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High fructose corn syrup–myth versus science


Like monosodium glutamate (MSG), the additive that everyone avoids, except there is absolutely no evidence that it does anything to anyone, high fructose corn syrup (HFCS) has evolved to become the current pariah of the food industry. Even the name sounds a bit chemical, with that “high fructose” leading you to believe it has to be bad. 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.

Hey, before we start, what are sugars?

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.

But it gets a bit more complicated. Many sugars form disaccharides that are compounds made of two monosaccharides covalently bound together. Table sugar, the white stuff in our sugar bowls, is sucrose that is a 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 (and syrup). 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 we get to make this even 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. Sugar is a major part of our lives.

Before we can continue onto our discuss about HFCS you need to know one important thing. 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.

There is one more important thing 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.

What is high fructose corn syrup?

HFCS consists of 24% water, and the rest fructose and glucose. There are two main types of HFCS, HFCS 55 (used mostly in soft drinks) which is approximately 55% fructose and 42% glucose; and HFCS 42 (used in other types of beverages and processed foods), which is approximately 42% fructose and 53% glucose. There is another type, HFCS-90, approximately 90% fructose and 10% glucose, which is used in small quantities for specialty applications (interestingly, low calorie drinks, because, for the same sweetness about 33% less calories are added), but it is primarily blended with HFCS 42 to make HFCS 55.

Well before the advent of HFCS, in the 1950′s, candy and soft drink manufacturers utilized “invert sugar” by exposing sucrose to a weak acid solution, then recrystallizing which dissociated the covalent bond between the glucose and fructose, and exposing the fructose molecule, which, of course, is so sweet, that it made the overall effect to be much more sweet with the same amount of sugar. This allowed the manufacturers of the candy and sodas to get more sweetness with less sugar, saving a lot of money. So, “high fructose” has been around since the 1950′s, exploiting the greater sweetness of fructose even before HFCS was available.

So, why was HFCS developed?

First, corn syrup is much cheaper than sucrose (table sugar), but it’s not as sweet because it has a higher 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 55. 

But natural sugars are better!!!

So how does HFCS compare to natural sugar products that we believe are better for you? Well, other than 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, in the case of apples, peaches and pears, even higher levels of fructose than HFCS. Remember, fructose is fructose. There is no chemical difference between the fructose created by plants or created by corn. It’s the same exact fructose molecule. The body thinks it’s the same. The body metabolizes it in the same way.

OK, I’m convinced. But is fructose bad for you?

Now the answer gets much more complicated. 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), less calories, and the same amount of fructose. 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. 

Therefore, you shouldn’t be eating sugars and sticking with whole grain foods to prevent type 2 diabetes. Oh wait, there’s no proof

One last thing. What’s with this blaming everything for excess weight? HFCS isn’t at fault, but it sure is easy to blame instead of yourself.

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