GM 'solutions' for the phosphate problem

 November 2016
 
Photo Creative Commons
As governments and environmentalists worry about the pollution of our waters by phosphates pouring out of intensive pig and chicken farms, and worry about the dwindling supplies of phosphate needed for fertilizers and feed supplements, and worry about increasing human micronutrient deficiencies, genetic engineers have come with their own 'solutions'.

The pollution problem comes from 'phytic acid'. Phytic acid is a sugar molecule with a stack of phosphate attached. Seeds and grains contain high levels of phytic acid which they need for healthy development and stress tolerance. Phytic acid in the diet is, however, a problem for humans, pigs and chickens because they can't digest it: it passes through their gut, interfering with the availability of iron, manganese, zinc and calcium as it goes, and passes out the other end as phosphate-rich manure.
 
Farmers feeding their pigs and chickens high-protein, high-phytic acid grain add an enzyme 'phytase' to break down the phytic acid in their livestock's diet.
 
Genetic engineers have added phytase enzyme into the system in their own ways.
 
Canadian biotech scientists have come up with GM pigs that can digest phytic acid by producing their own phytase [1].
 
Chinese biotech scientists have come up with GM maize seeds capable of healthy development despite digesting their own phytic acid with their own GM phytase enzyme.
 
Both biotech products aim to fatten pigs, chickens and humans on maize without the undigested phosphate-sugar compound polluting the environment and without micronutrient interference.
 
Problems solved? Or, are these more GM 'solutions' which just cause other problems?
 
Animals, such as cows, which can digest phytic acid in their diet don't produce their own phytase: they have gut microbes which do this for them and a slow digestive system to give the process time. GM animals which make phytase enzyme are going to excrete the enzyme in their manure. Similarly, livestock eating phytase-enzyme-enhanced GM feed (possibly further supplemented with added enzyme by the farmer, just to make sure) are going to excrete the enzyme in their manure. Because phytic acid is an important part of soil organic matter (humus) which is an important part of the soil's ability to retain water and an important part of the soil's ability to hold phosphates, all that artificial phytic-acid-degrading enzyme entering the soil will release the phosphate from it and cause the available phosphate in the soil to "drop like a rock" as it washes away.
 
One team of researchers found that GM phytase-enzyme-producing maize was pretty good at feeding maize borers (a major insect pest) leading to a crop loss of some 8%.
 
Prof. Joe Cumins pointed out that high phytase enzyme GM crops "do not have the ability to fabricate phosphorus to replace that required for human nutrition in the long run". Nor will these GM crops prevent phosphate being washed out of the soil and may in fact exacerbate it. Nor will they do anything to maintain our dwindling supplies of phosphate.
 
Another question is, since phytic acid is roughage in our diet, is it really unhealthy? Phytic acid has been "consistently and reproducibly associated with health benefits", including anti-cancer activity,
immune system enhancement and prevention of kidney stones. What happens to health when it's not there?
 
Pigs, chickens and humans naturally eat a very varied diet, which isn't naturally restricted to a single grain in vast quantities. They also have low-levels of gut microbes which can digest limited amounts of phytic acid. Studies show that the 'anti-nutrient' effect of phytic acid manifests only when large quantities are consumed in combination with a micro-nutrient-poor diet.
 
No discussion of GM maize would be complete without glyphosate rearing its ugly head. Maize is increasingly genetically transformed to withstand and accumulate this herbicide. Glyphosate will inevitably turn up in the same feed. Glyphosate is an anti-bacterial which kills the same friendly bugs that digest phytic acid; it also binds the same trace metal nutrients as phytic acid. Could the presence of this herbicide and other pesticides which are anti-microbials turn a minor anti-nutrient potential of phytic acid into a major one?
 

OUR COMMENT


Some simpler, safer and healthier, non-GM solutions present themselves: 
  • a diverse, natural diet for man and animals
  • use feed which is natural to the animal's physiology
  • convert to organic agriculture which increases and preserves organic matter and nutrients in the soil
  • rotate deep-rooting green manure crops in agricultural fields to capture and retain phosphate
  • stop using man-made GM 'solutions' to 'solve' problems caused by humans in the first place and which make things uncontrollably worse.
 
Background:
 
 
SOURCE:
  • Dr. Mae-Wan Ho, China's Transgenic Phytase Maize, Science in Society 67 Autumn 2015

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