Fructose, a not-so-sweet surprise?

Fructose has earned itself a special spot in the lime-light in the last ten years, and with good reason. One minute you hear fructose is bad, the next you see a commercial saying it's the same as sugar. One day you go to your alternative medicine doctor and they say stay away from the stuff, the next day you do to your medical doctor and they tell you to use agave nectar because it's low glycemic. It's all very confusing! Well, I'm here to help you sort out the facts, the myths, and most importantly, the marketing.

First of all, let's compare fructose to it's cousins, glucose and galactose. Each of these are monosaccharides (one-unit sugars) that contain 6 carbons. These are bound together to form disaccharides (two-unit sugars). Sucrose, table sugar, is a glucose bound to a galactose. Lactose is a glucose bound to a galactose. These are both so called "simple sugars" because only one bond needs to be broken to get back to sugar building blocks, monosaccharides. Starch, like the glycogen in muscle and liver cells, is made up of long strands of glucose molecules bound together for easy storage. Each of these bonds requires slightly different enzymes for digestion, but the end product that makes its way to your cells for energy is going to be one of these three basic sugars.

Fructose is naturally found in fruit, and is by no means an evil sugar all by itself. However, the invention of high fructose corn syrup (HFCS) in the 1970s has made fructose an all too common occurrence in the American diet today. While the Corn Refiners of America may try to bamboozle us into thinking that HFCS is "a natural sugar that comes from corn" and "like sugar, is fine in moderation", I'm here to tell you that these statements could not be further from the truth.

In terms of their caloric value fructose and glucose are practically the same, but there are several things that make fructose a completely different beast in regards to its effects on the human body.

1. The metabolism of fructose is quite different than glucose.  For you biochemistry nerds out there, in his YouTube video "Sugar: The Bitter Truth" Dr. Lustig details the differences between glucose and fructose metabolism [1]. The two main differences (aside from the hormonal interactions) is that almost all of the metabolic burden of fructose falls onto the liver, and that calorie-for-calorie fructose is more readily converted to fat.

2. Fructose affects the body, and it's hormones differently than glucose. Glucose requires the hormone insulin to get into cells, which triggers adipose (fat) cells to release a hormone called leptin. Leptin tells the brain "I've had enough", thus serving as a negative feedback mechanism to prevent over-consumption of sugar. These hormones also suppress the release of another hormone, ghrelin. Ghrelin is a hunger stimulating hormone that is produced in the stomach. Suppressing ghrelin while increasing leptin secretion gives you the feeling of satiety. However, fructose does none of these things, leaving you yearning for more sugar.

3. Perhaps most importantly, marketing for HFCS and fructose containing products such as agave nectar have lead people to believe that they are actually healthy. The Corn Refiners "sweet surprise" commercials [2] and print ads surely paint a convincing picture. By portraying the HFCS skeptic as a uninformed scare-mongers, who after being questioned by what can only be called the HFCS enthusiast can only shrug and mumble, the Corn Refiners have made it quite clear that you should feel silly for simply questioning their product [2]. I much prefer this spoof commercial [3].

Agave nectar is unique in that many well intentioned doctors are now recommending it as a sugar alternative to their diabetic patients. Touting it's shiny low glycemic index label proudly, agave has managed to find itself a nice little niche among those who have diabetes and a desire to follow a low sugar diet, but still crave sugar. The problem is that agave is NOT low sugar- it is low(er) in glucose. According to my searches, agave ranges anywhere from 70-85% fructose, as opposed to HFCS that is typically 55% fructose, or table sugar that is 50% fructose. The reason agave is low glycemic is that fructose does nothing to raise your blood sugar, because "blood sugar" actually means "blood glucose". When blood glucose raises, diabetics have to take insulin (see number 2). Since fructose does not interact with these hormones it is considered better for diabetics, but that could not be further from the truth. The problem is that they fail to tell you on that nice, shiny label that high fructose sweeteners such as agave will leave you wanting more sugar, is more readily converted by fat, places undue burden on the liver, and is, calorie for calorie, still a sugar.

The moral of the story yet again is that you can't trick the body. We should all be on a low sugar diet-  but this means all sugars and all sweeteners. Don't fool yourself any longer- there is no such thing as a healthy sweetener. I'm not saying don't enjoy your sweets every now and then, but sugar is truly something to be consumed in MODEST moderation.

In a previous post we talked about how artificial sweeteners like aspartame create a feeling of disconnect between the stomach and the brain which leaves you craving more sugar, in addition to the very real possibility of causing cancer [4]. Now we have learned that low glycemic sweeteners (aka high-fructose sweeteners) such as agave and HFCS not only leave you craving more sugar, but will make you more fat and stress your liver. I hope you use this information to make the healthiest possible choices in the future.


Too legit to quit,

Nikki Cyr, D.C.


Referenced links:
[1] https://www.youtube.com/watch?v=dBnniua6-oM  <-- More on the metabolism of fructose
[2] https://www.youtube.com/watch?v=lQ-ByUx552s  <--- Commercial funded by the Corn Refiners
[3] https://www.youtube.com/watch?v=hYiEFu54o1E  <--- The real deal!
[4] http://createanewbox.blogspot.com/2012/08/artificially-sweet-part-1-truth-about.html

Other good reads:
[5] http://www.foodrenegade.com/agave-nectar-good-or-bad/
[6] http://articles.mercola.com/sites/articles/archive/2010/01/02/highfructose-corn-syrup-alters-human-metabolism.aspx
[7] http://www.sciencedaily.com/releases/2008/12/081209221742.htm