This article is #10 of the 12 most popular posts on Skeptical Raptor during 2015. Stay tuned, I’ll be reposting the rest of them through New Year’s Day.
One of the most frustrating things I’ve observed in nearly six years of writing (here and in other locations), is that those who want to create a negative myth about a new technology (especially in food or medicine), one of the best ways to do it is mention “chemicals.”
And if the chemical sounds unnatural, the assumption is that it is unsafe. The so-called Food Babe has made a lot of money endorsing a belief that all chemicals are evil, ignoring the fact that all life, the air, and water are made of chemicals.
People have demonized monosodium glutamate (MSG), a food additive that makes people run away in terror if a Chinese restaurant doesn’t have a huge flashing sign in neon that says “NO MSG.” Of course, in just about every randomized study about MSG, researchers find no difference in the effects of MSG and non-MSG foods on a random population.
Another current satanic chemical is high fructose corn syrup (HFCS), which has evolved into one of the the most “chemicals” of the food industry. Even the name sounds a bit chemical, unnatural, dangerous. But is it?
That’s where we need to look at the science, because the answers to the questions are quite complicated and quite simple.
Let’s define what is a “sugar”
This could be heavy science. But it helps understand what sugars are and do, instead of myths.
Before we can even start talking about HFCS, we need to really talk about sugars. So, what exactly is a sugar? For most people, it’s the white stuff on the table, and according to everything we hear today, it should be avoided. However, like most things, sugar is much more complicated than that.
There are two broad types of sugars, aldose and ketose, along with over twenty individual, naturally-found sugars, called monosaccharides. Of all of those sugars, only four play any significant role in human nutrition: glucose, fructose, galactose, and ribose (which has a very minor nutritional role, though a major one as the backbone of DNA and RNA). Got that? Four sugars are all we can absorb into the human body.
There are other monosaccharides found in nature that can be consumed, but they either just feed the gut flora, or are enzymatically converted into one of the four basic sugars by the gut flora.
But here it gets a bit more complicated. Many monosaccharide sugars form disaccharides which are sugars made of two covalently bound monosaccharides.
Table sugar, the white stuff we put in our coffee, is called sucrose–a disaccharide made of one molecule of glucose bound to one molecule of fructose. Sucrose is also the main sugar in most other commercially purchased sugars that you find including brown sugar, molasses, beet sugar, and maple sugar.
Milk sugar is lactose, which is glucose and galactose; maltose is two glucose molecules; and there are a few dozen less common ones. Each has a slightly different taste, and some rare ones provide unique tastes to certain fruits and vegetables. But when these disaccharides enter the intestinal tract, they are quickly disassociated by water or acids plus enzymes into simple monosaccharides.
So when you put sucrose in coffee, and consume it, it will be broken down into two sugars that actually can be used by the body–glucose and fructose.
But we need to provide you with even more science (it’s not bad, I promise). We need to make this slightly more complicated.
Starches are also sugars. They are just long chains, or polymers, of individuals sugars, almost always glucose. Cellulose, which is a major component of paper, wood, natural plant fibers, and many other items, are glucose polymers. So are insect shells.
Generally, these long chain polysaccharides cannot be broken down by humans, though our intestinal flora can use them for food. In addition, bulk fiber, an important part of your diet for intestinal motility, is generally long chains of saccharides.
Remember, humans can only absorb monosaccharides like glucose, fructose, galactose and ribose. In other words, all of those disaccharides and polysaccharides must be broken down into the constituent monosaccharide before it has any usefulness for a human.
The gut has a variety of different enzymes that break down these starches and disaccharides–so sucrose cannot be absorbed, but it is broken down by sucrase into glucose and fructose, then absorbed. By the way, any disaccharide or polysaccharide that isn’t broken down remain in the gut, providing food for our gut bacteria, thereby maintaining a “healthy” digestive system. No I’m not advocating colon cleansing.
There is one more crucial point to note about these sugars, which will be important as we move along with this story. Fructose is 1.73 times more sweet than sucrose despite having the same exact caloric content. So technically, you could use about 58% less fructose than sucrose to get the same sweetness. You’re probably seeing where this is going, but stay tuned.
More heavy science about sugars
All individual sugars are the same across the planet. Glucose, fructose, galactose or ribose, whether produced by a plant, an animal, a bacteria, or a manufacturing plant in Iowa, are exactly the same molecule. Fructose is fructose is fructose, no matter the source.
I want to make this clear. There is simply no difference between the fructose and glucose in HFCS, and the fructose and glucose in sucrose, the disaccharide derived from cane sugar. The chemical formulas are exactly the same. It’s the exact same carbons, the exact same hydrogens, and the exact same oxygens. No difference.
I cannot repeat this enough, so I will. The components of sucrose from a sugar beet or sugar cane is chemically and scientifically identical to HFCS. Neither is more or less “natural” than the other.
This is one of the major misconceptions of the pseudoscience of the natural food world, that somehow a sugar from a living organism is magically different from a sugar from a manufacturing plant.
No organism’s physiology could distinguish between the fructose and glucose in HFCS from the fructose and glucose in cane sugar .All organisms, including humans, biologically metabolizes each fructose and glucose in relatively the same way. We should not endow HFCS with some special properties that it simply does not have.
What is high fructose corn syrup?
HFCS consists of 24% water, and the rest fructose and glucose–the water just makes the fructose and glucose into a syrup. That’s it, nothing more than fructose, glucose and water, no different than all of the other fructose, glucose and water molecules made into a syrup.
More science below, you can skip unless you’re just like me, obsessed with information:
So, why was HFCS developed?
First, high fructose corn syrup is much cheaper than sucrose (table sugar), but it’s more sweet because it has a lower glucose to fructose ratio than sucrose (and as we mentioned, fructose is very sweet). Second, it retained moisture better than sucrose (twice as many molecules). Third, it was available in a liquid form and didn’t caramelize as readily as sucrose (this last one could be an advantage or a disadvantage, depending on the use).
But here’s the most important point: HFCS allowed soda manufacturers to use less sugar — and thus fewer calories — in their products without reducing its sweetness. Using sucrose, sugar from cane or beets, would require 20% more sugar (along with 20% more sugar calories) than using HFCS.
But aren’t natural sugars better?
So how does HFCS compare to natural sugar products that we believe are better for you? Remember, the fructose and glucose in HFCS are exactly the same as the fructose and glucose in all other sugars.
So, unless you buy into that naturalistic fallacy, which claims that natural is better somehow, most naturally sweet products are very similar to HFCS in fructose content:
- Honey: about 17% water, with almost all the remainder being sugars. The main sugars are fructose 38%, glucose 31%, maltose 7%, sucrose 1.3%, other sugars 1.5%. In other words, honey could be considered a “high fructose” type of sweetener.
- Maple syrup: about 60% sugar, with that sugar being 95% sucrose, 4% glucose and 1% fructose.
- Apples: over 10% sugar, 57% fructose, 23% glucose and 20% sucrose. Very high fructose.
- Peaches: 8.4% sugar, 57% sucrose, 23% glucose and 18% fructose.
- Pears: 9.8% sugar, 64% fructose, 28% glucose and 8% sucrose.
- Grapes: 15% sugar, with the sugars being 53% fructose and 47% glucose.
In other words, some of these “natural” foods have as high or even higher levels of fructose than HFCS. And since we’ve established that fructose is fructose, no matter the source, consuming these foods will provide you more fructose than an equivalent amount of HFCS.
But is fructose bad for you?
Now the answer gets much more complicated, and frankly, we’ve got to go to some more esoteric science. Remember, because the food manufacturers are using less HFCS to get the same sweetness as sucrose, the amount of fructose consumed between a drink that contains just sucrose and one that contains just HFCS (and has the same sweetness level) is almost the same.
In other words, you’re getting the same amount of taste (because of the fructose), but consuming fewer calories, and the same amount of fructose as you would from sucrose. So your worries shouldn’t be about the fructose.
Moreover, strong scientific meta-reviews of clinical research have established that there is little evidence of links between increased fructose intake and any deleterious health effects:
- Health implications of fructose consumption: A review of recent data–”A moderate dose (≤ 50g/day) of added fructose has no deleterious effect on fasting and postprandial triglycerides, glucose control and insulin resistance. There is no existing evidence for a relation between moderate fructose consumption and hypertension. Fructose may induce hyperuricaemia, but mainly in patients with gout.” In other words, eating moderate amounts of fructose have no ill-effects. The issue remains that if you eat too much fructose (and any other sugar), there are deleterious metabolic effects, and that should be the major issue.
- Evidence-based review on the effect of normal dietary consumption of fructose on development of hyperlipidemia and obesity in healthy, normal weight individuals–” The results of the analysis indicate that fructose does not cause biologically relevant changes in TG (triglycerides) or body weight when consumed at levels approaching 95th percentile estimates of intake.
- Metabolic effects of fructose and the worldwide increase in obesity–”There is, however, no unequivocal evidence that fructose intake at moderate doses is directly related with adverse metabolic effects. There has also been much concern that consumption of free fructose, as provided in high fructose corn syrup, may cause more adverse effects than consumption of fructose consumed with sucrose. There is, however, no direct evidence for more serious metabolic consequences of high fructose corn syrup versus sucrose consumption.”
So, let’s review. Fructose is just a monosaccharide that is metabolized by the body. It is sweeter than other mono- and disaccharides, so less is needed, a lot less. HFCS is just a natural corn syrup with a higher fructose to glucose ratio to make it taste sweeter, so less is needed for the same sweetness.
Most naturally sweet products also have high fructose contents, hence their high sweet tastes. And from scientific reviews, there is no evidence that fructose has any effect on obesity or metabolic disease beyond what is expected from the consumption of any other sugar.
Does HFCS cause diabetes?
The reasons that have lead scientists to speculate about the link between HFCS and diabetes is a result of how galactose, fructose and glucose are treated differently by human metabolism. Glucose passes through the liver unchanged, and can be used by all cells for energy. The level of glucose is controlled by insulin, which causes it to be stored if the blood levels get high, and glucagon, another hormone which causes the release of glucose from storage. This control system is highly complicated, and in non-diabetics, is a finely tuned system.
Fructose and galactose don’t signal insulin, but are captured by the liver, eventually processed into a couple of different biochemicals, one of which is glucose. So, because fructose is treated in a different manner by the body, speculation has been that fructose might be implicated in T2DM. How the body controls blood sugar levels, and how fructose and galactose are involved in that control, is incredibly complex and would take at least a year of graduate level classwork to even begin to understand the physiology.
Except, there are some problems with this speculation about fructose and T2DM. For example, fructose has a very low glycemic index of 19 ± 2, compared with 100 for glucose and 68 ± 5 for sucrose. Because fructose is 1.73X sweeter than sucrose, diabetics can consume significantly less fructose (than other forms of sugars) for an equivalent level of sweetness. Studies show that fructose consumed before a meal may even lessen the glycemic response of the meal. In other words, specifically because of the sweetness and lower insulin reactivity, fructose may actually be preferred for those who are attempting a low glycemic index diet.
There are a few very poorly done studies (one that relied strictly on a simple questionnaire) which seem to claim that high fructose in the diet may lead to more hunger (possibly because it doesn’t trigger the feedback loops for hunger that glucose does). These studies barely meet the minimum standards of quality in scientific research. But these studies completely ignore the fact that rarely is fructose is consume alone, but usually with glucose, which will trigger the hunger-fullness feedback loops.
However, I admit to vastly oversimplifying how these sugars interact in the complex blood sugar regulation system. There is just not any convincing and plausible evidence that shows fructose, as opposed to all other monosaccharides, has some specific and unique effect on human metabolism.
Fructose and Type 2 diabetes
A lot of the current “mania” about HFCS and type 2 diabetes mellitus (T2DM) results from a recent article in an open source journal, Global Public Health (impact factor of 0.92), by Goran et al. The authors tried to establish a correlation between availability of HFCS foods and the incidence of Type 2 diabetes.
This type of study is at the population level, which may seem like it would give you great numbers; unfortunately, the problem is that it allowed so many confounding factors to be included (dietary patterns, quality and quantity of food, smoking, drinking, anything), while it ignored all sorts of other data that might provided us with a clear indication of causality. In other words, it is simply not a way to establish correlation, let alone causation.
Specifically, the problems with this study were:
- They assume that availability of HFCS foods is the major cause of obesity. It simply isn’t. It is possible that consumption of amounts of HFCS means high consumption of various others foods that might cause obesity. It could also be the availability of fast food or bacon.
- Obesity itself is not the single causal factor in T2DM, it is one of number of causes of the disease.
- Even though the researchers attempted to control for other factors, there are just too many factors that may skew the results at a country level. The best type of epidemiological study would a prospective study, which would allow for controlling of different factors along with getting more detailed data about each patient. A prospective study takes time, is expensive, but gives some of the best results upon which to confirm or refute a hypothesis about HFCS being causal to T2DM.
- The authors of this study took the easiest and simplest route to write a paper: they obtained country-level data for T2DM, Gross domestic product, HFCS production in foodstuffs, and calories consumed. This type of work takes a few days, and would require you just to leave the computer for sustenance. I could look up the sales of Xbox and Playstations in each country and compare it to T2DM, get it published in a bad journal, and make a name for myself that video gaming is correlated to Type 2 diabetes. And even if I could show some correlation between video gaming and diabetes, it wouldn’t be worth anything, though I’d make a big name for myself.
In a review article examining the health implications of HFCS, the author, James Rippe, MD, states that “most of the studies being cited to support the proposed linkages between fructose consumption and obesity and other metabolic conditions employ epidemiologic data that establishes associations rather than cause and effect.”
The study by Goran et al. above is a perfect example of the type of study dismissed by Dr. Rippe, who concludes that:
High quality meta reviews of the research about the correlation between HFCS and T2DM and other metabolic conditions have consistently shown that the data does not show any causality between fructose and metabolic disease.
We could cherry pick a few poorly designed epidemiological studies or force-feeding rats to induce diabetes studies, but neither of those types of studies provide us with solid or even intriguing evidence that HFCS has some responsibility for T2DM.
However, until we have two pieces of information–one, a high powered prospective epidemiological study, and two, a definitive explanation of how fructose could disrupt the metabolism leading to T2DM, we completely lack any reliable evidence to think that HFCS itself causes T2DM rather than simply any sugar. Because the hypothesis that is well understood, and well supported by evidence, is the one that says any sugar can lead to obesity, thus leading to a higher risk of T2DM.
If I were raising children, and frankly, I have, I would keep them from HFCS. And sucrose. And honey. And fruit juices. And cotton candy. And chocolate bars. And fatty foods. And potato chips. There is absolutely no reasonable and plausible evidence that HFCS is any more problematic than over-eating any food, playing too much video games, or whatever else is today’s cause of type 2 diabetes.
Therefore, you shouldn’t be eating sugars and sticking with whole grain foods to prevent type 2 diabetes. Oh wait, there’s no evidence that whole grain foods do anything.
One last thing. What’s with this blaming everything for excess weight? HFCS isn’t at fault, but it seems like everyone wants to blame HFCS rather than their own choices in type of food. What does it matter that your Coke or Pepsi has HFCS or “real” sucrose. Drinking too many of either over a lifetime will probably have the same exact negative effect on your health. Get real folks.
Sugar and the environment
There is a “movement” to push real (read cane) sugar back into many of our foods. So called real sugar sodas that use cane sugar instead of HFCS are popular, and more expensive.
The problem with cane sugar is that it’s bad for the environment. Producing cane sugar results in deforestation, pollution, wildlife habitat destruction, and industrial waste. Large portions of the Florida Everglades, the largest tropical wetland in the USA, have been drained for sugar cane plantations. The fertilizers used on vegetables, along with high concentrations of nitrogen and phosphorus that are the byproduct of decayed soil necessary for sugarcane production, were pumped into WCAs south of the EAA. The introduction of large amounts of these chemicals provided opportunities for exotic plants to take hold in the Everglades.
One can argue that corn farming has some of the same issues, but HFCS is a tiny portion of corn farming. Getting table sugar is almost the only reason to grow cane sugar.
Nevertheless, if we switched more to HFCS and other sugar sources, this can reduce the push for more cane sugar fields, which will have a major impact the health of the planet, especially in tropical areas.
Conclusions, the TL;DR version
It’s clear that there are individuals want to “prove” that high fructose corn syrup is unsafe and causes all sorts of problems to humans. But HFCS is a sugar syrup, close to honey in ratio of fructose to glucose. Just because it has this scary chemical name, high fructose corn syrup, people must think that it’s made up of some evil fructose chemical. But all fructose molecules are exactly the same, whether it’s in honey, a fruit, maple syrup, cane sugar, or HFCS.
In case you skipped all that boring science above, here’s the basic information.
- High fructose corn syrup is just two simple sugars connected together in water.
- All of its components are the same carbons, hydrogens, and oxygen atoms that are found everywhere in nature.
- The fructose and glucose components of HFCS are exactly the same as all other fructose and glucose in nature.
- Despite poorly designed research studies, there is no substantive evidence that HFCS causes excessive weight gain.
- HFCS probably has no effect on metabolic diseases, such as Type 2 diabetes, no more than any other sugar or foods.
Editor’s note: This article was originally published in June 2014. It has been completely revised and updated to include more comprehensive information, to improve readability and to add current research.
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