In the story I mentioned that elevated glucose and insulin levels cause problems in the body; here are some of those problems:
Glycation: When glucose or fructose molecules glom onto a protein (without being properly introduced by an enzyme) that is called “glycation.” It can contribute to many chronic diseases, including heart disease, cancer, diabetes, cataracts, Alzheimer’s disease, rheumatoid arthritis, premature aging, and more. Glycation of LDL particles in our blood can make them more likely to contribute to heart disease; glycated proteins are found in the amyloid plaques in the brain that are associated with Alzheimer’s. Glycated proteins in the lens of the eye contribute to cataracts. Glycation of proteins is a normal occurrence and is a big part of the aging process; but the more glucose and fructose in our blood, the more glycation happens (and the faster we age).
Glycated protein:
Increased oxidative stress: when glucose and fructose are burned for fuel in our mitochondria, something called “Reactive Oxygen Species” (ROS) are formed. Also known as “free radicals,” they can damage proteins, including our DNA. When a free radical steals an electron from another molecule it is called oxidation. Oxidized proteins become dysfunctional and cause inflammation. Free radicals contribute to many chronic diseases, including heart disease, cancer, diabetes, cataracts, Alzheimer’s disease, rheumatoid arthritis, premature aging, and more. Free radicals damage mitochondria, which in turn generate more free radicals in a classic vicious cycle. Although ROS generation is a normal part of metabolism and our cells have built-in defenses, if glucose and fructose levels rise too high those defenses are overwhelmed.
Free radicals:
Mitochondrial dysfunction: When our mitochondria get more glucose and fructose dumped on them than they can handle, they become dysfunctional. And since our cells rely on mitochondria to produce their fuel, dysfunctional mitochondria lead to dysfunctional cells; dysfunctional cells lead to dysfunctional organs. Mitochondrial dysfunction contributes to pretty much any chronic disease you can name. Mitochondrial dysfunction in the lining of our arteries can contribute to cardiovascular disease; mitochondrial dysfunction in the brain can contribute to depression, anxiety, bi-polar, and other mental health problems. And so on.
Dysfunctional mitochondrion (Artist’s rendering)
Damage to the lining of our blood vessels: Glucose in our bloodstream damages the protective lining of our blood vessels. This contributes not only to heart disease, but also, by damaging the very small blood vessels in our eyes, kidneys, and nerves it contributes to many of the complications associated with diabetes, such as neuropathy and retinopathy. Vascular damage can also contribute to dementia.
High blood pressure: High levels of insulin can cause the kidneys to hold onto more water, leading to greater blood volume; it can also cause the arterial walls to thicken. Both contribute to high blood pressure. Sugar and starch intake can have a large impact on our blood pressure.
Making us more vulnerable to some cancers: Most cancer cells undergo a mutation that renders them reliant on glucose fermentation to produce their energy (known as the Warburg effect). Those cancer cells require much more glucose than normal cells, and have more insulin receptors than normal cells. High levels of insulin and blood glucose create a hospitable environment for tumor growth. Lewis Cantley, discoverer of an enzyme called “PI3-kinase” and its role in the Warburg effect, is one of the world’s most respected and honored cancer researchers. (PI3-kinase helps cancer cells take in more glucose.) He had this to say about the link between insulin and cancer: “Our preclinical research suggests that if somewhere in your body you have one of these PI3K mutations and you eat a lot of rapid release carbohydrates, every time your insulin goes up, it will drive the growth of a tumor. The evidence really suggests that if you have cancer, the sugar you’re eating may be making it grow faster.’” (“Sugar” here being a reference to blood glucose.) (I am not here suggesting that sugar causes cancer, or that if we have cancer we can starve it out. But it certainly seems to create conditions for it to thrive.)
Dysregulation of our gut bugs: We have 100 trillion microbes living in our gut; some are good guys and some are bad guys. Researchers are beginning the task of figuring out how these microbes affect our health. But one thing is becoming clear: high levels of sugar and starch feed the bad guys, with negative results for our health.
This raises a question: If high levels of blood glucose cause damage, do normal levels of blood glucose do the same? Yes, they do. Nobody has an A1c score of zero, and everyone ages eventually. But our bodies have built-in mechanisms to repair most of that normal level of damage. But if the glucose levels are too high for too long those repair mechanisms fall behind and the damage increases over time.
Consider this analogy. A town has a crew responsible for repairing potholes and other road damage. They are adequately staffed and have the necessary supplies on hand to effect the repairs for the normal and expected amount of damage. But traffic patterns change, and more heavy trucks start coming through town, increasing the damage. The road crew is not staffed to handle it, and they don’t have enough materials to do the repairs. Road damage builds up over time. Think of high loads of fructose, glucose, and insulin as heavy trucks rolling through town.