Fructose Short-Circuits Glycolysis

First some terminology.

Fructose ... a five carbon sugar that occurs naturally in fruit, does not cause as much insulin to be secreted as glucose and tastes sweeter than glucose.

Glucose ... a six carbon sugar that is the breakdown product of glycogen(a polymer of glucose, multiple glucose units hooked together) that occurs naturally in potatoes and grains.

Glycogen ... multiple units of glucose hooked together (a polymer). What is typically called "complex carbohydrate" today.

Glycolysis ... derived from the Greek stem glyk- "sweet" and lysis meaning dissolution. The metabolic pathway for the initial utilization of glucose.

Phosphofructokinase ... the enzyme that catalyzes the reaction of fructose 6-phosphate to fructose 1,6-biphosphate. You don't need to understand anything more about this reaction other than the fact that if fructose comes from a source other than the degradation of glucose, it blocks this step for glucose until all the non-glucose derived fructose has been metabolized.

Glucose and Fructose Are Both Metabolized via Gylcolysis

Both fructose and glucose are metabolized via glycolysis. Both end up at some point as three carbon fragments. In order for glucose to be broken down into three carbon fragments it must first be metabolized to a five carbon sugar, actually fructose. This is where the trouble starts, since fructose is already a five carbon sugar. The following analogy I hope will aid in explaining this. The analogy, however, is far from perfect.

Whether we start out with separate glucose and fructose as in high fructose corn syrup or honey, or with fructose and glucose hooked together as in sucrose(common table sugar), makes no difference. As soon as sucrose hits the bloodstream, it is immediately broken down (hydrolyzed) to fructose and glucose.

Freda Fructose gets married to Gary (Glucose) Sucrose. They live happily on Sugar Lane. Both work in muscle and liver cells where they are metabolized usually into fat and slow the immune system to a crawl. They get up early in the morning and both have to get on the Glycolysis Road to get to work. Gary (Glucose) is one carbon atom heavier than Freda Fructose and because of that, he cannot cross the river on one of the lighter and faster bridges on their way to work. Freda Fructose however, being lighter, has no problem crossing the faster bridge and making the short-cut to the Glycolysis Road. Gary Glucose, however, has to get on the road well above the short-cut, since he is too heavy to take the lighter bridge short-cut.

The Phosphofructokinase Intersection

As usual Freda Fructose gets to the Phosphofructokinase intersection well before Gary Glucose. By the time Gary Glucose gets to the intersection, the traffic directing policeman is once again allowing all the Freda Fructoses to make the turn onto Glycolysis Road while, all the Gary Glucoses can do is sit in traffic and wait. Once again, Gary, and all the other Glucoses on their way to work, must sit and wait for all the Freda Fructoses to get on Glycolysis Road before they can continue.

LA Traffic Control

Traffic control sees all these Glucoses sitting stuck in traffic, just like traffic backs up everyday in LA. It reacts by injecting a lot of green lights (insulin) into the pathway for the Glucoses to get to work. Finally, all the Fructoses pass and now because there are too many green lights, all the Glucoses pass quickly. All of the sudden there are no Glucoses to be found on the Glycolysis Road. All the cells along the way that used to be able to snag some Glucose can't because there isn't any. Whether it is the excessive insulin that is the cause of so many of the lifestyle diseases we see today or, all the backed up Gary Glucoses decide to cause their own damage to the arteries they are in, I don't know. It is however, clearly established that the ingestion of sucrose (fructose and glucose) is related to many of our lifestyle diseases today including the extensive damage to the vascular system that occurs with adult onset diabetes mellitus. I know, my damaged arteries are up on this site.

Hypoglycemia

Now you begin to feel lightheaded, dizzy and a bit disoriented. Traffic control has injected too many green lights and the concentration of glucose drops precipitously. The brain starts to complain because it no longer has enough glucose to function. If the blood sugar gets low enough, serious complications can occur.

Fructose and Glucose Together

The combination of fructose and glucose should be avoided as much as possible. When you eat your fruit, try to allow at least an hour or preferably two, before eating potatoes, whole grains or rice. Also avoid as much as you can sucrose, high fructose corn syrup, honey and maple syrup or, any sweetener that has as it main ingredients, fructose and glucose.

Other Sweeteners

Brown Rice Syrup

Brown rice syrup is roughly about 45% maltose (two glucose units hooked together), 50% complex carbohydrates and 3% glucose. No glucose and fructose together but still sweet and I have known some people who can even get hypoglycemic from it.

Barley Malt Syrup

Made from whole barley it is about 65% Maltose and 30% complex carbohydrates.

Fruit Concentrates

These are usually combinations of glucose, fructose and sucrose and should be avoided.

Maple Syrup

Maple syrup is about 65% sucrose and should be avoided.

Today's Health Tip:

If you want sweet, you are safest with stevia. Next would be sweeteners derived from rice and barley. Sucrose, high fructose corn syrup, maple syrup and fruit juice concentrates should be avoided.

Reference:
Stryer Biochemistry Fourth Edition

Copyright John Mericle M.D. 2005 All Rights Reserved

**************
To really get off of sweets and "deprogram a sugar-coated palate," the MericleDiet is hard to beat. Generous servings of organic complex carbohydrates will keep you and your brain happy. To visit the MericleDiet follow the link below.
http://www.DrMericle.com
**************

One of our readers Wendy in the UK writes:

Just to let you know that according to the website below that takes you to Carol Bond Health Foods it is spelt Stevita. I couldn't find it anywhere on the site and through asking the chat section it was spelt differently. Thought you would like to know so that you can let the other newsletter recipients know.
Regards...
Wendy

PS Really enjoy the newsletter. Find it very informing so thank you. Gave up drinking milk last year after reading your article! Feel much healthier as a result.
**************

To take Stevia for a test drive or purchase some online follow the link below. I had luck just searching stevia but you could also search the product "Stevita."
http://www.drmericle.com/rcb.php
Thanks for your time.

DrMericle.com is devoted to achieving optimal health and peak performance through diet and lifestyle change. Dr. Mericle brings together a unique blend of formal training in organic chemistry and biochemistry, medical education, 29 marathons, 3 Hawaii Ironman competitions and a lot of practical real life experience.

---

Calculating Your Calorie Needs

In order to eat fewer calories than you need, you have to determine how many calories you actually need. Adults can calculate their approximate energy needs using the following formula:A. Body weight multiplied... Read More

Sports Nutrition Made Simple

Following these simple nutrition guidelines will allow you to lose weight, and an abundance of energy throughout the day.1) Hydrate with water throughout the day.2) Avoid processed foods3) Eat plenty of lean meats... Read More

3 Important Differences Between White Bread and Whole Wheat

For any kid who grew up eating doughy, thick Wonder Bread for lunch, the encouragement by dietitians and nutritionists to switch to whole wheat bread can be a tough transition.Bread, like any other... Read More

That Cookie Might Kill You!

Chances are you may have had a food product that contained Trans Fatty Acids. What's the danger you ask? I 'm about to share with you just a little of the hidden dangers... Read More

The Best Protein Powder

What is the best protein powder to buy? I get this question all the time, and really, there is no best protein - many are very good for different reasons! In my opinion,... Read More

What is the Cause?

The question most people think they need an answer to is what is the cause of their this or that? Many people pay it lip service, but what is cause really? Going with... Read More

Boost Your Immune System

The Immune System is probably the most important system in your body. It was designed by nature, millions of years ago, to aid the body in recovering from injuries and illness. In other... Read More

Policosinol and Cholesterol Reduction

The word cholesterol has become synonymous with poor health. Indeed, one does not typically hear the word used, or see it printed, unless it points to yet another distressing fact -- that high... Read More

Take Control of Your Health

In large part, you're in control of your health, not your doctor. And taking control of your health doesn't really depend on whether or not you have medical conditions.Taking control means developing habits... Read More

Rediscovering Protein - Corrective Action in the American Diet

Protein must be a part of a healthy diet for a simple reason: it is essential for life. Every single cell in the human body -- including bones, blood, skin, chemicals, and enzymes... Read More

Is Your Food Aging You?

Did you know that the food you eat could be prematurely ageing you? Science has made some amazing discoveries in the last decade in nutrition. We really should be taking note of what... Read More

Did You Start Your Life With Enough Probiotics?

Why does disease begin in the digestive tract? Your digestive tract is your first line of defense when it comes to your health. This is because of the good bacteria that resides there.... Read More

The Cost Of Being Sick And One Possible Alternative: Glyconutrition

A lot of people I've talked with about health supplements usually are coming from about the same place - you know: "been there, done that." People are tired of hearing about the latest... Read More

Why are Free Form Essential Amino Acids Necessary and What to Look For!

1. Look for high quality, crystalline, free-form, amino acids (AAs) Most amino acid blends on the market are actually reduced milk or soy proteins. These may contain small quantities of free form AAs... Read More

What You Eat Can Protect Your Skin from the Sun

(ARA) - By now you probably think you've heard all of the health reasons there are for eating your vegetables. But recently, researchers from Harvard University have announced that lutein -- a potent... Read More

Facts About Virgin Coconut Oil

Coconut oil is less known compare to olive oil, corn oil, canola oil or any other vegetable oil. It is sad to hear that many terrified titles such as "fat contributor" or "cholesterol... Read More

When You Eat at the Fridge

I spent a few days at a resort in Mexico this past summer for a friend's wedding. I've known her since the 2nd grade and it was a really fun time hanging out... Read More

Help Your Heart Grow

I turned into my parents' driveway in Maryland and parked the car. Before I could even step out and close the door, Mom flew out of the backyard, gesturing frantically."Your father had a... Read More

Constipation

Constipation is the passing of dry, hard faeces fewer than three times a week. Individuals who have constipation may find it painful and difficult to have a bowel movement, also other symptoms include... Read More

Juicing - A Beginners Guide

You can spot a juicer a mile off at the supermarket or greengrocer. Apart from the huge number of carrots and apples they are loading into their trolley, they also have that slightly... Read More

Clues for Fibromyalgia Relief

Fibromyalgia is a chronic and potentially life-altering disorder with symptoms such as extreme muscle pain, extraordinary fatigue and multiple tender and painful points. Fibromyalgia itself tends to be similar in many aspects to... Read More

Post Nasal Drip

Post nasal drip is a sensation of mucous build up in the throat. Sometimes you may even feel a dripping sensation from the back of your nose. The cause is over-production of mucous... Read More

Try a Slow-Carb Habit

Carbohydrates - found in grains, breads, pasta, and sugar, as well as vegetables, fruit, tofu, beans, and dairy - provide the body with the most efficient fuel for energy production and brain activity.... Read More

Mangos: Treat Your Skin and Your Taste Buds

Mango is my favorite fruit next to pineapples. They're sweet, juicy and delicious. This extraordinary fruit contains high amounts of vitamin A (contributing to it's meaty bright orange color). It also contains Vitamins... Read More

Avocado - Ooh, What a Lovely Pear!

Many people avoid avocados thinking them to be fattening, but the truth is they are packed with Essential Fatty Acids (EFAs) which burn fat so actually they make you thin! So now you... Read More

You Can Have Healthy Skin

With new research, new products and new skin protection advice popping up all the time, it is hard to figure out the best things to do to improve and protect your skin.A skin... Read More

Vitamin D - The Sunshine Vitamin!

Vitamin D is a fat-soluble vitamin like A and E. This vitamin is hard to obtain from food. Luckily, sunshine is a significant source of this vitamin because UV rays from the sun... Read More

Find Mineral Nutrition Online

Mineral nutritionSearching for mineral nutrition information is much easier today than ever before. I remember when we'd have to search manuals, books and do it at the library and also searching the encyclopedia.... Read More

The Power of Capsulized Foods

For most people, the concept of capsulized food? usually conjures up images of space travelers ingesting meals condensed into a compact pill. However, in modern-day reality, things are quite different. Capsulized foods are... Read More