Sentence:  Athletes' use of herbal <WSD>supplements</WSD> has skyrocketed in the past two decades. At the top of the list of popular herbs are echinacea and ginseng, whereas garlic, St. John's wort, soybean, ephedra and others are also surging in popularity or have been historically prevalent. 
Meaning of the word marked with <WSD> tags:  Something added, especially to make up for a deficiency.