Edzard Ernst, professor of complementary medicine at Peninsula Medical School in Exeter, said Charles is exploiting a gullible public at a time of financial hardship...

"Prince Charles contributes to the ill health of the nation by pretending we can all overindulge, then take his tincture and be fine again," he said in a statement.

"Under the banner of holistic and integrative healthcare, he thus promotes a 'quick fix' and outright quackery."

The 60-year-old prince, a long-time advocate of alternative and sustainable agriculture, founded Duchy Originals in 1990 to promote organic food and farming, with profits going to charity.