Yet more about iron (and other assorted micronutrients). A recent post of mine elicited a comment from Glenn to the effect that breeders have screened germplasm collections of the major staples for micronutrient composition. I was skeptical about the extent to which this has been done (though not, I must add, about the fact that there will be much more of it in the future). Another post, this one by Jeremy, suggested that there was precious little information out there about variety-level nutritional information.
Well, I’ve now come across a paper that allows us to put some numbers on the amount of screening that has been done for one staple crop, the potato. There’s only an abstract freely available online, but a paper by CIP scientists reports (among other things) on micronutrient levels in native potato varieties in Peru:
Several studies have reported mineral concentrations in improved potatoes… However, limited information was available about the mineral concentration of potato germplasm and breeding materials until 2006. A detailed study was undertaken to determine the levels of Fe and Zn in 37 native varieties, both grown by farmers as well as from the collection under custody at CIP.
The potatoes were grown in a couple of different places. There was lots of variation, both genetic and due to the environment where they were grown, and also an interaction between these factors. And the heritability was high, suggesting that there is potential for improvement through selection and breeding.
But let’s remember that the total CIP potato collection amounts to over 7,500 accessions. That means that some 0.5% has been screened. A good start, but still only a start.
I attended a good presentation given by a representative for the Harvest Plus programme yesterday. They had calculated that about 500 million US$ are spent on handout of A-vitamin pills in developing countries each year. Clearly it would be better to get those vitamins through proper food.
“Diets deficient in micronutrients are characterized by high intakes of staple food crops (such as maize, wheat and rice), but low consumption of foods rich in bioavailable micronutrients such as fruits, vegetables, and animal and fish products.â€
By breeding for “biofortification†of staple crops they focus on three critical micronutrients lacking in the diets of the poor: Vitamin A, Zinc, and Iron. And their target crops are rice, wheat, maize, cassava, sweetpotato and beans. Fascinating, and I see why it attracts donors, but I still think there is something odd with the logic. Would it not be better to promote the crops and food that have the micronutrients in the first place? Or breed to enhance the market value of the lesser used crops that nutritionally complement the staples?
Thanks, Ola. I make reference to your comment in another post, here.
I would just like to add, though it is true that plants vary in the amount of micronutrients they accumulate, the real issue with these elements is in the soil. Zinc can’t be accumulated if it has been removed from the soil by plats pumped of NPK where no attention has been paid to replenishing the full range of nutrients. That soil will provoke other problems such as pests as well. The key to adequate micronutrient nutrition is healthy, organic soil and the variety of crops and cuisine that most traditional cultures can provide.