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On this World Health Day, you will be seeing a lot about high blood pressure. You can read about how hypertension is pervasive around the world, and 90% of the residents of industrialized countries will be diagnosed with high blood pressure at some time in their lives. You can read about how high blood pressure raises the risk of heart attack and stroke, and how it can be controlled by the DASH diet.
But what you won't read about anywhere else is how high blood pressure, kidney disease, and obesity are tied together, and how relieving one treats the others.
The Deadly Trio of Hypertension, Obesity, and Renal Disease
Probably in your everday life you have noticed that not everyone who has high blood pressure is overweight, and not everyone who is overweight has high blood pressure. Just about everyone who has kidney disease, however, has high blood pressure, and a significant percentage of people who have high blood pressure will eventually develop kidney disease if they do not succumb to heart attack or stroke first.
The progressive worsening of kidney disease and hypertension, however, turns out to be dependent on hormones that are, or aren't, produced by fat cells.
High blood pressure worsens kidney damage and kidney damage worsens high blood pressure. The fat cells, however, enter the process by releasing too much of a hormone called leptin or too little of a hormone called adiponectin.
Too Much Protein Is as Big a Problem as Too Much Fat
When fat cells produce more leptin, the kidneys work harder to filter the bloodstream of the byproducts of "leftover" amino acids, urea and sugar. We often think of protein as a free food, but the reality is that our bodies have to break down protein into amino acids, and then reassemble the amino acids in a precise order to make the human proteins. (The protein from a steak or cereal or milk or soy won't "fit" in human tissue.)
If there is too much protein in the diet, the liver uses it to make sugar, with urea as a byproduct. Urea is toxic, so the kidneys have to filter it out. When fat cells release too much of a hormone called leptin, however, the kidneys strain to filter out protein, too. They release other hormones that force more blood through their glomerular filturation apparatus, by raising blood pressure. This is the underlying process that causes what is widely known as "essential" or "idiopathic" high blood pressure, which was not very well understood by science until very recently.