product’s release into the market. Critics of genetic modification, however, have cited studies that identify potential problems with genetically modified crops. Test animals fed glyphosate-tolerant soya beans (known as Roundup Ready, these beans are genetically bred to allow the farmer to freely spray the weed killer Roundup without harming the crop) show alterations in liver, pancreatic, intestinal and testicular tissue compared to animals fed conventional soya beans. The difference is believed to be due to unexpected DNA rearrangement near the gene insertion site, yielding altered proteins in food with potential toxic effects.9
It took the introduction of gene modification to finally bring the notion of safety testing for genetically altered plants to light. Public outcry has prompted the international agricultural community to develop guidelines, such as the 2003 Codex Alimentarius, a joint effort by the Food and Agricultural Organization of the United Nations and the World Health Organization, to help determine what new genetically modified crops should be subjected to safety testing, what kinds of tests should be conducted and what should be measured.
But no such outcry was raised years earlier as farmers and geneticists carried out tens of thousands of hybridisation experiments. There is no question that unexpected genetic rearrangements that might generate some desirable property, such as greater drought resistance or better dough properties, can be accompanied by changes in proteins that are not evident to the eye, nose or tongue, but little effort has focused on these side effects. Hybridisation efforts continue, breeding new ‘synthetic’ wheat. While hybridisation falls short of the precision of gene modification techniques, it still possesses the potential to inadvertently ‘turn on’ or ‘turn off’ genes unrelated to the intended effect, generating unique characteristics, not all of which are presently identifiable.10
Thus, the alterations of wheat that could potentially result in undesirable effects on humans are not due to gene insertion or deletion, but are due to the hybridisation experiments that predate genetic modification. As a result, over the past fifty years, thousands of new strains have made it to the human commercial food supply without a single effort at safety testing. This is a development with such enormous implications for human health that I will repeat it: modern wheat, despite all the genetic alterations to modify hundreds, if not thousands, of its genetically determined characteristics, made its way to the worldwide human food supply with nary a question surrounding its suitability for human consumption.
Because hybridisation experiments did not require the documentation of animal or human testing, pinpointing where, when and how the precise hybrids that might have amplified the ill effects of wheat is an impossible task. Nor is it known whether only some or all of the hybrid wheat generated has potential for undesirable human health effects.
The incremental genetic variations introduced with each round of hybridisation can make a world of difference. Take human males and females. While men and women are, at their genetic core, largely the same, the differences clearly make for interesting conversation, not to mention romantic dalliances. The crucial differences between human men and women, a set of differences that originate with just a single chromosome, the diminutive male Y chromosome and its few genes, set the stage for thousands of years of human life and death, Shakespearean drama and the chasm separating Homer from Marge Simpson.
And so it goes with this human-engineered grass we still call ‘wheat’. Genetic differences generated via thousands of human-engineered hybridisations make for substantial variation in composition, appearance and qualities important not just to chefs and food processors, but also potentially to human health.
WHETHER IT’S A LOAF OF organic high-fibre multigrain bread or a mass-produced biscuit, what exactly are you eating? We all know that the biscuit is just a processed indulgence, but conventional advice tells us that the former is a better health choice, a source of fibre and B vitamins, and rich in ‘complex’ carbohydrates.
Ah, but there’s always another layer to the story. Let’s peer inside the contents of this grain and try to understand why – regardless of shape, colour, fibre content, organic or not – it potentially does odd things to humans.
WHEAT: SUPERCARBOHYDRATE
The transformation of the domesticated wild grass of Neolithic times into the modern brownies, cupcakes or Victoria sponge requires some serious sleight of hand. These modern configurations were not possible with the dough of ancient wheat. An attempt to make a modern jam doughnut with einkorn wheat, for example, would yield a crumbly mess that would not hold its filling, and it would taste, feel and look like, well, a crumbly mess. In addition to hybridising wheat for increased yield, plant geneticists have also sought to generate hybrids that have properties best suited to become, for instance, a chocolate cupcake or a seven-tiered wedding cake.
Modern Triticum aestivum wheat flour is, on average, 70 per cent carbohydrate by weight, with protein and indigestible fibre each comprising 10 to 15 per cent. The small remaining weight of Triticum wheat flour is fat, mostly phospholipids and polyunsaturated fatty acids.1 (Interestingly, ancient wheat has higher protein content. Emmer wheat, for instance, contains 28 per cent or more protein.2)
Wheat starches are the complex carbohydrates that are the darlings of dietitians. ‘Complex’ means that the carbohydrates in wheat are composed of polymers (repeating chains) of the simple sugar, glucose, unlike simple carbohydrates such as sucrose, which are one- or two-unit sugar structures. (Sucrose is a two-sugar molecule, glucose + fructose.) Conventional wisdom, such as that from your dietitian or the USDA, says we should all reduce our consumption of simple carbohydrates in the form of sweets and fizzy drinks, and increase our consumption of complex carbohydrates.
Of the complex carbohydrate in wheat, 75 per cent is the chain of branching glucose units, amylopectin, and 25 per cent is the linear chain of glucose units, amylose. In the human gastrointestinal tract, both amylopectin and amylose are digested by the salivary and stomach enzyme amylase. Amylopectin is efficiently digested by amylase to glucose, while amylose is much less efficiently digested, some of it making its way to the colon undigested. Thus, the complex carbohydrate amylopectin is rapidly converted to glucose and absorbed into the bloodstream and, because it is most efficiently digested, is mainly responsible for wheat’s blood-sugar-increasing effect.
Other carbohydrate foods also contain amylopectin, but not the same kind of amylopectin as wheat. The branching structure of amylopectin varies depending on its source.3 Amylopectin from legumes, so-called amylopectin C, is the least digestible – hence the schoolkid’s chant, ‘Beans, beans, they’re good for your heart, the more you eat ’em, the more you. . . .’ Undigested amylopectin makes its way to the colon, whereupon the symbiotic bacteria happily dwelling there feast on the undigested starches and generate gases such as nitrogen and hydrogen, making the sugars unavailable for you to digest.
Amylopectin B is the form found in bananas and potatoes and, while more digestible than bean amylopectin C, still resists digestion to some degree. The most digestible form of amylopectin, amylopectin A, is the form found in wheat. Because it is the most digestible, it is the form that most enthusiastically increases blood sugar. This explains why, gram for gram, wheat increases blood sugar to a greater degree than, say, kidney beans or crisps. The amylopectin A of wheat products, complex or no, might be regarded as a supercarbohydrate, a form of highly digestible carbohydrate that is more efficiently converted to blood sugar than nearly all other carbohydrate foods, simple or complex.
This means that not all complex carbohydrates are created equal, with amylopectin A-containing wheat increasing blood sugar more than other complex carbohydrates. But the uniquely digestible amylopectin A of wheat also means that the complex carbohydrate of wheat products, on a gram-for-gram basis, are no better, and are often worse, than even simple carbohydrates such as sucrose.
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