Roughly half the world's people are iron-deficient,
due to a lack of appropriate food. Even in plants
that have plenty of iron in them, it's often stored in a way that
counteracts the body's ability to absorb it.
Roughly half the world's people are iron-deficient,
due to a lack of appropriate food. Even in plants
that have plenty of iron in them, it's often stored in a way that
counteracts the body's ability to absorb it.
Due to ethical and environmental concerns, the most appropriate solution here isn't to switch people from a plant-based to an animal-based diet. A more reasonable solution may be to increase people's ability to absorb the iron that's naturally present in plants.
Dietary supplements can be of use here, but distributing them cheaply and efficiently to remote locations and resource-limited nations (i.e. the people most in need) is challenging. A new approach is needed.
Addressing this need, Xin Lei (Cornell University, United States), Huixia Shou (Zhejiang University, China), and coworkers have genetically engineered rice to synthesize nicotianamine, an iron absorption promoter. They have shown that it is twice as effective at this function than the supplement ascorbic acid (vitamin C), based on the ability of a model cell line to synthesize a protein important in iron storage and release.
Genetic engineering and evaluation.
The scientists inserted the nicotianamine synthase gene (the DNA sequence that codes for the synthesis of the enzyme that synthesizes nicotianamine) into Japonica rice. Rice growth and health were unaffected, i.e. no effect on plant height, seed weight, growth time, or other obvious characteristics were observed.
The genetic engineering was successful, in terms of the capacity of the rice to synthesize nicotianamine; its levels were between 3.3 and 8.2 times higher than native rice. Furthermore, iron and zinc were present in higher levels (19% to 55%) in the genetically-engineered plants.
The scientists then tested the ability of Caco-2 adenocarcinoma cells to process iron. This is a cell line often used to predict the rate of nutrient absorption in the intestines.
If the iron synthesized by the genetically engineered rice is available for absorption, the cells should synthesize enhanced quantities of ferritin, a protein important in iron storage and release. They found that their cells produced at least twice as much ferritin protein as control cells, when the cell line was incubated in pre-digested genetically-engineered rice, controlling for the iron content of the rice digests.
Notably, nocotianamine promoted ferrous iron (Fe+2) bioavailability over twice as effectively as ascorbic acid (vitamin C). Therefore, this approach is even more effective than a standard dietary supplement at increasing iron absorption by the body.
Implications.
Rice, a staple food that provides roughly 20% of world calorie intake, has been genetically engineered for the purpose of correcting iron deficiency. Based on model cell studies, this development will be very helpful for correcting an important nutrient imbalance in resource-limited nations.
for more information:
Zheng, L., Cheng, Z., Ai, C., Jiang, X., Bei, X., Zheng, Y., Glahn, R. P., Welch, R. M., Miller, D. D., Lei, X. G., & Shou, H. (2010). Nicotianamine, a Novel Enhancer of Rice Iron Bioavailability to Humans PLoS ONE, 5 (4) DOI: 10.1371/journal.pone.0010190