Wheat breeding has traditionally focused on traits
that aim to improve grain yield, disease resistance, a biotic stress tolerance,
and industrial quality. This breeding effort has resulted in substantial
improvements in industrial quality that has helped meet the energy needs of
people around the world. Recent evidence suggests that apart from producing
more food, improvement in the nutritional quality of food is
essential. It is estimated that three billion people suffer from
iron and zinc deficiencies worldwide. Iron deficiency anemia is by far the most
common micronutrient deficiency observed in developing countries and millions
more are also at risk of zinc deficiency. There are several strategies that are
currently used to increase the nutritional value of wheat; these are food
fortification, and education. Food fortification meaning adding traces of
elements and vitamins into wheat.
There is about three hundred million tonnes of
wheat produced in developing countries. It is estimated that four hundred and
forty million tonnes will be needed by 2020 due to the increase in the
population according to Annals of Applied Biology article, “Adapting wheat
cultivars to resource conserving farming practices and human nutritional needs”
written by Dr. Trethowan. This projected increase in production will have to be
achieved against a backdrop of less water for agriculture and little new
available land for production. Because of this, the idea is not to increase the
amount of wheat produced, but to enhance the quality of the wheat. The
International Maize and Wheat Improvement Center (CIMMYT), based in Mexico has
been conducting research on nutrition-related traits for more than two decades.
They have come up with the theory that the solution to improving wheat may be
in the economic policies. These policies would allow research to be conducted
in different parts of the world headed by the CIMMYT, in order to achieve the
perfect wheat.
Improvements in the nutritional quality will be
largely achieved by genetic improvements. Some Governments have realized the
importance in genetic improvements and have introduced food fortification
programs to reduce iron and zinc deficiencies and hopefully
malnutrition. Dr. Trethowan believes introducing genes from other species
using genetic transformation is the only genetic alternative to improving the
nutritional value of wheat. Wheat is widely known for having various
concentrations of iron and zinc. Wheat flour holds twenty eight percent of iron
and twenty seven percent of zinc. However, the genetic variation currently
available in the wheat gene pool for iron and zinc may prove to be insufficient
to meet the dietary needs of low-income families across the nation.
Best sources of high iron and zinc concentrations
are in wheat variations that exist in the wild. Iron and zinc levels in wheat
vary depending on the growing environment and the genetic composition of the
materials. To improve iron and zinc grain concentrations, plant breeders
require genetic variations for these characters that are genuine to various
locations. According to Dr. Trethowan, past attempts have shown these efforts
to be expensive and unsustainable in the long term. To further complicate
matters, genetic variation for other essential elements and vitamins, such as
vitamin A, are not present in wheat.
The reason it is so important to improve the
nutritional value of wheat, is because it is one of the main ingredients in,
supposedly, healthy cereals. The cereal advertised as being the secret to a
healthy living; whole grain cereals. According to Dr. Ragaee, head scientist
on, “Effects of fiber addition on antioxidant capacity and nutritional quality
of wheat,” whole grain cereals contain essential parts and naturally occurring
nutrients of the entire grain seed. Even if the grain had been processed, it
will hold the same nutrients that are found in the original grain.
Whole grain cereals contain high concentration of starch, which increases
the glucose in the blood stream. Decreasing the amount of starch in cereal
could increase the nutritional quality of cereal while also emphasizing the
amount of slowly digestible starch and resistant starch. Slowly digestible
starch is a starch fraction that is digested in the small intestine at a lower
rate. It also creates an average flow of glucose in the blood. Resistant starch
is the starch portion that cannot be digested in the small intestine, but
ferments in the large intestine. This results in the production of hydrogen,
carbon dioxide, methane and short chain fatty acids; all results are good for
the human body. To increase the levels of SDS and RS will not be easy due to
the change in the environment in the last three decades and the increase in
demand for wheat.
Professor Ben De Lumen of University of California
Berkeley, Ph.D in Agricultural Chemistry and Biochemistry from University of
California Davis, believes, “Digestibility is not a serious issue in starch. If
one wants to take advantage of carbohydrates in starch, it has to be digested
and converted into sugars. All starch can be digested eventually whether slowly
or rapidly. Any starch which is not digested acts like dietary fiber
which has its benefits too.” That being said, further research in decreasing
the amount of starch in cereal may be put on hold, due to the lack of
significant to the human race.
It is safe to say improvements in the nutritional
quality of wheat will largely be realized through genetic improvement. CIMMYT
recent breeding efforts of transferring high iron and zinc concentrations from
wheat and other wild species have made recent breakthroughs. Dr. Trethowan
happily shared that the synthetic wheat created by breeders in Mexico, has been
identified of having high levels of iron and zinc. This is due to the addition
of Triticum dicoccum, and Aegilops tauschii; two grains found in wild wheat
species. The cross breading in CIMMYT’s wheat breeding programs are now
trying to grow the synthetic wheat in different locations in the world.
Elite breeders are working on growing the synthetic wheat in large areas
in South Asia. So far, there have been higher levels of iron and zinc in the
new fields. These may be due to the effects of different breeding techniques
and the environment interaction with the seeds. Further assessments are being
made to validate the findings. Improving wheat’s nutritional value will take a
while, but that doesn’t mean one should avoid products that contain wheat.
However, a product may not be as healthy as advertised.
A stalk of wheat located in
the CIMMYT breeding program in Mexico from apimages.com
- Bernard Essoka
