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CLA - Conjugated or Compromised?

PART 3: Animal Studies


Extensive research using CLA has been carried out in rats and mice, but broiler chickens and laying hens, chick embryos, pigs, guinea pigs, hamsters, steers and cows, rabbits, fish, horse, and/or tissues from these animals have also been studied.



 

Results. The studies show positive changes brought about by CLA in animals, as well as negative changes. The positive changes include:

  • Decreased fat in lean but not in obese rats when CLA was fed as 0.5% of food;9
  • Changed prostaglandin synthesis in ram seminal vesicle tissue;10
  • In rats, decreased leptin, a protein involved in obesity, by 42%, and changed the levels of several enzymes in rats;11
  • Improved glucose tolerance and insulin activity, and enhanced activity of enzymes important for glucose and fat metabolism in rats when fed CLA as 1.5% of food;12
  • Decreased adipose tissue and increased fat cell death in adipose tissue when fed to mice as 2% of food;13
  • Improved aspects of immune system functioning in nursery pigs at 1.33 and 2% of food intake;14
  • Reduced antigen-induced histamine and PGE2 release in guinea pig trachea when fed at 0.25% of food intake;15
  • Reduced cholesterol, possibly by decreasing the activity of an intestinal enzyme in hamsters fed 20g/kg (2%) of food;16
  • Inhibited tumor initiation, and perhaps also inhibited metastasis in mice fed 0.5 to 1% of the diet;17
  • Activated PPARgamma (peroxisome proliferator-activated receptor), which may explain its anti-diabetic effects, in rats;18
  • Altered back fat and milk fatty acid composition in sows;19 depending on your viewpoint, this may be positive or negative;
  • Protected against autoimmune disease (lupus) related body weight loss and prolonged survival time in mice; but also speeded up development of autoimmune symptoms in autoimmune-prone mice;20
  • Reduced adipose cell size without changing the number of adipose cells when fed at 0.5% of food intake, and also decreased monounsaturated fatty acids;21
  • At 3% of food weight, rats deposited less body fats, more lean (muscle), and had 41% less cholesterol in their livers;22
  • At 1% of food weight, fish tissues increased in CLA, lipid content was lower, feed efficiency was better, and fatty acid concentrations in liver and muscle were different;23
  • In cows, 10g/d of the t10,c12 isomer of CLA decreased milk fat percentage and yield by more than 40%;24 this is positive if you are want cows to give skim milk, or negative since reduction of milk fat affects the health of calves and decreases butter yield;
  • Increased immunoglobulin production in spleen lymphocytes, in rats fed CLA at 0.25% of food weight;25
  • In mice, t10,c12 CLA, but not the c9,t11 isomer produced body composition changes;26
  • At up to 1% of feed in rats, CLA depressed the production of omega-6 metabolites (GLA, DGLA, and AA);27 this might be positive or negative, since omega-6 metabolites play important roles in health;
  • At 2% dietary CLA in rats, vitamin A (retinol) increased by five times;28
  • In mice, 1% CLA reduced both tumor size and metastasis;29
  • At 1% of feed, CLA reduced the levels of food-induced allergic reaction;30
 

 

 
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