Home
>
Nutrition
>
Fructose Short-Circuits Glycolysis

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

**************
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
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.

scheduled cleaning services Lake Forest ..

In The News:

Expert cybersecurity tips help Mac owners remove malware infections and strengthen defenses with antivirus software, password managers and system updates.

Meta's AI chatbot training rules bans sexual roleplay with minors and block access to child abuse material as regulators scrutinize its safety measures.

Online banking users face a new threat: web injection scams that overlay fake pop-ups to steal logins. Here’s how to spot them and protect your accounts.

Meta introduced Teen Accounts to Facebook and Messenger while launching a School Partnership Program for U.S. educators to report bullying within 48 hours.

Executive order signed by President Donald Trump tasks Robert F. Kennedy Jr.'s MAHA Commission with using AI to find new cures for childhood cancers.

New FileFix attack tricks Facebook and Instagram users into running malicious PowerShell commands disguised as Meta account maintenance to deploy StealC infostealer.

Step-by-step instructions help users migrate to Windows 11 while preserving emails, contacts, documents, and software licenses during the transition.

Chrome faces its sixth zero-day attack in 2025 as Google patches critical V8 engine flaw CVE-2025-10585 discovered by Threat Analysis Group.

The Hypershell X Ultra exoskeleton features 12 terrain modes and carbon fiber construction to enhance hiking, cycling and outdoor adventures.

Personal data from public records and data brokers helps scammers create tailored scam stories, making their calls and emails more believable to potential victims.

Uber Eats partners with drone delivery startup Flytrex to test autonomous food delivery services in U.S. markets, marking the company's first investment in drone technology.

OpenAI announces 120-day plan to strengthen ChatGPT safeguards for teens, including parental controls and expert council on AI wellbeing.

Spam emails can help improve security — if reported correctly. Learn how to report spam across major email services and get key tips to protect your inbox and personal data.

Harvard researcher Avi Loeb says comet 3I/ATLAS weighs 33 billion tons and spans 3.1 miles, making it far larger than previous interstellar visitors.

The Glassboro Public School District in New Jersey has partnered with ZeroEyes and InformaCast to detect visible firearms and alert staff and law enforcement within seconds.

Hackers use fake Google search results to trick users into downloading lookalike apps laced with malware that have been pushed to the top.

Generative A.I. has lowered barriers for sophisticated cyberattacks as hackers exploit ChatGPT and other tools to forge documents and identities.

IOS 26's new features include bigger lock screen clocks, dirty lens alerts, and improved spam detection for iPhones.

Stay up to date on the latest AI technology advancements and learn about the challenges and opportunities AI presents now and for the future.

Sophisticated phishing scams now exploit Apple's iCloud Calendar invite system to bypass spam filters and trick users into calling fake support numbers.

Complete guide to medication tracking apps for iPhone and Android users, featuring built-in Health apps, MediSafe, MyTherapy, and smart pill dispensers.

Alef Aeronautics plans to begin production of its electric flying car Model A by late 2025, following FAA approval for limited testing at five airport locations.

Five common overpayment scams use fake checks and third-party payment requests to steal money from unsuspecting victims across various scenarios.

The Robeta Ananya luxury camper van features a full living room, ceiling bed, washer-dryer, and complete kitchen starting at $295,000 for the limited Founders' Edition.

Scammers exploit retirees' trust and assets through fake debt collection calls, but proper verification methods and reporting can stop these fraudulent schemes.

Fructose Short-Circuits Glycolysis

Nutrition