High fructose corn syrup and chocolate milk

I've received some questions and I'm going to take my time and respond to them, so be patient. Today I'm going to hit on high fructose corn syrup and chocolate milk. Although they don't sound related, they are... sort of.

Next I will present my take on the Paleo-diet, and will likely talk grains at the same time. I think it may surprise some people to hear me say this, but the Paleo diet has a lot going for it. It also has some weaknesses. I will dance a little around that topic because my mentor in my master's program was the author of "The Paleo Diet" and while I have nothing but the utmost respect for him, we may have different ideas on some things. Norm, I like that you disagree with me on some things, you should. If you take everything that you read in a blog as 100% the way it has to be, you are naive. The information I present is based on my graduate research, but for all you know I could be a 12 year old who has learned a few big words.

I'll then talk about bone health and supplementation. I think I have a different approach then most, but it's a good one.

And yes, Taylor, I will also address your comment from yesterday. Taylor called me a "raving tree-hugger". Thanks, I'll take that as a compliment (whether it was intended or not). I may address this along with the Paleo-diet, but if that post gets to long, I will address what my nutrition advice would be if I weren't a "raging tree-hugger".

I don't think introductions are supposed to be that long... sorry. Today I'll address high fructose corn syrup. If you want the abbreviated version, go read my post on food processing or carbohydrates and hunger. This post may become a little technical for some, but Chad asked for it. Let me know if you like this much technical stuff, I have a fear that it will go over many heads.

So why is high fructose corn syrup (HFCS) so bad? When you eat glucose (not HFCS), it enters your blood and then is taken up by cells through a GLUT 4 transporter. On the inside of the cell the glucose is phosphorylated (a big phosphate molecules is stuck to the glucose so it can't leave the cell). Then, depending on the energy state of the cell (whether it is in usage mode, or storage mode) your body will either metabolize that glucose molecule to be used as energy or it will store the molecule as glycogen to be used later. The energy state of the cell is "measured" primarily through an enzyme called phosphofructokinase (that's the rate limiting step of glycolysis) That is how it is supposed to work.

Fructose is able to enter the cell via a different, less regulated GLUT transporter. Once the Fructose is in the cell, it is phosphorylated (so it can't leave). This is similar to glucose, but a phosphorylated fructose molecule has already passed the phosphofructokinase step in the glycolysis pathway so it WILL be used for energy. That may sound like a good thing but it's not.

First, I need to differentiate between fructose (which is the primary sugar in fruit) and HFCS which is used as an inexpensive sweetener. Fruits are relatively low calorie and although most of their sugar is from fructose, fructose is much sweeter than glucose so there is relatively little fructose in fruit. HFCS on the other hand, is used abundantly in processed foods and it is about a 50/50 fructose/glucose mixture (actually they come in different concentrations, but I think the 50/50 is the most commonly used). With HFCS you get, not only a lot more fructose, but a significant amount of glucose at the same time. This is a recipe for disaster.

This may seem completely random in the middle of a HFCS article, but I"m going to sidetrack to chocolate milk to build a basis for the rest of the HFCS thing. Chocolate milk, is a wonderful post exercise drink and here is why. My masters thesis showed that milk causes relatively extreme insulin spikes, but with very little change in blood glucose. For a sedentary individual, this is bad. Chocolate milk will provide an insulin spike that will cause the GLUT 4 molecules to assemble on cell membranes ready to pick up any possible glucose. The high sugar content of chocolate milk will provide lots of sugar for the GLUT 4 molecules to pick up. Since you are no longer exercising and insulin levels are high (which slows down phosphofructokinase and puts the body in a storage state) this will lead to the storage of glucose. After an endurance event this is essential to recovery of glycogen stores that were lost during exercise.

Back to HFCS. The glucose part of high fructose corn syrup will induce an insulin spike and let glucose into the cell to be stored. The fructose will also enter the cell, but it is not readily stored because it has already passed the phosphofructokinase step in glycolysis so it is going to produce energy. But what if you aren't doing anything and your body already has enough energy? You already have high insulin levels which is a signal the body uses to say we aren't using energy and we need to store stuff, so now the cells say, we've got enough and we aren't going to send GLUT 4 to the surface of the cell, even though insulin is present and demanding it. (We call this insulin resistance, it is a precursor to diabetes). Do you see the problem?

OK, I laid that out so simply (at least I thought so). It's not that simple. HFCS is not the sole cause of diabetes, not even close, but it is a contributor. Your body is extremely durable and able to cope with these sorts of situations. It takes years or even decades of overfeeding a body before the development of diabetes. The HFCS in ketchup (with the relatively small quantity of ketchup that is eaten in a day) is not enough to make a huge difference in your life. However, HFCS is in EVERYTHING that is processed. Over consumption of HFCS will lead to problems. On a similar note, HFCS is not found in fresh fruits and vegetables, whole grains, nuts, meats, dairy, etc. I have taught people before that a diet that eliminates HFCS and trans fats will be a good diet. (That's true, except you could ruin it with saturated fat if you really tried).

There you are, HFCS and chocolate milk mixed into one simple post.