Quinine bark is harvested today much as it has been for hundreds of years. The tree trunks are beaten and the peeling bark is removed. The bark partially regenerates on the tree and, after a few years and several cycles of bark removal, the trees are uprooted and new ones are planted. The commercial quinine market today is difficult to calculate. It is thought that 300-500 metric tons of quinine alkaloids are extracted annually from 5,000-10,000 metric tons of harvested bark. Nearly half of the harvest is directed to the food industry for the production of quinine water, tonic water, and as an FDA-approved bitter food additive.