Like
honey and
propolis, other well-known honeybee products that are gathered rather than secreted (i.e., in contrast to
royal jelly and
beeswax), the exact chemical composition depends on the plants from which the
worker bees gather the pollen, and can vary from hour to hour, day to day, week to week, colony to colony, even in the same
apiary, with no two samples of bee pollen being exactly identical. Accordingly, chemical and nutritional analyses of bee pollen apply only to the specific samples being tested and cannot be extrapolated to samples gathered in other places or other times. Although there is no specific chemical composition, the average composition is said to be 40–60% simple sugars (fructose and glucose), 20–60% proteins, 3% minerals and vitamins, 1–32% fatty acids, and 5% diverse other components. Bee bread is a niche for yeasts and bacteria, including
lactic acid bacteria,
Bifidobacterium,
Bacillus spp., and others. A study of bee pollen samples showed that they may contain 188 kinds of
fungi and 29 kinds of
bacteria. Despite this microbial diversity, stored pollen is a preservation environment similar to honey, and contains consistently low microbial biomass. ==Dietary supplement==