As documented by the Transnational Institute:

The 2007 UN Declaration on the Rights of Indigenous Peoples – recently endorsed by the United States in December 2010 – states that “indigenous peoples have the right to maintain, control, protect and develop their cultural heritage, traditional knowledge and traditional cultural expressions.”

The decision to ban coca chewing fifty years ago was based on a 1950 report elaborated by the UN Commission of Inquiry on the
Coca Leaf with a mandate from ECOSOC, after a brief visit to Peru and Bolivia. The head of the Commission, Howard B. Fonda, gave an interview in Lima in September 1949, before beginning his work:

“We believe that the daily, inveterate use of coca leaves by chewing … not only is thoroughly noxious and therefore detrimental,
but also is the cause of racial degeneration in many centers of population, and of the decadence that visibly shows in numerous Indians – and even in some mestizos – in certain zones of Peru and Bolivia. Our studies will confirm the certainty of our assertions and we hope we can present a rational plan of action … to attain the absolute and sure abolition of this pernicious habit.”

To misquote Frank Zappa ..Imperialism is not dead it just smells funny.

Mama Coca presenting the 'Divine Plant' to the Old World

The Huitoto people use coca as part of the social and ceremonial traditions. Here is Mariano the shaman with a coca bush.

Ofrenda Ceremony in the Andes, Curandera Doris Rivera Lenz with coca leaves.