Sugar and salt are partners in crime, the crime of hypertension. But sugar is a silent partner. Nobody hears about the role of sugar in high blood pressure. Salt gets all the press. But while everyone watches salt, sugar gets away with murder.
When researchers tested a high sugar diet on blood pressure in hypertensive rats, they found that such a diet markedly increased the rats' blood pressure in only two weeks.
Most important, the high blood pressure was reversible with a low-sugar diet. When this study was duplicated with human subjects, the results were the same.
Sugar and insulin - How it works
How does sugar cause blood pressure to rise? By its effect on insulin. Shortly after being eaten, most simple sugars are quickly broken down into glucose, which is then released into the bloodstream.
The sudden escalation in blood glucose is followed by an immediate rise in serum insulin. This is why insulin is known as a sugar hormone. It is well known for its ability to regulate blood sugar levels and for its role in diabetes. What is not so well known is that insulin is also a potent sodium-retaining hormone. In the 1970s it was conclusively demonstrated that elevation of blood insulin results in increased re-absorption of sodium by the kidneys, causing retention of sodium in the body.
This produces the same effect as too much sodium in the diet. Since sodium always holds water, the kidneys retain fluid along with the sodium, thus increasing blood volume and raising blood pressure.
This is not the only way that sugar, via insulin, raises blood pressure. Normal blood pressure is created by the heart pumping blood into the large arteries. The large arteries branch out into more than 100,000 very tiny arteries, or arterioles, which bring the blood to the organs, tissues and cells.
Because of their small size (less than one-hundredth of an inch in diameter), these arterioles produce a resistance to the flow of blood out of the large arteries. Thus, normal blood pressure is due to the heart pushing blood against the resistance of the arterioles.
Tiny smooth muscle cells line the walls of the arterioles. Excess insulin increases the number of these smooth muscle cells, thickening the arterioles and narrowing the opening through which the blood flows. This narrowing increases resistance, thus increasing blood pressure beyond normal levels.
Besides stimulating the growth of the smooth muscles that constricts arteries, excess insulin also increases the production of serum triglycerides, decreases the levels of HDL, the "good" cholesterol, and promotes increased levels of total cholesterol and LDL, the "bad" cholesterol.
It promotes an increase in cholesterol deposits in the arteries, thus further narrowing the opening and increasing blood pressure. People with hypertension have elevated levels of insulin, elevated triglycerides, elevated LDL and decreased HDL cholesterol.
Diabetes, obesity and high blood pressure
Further evidence in support of the role of sugar in hypertension is the fact that type 2 diabetics are very prone to hypertension. They have both a high level of sugar in the blood and also a high level of insulin.
They produce insulin, but their cells are resistant to the hormone. Therefore, insulin is not able to do its job of depositing glucose into the cells. Insulin remains elevated in the blood along with glucose. Diabetics, therefore, are subject to all the effects of excess insulin described above.
Being obese greatly increases the chances for developing hypertension. In all populations that have been studied, overweight people have an increased likelihood of high blood pressure. Obesity also results in increased levels of insulin.
In obesity there is a decreased ability of muscle and fat cells to respond to insulin. A particularly telling study has shown that in people on low calorie reducing diets with lots of simple sugar, blood pressure did not drop; whereas people whose diet had the same number of calories but very little sugar did obtain a reduction in blood pressure.
How can we use this knowledge to keep from getting high blood pressure or to lower pressure that is already elevated?
The answer is simple, though not necessarily easy. If you ate totally unprocessed foods, eliminating sugar in all its forms, ate ample fruits and vegetables, and used salt sparingly, preferably unprocessed sea salt, you would probably see a drop in your blood pressure.
Next week I will detail what such an eating plan would consist of. The information for this article was obtained from an excellent book on the subject, The Blood Pressure Solution: A Scientifically Proven Program for Preventing Strokes and Heart Disease, by Richard D. Moore, M.D., Ph.D.
Mary Lou Williams, M. DE., is a lecturer and writer in the field of nutrition. She welcomes inquiries. She can be reached at 267-6480.