CONJUGATED LINOLEIC ACID (CLA) weight loss and side effects, benefits; research finds zhion@zhion.com May 7, 2006
Conjugated linoleic acid (CLA) is a group of positional and geometric isomers of linoleic acid (LA, C18:2 cis-9, cis-12). From a few recent research studies, conjugated linoleic acid (CLA) may have a substantial impact in reducing body fat and increasing muscle mass. Conjugated linoleic acid (CLA) may offer protection against atherosclerosis and cancers. Probably, beause of these multiple possible health benefits, conjugated linoleic acid (CLA) has became one of the most popular sport supplements in the market.
SOURCES OF CONJUGATED LINOLEIC ACID (CLA) Conjugated linoleic acid (CLA) is found mainly in dairy products, beef, poultry, eggs, and corn oil. Bacteria that live in the intestine of humans can convert linoleic acid to conjugated linoleic acid (CLA). The source of conjugated linoleic acid (CLA) for some supplements are derived from safflower oil. Most brands of conjugated linoleic acid (CLA) on the market today contain 70% conjugated linoleic acid (CLA); with no trans-fats present.
SIDE EFFECTS of CONJUGATED LINOLEIC ACID (CLA)
Conjugated linoleic acid (CLA) is probably safe to healthy human subjects. However, it may impose serious side effects to overweight subjects.
OVERWEIGHT SUBJECTS Conjugated linoleic acid (CLA) may increase the risk for heart disease. In a study, overweight volunteers who took 4.5 grams of conjugated linoleic acid (CLA) daily for one year had an increase in their blood levels of lipoprotein(a), a risk factor for heart disease. [1] Conjugated linoleic acid (CLA) may also reduce the insulin sensitivity for overweight men. A reduction in insulin sensitivity was also observed in a study of overweight men without diabetes after treatment with 3 grams of conjugated linoleic acid CLA daily for three months. [2] Conjugated linoleic acid (CLA) feeding was found to promote insulin resistance in obese/diabetic mice by at least inverse regulation of leptin and adiponectin, and TNFalpha, adipocytokines known to either ameliorate or deteriorate insulin sensitivity, respectively. [3] In another study of people with type 2 diabetes, supplementing with 3 grams of conjugated linoleic acid (CLA) daily for eight weeks significantly increased blood glucose levels by 6.3% and decreased insulin sensitivity. [4] However, researchers also found that 4 grams of conjugated linoleic acid (CLA) daily for eight weeks improved insulin sensitivity of young men. [5]
t10,c12-CLA-induced hyperinsulinemia may trigger liver steatosis (fatty liver), by inducing both fatty acid uptake and lipogenesis. [6] Conjugated linoleic acid CLA supplementation induces a profound reduction of leptin, adiponectin and then excessive secretion of insulin and hepativc lipid content in a study of mouse. These observations cast doubt on the safety of dietary supplements containing CLA. [7]
CONJUGATED LINOLEIC ACID (CLA) BENEFITS
Various studies have demonstrated that conjugated linoliec acid (CLA) is an antioxidant, and it has multiple health benefits on various chronic diseases such as atherosclerosis and cancer.
BENEFITS ON CHOLESTEROL AND ATHEROSCLEROSIS Conjugated linoleic acid CLA has antiatherosclerotic and antioxidant activity by increasing oxidative stability in plasma and hepatic membrane in the vitamin E-deficient rats [8] Individual conjugated linoleic acid CLA isomers was shown to reduce atherosclerotic lesion development in hamsters. [9]In a cell culture, conjugated linoleic acid (CLA) reduces apoB100 production and secretion compared to saturated and polyunsaturated fatty acids, possibly by limiting the availability of free cholesterol (required for apoB100 production). A reduction in apoB100 production in the body would decrease the levels of VLDL and atherogenic LDL and thus reduce the risk of developing cardiovascular disease. Some other studies in animals also showed that conjugated linoleic acid (CLA) may reduce the risk of atherosclerosis . [15-17]
BENEFITS ON CANCERS Dietary conjugated linoleic acid CLA was shown to inhibit colon tumor cell proliferation in vitro and in vivo via the CDK inhibitor p21(CIP1/WAF1). [15] And, various basic research studies have demonstrated that conjugated linoleic acid (CLA) might reduce the risk of several types of cancers including breast, prostate, colorectal, lung, skin, and stomach. [10-13] Scientists have also investigated on howconjugated linoleic acid (CLA) inhibited cancer cell growth extensively. Conjugated linoleic acid CLA may trigger apoptosis in the estrogen unresponsive MDA-MB-231 human breast cancer cell line via mechanisms involving above all the mitochondrial pathway. [14]
BENEFITS ON IMMUNE FUNCTIONS Conjugated linoleic acid CLA improved performance, lymphocyte proliferation, and increased the CD8+ lymphocyte population, while reduced the production of PGE2 and interleukin-lbeta (IL- 1beta). Supplementation of conjugated linoleic acid; CLA enhanced lymphocyte proliferation function, possibly by regulating the PGE2 production, and improved growth performance of pigs. [15]
BENEFITS ON GLUCOSE TOLERANCE? Animal research suggests an effect of conjugated linoleic acid (CLA) supplementation on improving glucose tolerance. [16]
BENEFIT ON WEIGHT MANAGEMENT There are a few studies showing that conjugated linoleic acid (CLA) is effective on reduction of body fat. In a study, conjugated linoleic acid (CLA) significantly reduced percent body fat, but did not significantly reduce body weight [17] In another study, supplementation with 4.2 grams of conjugated linoleic acid (CLA); per day for four weeks produced a reduction in waist size but not weight loss. [18]
CONJUGATED LINOLEIC ACID IN MILK Supplementation of vegetable oils tended to improve milk production of lactating cows, and the conjugated linoleic acid (CLA) content in milk fat was significantly increased. Soybean oil seemed to be the optimal source to increase conjugated linoleic acid (CLA) production. [17]
THIS CONJUGATED LINOLEIC ACID (CLA) ARTICLE IS FOR YOUR REFERNCE ONLY. IF YOU HAVE ANY QUESTION ABOUT CONJUGATED LINOLEIC ACID (CLA) OR YOUR HEALTH , PLEASE, CONSULT WITH YOUR DOCTOR IMMEDIATELY. ALL RIGHTS RESERVED 2006
REFERENCE [1] Gaullier JM et al. Conjugated linoleic acid supplementation for 1 y reduces body fat mass in healthy overweight humans. Am J Clin Nutr 2004;79:1118?25.][2] Riserus U et al Effects of cis-9,trans-11 conjugated linoleic acid supplementation on insulin sensitivity, lipid peroxidation, and proinflammatory markers in obese men. Am J Clin Nutr 2004;80:279?83] [3] Ohashi A et al, Health Sciences University of Hokkaido, Conjugated linoleic acid deteriorates insulin resistance in obese/diabetic mice in association with decreased production of adiponectin and leptin. J Nutr Sci Vitaminol (Tokyo). 2004 Dec;50(6):416-21 [4]Moloney F, et al. Conjugated linoleic acid supplementation, insulin sensitivity, and lipoprotein metabolism in patients with type 2 diabetes mellitus. Am J Clin Nutr 2004;80:887-95][5] Eyjolfson V, et al. Conjugated linoleic acid improves insulin sensitivity in young, sedentary humans. Med Sci Sports Exerc 2004;36:814?20 [6] Clement L et al, Ecole Nationale Superieure de Biologie Appliquee a la Nutrition et a l'Alimentation, France, J Lipid Res. 2002 Sep;43(9):1400-9.][7] Poirier H et al, University of Burgundy, France, Hyperinsulinaemia triggered by dietary conjugated linoleic acid is associated with a decrease in leptin and adiponectin plasma levels and pancreatic beta cell hyperplasia in the mouse. Diabetologia. 2005 May 3; 2005.[8] Kim HK et al, Korea Food Research Institute, Dietary conjugated linoleic acid reduces lipid peroxidation by increasing oxidative stability in rats. J Nutr Sci Vitaminol (Tokyo). 2005 Feb;51(1):8-15. [9] Mitchell PL et al, Dalhousie University, Canada, Effect of conjugated linoleic acid CLA isomers on lipoproteins and atherosclerosis in the Syrian Golden hamster. Biochim Biophys Acta. 2005 May 23 2005. [10] Cesano A et al. Opposite effects of linoleic acid and conjugated linoleic acid on human prostatic cancer in SCID mice. Anticancer Res 1998;18:1429-34. [11] Thompson H et al. Morphological and biochemical status of the mammary gland as influenced by conjugated linoleic acid: implication for a reduction in mammary cancer risk. Cancer Res 1997;57:5067-72.[12] Ip C. Review of the effects of trans fatty acids, oleic acid, n-3 polyunsaturated fatty acids, and conjugated linoleic acid on mammary carcinogenesis in animals. Am J Clin Nutr 1997;66(suppl):1523S-29S [review]. [13] Parodi PW. Cows? milk fat components as potential anticarcinogenic agents. J Nutr 1997;127:1055-60 [review].[14] Miglietta A University of Torino, Italy, Conjugated linoleic acid induces apoptosis in MDA-MB-231 breast cancer cells through ERK/MAPK signalling and mitochondrial pathway. Cancer Lett. 2005 May 7; 2005][15] Lim DY et al, Hallym University. Korea, Inhibition of colon cancer cell proliferation by the dietary compound conjugated linoleic acid is mediated by the CDK inhibitor p21(CIP1/WAF1). J Cell Physiol. 2005 May 5; 2005 [15] Pal S et al, Curtin University of Technology, Australia, Conjugated linoleic acid suppresses the secretion of atherogenic lipoproteins from human HepG2 liver cells. Clin Chem Lab Med. 2005;43(3):269-74. [16] Nicolosi RJ, et al. Dietary conjugated linoleic acid reduces plasma lipoproteins and early aortic atherosclerosis in hypercholesterolemic hamsters. Artery 1997;22:266-77. [17] Lee KN, et al. Conjugated linoleic acid and atherosclerosis in rabbits. Atherosclerosis 1994;108:19-25. [15] Lai C et al, China Agricultural University, Effects of dietary conjugated linoleic acid supplementation on performance and immune function of weaned pigs. Arch Anim Nutr. 2005 Feb;59(1):41-51. [16] Houseknecht KL et al. Dietary conjugated linoleic acid normalizes impaired glucose tolerance in the Zucker diabetic fatty fa/fa rat. Biochem Biophys Res Commun 1998;244:678-82] [17]Zheng HC et al, Zhejiang University, China, Effects of dietary sources of vegetable oils on performance of high-yielding lactating cows and conjugated linoleic acids in milk. J Dairy Sci. 2005 Jun;88(6):2037-42.[17] Thom E, Wadstein J, Gudmundsen O. Conjugated linoleic acid reduces body fat in healthy exercising humans. J Int Med Res 2001;29:392-6] [18] Riserus U, Berglund L, Vessby B. Conjugated linoleic acid (CLA) reduced abdominal adipose tissue in obese middle-aged men with signs of the metabolic syndrome: a randomised controlled trial. Int J Obes 2001;25:1129-35]
Conjugated linoleic acid (CLA) has rapidly become one of the most talked about weight loss products since its introduction to the public in the late 90s.