Each of the four varieties of vegetables commonly sold in the study area was selected by random sampling from the vendors in the open air markets. Samples of vegetables leaves weighing 250 g for each variety (kales (Brassica oleracea var. acephala), cabbage (Brassica oleracea capitata), spider flower (Gynandropsis gynandra) and black nightshade (Solanum nigrum)) were collected each day from the vendors by random sampling. The leaves of the four vegetable varieties were chosen because they are the major ones eaten by residents of Kisii Municipality.