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
|
|
|
