Cape Town - Sam Broster, an English rugby player, claims his positive drugs test was a result of eating biltong.
According to BBC Sport, Broster tested positive for the anabolic agent clenbuterol following a test at Macclesfield in July 2014.
He was suspended from all sport for two years by UK Anti-Doping (UKAD), with the ban - which has been in place since August 2014 - to continue through to August 15, 2016.
The Rugby Football Union found no basis for reducing the sanction, despite the player blaming eating biltong on his positive test.
UKAD's director of operations, Pat Myhill, said in a statement: "Meat is an area of particular risk with clenbuterol as a contaminant, having caused adverse analytical findings in the past."
"However, proving meat contamination is not straightforward, not least because the meat that has been contaminated will, in most cases, have been eaten.
"Finding evidence to support this defence can therefore be difficult."