Effects of Conjugated Linoleic Acid Supplementation During Resistance Training on Body Composition, Bone Density, Strength, and Selected Hematological Markers

Abstract

Conjugated linoleic acids (CLA) are essential fatty acids that have been reported in animal studies to decrease catabolism, promote fat loss, increase bone density, enhance immunity, and serve as an antiatherogenic and anticarcinogenic agent. For this reason, CLA has been marketed as a supplement to promote weight loss and general health. CLA has also been heavily marketed to resistance-trained athletes as a supplement that may help lessen catabolism, decrease body fat, and promote greater gains in strength and muscle mass during training. Although basic research is promising, few studies have examined whether CLA supplementation during training enhances training adaptations and/or affects markers of health. This study evaluated whether CLA supplementation during resistance training affects body composition, strength, and/or general markers of catabolism and immunity. In a double-blind and randomized manner, 23 experienced, resistance-trained subjects were matched according to body mass and training volume and randomly assigned to supplement their diet with 9 g;pdd(-1) of an olive oil placebo or 6 g;pdd(-1) of CLA with 3 g;pdd(-1) of fatty acids for 28 days. Prior to and following supplementation, fasting blood samples, total body mass, and dual-energy X-ray absorptiometry (DEXA) determined body composition, and isotonic bench press and leg press 1 repetition maximums (1RMs) were determined. Results revealed that although some statistical trends were observed with moderate to large effect sizes, CLA supplementation did not significantly affect (p > 0.05) changes in total body mass, fat-free mass, fat mass, percent body fat, bone mass, strength, serum substrates, or general markers of catabolism and immunity during training. These findings indicate that CLA does not appear to possess significant ergogenic value for experienced resistance-trained athletes.

Conjugated linoleic acid and obesity control: efficacy and mechanisms

“…In contrast, other human clinical studies failed to show any effect of dietary supplementation of CLA on the fat mass. 31,111,[116][117][118][119][120] It should be pointed out that reductions of body fat by CLA in these aforementioned human studies were much less than those observed in animals. In addition, there was no doseresponse of CLA on human fat mass observed.…”

“…Human studies did not show a significant effect of CLA on body weight. [27][28][29][111][112][113][114][115][116][117][118][119][120] Some human studies showed slight reductions of body fat mass or calculated fat percentage after CLA supplementation, [27][28][29]112,113,115 while others failed to show any effect. 31,102,[107][108][109][110][111] The effect of CLA on insulin sensitivity and glucose control are also inconsistent.…”

“…Most studies Conjugated linoleic acid and obesity YW Wang and PJH Jones failed to show any reduction of body weight in healthy obese or nonobese men and women after supplemented with CLA ranging from 0.7 to 6.8 g/day. [27][28][29][111][112][113][114][115][116][117][118][119][120] Only a recent study conducted in type II diabetics showed that supplementation with 6 g/day of CLA (39% t10c12 and 37% c9t11) for 8 weeks produced an inverse correlation between plasma t10c12 levels and body weight changes. 121 These results suggested that CLA may reduce body weight of diabetes subjects, but not healthy obese and nonobese individuals.…”

The effect of 6 months supplementation with conjugated linoleic acid on insulin resistance in overweight and obese

“…Commercially available preparations of conjugated linoleic acid (CLA) contain mainly a mixture of two main positional and geometric isomers (trans-10, cis-12 and cis-9, trans-11) and have been tested in several human studies with varying results regarding change in body composition, [1][2][3][4][5][6][7][8][9][10][11][12] stimulation of immune response, 13 effects on lipid metabolism 14 and glucose metabolism. [15][16][17][18] CLA as a food supplement is widely promoted for reduction of body fat.…”

Os efeitos do ácido linoléico conjugado no metabolismo animal: avanço das pesquisas e perspectivas para o futuro

“…A partir de então muitos foram os estudos com diversos animais [102][103][104] , com culturas de adipócito de roedores e humanos [105][106][107][108][109] e com humanos 8,65,[74][75][76][77][78][79][80]90,95,96,[110][111][112][113][114][115][116] , que surgiram com o objetivo de avaliar a propriedade de redução da gordura corporal, bem como elucidar os mecanismos de ação pelos quais o CLA desempenha esse papel.…”