CONJUGATED LINOLEIC ACID
(CLA) weight loss and side effects, benefits;  research finds      
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.
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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][S1] Norris LE, Collene AL, Asp ML, Hsu JC, Liu LF,
Richardson JR, Li D, Bell D, Osei  K, Jackson RD, Belury MA. Comparison of dietary
conjugated linoleic acid with safflower oil on body composition in obese postmenopausal
women with type 2 diabetes mellitus. Am J Clin Nutr. 2009 Jun 17.
Abstract

Conjugated linoleic acid (CLA) is a group of positional and geometric isomers
of linoleic acid (LA, C18:2 cis-9, cis-12).

Conjugated linoleic acid (CLA) is popular in health supplement industry as it
may have benefits of reducing body fat and increasing muscle mass. A few
studies also suggest that conjugated linoleic acid (CLA) may also have
benefits of lowering the risk of atherosclerosis and cancers for some people.

Sources of Conjugated Linoleic Acid (CLA)

Conjugated linoleic acid (CLA) is available in dairy products, beef, poultry,
eggs, and corn oil. Bacteria that live in the intestine of humans can also
convert linoleic acid to conjugated linoleic acid (CLA).

Conjugated Linoleic Acid (CLA) Supplements

The source for some conjugated linoleic acid (CLA) supplements are
safflower oil. Most brands of conjugated linoleic acid (CLA) on the market
today contain 70% conjugated linoleic acid (CLA); with no trans-fats present.

Potential Health Benefits of Conjugated Linoliec Acid – Research
Supports

Atherosclerosis and Cholesterol
A study has shown the anti-atheroslerotic and antioxidant activities of
Conjugated linoleic acid (CLA) via 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 the development of
atherosclerotic lesion 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]

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 how conjugated 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]

Immune Function
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]

Diabetes / Glucose Tolerance
Animal research suggests an effect of conjugated linoleic acid (CLA)
supplementation on improving glucose tolerance. [16]

Weight Management
Conjugated linoleic acid (CLA) may benefit people who want weight loss.
Some studies showed that conjugated linoleic acid (CLA) is effective on
reduction of body fat. In one 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]

Safflower oil is a common source for conjugated linolieic acid (CLA), but, the
effects of taking conjugated linolieic acid (CLA) and safflower oil on body
mass index (BMI), total and trunk adipose mass, as well as the lean meat
(tissue) can be very different. Norris LE and co-researchers compared the
effects of 2 dietary oils, conjugated linoleic acid (CLA) and safflower oil (SAF),
on body weight and composition in obese postmenopausal women with type-2
diabetes in a 36-week study. They found that supplementation with
conjugated linoleic acid (CLA) reduced body mass index (BMI) (P = 0.0022)
and total adipose mass (P = 0.0187) without altering lean mass. The effect of
CLA in lowering BMI was detected during the last 8 wk of each 16-wk diet
period. In contrast, safflower oil had no effect on BMI or total adipose mass
but reduced trunk adipose mass and increased lean mass. Safflower oil also
significantly lowered fasting glucose and increased adiponectin.  [S1]

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]


SIDE EFFECTS of CONJUGATED LINOLEIC ACID (CLA)

The side effects of conjugated linoleic acid (CLA) can be very serious for
overweight people, especially when it is at high doses. 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). Lipoprotein(a) is 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 also 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] On the other hand, researchers also found
that 4 grams of conjugated linoleic acid (CLA) daily for eight weeks improved
insulin sensitivity of young men. [5]

Another potential serious side effect of conjugated linoleic acid (CLA) is the
fatty liver. 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]

Since the side effects of conjugated linoleic acid can be very serious, users
must consult with their medical doctors before taking the supplements.