A friend recently suggested that dwarf grains might be a key component in the recent explosion of health conditions like obesity and gluten (or other wheat-related) sensitivities.
According to Wikipedia:
The Green Revolution, or Third Agricultural Revolution, is a set of research technology transfer initiatives occurring between 1950 and the late 1960s, that increased agricultural production worldwide, particularly in the developing world, beginning most markedly in the late 1960s. The initiatives resulted in the adoption of new technologies, including high-yielding varieties (HYVs) of cereals, especially dwarf wheats and rices, in association with chemical fertilizers and agro-chemicals, and with controlled water-supply (usually involving irrigation) and new methods of cultivation, including mechanization.
Most people would say that this has been good because we now have a lot fewer people starving to death. We also have a lot more fat people. There’s an obvious link, inasmuch as it is much easier to be fat if there is more food around, but we’re investigating a less obvious link: does the nutritional/other content of new wheat varieties contribute to certain modern health problems?
Continuing with Wikipedia:
The novel technological development of the Green Revolution was the production of novel wheat cultivars. Agronomists bred cultivars of maize, wheat, and rice that are the generally referred to as HYVs or “high-yielding varieties“. HYVs have higher nitrogen-absorbing potential than other varieties. Since cereals that absorbed extra nitrogen would typically lodge, or fall over before harvest, semi-dwarfing genes were bred into their genomes. …
Dr. Norman Borlaug, who is usually recognized as the “Father of the Green Revolution”, bred rust-resistant cultivars which have strong and firm stems, preventing them from falling over under extreme weather at high levels of fertilization. … These programs successfully led the harvest double in these countries.
Plant scientists figured out several parameters related to the high yield and identified the related genes which control the plant height and tiller number. … Stem growth in the mutant background is significantly reduced leading to the dwarf phenotype. Photosynthetic investment in the stem is reduced dramatically as the shorter plants are inherently more stable mechanically. Assimilates become redirected to grain production, amplifying in particular the effect of chemical fertilizers on commercial yield.
HYVs significantly outperform traditional varieties in the presence of adequate irrigation, pesticides, and fertilizers. In the absence of these inputs, traditional varieties may outperform HYVs.
In other words, if you breed a variety of wheat (or rice, or whatever) that takes up nutrients really fast and grows really fast, it tends to get top-heavy and fall over. Your wheat then lies on the ground and gets all soggy and rotten and is impossible to use. But if you make your fast-growing wheat shorter, by crossing it with some short (dwarf) varieties, it doesn’t fall over and it can devote even more of its energy to making nice, fat wheat berries instead of long, thin stems.
(I find it interesting that a lot of this research was done in Mexico. Incidentally, Mexico is also one of the fattest countries–on average–in the world.)
But we are talking about making the plant grow faster than it normally would, via the intake of more than usual levels of nutrients. This requires the use of more fertilizers, as these varieties can’t grow properly otherwise.
I’ve just started researching this, so I’m just reading papers and posting some links/quotes/summaries.
Elevating optimal human nutrition to a central goal of plant breeding and production of plant-based foods:
… However, deficiencies in certain amino acids, minerals, vitamins and fatty acids in staple crops, and animal diets derived from them, have aggravated the problem of malnutrition and the increasing incidence of certain chronic diseases in nominally well-nourished people (the so-called diseases of civilization). …
The inadequacy of cereal grains as a primary food for humans arises from the fundamentals of plant physiology. … Their carbohydrate, protein and lipid profiles reflect the specific requirements for seed and seedling survival. This nutrient profile, especially after selection during domestication , is far from optimal for human or animal nutrition. For example, the seeds of most cultivated plants contain much higher concentrations of omega-6 fatty acids than omega-3 fatty acids than is desirable for human nutrition [15, 16], with few exceptions such as flax, camelina (Camelina sativa) and walnuts. …
The authors then describe what’s up up with the fats–for plants to germinate in colder temperatures, they need more omega-3s, which are more liquid at colder temperatures. Plants in warmer climates don’t need omega-3s, so they have more omega-6s. (Presumably omega-6s are more heat tolerant, making them more stable during high-temperature cooking.)
Flax and walnut have low smokepoints (that is, they start turning to smoke at low temperatures) and so are unsuited to high-temperature cooking. People prefer to cook with oils that can withstand higher temperatures, like peanut, soy, corn, and canola.
I think one of the issues with fast food (and perhaps restaurant food in general) is that it needs to be cooked fast, which means it needs to be cooked at high temperatures, which requires the use of oils with high smokepoints, which are not necessarily the best for human health. The same food cooked more slowly at lower temperatures might be just fine, though.
There is a side issue that while oil smoking is unpleasant and bad, the high-temperature oils that don’t smoke aren’t necessarily any better, because I think they are undergoing other undesirable internal changes to prevent smoking.
Then there’s the downstream matter of the feed cattle and chickens are getting. My impression of cattle raising (from having walked around a cattle ranch a few times) is that most cattle eat naturally growing pasture grass most of the time, because buying feed and shipping it out to them is way too expensive. This grass is not human feed and is not fungible with human feed, because growing food for humans requires more effort (and water) than just letting cows wander around in the grass. Modern crops require a lot of water and fertilizer to grow properly (see the Wikipedia quote above.) This is why I am not convinced by the vegetarian argument that we could produce a lot more food for humans if we stopped producing cows–cattle feed and human feed are not energy/resource equivalent.
However, once the cows are grown, they are generally sent to feedlots to be fattened up before slaughter. Here they are given corn and other grains. The varieties of grains they are fed at this point may influence the nature of the fats they subsequently build:
Modern grain-fed meat and grain-rich diets are particularly abundant in omega-6 fatty acids, and it is thought that a deficiency of omega-3 fatty acids, especially the EPA and DHA found in fish oils, can be linked to many of the inflammatory diseases of the western diet, such as cardiovascular disease and arthritis (Hibbeln et al., 2006). DHA has been recognized as being vitally important for brain function, and a deficiency of this fatty acid has been linked to depression, cognitive disorders, and mental illness (Conklin et al., 2007).
Let’s get back to the article about plant breeding. I thought this was interesting:
The biological basis of protein limitation in seed-based foods appears to be the result of evolutionary strategies that plants use to build storage proteins. Seed storage proteins have evolved to store amino nitrogen polymerized in compact forms, i.e. in storage proteins such as zein in maize, gluten in wheat and hordein in barley. As the seed germinates, enzymes hydrolyze the storage proteins and the plant is able to use these stored amino acids as precursors to re-synthesize all of the twenty amino acids needed for de novo protein synthesis.
So if we make plants that absorb more nitrogen, and we dump a lot more nitrogen on them, do we get wheat with more gluten in it?
Another book I read, Nourishing Traditions, which is really a cookbook, claims that our ancestors generally ate their grains already sprouted. This was more accidental than on purpose–grains often sat around in storage, got wet, and sprouted. Sprouting (or germinating) makes the wheat use stored gluten to make amino acids. Between sprouting, fermentation (sourdough bread) and less nitrogen-loving wheat varieties, our ancestors’ breads and porridges may have had less gluten than ours.
In the laboratory of the first author we have taken two different approaches to improving the protein quality of crops. First, we successfully selected a series of high lysine wheat cultivars over a period of twenty years, by standard breeding methods . … Surviving embryos consistently had elevated levels of lysine relative to parental populations and the seed produced from these embryos also had increased levels of lysine. The increased nutritional value of these lines, however, carried a cost in terms of lower total yield. A striking result was that grasshoppers, aphids, rats and deer preferentially feasted on the foliage of these high lysine wheats in the field, rather than on neighboring conventional low lysine wheats. The highest lysine wheat had the highest predation and subsequently the lowest yield (D.C. Sands, unpublished field observations). … Thus, we are led to the hypothesis that selection for insect resistance may have inadvertently resulted in the selection for lower nutritional value…
Then the authors talk about peas, of Gregor Mendel fame. Two varieties of peas are wrinkled and smooth. The smooth, plump ones look nicer (and probably taste sweeter). The plump ones store sugar in a form that we digest more quickly, resulting in faster increases in blood sugar. They are thus more likely to get stored as fat.
Breeders and buyers are biased toward plump seeds and tubers, in peas and many other crops.
Incidentally, the outside of the wheat grain–the part we discard when producing white flours but keep when making “whole” wheat flour–contains phytates which interfere with iron absorption and other irritants designed by the plant to increase the chance of grazers passing the seed out the other end without digestion. (However, the creation of white flours may remove other nutrients.)
It’s getting late, so I’d better wrap up. The authors end by noting that fermentation is another way to potentially increase the nutritional content of foods and suggest a variety of ways scientists could make grains or yeasts that enhance fermentation.
A few more studies:
The nutritional value of crop residue components from several wheat cultivars grown at different fertilizer levels:
Nine wheat cultivars were grown at two test sites in Saskatoon, each at fertilizer levels of 0, 56, 224 kgN ha−1. Proportions of leaf, stem, chaff and grain were obtained for each level. Significant cultivar differences were observed at each site for plant component yields. A significant increase in the proportion of leaf components and a significant decrease in the proportion of the grain components was observed as soil nitrogen levels increased. Crude protein contents of plant components varied significantly with both cultivar and fertilizer level. Significant differences in digestibility in vitro also existed among cultivars. Increasing fertilizer levels significantly improved the digestibility in vitro of the leaf but not of the chaff.
Genetic differences in the copper nutrition of cereals:
Seven wheat genotypes, one or barley and one of oats were compared for their sensitivity to sub optimal supplies of copper, and their ability to recover from copper deficiency when copper was applied at defined stages of growth Copper deficiency delayed maturity, reduced the straw yield and severely depressed the gram yield In all genotypes. …
Genotypes with relatively higher yield potential were less sensitive to copper deficiency than those with lower yield potential … There was no apparent association between dwarfness and sensitivity to copper deficiency in wheat.
An article suggesting we should eat emmer wheat instead of modern cultivars:
… The production and food-relevant use of domesticated modern-day wheat varieties face increasing challenges such as the decline in crop yield due to adverse fluctuating climatic trends, and a need to improve the nutritional and phytochemical content of the grain, both of which are a result of centuries of crop domestication and advancement of dietary calorie requirements demanding new high-yield dwarf varieties in the last five decades. The focus on improving phenotypic traits such as grain size and grain yield towards calorie-driven macronutrients has inadvertently led to a loss of allelic function and genetic diversity in modern-day wheat, which suffers from poor tolerance to biotic and abiotic stresses, as well as poor nutritional and phytochemcial profiles against high-calorie-driven non-communicable chronic diseases (NCDs).The low baseline phytochemical profile of modern-day wheat varieties along with highly mechanized post-harvest processing have resulted in poor health-relevant nutritional qualities in end products against emerging NCDs. …
Ancient wheat, such as emmer with its large genetic diversity, high phytochemcial content, and better nutritional and health-relevant bioactive profiles, is a suitable candidate to address these nutritional securities…
There’s a lot of information about emmer wheat nutrition in this article/book.