According to the American Heart Association, primary hypertension, or high blood pressure, is the most common form of hypertension, affecting 74 million adults in the U.S. Hypertension is typically defined as a systolic blood pressure, or top reading, higher than 140 mm Hg or a diastolic blood pressure, or bottom reading, higher than 90 mm Hg. Because primary hypertension is likely to be hereditary, it tends to return unless continuously treated. A more rare form of hypertension is secondary hypertension, which is hypertension that is secondary to, or comes from, an abnormal condition in the body's organs or systems.
Genetic Factors
According to the American Heart Association, 25 percent adults suffer from chronic hypertension. Researchers believe chronic hypertension is hereditary, but they have not yet found the genes responsible for the disorder. One reason for this may be that the genetic factors responsible for hypertension are highly complex, reports an international research team in April 2010 in the journal "Genome Research." The team sequenced the genome of the animal model spontaneously hypertensive rat strain, or SHR, and found 788 mutations on the genome compared to the control rat strain. Many of the mutations were on genes that express proteins involved in cellular, neurological and immunological processes.
Chronic Stress
Chronic stress is a contributing factor to recurrent hypertension. Chronic stress includes not only stress that comes from pressure at work or at home but also stress triggered by lifestyle factors such as sleep habits, reports a research team in the April 2009 issue of "Sleep." The researchers found that people who sleep less than five hours a night on average are 500 times more likely to develop hypertension compared to normal sleepers. A chronic short-sleep duration leads to hyper-secretion of the stress hormone cortisol, which is a well-known trigger of high blood pressure, the researchers note.
Dietary Factors
Dietary factors can trigger recurrent high blood pressure in people prone to primary hypertension. Among the dietary factors that most frequently trigger recurrent hypertension are high intakes of low-density lipoprotein, or bad, cholesterol; alcohol; salt; and high fructose corn syrup. Certain foods may also lower blood pressure. These include foods high in high-density lipoprotein, or good, cholesterol and fiber, including fruits, vegetables, legumes and whole grain products. However, there is not always a direct correlation between high cholesterol foods and high blood pressure. While egg yolks contain high concentrations of cholesterol, they also seem to contain chemicals that lower blood pressure, reports a Canadian research team in the January 2009 issue of "Journal of Agricultural and Food Chemistry." In a series of laboratory studies, the team found chemicals in fried and boiled eggs that, in principle, can turn into peptides with blood pressure-lowering activity in the stomach and small intestine. The findings are still to be tested directly on humans.
Exercise
Researchers believe that exercise has a blood-pressure and cholesterol-lowering effect. However, extreme exercise can induce high blood pressure, according to a study published in the March 2007 issue of "The American Journal of Cardiology." The researchers stumbled on this finding when a middle-aged physician and marathon runner, who was not predisposed to heart disease, failed a heart test measuring calcium plaques in the heart. The researchers speculate that extreme exercise can have the same effect on hypertension as other forms of chronic stress.
References
- American Heart Association: High Blood Pressure Statistics
- "Genome Research"; The Genome Sequence of the Spontaneously Hypertensive Rat: Analysis and Functional Significance; S.S. Atanur et al.; April 2010
- PubMed Central: "Sleep"; Insomnia With Objective Short Sleep Duration Is Associated With a High Risk for Hypertension; Alexandros N. Vgontzas, M.D.,et al.; April 2009
- "Journal of Agricultural and Food Chemistry"; Angiotensin I Converting Enzyme Inhibitory Peptides From Simulated in Vitro Gastrointestinal Digestion of Cooked Eggs; Kaustav Majumder and Jianping Wu; January 2009
- "American Journal of Cardiology"; Exercise-Induced Hypertension, Endothelial Dysfunction and Coronary Artery Disease in a Marathon Runner; Radha Goel et al.; January 2007
