Botany of Sugars


  1. Origins of Sugar
  2. Commoditization of Sugars
  3. Kinds of Sugars and their Chemistries

Festive foods often hinge on the remarkable nature of sugar, almost universally desired for sweetness and texture – certainly universally necessary for energy and building blocks. But what makes something a sugar, where does it come from, and why do we read articles that denounce sugar as dangerous, even toxic?

As commodities, sugars (principally sucrose, glucose, and fructose) are produced from a few agriculturally important plants. But plants across the board are in the business of making sugars; glucose is, after all, the typical result of photosynthesis. It is the production of sugar that makes plants the basis of the food chain, the “producers” – spinning out carbohydrates, proteins, and fats from earth, air, fire (sunlight), and water. Their incredible sugary resources have proven crucial to animals of every breed. Insects and birds probe flowers for nectar, which can have sugar concentrations ranging from under 10 to over 70%. Bees turn nectar into honey, plundered for sweet calories by countless generations of humans and bears. Native Americans learned to harvest sap from maple trees, which today is concentrated as maple syrup. Manna, famed as a miraculous gift for desert peoples, is thought to result from sugar exudates of desert trees. And fruit, from dates to apples and grapes, has provided important sweet, energy-rich food sources. Dried dates, for example, are 60 percent sugar by weight, while raisins are even higher, around 70 percent.

Trees and vines, however, are pikers when it comes to sugar production. No other plant group equals the capabilities of the grasses, which make most of the sugars we consume. Corn, wheat, and rice are remarkably efficient photosynthesisers – truly excellent at making sugar (glucose). We don’t especially think about sugar in relation to the grains, because their sweet wealth is stored mostly as more complex carbohydrates (mainly starch, which botanists call amylose). Plant starch, a polysaccharide made entirely of glucose, feeds us and our livestock. But that was not always the case.

You may be aware of Walter Voegtlin’s Paleo diet, based on the assumption that pre-agricultural humans consumed fruit, nuts, seed and grains, roots, leaves, insects, and flesh. Those Paleolithic folk led lean and brief lives compared to humans today. The Paleo diet, and its contemporary cousins, Atkins and South Beach, are decidedly non-vegetarian, emphasizing proteins and shunning carbs. Paleo assumes we should step back to a time before agriculture drove major changes to the human diet, a tough-love proposal for a world that gorges itself on Neolithic fare. It seems the agrarian Neolithic sorts thrived on grain-based foods, supplemented with meat and dairy associated with animal husbandry. That Neolithic diet, despite what you may think about it, supports the world today – and it is totally based on glucose.

Though proteins and starches are also staples, humans seem always to have sought and favored sweet substances (usually the simple sugars), which meant a quick energy boost in an otherwise earthy diet. The appetite for sweet foods and the pleasure they bring to the palate necessarily relates to the importance of basic sugars to our metabolism. Thus any ancient human, paleo or neo, would have had a sweet tooth, a yearning which we inherit. Those sweet sugars, based on syrups, honey, and fruit, were valued wherever encountered. But only in one place on the globe was there a plant, a cane (a grass), known for its perpetually sweet sap.

That place is thought to be the island of New Guinea, the largest island at the farthest end of the world’s greatest archipelago, anciently the exotic outsider to what we call Greater India…. Along the archipelago’s 25,000 islands, sugarcane migrated to India, where it became highly prized.

Though cane juice is more than 10% sugar, the pure extract cannot be stored. It would ferment too rapidly. Heat reduction to syrup or sticky masses of molasses-laden crystals was a remarkable advance. Because brown syrup and sugar are so highly concentrated that bacteria and fungi do not prosper, these products have shelf life and portability. Still, that early sugar never became “foodstuff”…., rather it was used and traded as a spice, and sometimes as a medicine. Even where the plant grew natively, production required so much effort that sugar remained rare and costly.

Because sugarcane is a tropical grass, cultivation is limited to tropical and subtropical zones. Thus, by 600 AD, sugarcane planting and processing had migrated to warmer regions of China and west to Egypt, where sugar became embedded in Muslim diets. Despite the toil required, this sugar was good stuff and became one of the products that made its way to Europe through ancient trade routes.

Westerners had grown accustomed to exotic spices from the Orient – cinnamon, cloves, nutmeg, black pepper, and parcels of raw sugar. Those other spices remained purely exotic however, whereas sugar could be more easily grown. Cultivation arrived in Sicily with Arabic rule in the 9th century. Sugar availability increased (albeit slowly) because this spice brought so much to the table. Records indicate the Mayor of Winchester was tasked to provide 3 pounds of sugar for a banquet in 1226, honoring England’s King Henry III. He payed today’s equivalent of $450 for that pleasure. The luxury threshold would be lowered as Europeans eventually adopted cane cultivation, spreading it to Old World islands. There was even a precedent for running Old World plantations with slave labor, since sugar cultivation requires industrial strength effort.

Big Sugar
Still, demand increased and supply remained limited until the age of “big sugar” – the harbinger of which was Christopher Columbus’s second voyage to the New World, when he introduced sugarcane cultivation to Santo Domingo. At the time, this was not so clearly a world-changing event. Columbus was well-familiar with European sugar growers, and after all, he thought he had discovered the western route to the East Indies, the home of sugar. The globalization of sugarcane cultivation, sugar (sucrose) production and trade became a 500 year story of economic and social boom and bust, in that:

  1. Sugar production could not remain a cottage industry. For many technical reasons, mostly due to the reality that sugarcane juice must be extracted very soon after harvest, sugar cane had to be grown in large plantations where sugar could be processed immediately.
  2. Sugar demand rose so abruptly that production and supply were nationalized, with control of sugar sources playing into the unending series of European wars from 1600 to 1900.
  3. Science and technology constantly upended sugar economics through introductions such as:
    1. new selections of higher-producing cane,
    2. centrifugal separation,
    3. production of sugar from beets – plants adapted to the temperate, even colder climates like Russia, Germany, and France, and the ability to manipulate sugar content and level of sweetness in corn syrups.

Rather than attempt to relate the entire story of sugar globalization (which has been told in many books and web articles), the following recitation of data and developments summarizes the origin, spread, and tumultuous rise of sugar to its apogee at the end of the 20th Century.

7th Century – By this time, sugar cane cultivation had spread from India to China and North Africa

10th Century – Cane sugar was know throughout Europe as a luxury spice. Cultivation and processing of sugar cane was introduced to the Mediterranean with the spread of Muslim control.
15th Century – Europeans had begun to establish their own sugar cane plantations on Madeira and the Canary Islands. At the end of the century, on his 2nd Voyage, in 1493, Columbus imported sugar cane to the island he called Santo Domingo, which today is Hispaniola

16th Century – Brasil became a major producer of cane sugar. The increasing availability of sugar would lead to lower prices and growing access to sugar for all economic levels.

17th Century – Sugar became a crucial ingredient for the growing popularities of chocolate, coffee, and tea.
1624 Francis Bacon published Nova Atlantis. In one passage, he proposed a gallery of inventors, which would include a statue to the “Inventours of Sugars” (Smith, 2015).

18th Century – Though still a costly spice, European sugar consumption averaged about four pounds a person in 1700. In addition to evolving use in existing foods, preserves & marmalades, candies, and fermented beverages, sugar had been married to newly-globalized products of growing popularity, such as coffee, chocolate, and tea. With democratization of those beverages, sugar replaced honey as the sweetener of choice.
1747 Marggraf reported successful extraction of sugar from beets.
1785 Thomas Clarkson spearheaded a boycott against slavery sugar, which poet Robert Southey called “the blood-sweetened beverage”. Others joined the discussion. In his 1788 poem, Pity for Poor Africans, William Cowper wrote:

I own I am shock’d at the purchase of slaves, 
And fear those who buy them and sell them are knaves;
What I hear of their hardships, their tortures, and groans
Is almost enough to draw pity from stones.
I pity them greatly, but I must be mum,
For how could we do without sugar and rum?
Especially sugar so needful we see?
What? give up our desserts, our coffee and tea!

19th Century – In 1800, at the dawn the century, English sugar consumption is estimated at 18 pounds per person per year (Aronson & Budhos, 2010. Sugar Changed the World: A Story of Magic, Spice, Slavery, Freedom, and Science), but that would rise as sugar-based products (such as jams preserves, and beverages) continued to grow in popularity and affordability among working class peoples.

Though still predominately grown and manufactured through slave labor, the century began with the only successful slave-led revolt (which liberated Haiti from French control). Sugar production shifted, gradually, away from reliance on slave labor, as abolition movements succeeded. By the end of the century slavery was abolished in most countries. But traditional sugar production was changing in other major ways. In 1851 David Weston introduced centrifugal separation to production in Hawaii (see improvements, US Patent Nos. 236,389. Jan. 4,1881). Centrifuging sugar pulls syrup from the crystals, a technology which proved to be a major breakthrough that streamlined production at the very time the cost of labor increased due to the disappearing institution of slavery. Cane sugar also gained serious competition as Northern European countries mainstreamed sugar beet production.

20th Century – Sugar production (from both cane and beets) was completely industrialized. Price controls and regulation became standard procedure, as sugar was now a dietary necessity throughout the world.
1972 John Yudkin’s Pure, White, and Deadly: The Problem of Sugar was published.

During the 20th century the story became more complex, even more sinister, because sucrose, the historical sugar of commerce and kitchen, acquired surrogates. Remembering that sucrose is a two-unit sugar (a disaccharide), consisting of one glucose molecule united to one fructose (fruit sugar), we know it breaks down to a fifty-fifty solution of the two monosaccharides. Back in the 19th century people had discovered you can break cornstarch into glucose units, which was useful. But glucose is less sweet than the equivalent mass of sucrose, and packs only half the sweetness as the same amount of fructose (fruit sugar). After a century of trials, scientists in Japan devised a method to stabilize enzymes that convert glucose to fructose, giving new life and breadth to cornstarch. The product, called High Fructose Corn Syrup (in the US), changed the sugar world. These sugars have become a powerhouse. Today’s average American diet includes over 100 pounds annually of added sugar. In 1016, world consumption of table sugar was projected at 386 trillion pounds.

Pure sucrose was never a significant part of Paleolithic, or even Neolithic diets, but it has become a significant component of diets today. It is worth learning more about sugars in order to determine for yourself what that might mean for your own health and well-being.

As Foodstuff, What is a Sugar?

Nutritionally, for humans, sugars boil down to a suite of three simple sugars (monosaccharides) and three dual sugars (disaccharides). For the moment we need only to recognize three sugars already discussed – glucose, fructose, and sucrose (their derivative disaccharide).

In popular culture, sugar implies sweet, but sweetness varies. We know the most important sugar, the sugar that forms the basis of our metabolism and the only sugar you actually require, is glucose. It is sweet, but fructose is twice as sweet. Sucrose, a disaccharide made from one glucose bonded to a fructose, is in the middle.

Though least sweet of the triad, glucose is critical to the story, because it is the common energy compound for almost all life forms. Glucose is the sugar plants create through photosynthesis. Everything about animal metabolism relates to glucose, and it is highly regulated by remarkable and complex mechanisms. Most adults have around 5 liters of blood, and following a meal our systems are working to get the glucose content back to a normal level, which is 1 gram per liter. That means you have 5 grams of glucose, just a bit more than a teaspoon, coursing through your veins and arteries.

Core reliance on maintaining that right balance of glucose is manifest through an intricate insulin-based management system. And sometimes glucose is the only energy source that will do. The brain, for example, relies almost purely on blood glucose for nourishment, as do the testes. Indeed, hypoglycemia (abnormally low blood glucose) can prove immediately fatal, while the body has remarkable capacity to cope with short-term hyperglycemia. In an earlier world, a sweet tooth would have been truly important to promote a diet as rich in naturally-occurring sugars as possible, and it would have been crucial human metabolism could cope with an occasional sugar feast.

We eat sucrose and starches, but only glucose is “required” as part of our diets. Our bodies can make any fructose we need. It is also true we can convert fructose to glucose, but that is not the normal course of events. Fructose is handled separately, through its own transporting system and apart from reliance on insulin. Unlike glucose, which is metabolized in all bodily tissues, fructose is dealt with in the liver, where it normally is converted to glycogen (animal starch, which is essentially chains of pure glucose).

Nutrition is its own world of language and fads. Sugars, which are about energy and building blocks, are the topic of our day. Years ago, most of us thought of sugar solely in terms of sucrose – sweetness, calories, weight gain, tooth decay, etc. Anyone who has consulted a dietician or dietary coach will know this has changed.

And corn (which is key to that change) is in the news, because corn is a major source of pure sugar. Don’t think this is about corn on the cob, or cornmeal. As early as 1844 cornstarch production was a major industry. Merely ten years later companies began selling corn syrup (made from corn starch). Like starch, corn syrup is natively pure glucose, not as sweet as sucrose, but useful in many regards.

Today, corn syrup is the equivalent of liquid sucrose. This equivalency came about as the result of research developments in 1965, when Yoshiyuki Takasaki and Osamu Tanabe (of the Japanese Fermentation Institute) developed a stable process to convert glucose to fructose. The tantalizing promise of that conversion had been the holy grail of the corn syrup industry. If a company could make corn syrup as sweet as sucrose, the world would change. And it did, very quickly. By 1967, Clinton Corn Processing Company had licensed rights to this enzyme for the US, and their scientists worked out kinks to industrialize the process. In a complex and rapid series of moves, large companies (particularly ADM) consolidated this emerging resource, marketing and defending high fructose corn syrup, which is usually called HFCS. By 1984 both Coca Cola and Pepsi converted to use of the new sweetener. Already liquid, more stable in solution, easily incorporated, and subsidized by the US government, HFCS quickly rose to equal status with sucrose for industrial food production.

Where does that leave us with sugar consumption? As recounted in the timeline, records suggest that around the beginning of the 18th century, when sugar was becoming available to the general populace, annual average consumption was around 4 pounds a person. As mentioned earlier, today the American per capita consumption of pure sugars (either as sucrose or high fructose corn syrup) exceeds 100 pounds each year. Each pound of sucrose has 1,775 calories, thus a person with an average intake of 100 pounds of sugar a year is also averaging 500 calories, daily, from sugar alone. The World Health Organization recommends an adult should control daily sugar consumption to 6 teaspoons (about 144 calories). With 109 teaspoons in each pound of sugar, this suggests the upper limit of consumption should be around 20 pounds a year – a fifth of today’s national average and a value we passed in the late 19th century.

Even that is high. Humans did not evolve in a world of abundant free sugar, though we require it to keep us going. Today we worry about hyperglycemia, but as pointed out earlier, evolutionarily, hypoglycemia was the problem. It is evident that the nearly-addictive sweetness of glucose, fructose, and sucrose relates directly to an inherent human need for sugars. But given our physiologies, consuming quantities of pure sugar is simply unnatural – unnatural and potentially dangerous.

A century ago, when sugar consumption had already risen considerably, observed incidents of diabetes were 3 cases per 100,000 people, compared to 8,000 per 100,000 people today. More recent data, available from the US Center for Disease Control (CDC), documents Diabetes at under 1% in 1958 and slightly over 7% in 2014. Significantly, use of HFCS came about in this same time period.

What does this mean for you, for me? It means most Americans are overdosing on sugar. Perhaps more significantly, we have altered the composition of sugars we consume. Recalling three related sugars: glucose, fructose, and sucrose, we know fructose is constructed and behaves differently from glucose, and our bodies handle it through different mechanisms. Sure, fructose can be converted to glucose, but it more readily is turned into glycogen (animal starch) or even fat. The neolithic diet, one based on carbs is truly about glucose, because plant starches are pure glucose. The modern sucrose and HFCS diet delivers sugar in a 50:50 ratio of glucose to fructose.

The Brix unit is named for Adolf Brix, one of several people who devised a sys-tem for measuring the concentration of sugar in a water solution. Because dis-solved sugar bends light, and the extent to which a solution “bends” transmitted light (like a lens) depends on sugar con-centration, we can use a lens (a refracto-meter) to measure the concentration of sugar in a solution (the ºBx). This is how vintners field check the level of sugar in their crops.

For years, this was not considered an issue. Dietitians actually supported consumption of fructose because it does not impact insulin level and it is sweeter than sucrose (or glucose), thus less may be needed.

People have begun to question that wisdom. Most likely humans historically consumed modest levels of fructose, which might have appeared seasonally, or at least sporadically. Given the modern, steady availability of sucrose and high fructose corn syrup, we have experienced a shift to sweetness that upped the fructose composition of our sugar intake. Most significantly, our sugar consumption is not an occasional binge, it is ongoing.

CONCLUSION: People the age of the author are also of an age to recall sequential dietary woes; each decade gives us a new concern: cholesterol, triglycerides, trans-fats, burned meat, salt, sugar, and now more specifically high fructose corn syrup. The lesson in all of these is moderation, because everything you ingest has some limit. The LD-50 for water is 70 g/kg body weight, for salt 3 g/kg, and for sugar, 30 g/kg.

The paleo diet reminds us there was a time when people were constantly challenged to power their own bodies – sugar was at a premium. In our world, people like Mark Phelps might require 8,000 Calories a day, with a basal metabolism of 2,000 Calories. But that intake does not work out for most of the population, especially for those of us fortunate enough to live longer than our ancestors, with abundant food, in a time of plenty. There comes an age and a stage when what we consume needs to be regarded as much like medicine as any other substance.

You need sugars, most particularly glucose. You deal well with fructose, though it is not the primary energy source for body maintenance. And you are allowed occasional binges… What is not in the cards is a regular diet rich in simple sugars, especially fructose.

Some Definitions & Discussion:
Calories: So what are Calories and where do they come from? Nutritionally, calories are the available energy stored in carbon-to-carbon bonds of the food we consume – most significantly in glucose. Adding up calories in our diets, we talk about food in terms of carbohydrates, proteins, and fats – with most people being aware that fats are twice as rich in calories as carbohydrates and proteins. Regardless as to your diet, however, everything boils down to calories present in glucose, because proteins, fats, and other carbohydrates are generally converted to glucose or compounds in its breakdown sequence when energy is harvested.

Be aware that dietitians talk about capital “C” Calories, which to a chemist are really kilocalories. Importantly those kilocalories (big-C calories) are one way governments describe food energy in larger terms – a measure by which we discuss feeding the world. The FAO (Food and Agriculture Organization of the United Nations) calculates the millions of kilocalories it takes to feed a population, as compared to how many million kilocalories are produced through various agricultural systems.

For example, FAO estimates that in 2008, around 161 million hectares of the world’s arable lands were planted to corn, yielding a food value of 2.974 quadrillion kilocalories (that is 2,974,000,000,000,000). Increasingly, FAO and other organizations are moving to discussing food in terms of mechanical energy, which is measured in joules. For food resources, the useful term is the megajoule, or MJ.

What is a carbohydrate? Pretty much the same thing as a sugar, but even more inclusive. As the term suggests, carbohydrates seem to be hydrated carbon – molecules made of carbon and water (though, from closer analysis of photosynthesis we know that is not exactly how they are assembled.) Generally, these water-soluble compounds are constructed of carbon, hydrogen, and oxygen in predictable proportions, mostly CnH2nOn.

Many important plant compounds are carbohydrates, including the numerous sugars and sugar-based molecules
(monosaccharides, disaccharides, oligosaccharides, and polysaccharides). The most abundant carbohydrate is cellulose, which is a glucose polysaccharide that is indigestible by most animals. Plants, of course manufacture quantities of a digestible polysaccharide called amylose, i.e. plant starch. Carbs, in dietary terms, are mostly starches and other complex compounds that are not sweet, and sometimes not even digestible.

Sugars and Sweetness: What makes something a sugar? People say “sugar” when their thoughts are directed to the smaller carbohydrates – compounds we call monosaccharides and disaccharides. There is also the implication of a “sweet” taste. But not all sugars are sweet, and even sweet sugars vary. You can read up on the “historical theories of sweetness” in Wikipedia, and examine a succession of ideas as to what makes food sweet to humans. [See also: Sweetness, in this Reader, Chapter 10, Section 1, Techniques.]

Over a century ago, Georg Cahn (in Germany) noted that sweetness is associated with the presence of several hydroxyl (-OH) groups in a molecule, but he also observed that Chlorine affects sweetness. And then, there is “sugar of lead” (lead acetate), a sweet, crystalline compound that appears to have been a component of ancient Mediterranean grape-derived sugars (which the Romans called defrutum and sapa) made from grape must, boiled down in lead and copper kettles. That leaves a lot of mysteries in its wake. The understanding is not resolved; people still wonder what causes something to taste sweet. Researchers assume we will someday discover oral “receptor” sites that are triggered by certain characteristics of molecules we perceive as sweet. But we remain at odds as to many issues related to the nature of our sweet tooth.

Things are more complex yet, because there is no absolute way to gauge sweetness. We can and do determine the concentration of known sugars in a solution. Vintners check sugar concentration (percent concentration is water is measured in Brix, i.e. ºBx) to calculate the probable level of sweetness in order to determine harvest time. But that assumes we know the composition of the solution, and we do not expect other flavors to modify the sweetness level.
In general, there are so many variables that sweetness remains basically subjective, so we use a bioassay (a taste test) to compare sweetness against a sucrose standard (given a value of 1). A researcher might ask people to score how a substance tasted at different concentrations compared to sucrose solutions. Through comparing perceived sweetness at differing concentrations, researchers can generating a scale. Though this method, people have determined that fructose sweetness rates 1.73 (as compared to 1 for sucrose), while glucose comes in at 0.7.

In the 19th century, one way chemists studied chemicals and materials was to pass polarized light through solutions and crystals to study how the angle of the polarized light shifted. When dissolved in water, sucrose (table sugar) is known to shift light to the right (by 65 degrees). Once scientists experimented with the sucrose, they realized that it is really a 2-sugar compound (a disaccharide), because when acid is added to the mix, sucrose breaks into two molecules
(monosaccharides) – one glucose and one fructose. Like sucrose, the common form of glucose also causes light to rotate to the right, thus scientists named it
“dextrose” – indicating right-handed. The second simple sugar, fructose, was found to rotate light to the left, and was therefore called “levulose”.

Naturally occurring fructose actually shifts light more strongly than glucose, thus when sucrose is dissolved in water and “hydrolyzed” (breaking sucrose into glucose and fructose), scientists observed that the new solution shifted light to the left 20 degrees. That is the origin of the term “invert” sugar. – which is sucrose that has been broken into glucose and fructose.
The story behind this discovery explains a lot about both early chemistry and the nature of sugars. Searching the web for “optical rotation” you will discover optical rotation was first observed by François Jean Dominique Arago in 1811, while studying quartz. A plane of polarized light can be shifted (rotated) by passing it through crystals and solutions. Optical rotation became part of a standard chemical description. As Louis Pasteur discovered by studying Tartaric Acid (from grape must), many organic molecules have two forms. The form that rotates light to the right is termed the D-form, while its mirror image (which rotates light to the lef) is the L-form. Glucose and Fructose each have a D-form and an L-form, but in nature, D-glucose is common, whereas L-glucose is not. The story is different with Fructose; the naturally occurring form is L-fructose, which shifts light to the left.

Activity: See: Chirality of Sugars, Royal Society of Chemistry website:

Some calculations seem a bit extraordinary. For example, the sweetest substance (reported in Wikipedia) is lugduname, said to have a value of 225,000, suggesting that dropping 1/225,000 teaspoon of lugduname in your tea will have the same impact as a teaspoon of sugar. Whether that will make the medicine go down, is also subjective.

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