Biofortification
Biofortification aims to increase
the concentration of essential trace elements in crops to improve human
health and agricultural productivity. The most commonly deficient elements
in the diet of humans are Fe and Zn. Selenium and I are also deficient in
many areas. Rice (Oryza spp.)
and wheat (Triticum spp.) are
the target crops for many biofortification programmes, because they are
the staple food for most of the earth’s population. Rice forms a larger
part of the diet in poor countries, where people consume less meat that
would otherwise provide Fe and Zn.
Biofortification has several
advantages over simply adding essential trace elements to the final product,
e.g. flour, or taking dietary supplements. Physiologically accumulated trace
elements in plants provide a constant source of the trace element with less
risk of toxicity due to an overdose, or deficiency caused by gaps in supply
of the trace element-spiked product. Physiologically accumulated trace
elements in plant parts are also more bioavailable to humans. If the
biofortification arises from genetic modification of the crop, via either
traditional breeding or in vitro gene manipulation, then recurrent costs are
low, and the germplasm could be shared internationally, reaching people with
limited access to commercially fortified food or supplements.
Biofortification is not restricted
to humans. Livestock commonly suffer from trace element deficiencies where
the trace elements occur at low concentrations in the soil. Pasture species
tend to take up low concentrations of trace elements from soil compared to
trees and shrubs. Poplars and willows accumulate high concentrations of Zn
and Co relative to pasture species and this may be linked to observed health
benefits in sheep and cattle when the trees are used as stock fodder. A
potential problem of using poplars and willows as stock fodder is their high
accumulation of Cd; although varieties exist that accumulate high Zn and Co,
but low Cd.
On contaminated sites where the
contaminant is also an essential nutrient, food or fodder crops can be
produced that contain high concentrations of an essential nutrient. Broccoli
and Brassica juncea (L.) could
supplement Se to animal diets, when these plants are grown on contaminated
soil.
