Generally NO. Moisture within the pulp of a cactus is very
acidic and many cacti contain toxic alkaloids. You can, however,
eat the fruit. The moisture is acidic because of the way many
succulents, including cacti, carry on photosynthesis, the
process by which carbon dioxide and water are turned into
carbohydrates. Most plants have their pores (stomates) open
during the day to take in carbon dioxide, and use sunlight as a
catalyst for the reaction: Carbon dioxide + water sugar +
oxygen. But in the desert, plants with pores open during the hot
days, lose much water through evapotranspiration. So, succulents
use a modified version of photosynthesis called CAM
(Crassulacean Acid Metabolism). CAM plants open their stomates
only at night when it is cooler so there is less
evapotranspiration. Because there is no sunlight to act as a
catalyst, carbon dioxide is stored as an organic acid,
principally Malic Acid (C4H6O5). Carbon dioxide is gradually
released from the acid during the next day. CAM plants use about
one-