The present invention relates to a glucomannan with a molecular size of 730 kDa, called DOP, which was previously identified as the unique authentication marker of the expensive herb Dendrobium officinals, as the main component for combating fatigue in subjects in need thereof. In particular, the present invention provides the required dosage for DOP to provide a potent anti-fatigue effect, stronger than Rhodiola rosea extract, and has significant potential to form an anti-fatigue health product.
