|Figure 1: Chemical structure of leucine.|
Lean tissue mass did not change or differ between groups and at 0, 3, and 6 mo were 61.9 ± 1.1, 62.2 ± 1.1, and 62.0 ± 1.0 kg, respectively, in the leucine group and 62.2 ± 1.3, 62.2 ± 1.3, and 62.2 ± 1.3 kg in the placebo group. There also were no changes in body fat percentage, muscle strength, and muscle fiber type characteristics. Blood glycosylated hemoglobin did not change or differ between groups and was 7.1 ± 0.1% in the leucine group and 7.2 ± 0.2% in the placebo group. Consistent with this, oral glucose insulin sensitivity and plasma lipid concentrations did not change or differ between groups.These results, derived from a study in diabetic patients and via supplementation of only one of the three BCAAs (leucine, isoleucine, valin) stands in contrast to findings of Zhang et al. (Zhang. 2011) who showed only very recently, that supplementation with only 5g of BCAAs
[...]temporarily increased plasma insulin levels and affected plasma concentrations of FFAs, but had almost no effect on glucose or urea nitrogen.Against the background that the Zhang study was conducted with healthy, normo-insulinemic subjects, it is most likely that the absence of measurable effects on glucose measurements Leenders et al. describe, must be attributed to the fundamental inability of the type II diabetics' pancreases to respond to the leucine-induced stimulus. A possible synergy (beyond the action of leucine, alone) of leucine, isoleucine and valine, the three BCAAs administered in the Zhang study would yet be another point to consider, before discarding leucine and/or BCAAs as a treatment strategy for two of the major symptoms of the metabolic syndrome: Obesity (body composition) and diabetes (glucose homeostasis).