Main causes of hypertension: insulin resistance
March 2, 2021
Hypertension, or higher than normal blood pressure, is indicated by any reading above 120/80, with the first number referring to the systolic pressure measurement, and the second referring to diastolic pressure measurement, which respectively gauge the heart’s ability to contract and relax. For a detailed explanation of blood pressure, please refer to the article on this page entitled “What is hypertension”.
Systolic contractions are controlled by the sympathetic nervous system, the same one that is in charge of your fight-flight-or-freeze response, whereas diastolic relaxation is controlled by the parasympathetic nervous system, your rest-and-digest mechanism. This is basically because when in a state of perceived danger or stress, the body naturally rushes blood to muscles and extremities in order to confront or escape peril, and does so by increasing heart rate and output, whereas in a state of relaxation or while digesting food, blood flow is needed all around the gut area to properly process and convey nutrients to cells. [For reference, pulse rate at rest should be at 72 in healthy individuals. A higher or lower reading may signal a problem, though heart rate and blood pressure changes do not necessarily go hand in hand].
The number one cause of hypertension is a disorder called hyperinsulinemia, or excessive blood plasma insulin, and more specifically insulin resistance. But what exactly does that mean? When you consume sugar, in its plain form or in any carbohydrate form, your pancreas produces a hormone called insulin, which sweeps the broken down glucose out of the blood and into cells to be used for energy, the energy you need to go through your day, or stored in the liver or muscles for later use. Insulin knocks at the cells’ receptor doors, so to speak, and the doors open to let that glucose in. In the presence of excess insulin, those doors start to shut down and no amount of knocking will help. This is a simple way of explaining insulin resistance, a condition in which tissue receptors become blunt to insulin stimulation, causing circulating blood sugar levels to go up (hyperglycemia) and the pancreas to increase its insulin output in an effort to resolve the situation (compensative hyperinsulinemia). This condition causes hypertension in a couple of interconnected ways: excess glucose causes a shift of fluid from the inside environment of the cells (intracellular) to the outside (extracellular), resulting in plasma volume expansion and blood pressure elevation; the excess insulin causes sodium reabsorption in the kidneys, leading to fluid retention, which of course increases all fluid pressure, blood included; insulin also overstimulates the sympathetic (fight-or-flight) nervous system, also causing a rise in blood pressure. We will look at the roles of sodium and potassium in blood pressure in a separate article.
Chronically, both insulin resistance and hyperglycemia cause vascular damage through several mechanisms, including increased advanced glycation end products (proteins or lipids that become damaged after extended exposure to sugars), oxidative stress, and inflammation, leading to increased arterial stiffness (atherosclerosis) and blood pressure elevation.
The average American consumes about 75 grams, or 6 tablespoons of added sugar per day. Beverages are the most obvious source: soft drinks contribute 25% of that intake, fruit drinks up to 15%. One leading brand of yogurt contains 7 teaspoons (29 grams) of sugar per serving. Most of the added sugar in the SAD, however, is ‘hidden in plain sight’ in processed foods such as ketchup, salad dressings, sliced bread, pasta sauce, frozen dinners and cereals, under several chemical names, which makes them hard to recognize at a cursory glance of the label. To make bad worse, the presence of fructose in the majority of these foods as a sweetener, often as High Fructose Corn Syrup, slyly renamed as isoglucose, natural corn syrup, maize syrup and glucose syrup, makes these foods inherently dangerous to human health. Fructose is not metabolized by the body the same way as glucose, and it is linked to Insulin resistance, leptin resistance (leptin is a hormone that regulates energy intake and appetite), and dyslipidemia.
Insulin resistance and hypertension are associated with an unhealthy lifestyle and a systemic low grade inflammation, the blight of the Western diet and way of life. Along with increasing exercise and NEAT activities, a targeted nutrition plan can be positively impactful in the management of insulin resistance. A combination of time-restricted feeding, or intermittent fasting, and low-carb feeding regime, can almost always, and fairly quickly, lead to increased insulin sensitivity while balancing hormones, reducing weight, decreasing inflammation and oxidation from the by-product of high sugar metabolites. The intermittent fasting approach is particularly valid, in that it also triggers a process called autophagy, in which the body gets rid of old and no longer metabolically sound cells and is able to progressively restore functionality of biological chemical processes.
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References:
https://pubmed.ncbi.nlm.nih.gov/7898093/
https://pubmed.ncbi.nlm.nih.gov/15504934/
https://www.ahajournals.org/doi/full/10.1161/01.HYP.30.5.1144
https://dmsjournal.biomedcentral.com/articles/10.1186/1758-5996-6-12