We’re going to switch gears this week and address a topic that, due to the powers that be, is surrounded by uncertainty and conflicting messages. Without getting into the history of how and why high fructose corn syrup became a staple of the American diet, we will cut to the chase and hit you with some of the science behind the breakdown of this sugar in our bodies. The hope is that the following information will help clear up any confusion created by ads like the one below:
What is Fructose?
Like glucose, fructose is a sugar molecule, differing in the total number of carbons. Fructose naturally occurs in things like fruit, veggies and in other food as sucrose (a glucose and fructose molecule bonded together). Naturally occurring fructose found in fruits should still be consumed in moderation, but is not as harmful for a couple of reasons:
1) Fruit also contains a whole food source of essential vitamins and minerals.
2) Fruit is also packing a load of fiber. This fiber has numerous positive effects on the breakdown of the sugars in the fruit including slowing down the rate of absorption in the intestines (thus controlling insulin and blood sugar levels). Fiber is also responsible for triggering the release of a hormone called PYY, which tells us when to stop eating.
High fructose corn syrup on the other hand is a man-made creation made by the processing and reprocessing corn starch. While this extends the shelf life of food and lowers the cost of production (as corn is government subsidized), it does not contain any of the vitamins, minerals or fiber that make some fructose containing fruits a healthy choice.
The Problem is in the Metabolism
To understand the hazardous issue associated with highly concentrated doses of nutrient empty fructose, we must first look at how glucose is broken down.
(Bear with me here; as this brief explanation of glucose metabolism will help you better understand the problem with fructose.)
When we consume glucose, roughly 80% of it is distributed and utilized as energy by virtually every cell throughout the body. This leaves roughly 20% of it to be processed by the liver into glycogen (stored glucose used to live in between feeding). Once the liver is full, any leftover glucose is then converted into something called VLDL (very low density lipoproteins) which promote fat storage and when seen in excess, coincide with cardiovascular disease. So it is true, excess sugar/carbs of any kind is a bad thing.
The metabolism of glucose also involves the triggering of insulin (released by the pancreas to deliver the glucose to your body’s cells) and the release of a hormone called leptin, which like the aforementioned PYY, sends a message to our brain that we are full.
The Effects of Fructose Metabolism
Increased Body Fat
The issue with fructose starts with the fact that only our livers can metabolize it. So right off the bat we see a difference between glucose (~20% going to the liver) and fructose (~90% going to the liver) as far as work load for our livers. This means the liver glycogen is filled first, leaving all the remaining fructose and glucose in the liver to be converted into VLDL and then fat. This fat can remain in the liver causing problems there or be transported out and distributed throughout your body.
Due to fructose being a different beast than glucose, different enzymes are required to break it down. One of these enzymes ultimately ends up as uric acid, which is a waste product that we excrete in our urine. Traditionally, gout has been attributed to the breakdown of chemical compounds called purines which are seen in food such as liver, anchovies, mackerel, dried beans and peas, beer, and wine. The purine breakdown leads to elevated levels of uric acid in the blood which can then deposit crystals in the joints causing the pain and destruction associated with gout.
Due to uric acid being a by-product of the metabolism of fructose, one can see why excess or HIGH FRUCTOSE can lead to the development of gout. Studies have shown an association with high fructose dense soda consumption and gout. Interestingly the same correlation was not shown in the consumption of diet soda. What’s the difference? The high fructose corn syrup.
High Blood Pressure
The excess uric acid also wreaks havoc by blocking an enzyme that is responsible for the production of nitric oxide in our bodies. Endogenously produced nitric oxide is very important to us because it dilates the blood vessels providing a natural way of lowering our blood pressure.
This association has been further demonstrated by the administering of a medication called allopurinol to patients with high blood pressure. Allopurinol is normally given to patients with gout, in order to alleviate the symptoms of excessive uric acid buildup. What was found was that allopurinol also lowered the blood pressure. What does this mean? It shows us that excessive uric acid, which is a by-product of excessive fructose intake, can lead to high blood pressure.
Again, due to the different steps involved in the metabolism of fructose, numerous signaling hormones do not function as they do with the consumption of glucose. Fructose breakdown actually decreases our brains sensitivity to leptin. Meaning, the message sent from the stomach to the brain to convey the message that we are “full” never arrives. Compound that with the fact that fructose does NOT suppress another hormone called Ghrelin, which is a hunger hormone that is normally suppressed by feeding. So as we can see, meals or drinks (soda AND juices) can actually trigger overconsumption and subsequent obesity, type II diabetes, etc.
If you’ve read any previous posts, we’ve touched on the subject of AGEs (advanced glycation end products) before. Without reiterating why these are so bad, the take home message here is that fructose is seven times more reactive than glucose in forming AGEs. This is not a good thing.
So there you have it; some of the reasons why regular consumption of fructose and especially HIGH fructose corn syrup is actually bad for you. It’s rough on consumers due to the fact the HFC is a main ingredient in the majority of processed foods. This can be avoided by cutting back on the boxed, canned, bagged items and sugary drinks (soda, juice, sports drinks) and consuming more fresh produce, raw, unsalted nuts and leans meats.
In light of this information, it seems as if this commercial would be a better fit: