Sugars are healthful components of food when found naturally in milk, fruit, and
vegetables. But sugar has the potential to harm health when added in large amounts
to processed foods in the form of sucrose (table sugar), high-fructose corn syrup, or
dozens of other sugar forms that contain the molecule sucrose that is digested into
glucose and fructose.
Consumption of fructose increased fivefold in the last century and doubled over the
past thirty years, concomitant with the burgeoning obesity pandemic. Lustig notes
that in the story of obesity, “Fructose is very sweet and is inevitably metabolized to
fat. It is the primary (but not the sole) villain…” He notes that if you are starving
or energy depleted after running a marathon, fructose can quickly and healthfully
help restore the liver’s stores of glycogen. But for most of us, all the extra sugar
in the American diet from processed foods, soft drinks, juices, bakery goods, and
desserts has major negative implications for health.
Calorie for calorie, the ethanol in alcoholic drinks and fructose are more toxic than
other energy sources, especially to your liver. Ethanol is a cellular poison. Most
of it is metabolized by the liver. Any amount that is not metabolized for energy
gets turned into fat in the liver or muscles and causes liver damage and insulin
resistance. Ethanol stimulates the brain’s reward system and decreases the brain’s
executive functioning. This is a recipe for addiction.
Fructose metabolism is similar to that of ethanol. Unlike glucose that can be metabolized throughout the body, almost all fructose is metabolized by the liver into glycogen or triglycerides.
Fructose induces liver insulin resistance that in turn leads to
high levels of insulin, disruption of leptin signaling by high insulin, (so you want to
eat more), failure to decrease ghrelin, (so the “I’m full” signal is not sent), excess fat
storage, and over-time, development of the unhealthy metabolic syndrome. Lustig
points out that the toxic effects of both ethanol and fructose are dose-dependent,
with each having a threshold for damage. “Fructose toxicity” occurs when ingestion
of about 50 grams per day is exceeded. Perhaps half of Americans consume
more than 50 grams of fructose per day. As is described in a previous blog, epidemiology reveals another important downside of high consumption of sugar—a strong correlation between the amount of sugar consumed and the likelihood
David Ludwig, a Harvard T. H. Chan School of Public Health professor, suggests
that the overweight and obesity epidemic is mainly because of our food environment
and increased consumption of highly processed foods such as white bread,
white rice, cookies, crackers and sugar-sweetened beverages. He suggests that
the way that these overly processed high glycemic index foods produce obesity is
through causing a surge in levels of blood sugar, the release of insulin, greater incorporation
of glucose into fat, and hunger.
This blog presents opinions and ideas and is intended to provide helpful general information. I am not engaged in rendering advice or services to the individual reader. The ideas, procedures and suggestions in that are presented are not in any way a substitute for the advice and care of the reader’s own physician or other medical professional based on the reader’s own individual conditions, symptoms or concerns. If the reader needs personal medical, health, dietary, exercise or other assistance or advice the reader should consult a physician and/or other qualified health professionals. The author specifically disclaims all responsibility for any injury, damage or loss that the reader may incur as a direct or indirect consequence of following any directions or suggestions given in this blog or participating in any programs described in this blog or in the book, The Building Blocks of Health––How to Optimize Your Health with a Lifestyle Checklist (available in print or downloaded at Amazon, Apple, Barnes and Noble and elsewhere). Copyright 2021 by J. Joseph Speidel