In the study, which was meant to test, whether silymarin a scientifically proven (Dixit. 2007; Saller. 2009; Surai. 2015) "powerful antioxidant" (Shirali. 2016), will also affect athletic performance, N = 45 (unfortunately) previously untrained men were randomly assigned to one out of the following five groups: (a) endurance training with placebo (ET + P), (b) endurance training with 140 mg of silymarin/day (ET+S), (c) strength training with placebo (ST+P), (d) strength training with 140 mg of silymarin/day (ST + S) and (e) a placebo (C) to identify both, the effects of exercise and supplementation.
Anthropometrical and VO2max measurements and ELISA assay for paraoxonase (PON), leptin and adiponectin levels were performed at the beginning and after the 4-week of the study. Of these, the latter were meant to identify the mechanism behind the effects of exercise + silymarin supplementation.
|Figure 1: Changes in body composition and physical fitness over four weeks of exercise training plus/minus 140mg/day of silymarin (ethanol extract from dried Silybum marianum seeds | Shirali. 2016)|
- the additive beneficial effect of silymarin on VO2max in the strength training (ST + S) and
- the subtractive negative effect on VO2max in the endurance training (ET) group
|Figure 2: %-changes in plasma PON, adiponectin and leptin levels in resp. to 4 wks of exercise +/- silymarin (Shirali. 2016).|
Addendum: What else do we know?
From previous studies, we also know that silymarin appears to increase the use of fat / trigs during exercise while sparing muscle glycogen (Choi. 2016). The latter may be one, yet certainly not the only reason why the study at hand and a previous study by Barari et al. (2014), both suggest that silymarin can help you lose body fat in the absence of energy systemic restriction... speaking of wich: the lack of dietary control is not necessarily a weakness of the study at hand; after all, a study without dietary control provides evidence that a given supplement will work in the real world, where people often fail to adhere to energy restricted diets - plus: the mood improving effects of silymarin Nazarali et al. (2015) observed in 40 female athletes may be an added bonus I haven't even mentioned yet.
Last question: Do I have to pay extra for "super-bioavailable" silymarin
As Angelo points out in response to the publication of the article at hand, silymarin has a suboptimal bioavailability - meaning: not all the silymarin you ingest will actually make it into your blood. Now, that's correct, but supplement producers abuse the notion of a low bioavailability to make money on allegedly "superior" silymarin products.
|Figure 3: Primary reasons for poor oral bioavailability of Silymarin (Javed. 2011)|
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