatty acids, but rather is beneficial.[citation needed] CLA is a conjugated system, and in the United States, trans linkages in a conjugated system are not counted as trans fat for the purposes of nutritional regulations and labeling. Unlike most trans fatty acids found in the human diet, CLA occurs naturally, produced by microorganisms in the fore-stomach of ruminants. Non-ruminants, such as humans, may be able to produce some isomers of CLA from non-conjugated ruminant fats. One such example is vaccenic acid, which could be converted to CLA by delta-9-desaturase.[1]

Various antioxidant and anti-tumor properties have been attributed to CLA, and studies on mice and rats show promising results in reducing mammary, skin, and colon tumor growth [2]; however, it is suspected that sufficient concentrations to achieve anti-inflammatory effects within human tissues may not be attainable via oral consumption.[citation needed]

Many studies on CLA in humans show a tendency for reduced body fat[3], particularly abdominal fat, changes in serum total lipids and decreased whole body glucose uptake. The maximum reduction in body fat mass was achieved with a 3.4 g daily dose[4]. CLA supplementation has, however, been shown to increase C-reactive protein levels and to induce oxidative stress[5] and to reduce insulin sensitivity and increase lipid peroxidation.[6]

CAS registry number: 2420-56-6, Molecular Formula: C18H32O2

Other benefits

CLA may be beneficial in other aspects, including prevention of breast and colon cancer.[citation needed] title = Dairy Fat Gets a Reprieve|url=http://www.newhope.com/nutritionsciencenews/NSN_backs/Feb_00/natnews_1.cfm|accessdate = 2007-08-11

Possible Side Effects of Purified Isomers of Dietary CLA

There are concerns that the use of CLA by overweight people may actually cause insulin resistance, leading to an increased risk for developing diabetes.[7]. [1]

A recent study (2006) conducted in mice by the US Department of Agriculture gives account of some highly concerning effects of CLA: it can dramatically induce essential fatty acid redistribution (DHA and AA) in various organ tissues. The same study raises the concern that it might pose significant risks, especially regarding cardiovascular health and inflammatory diseases. DHA content in heart tissue for instance was found to be reduced by no less than 25% by certain CLA isomers, while spleen DHA increased 6-fold and spleen AA was reduced to only 5% of its normal levels in that tissue. [8]. Another study (2005) of CLA supplementation of hatching chicks showed high mortality and low hatchability rate among the CLA-supplemented groups, and also a decrease in brain DHA levels of CLA-incubated chicks. [2]

Dosage

CLA is available commercially in doses of about 500mg to 1300mg (or .5 g to 1.3 g). The optimal dosage is about 3.4 g, with larger doses showing little or no improvement.[citation needed]

CLA should be taken with protein-rich food to prevent side effects, including diarrhea, nausea, and stomachache.[citation needed]

Dietary Sources

Kangaroo meat may have the highest concentration of CLA when compared with other foods.[9] Food products of grass-fed ruminants (e.g. lamb, beef) are good sources, and contain much more CLA than those from grain-fed animals. [10] In fact, products of grass fed animals can produce 300-500% more CLA than cows fed the typical diet of 50% hay and silage, with 50% grain. [11]

See also

References

  1. Banni S, Angioni E, Murru E, Carta G, Melis M, Bauman D, Dong Y, Ip C (2001). "Vaccenic acid feeding increases tissue levels of conjugated linoleic acid and suppresses development of premalignant lesions in rat mammary gland". Nutr Cancer. 41 (1–2): 91–7. PMID 12094634.
  2. Belury, M.A. (2002). "Inhibition of carcinogenesis by conjugated linoleic acid: Potential mechanisms of action". Journal of Nutrition. 132 (10): 2995–2998. PMID 12368384. Unknown parameter |month= ignored (help); |access-date= requires |url= (help)
  3. Thom E, Wadstein J, Gudmundsen O. (2001). "Conjugated linoleic acid reduces body fat in healthy exercising humans". The Journal of International Medical Research. 29 (5): 392–396. PMID 11725826. Unknown parameter |month= ignored (help); |access-date= requires |url= (help)
  4. Blankson H, Stakkestad JA, Fagertun H, Thom E, Wadstein J, Gudmundsen O. (2000). "Conjugated linoleic acid reduces body fat mass in overweight and obese humans". Journal of Nutrition. 130 (12): 2943–2948. PMID 11110851. Retrieved 2006-05-27. Unknown parameter |month= ignored (help)
  5. Risérus U, Basu S, Jovinge S, Fredrikson GN, Arnlöv J, Vessby B (2002). "Supplementation with conjugated linoleic acid causes isomer-dependent oxidative stress and elevated C-reactive protein: a potential link to fatty acid-induced insulin resistance". Circulation. 106 (15): 1925–9. PMID 12370214.
  6. Risérus U, Smedman A, Basu S, Vessby B (2003). "CLA and body weight regulation in humans". Lipids. 38 (2): 133–7. PMID 12733745.
  7. Ulf Risérus, MMed; Samar Basu, PhD; Stefan Jovinge, MD, PhD; Gunilla Nordin Fredrikson, PhD; Johan Ärnlöv, MD; Bengt Vessby, MD, PhD (2002). "Supplementation With Conjugated Linoleic Acid Causes Isomer-Dependent Oxidative Stress and Elevated C-Reactive Protein". American Heart Association Journals. 01.CIR.0000033589.15413.48v1. Retrieved 2007-02-19. Unknown parameter |month= ignored (help)
  8. "Fatty Acid Profiles of Liver, Adipose Tissue, Speen, and Heart of Mice Fed Diets Containing T10, C-12-, and C9, T11-Conjugated Linoleic Adic".
  9. "Kangaroo meat - health secret revealed" (Press release). Commonwealth Scientific and Industrial Research Organisation (CSIRO). 2004-04-23. Retrieved 2007-01-23. Check date values in: |date= (help)
  10. T. R. Dhiman, L. D. Satter, M. W. Pariza, M. P. Galli, K. Albright, and M. X. Tolosa (2000). "Conjugated Linoleic Acid (CLA) Content of Milk from Cows Offered Diets Rich in Linoleic and Linolenic Acid". Journal of Dairy Science. 83 (5): 1016–1027. PMID 10821577. Retrieved 2006-05-27. Unknown parameter |month= ignored (help)
  11. T. R. Dhiman (2001). "Role of diet on conjugated linoleic acid content of milk and meat" (PDF). Journal of Animal Science. 79. Retrieved 2007-03-09.
  • Al Sarakbi W, Salhab M, Mokbel K. Dairy products and breast cancer risk: a review of the literature. Int J Fertil Womens Med. 2005 Nov-Dec;50(6):244-9. Review.
  • Bhattacharya A, Banu J, Rahman M, Causey J, Fernandes G. Biological effects of conjugated linoleic acids in health and disease. J Nutr Biochem. 2006 Dec;17(12):789-810. Epub 2006 May 2. Review.
  • Ip MM, Masso-Welch PA, Ip C. Prevention of mammary cancer with conjugated linoleic acid: role of the stroma and the epithelium. J Mammary Gland Biol Neoplasia. 2003 Jan;8(1):103-18. Review.
  • Kritchevsky D. Antimutagenic and some other effects of conjugated linoleic acid // British Journal of Nutrition. – 2000. – 83, N 5. – P. 459-465.
  • Larsson S. C., Bergkvist L., Wolk A. High-fat dairy food and conjugated linoleic acid intakes in relation to colorectal cancer incidence in the Swedish Mammography Cohort // American Journal of Clinical Nutrition. – 2005. – 82, N 4. – P. 894-900.
  • Lee KW, Lee HJ, Cho HY, Kim YJ. Role of the conjugated linoleic acid in the prevention of cancer. Crit Rev Food Sci Nutr. 2005;45(2):135-44. Review.
  • Maynard L. J., Franklin S. T. Functional foods as a value-added strategy: the commercial potential of "cancer-fighting" dairy products // Review of Agricultural Economics. – 2003. – 25, N 2. – P. 316-331.
  • Miller Á., Stanton C., Murphy J., Devery R. Conjugated linoleic acid (CLA)-enriched milk fat inhibits growth and modulates CLA-responsive biomarkers in MCF-7 and SW480 human cancer cell lines // British Journal of Nutrition. – 2003. – 90, N 5. – P. 877-885.
  • Pariza MW, Park Y, Cook ME. Conjugated linoleic acid and the control of cancer and obesity. Toxicol Sci. 1999 Dec;52(2 Suppl):107-10. Review.
  • Tanaka K. Occurrence of conjugated linoleic acid in ruminant products and its physiological functions // Animal Science Journal. – 2005. – 76, N 4. – P. 291-303.
  • Voorrips L. E., Brants H. A. M., Kardinaal A. F. M., Hiddink G. J., Brandt P. A., van den Goldbohm R. A. Intake of conjugated linoleic acid, fat, and other fatty acids in relation to postmenopausal breast cancer: the Netherlands cohort study on diet and cancer // American Journal of Clinical Nutrition. – 2002. – 76, N 4. – P. 873-882.

da:Konjugeret linolsyre de:Konjugierte Linolsäure nl:Conjugated Linoleic Acid sv:CLA



Linked-in.jpg