|
|||||||||
|
|||||||||
|
|||||||||
|
|||||||||
(Continued from page 1)
Some clinical results
indicate that CLA may lightly decrease body fat in humans, particularly
abdominal fat, but no effects on body weight or body mass index and no
general improvement in lipid or glucose metabolism have been reported in
any intervention study (Table 1). Rather,
the 10/12-CLA isomer unexpectedly caused significant impairment of the
peripheral insulin sensitivity as well as of blood glucose and serum lipid
levels. (1-5) Moreover, the reason for the apparent inconsistencies in
these clinical studies lies in the fact that the metabolic effects of CLA
in humans in general, and isomer-specific effects specifically, are complex
and not well characterized.
| Table 1. Human intervention studies of conjugated linoleic acid |
|
|
(% diet) |
|
|
|
|
|
|
with exercise |
42 days
2.25 g/d (0.3%) |
2-isomers
no control |
Decrease in FM, waist measurement and decrease in BW |
Decrease in Cholesterol, decrease in TG
Trend for decrease in LDL and decrease in HDL |
N/A |
(6) 2000 |
|
BMI ~ 29 |
84 days
1.7 g/d (0.24%) 3.4 g/d 5.1 g/d 6.8 g/d (1%) |
2-isomers
Tonalin™ vs placebo |
Decrease in FM at 3.4 and 6.8 g/day | No effect | N/A | (7)
2000 |
|
BMI ~30 |
84 days
3.4 g/d (0.5%) |
2-isomer
Tonalin™ vs placebo |
No effect | No effect | No effect | (15)
2000 |
|
BMI ~ 22 |
64 days
3.9 g/d (0.6%) |
4 isomers
Tonalin® vs placebo |
No effect BW/FFM | No effect | N/A | (13,14)
2001 |
|
BMI ~ 23 |
84 days
1.8 g/d (0.25%) |
2-isomers
Tonalin® vs placebo |
Decrease in FM
No effect BW |
N/A | N/A | (8)
2001 |
|
BMI ~ 25 |
84 days
4.2 g/d (0.6%) |
2-isomers
Minor Natural vs placebo |
Decrease in FM
No effect BW |
No effect | N/A | (9)
2001 |
|
BMI ~ 23 |
56 days
0.7/1.4 g/d (0.1% to 0.2%) |
2-isomers
TrofoCell |
Decrease in FM
No effect on BW |
Decrease in HDL; Trend for decrease in cholesterol | N/A | (10)
2001 |
|
BMI ~ 32 |
28 days
4.2 g/d (0.6%) |
2-isomers
vs placebo |
Decrease in SAD | No effect | N/A | (11)
2001 |
|
BMI ~ 30 |
84 days
3.4 g/d (0.5%) |
10/12-isomer
2-isomer vs placebo |
10/12-CLA decrease in BW, decrease
in BMI, decrease in waist, decrease in SAD
and decrease in BF from baseline. Increase in LM from baseline. Mixture decrease in SAD, decrease in BF, and increase in LM from baseline. |
10/12-CLA Decrease
in HDL Mixture Decrease in HDL |
10/12-CLA increase in IR | (5)
2002 |
|
|
28 days
6 g/d (0.85%) |
4-isomer
vs placebo |
No effect | N/A | N/A | (16)
2002 |
|
BMI ~23 |
56 days
3 g/d (0.4%) |
50:50-CLA
80:20-CLA vs placebo |
No effect |
Decrease in TG with 50:50-CLA Decrease in VLDL with 80:20-CLA |
No effect | (17)
2002 |
|
|
56 days
6 g/d (0.85%) |
2-isomers
as FFA vs placebo |
Decrease in BW with increase in plasma levels of CLA associated with 10/12-isomer | N/A |
Increase in plasma CLA |
(18)
2003 |
|
|
91 days
1.8 g/d (0.25%) 3.6 g/d (0.5%) |
2-isomer
Tonalin vs placebo |
Increase in FFM during regain in dose- dependent manner | No effect | No effect | (4)
2003 |
| Abbreviations: 2-isomers = equal amounts
of the 9/11- and 10/12-isomers; 4-isomers = equal amounts of 9/11- and
10/12-isomers, but generally one-half the amount found in 2-isomer mixture;
BF = body fat;
BMI = body mass index; BW = body weight; d= day; FFM = fat-free mass; FM = fat mass; FFA = free fatty acid; g= gram; IR = insulin resistance; LM = lean mass; NA = not applicable due to lack of measurement; SAD = sagittal abdominal diameter. |
