Tuesday, August 12, 2008

High-Fructose Corn Syrup VS. Table Sugar

I was reading this study for work and it reminded me that I think we blame high-fructose corn syrup (HFCS) too much:
Dietary Sugars Stimulate Fatty Acid Synthesis In Adults, Journal of Nutrition, 2008

If you're skipping HFCS because you don't want the fructose, you may as well skip sugar, cane syrup, honey, maple syrup, and fruit syrups ... because they all deliver the same if not more of a fructose punch. (HFCS is derived from modified corn starch.)

The study above was very small - 4 men and 2 women. It found that beverages containing more fructose than glucose resulted in more fat production - both after the beverage was consumed (even though no fat was consumed), and again after a meal 4 hours later. That is, the liver manufactured more triglycerides when higher-fructose beverages were consumed, than when higher-glucose beverages were consumed, and there was a carry-over effect to subsequent meals. (However, higher-glucose beverages raised post-meal blood glucose and insulin more than higher-fructose beverages.)

There's something that stands out in this study for me - the amount of fructose in those beverages, and the implication that high-fructose corn syrup (HFCS) is to blame.

There were three beverages tested. All contained 85 grams of sugar, as:
  • 100% glucose
  • 50% glucose and 50% fructose
  • 25% glucose and 75% fructose
Which works out to:
  • 85g glucose and 0g fructose
  • 42.5g glucose and 42.5g fructose
  • 21g glucose and 64g fructose
That 40 or 50 grams of fructose is a lot for a few gulps, especially when you consider a beverage usually accompanies other possibly fructose-containing foods. It's not something you'd find easily in nature:
  • One cup chopped carrot contains 1g fructose (plus 2g wrapped up in sucrose)
  • One cup cherry tomatoes contains 2g fructose
  • One medium banana contains 6g fructose (plus 1.5g wrapped up in sucrose)
  • One cup of blueberries contains 7g fructose
  • One medium apple contains 9g fructose (plus 1g wrapped up in sucrose)
  • One cup grapes contains 12g fructose
Those test beverages add up to a lot of bananas, as regards fructose at least.

But are HFCS-sweetened foods much higher in fructose than foods sweetened with cane sugar?

By "wrapped up in sucrose" in the list above, I mean that common table sugar, also known as sucrose, is a disaccharide; it consists of two single sugars (monosaccharides) bound together, in this case, a molecule of glucose and a molecule of fructose. So -- table sugar contains fructose, in an amount not much different from high-fructose corn syrup, while honey and maple syrup provide even more fructose:
  • One teaspoon of table sugar (sucrose: 50% glucose and 50% fructose) contains 4g sugar, about 2g glucose and 2g fructose.
  • One tablespoon high-fructose corn syrup (HFCS: 45% glucose and 55% fructose) contains 5g sugar, about 2g glucose and 3g fructose.
  • One tablespoon pure corn syrup (100% glucose) contains 5g sugar, hardly any fructose.
  • One tablespoon honey contains 17g sugar, about 8g glucose and 9g fructose.
  • One tablespoon maple syrup contains 12g sugar, about 6g fructose tied up in sucrose.
If you sweetened a cup of coffee or tea with a teaspoon of sugar, or two teaspoons of high-fructose corn syrup, you'd be consuming roughly the same amount of sugar, the same amount of fructose, and not such an unnatural amount of either, considering the above examples. There is the need to disengage fructose from its partner glucose when you eat table sugar, a step not necessary when you eat HFCS (or when you eat fruit), but our body is very efficient at digesting (breaking apart) sucrose.

In my mind, it becomes unnatural when one consumes 40, 50, 60, or more grams of fructose in a few fell swoops, whether it be as sucrose, or as HFCS. Unfortunately, the amount of fructose tested in this study (42.5g and 64g) may be unnatural, but it is not uncommon:
  • One medium (21 ounce) cola beverage, if it was sweetened with high fructose corn syrup, might contain about 26g glucose and 32g fructose (58g total sugars - about 15 teaspoons of sugar)
  • One medium (21 ounce) cola beverage, if it was sweetened with table sugar, might contain about 29g glucose and 29g fructose (58g total sugars - about 12 tablespoons of HFCS).
There may be other reasons not to recommend HFCS, but for its fructose content, or its calories, it's not that much different from plain sugar. It's the amount of these sweeteners being added to foods that's causing problems.

Below is a nice graphic from the New York Times of the making of HFCS. Above is a photo of the final product.

Click for larger.


Anonymous said...

hfcs has been linked with liver damage and something to keep in mind is that without government subsidizing corn it would no longer be cheaper than sugar. I don't think genetically modified organisms should be allowed in the marketplace let alone subsidized

Dr BC said...

Yes, the difference is this: a) GM corn, b) Digestion of fructose in liver, as against every cell in body. Hence concentration in liver causing damage there.

Then, as described elsewhere in article the concentrated liquid syrup is consumed in larger amount and hence intake is usually much larger. It is like drinking an orange or carrot juice glass, which one may consume more than one glass. However, If one wants to eat them raw, one will not be able to consume as much.

So the issue here is fructose and it's metabolism in liver and unwittingly consuming much higher calories.

David Isaak said...

"If you're skipping HFCS because you don't want the fructose, you may as well skip sugar, cane syrup, honey, maple syrup, and fruit syrups ..."

I do. Because that's absolutely correct.

It's hilarious to me that health-food stores are now selling soft drinks emblazoned with labels that boast "Sweetened with Pure Cane Sugar!"

Kieran O'Neill said...

@David, I think the cane sugar in those drinks is for flavour, not health reasons (at least I hope people are seeing it as such). Cane sugar is much tastier than beet sugar, and far, far more so than corn syrup (which is basically flavourless). Beet sugar and corn syrup are the most commonly used sweeteners here in North America, and most of the sugar you find on supermarket shelves is beet.

But anyway, yes, all things in moderation. I don't skip all of the above sweeteners, but I don't exactly drink soft drinks on a regular basis either (except maybe for the cane sugar ones as a rare treat).

Oh, and this article is great. I had been seeing and hearing lots of popular fear of the dreaded HFCS (seems to have a bit of a partisan feel to it), but had always suspected just from the name (and my degree in biochemistry) that it was nothing more than an invert syrup, just as honey, maple syrup, golden syrup, etc. I'm now quite certain that it is no different.

Which is not to say that there aren't social/economic/political issues with it, most notably 1) such high subsidisation of corn that corn syrup is cheaper than sugar and 2) the ubiquitous use of sugars in the modern North American diet.

Anonymous said...

Don't forget that HFCS's fructose is *unbound* and is converted into triglycerides in the liver within hours of consumption - it's a huge blast of unbound fructose at once. The breakdown of the fructose in say sucrose (table sugar) requires an extra step, and it happens in more of a trickle stream over more than twice the length of time.

HFCS has been proven in several studies such as http://www.princeton.edu/main/news/archive/S26/91/22K07/ to be a major contributing factor in the onset of obesity and other metabolic dysfunction. Take 5 minutes and read that abstract... Metabolism of various sugars is more complex than the "Sugar is Sugar!" argument encompasses, so it's worth taking the time to educate yourself on this important subject.