In a new study, researchers found high blood sugar in obesity appears to gum up the works of the circadian clocks inside cells that help regulate the timing of many body functions across the 24-hour day and drive the risk of heart disease.
They demonstrated that blood sugar and heart health problems are intrinsically linked to obesity.
The research was conducted by a team from Augusta University.
Circadian clocks set the rhythm of our bodies so that we eat, sleep and wake at the right time.
What is less well recognized is the important role of circadian clocks in anticipating these events and preparing our organs and cells so they function optimally at the right time as well as anticipating when to rest and rejuvenate.
Every cell in the body has a clock in it that is used to anticipate daily needs.
Blood pressure and heart rate drop at nighttime and surge in the morning when your feet hit the ground and blood must fight against gravity.
Sleep is supposed to be a period of rest and recovery for each of our cells just like it is for us overall.
At daybreak, genes active at night should be turned off, and genes important for daily activities should be turned on and our metabolism should switch from a restorative to active phase.
Blood flow adjusts to match these dynamic metabolic needs, and our circadian clocks are sort of intermediaries between metabolism and our cardiovascular system that coordinate changes in metabolism with changes in cardiovascular gene function.
The team has evidence that obesity can break these links between metabolism and cardiovascular regulation.
Excessive food consumption, particularly foods that are high in sugar and carbohydrates, some of which our body also breaks down into glucose, dampens clock function and imperils heart health.
They have documented both high glucose levels and significant circadian dysfunction in a mouse model of hyperphagia.
The found these obese mice have tremendous appetites, high glucose and high blood pressure that does not dip at night when it should, and most importantly, dysfunction of the single layer of endothelial cells that line blood vessels.
Endothelial dysfunction is a major initiator of atherosclerosis, and what many of us think of as heart disease.
Dysfunctional endothelial cells become inflamed, sticky and produce more damaging reactive oxygen species and less nitric oxide, which impairs blood vessel dilation.
The result can be a tortuous passageway for blood, sticky walls where cells pile up and coronary artery disease.
The scientists note that if you have a healthy musculature despite obesity, it mitigates, at least for a time, the impact of high glucose on the vasculature. Muscle is a first and fast user of glucose, quickly pulling it out of the circulation.
Obese mice, like humans, lose muscle mass. In some studies, they preserved muscle mass in obese mice, which also prevented heart damage.
They note that both aging, when muscle naturally loses volume even in individuals who remain active, and spinal cord injuries or other conditions that leave us immobile, have some of the same heart risks like obesity.
The lead author of the study is Dr. David Stepp, a vascular biologist.
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