Dr James Morton investigates whether CLA is a fad or could actually have some beneficial uses for athletes.
What is CLA?
Conjugated linoleic acid (CLA) refers to a group of positional and geometric isomers of the fatty acid, linoleic acid. CLA is a natural component of fats found in ruminant animals and hence we can obtain it from our diet mainly by consuming meat and dairy products.
When consumed naturally, the most abundant CLA isomer is the cis-9, trans-11 whereas in supplemental form, CLA is typically found as a mix of the cis-9, trans-11 and trans-10, cis-12 isomers. CLA has many reported biological effects including anticarcinogenisis, antiatherogenesis and immune modulation though it is perhaps most widely known amongst athletic circles for its purported capacity to alter body composition.
The potential benefits of CLA
Indeed, meta-analyses (Whigham et al. 2007) have confirmed that CLA supplementation (at 3-6 g per day) leads to 'moderate body fat loss' when compared with placebo supplementation, though the focus of research attention has typically been in already overweight individuals. When studied over a 12 week period, such weight loss has been shown to equate to 1 kg of fat mass, an amount that is certainly relevant for elite sport performance.
Although the precise mechanism underpinning such exacerbated body fat loss is not currently well defined, CLA may exert its modulatory effects on reducing fat storage and activating key regulatory enzymes associated with regulating lipid oxidation (Martins et al. 2015).
It is noteworthy, however, that CLA does not contribute to fat loss via thermogenesis and hence CLA should not be considered in the same bracket as "fat burning" supplements. Furthermore, no adverse effects have been reported when studied over a 6-24 month supplementation period (Watras et al. 2007; Gaullier et al. 2005, 2007).
From an applied perspective, CLA supplementation (e.g. 3-6 g per day) could therefore be combined with a well balanced diet and structured exercise plan in an attempt to help aid weight management and body fat loss. Furthermore, CLA has been shown to reduce body fat and weight gains during a 'holiday' season and hence, CLA supplementation during the off-season may also be a strategy to adopt at the elite end of sports performance.