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Examining the Role for
Conjugated Linoleic Acid in
HIV/AIDS - Part II:
Clinical Intervention Trials
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(Continued
from page 2)
Body Composition:
In adult humans the ability of CLA to lower adipose tissue mass is inconsistent.
As seen in Table 1 positive results were presented in nine studies (4-12),
while five studies reported no effect (13-17) For example, when overweight
or obese human subjects were supplemented with CLA at 3.4 to 6.0 grams
(g) per day for 12 weeks, a significant reduction in fat mass was observed.
(7) However, in people consuming 3.0 g CLA per day for 12 weeks, no benefit
was observed for body weight or adiposity. (13) More recent studies have
demonstrated that CLA supplementation reduces body weight, leptin and body
adiposity in people. (8, 9, 18) It is likely that dose, duration of treatment
and the isomeric composition of CLA each impact the ability of CLA to affect
body composition in humans.
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"Only
two studies report a decrease in serum triglycerides (TG) with CLA."
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Serum Lipids:
As seen for body composition, the clinical effects of CLA on serum lipids
in humans have been inconsistent. While four studies note decreases
in cholesterol, LDL cholesterol and VLDL cholesterol or a trend to decreasing
cholesterol (5,6,10,17), seven published reports indicate no effects of
CLA on serum lipids (Table 1). Only
two studies report a decrease in serum triglycerides (TG) with CLA. (6,
17)
While these results may
seem at odds with the animal studies, it must be kept in mind that no cholesterol-lowering
effects have been observed in animals at doses lower than 0.5 to 1 % CLA
in the diet. (19, 20) With the highest doses in clinical intervention studies
generally in this range, it is reasonable that clinical studies only suggest
trends or fail to see positive effects.
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CLA Clinical Effect
on Type 2 Diabetes: In view of the conflicting findings on CLA in animal
models, particularly with regard to effects on insulin and glucose levels,
it is important to consider the human data that are available on CLA. Belury
examined the effect of CLA in the management of type 2 diabetes. In a double-blind,
randomized study of type 2 diabetics, using 6 g per day of CLA given for
a period of 8 weeks, researchers studied the metabolic parameters of diabetes.
CLA supplementation significantly decreased fasting blood glucose but had
no effect on fasting insulin levels. (18) While leptin levels were shown
to decrease with CLA treatment, no effect on insulin and glucose levels
was observed in a study in healthy female volunteers who received 3 g per
day CLA for a period of 64 days. (21)
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