Risk Factors for Hypertension
Hypertension is the medical term for high blood pressure. Approximately 90% of people with high blood pressure have "essential" or "idiopathic" hypertension, the cause of which is poorly understood. As used here, the terms "hypertension" and "high blood pressure" refer only to this most common form and not to high blood pressure either associated with pregnancy or clearly linked to known causes such as Cushing's syndrome, pheochromocytoma, or kidney disease.
AgeMany people develop hypertension late in life, though much of the relationship between age and blood pressure is due to cumulative effects of dietary and lifestyle habits.1 Preventive dietary and lifestyle factors are discussed elsewhere in this section.
Alcohol (High Intake)Many studies have found a relationship between alcohol consumption and blood pressure. A recent review of the research reported that beyond approximately three drinks per day, blood pressure increases in proportion to the amount of alcohol consumed.2 The effects of having one or two drinks per day on blood pressure remains less clear.3
CaffeineShortly after consuming caffeine, blood pressure increases.4 In an analysis of eleven trials lasting almost two months on average, coffee drinking led to increased blood pressure, though these increases were mostly small or moderate.5 Drinking caffeine-containing tea has been reported to raise blood pressure immediately after consumption, though blood-pressure-raising effects were not seen over longer (24 hour) periods.6
Despite reports suggesting short-term blood-pressure-raising effects resulting from caffeine ingestion, a few studies have claimed that long-term coffee drinkers have lower blood pressure than those who avoid coffee.7, 8 The consequences of long-term caffeine avoidance on blood pressure remain unclear. Significant amounts of caffeine are found in regular coffee, black and green tea, chocolate, some soft drinks, and some medications.
CalciumThough dietary calcium may help protect against high blood pressure, only small differences in blood pressure can be accounted for by calcium intake.9 Dairy products (preferably non-fat), sardines, canned salmon, dark green leafy vegetables, and legumes contain significant amounts of calcium.
GeneticsHypertension occurs more frequently in people with a family history of high blood pressure.10 However, genetic susceptibility may not be enough to cause hypertension unless dietary and lifestyle risk factors are also present.11
Glucose IntoleranceGlucose intolerance refers to the inability of the body to maintain normal blood glucose levels. Severe glucose intolerance results in diabetes mellitus. Milder impairment of glucose tolerance increases the risk of other diseases.12 People who have diabetes or impaired glucose tolerance are at increased risk for hypertension,13 and this association is not completely explained by other risk factors shared by these conditions, like obesity and advanced age.14 (See Diabetes in Profiler for prevention, and Diabetes in Healthnotes Online for treatment.)
MagnesiumEvidence that dietary magnesium protects against high blood pressure has been inconsistent.15 Diets high in magnesium are usually rich in fruits, vegetables and other plant products, which have other beneficial effects on blood pressure (see Vegetarian diet).16
ObesityPeople who are overweight are at increased risk of hypertension.17 In particular, "male-pattern" obesity characterized by excess abdominal fat (as opposed to fat accumulation in the thighs and buttocks) appears most directly associated with an increased risk of hypertension.18 Weight-loss in overweight people with high-normal blood pressure has been shown to be an effective way to prevent future increases in blood pressure.19,20
PotassiumLow potassium intake from the diet is associated with increased blood pressure.21 Conversely, high intake of dietary potassium may protect against developing hypertension,22 though not all studies have found this relationship.23 Bananas, avocados, other fruits and vegetables, soybeans, and potatoes are high in potassium. People who are taking potassium-sparing diuretic prescription drugs must not increase dietary potassium intake without first consulting their prescribing physician.
Salt (High Intake)People in primitive societies that consume very little salt suffer from little or no hypertension.24 High salt intake has also been associated with hypertension in western societies.25 Drastically reducing salt from the diet lowers blood pressure in most people,26 though some people will respond to more modest reductions in salt intake.27 A recent controlled study found that a low-salt diet prevented hypertension in people with high-normal blood pressure.28 In addition to avoiding the use of salt at the table, people attempting to reduce their salt intake should reduce intake of processed and restaurant foods containing added salt.
Sedentary LifestyleSedentary people have a 20-50% increased risk of hypertension compared to more active people.29 Regular exercise reduces the risk for many diseases, including hypertension,30 and has been reported to lower blood pressure even in people who have normal blood pressure.31 People who are over the age of 40 or who have a history of heart disease should consult a healthcare professional before beginning an exercise regime.
StressCertain types of psychological stress appear to increase the risk of hypertension. In one study, a high level of anxiety increased hypertension risk in middle-aged men, but not in women or older men.32 In another trial, however, the same workers did find such a link in women.33 Other research has found significant increases in blood pressure linked to job-related stress or dissatisfaction with one's job.34,35 People who suppress feelings of aggression appear to have greater increases in blood pressure over time compared with those who do not suppress such feelings.36 Whether stress reduction training or psychological intervention would help protect against hypertension remains unknown.
Vegetarian DietPeople who eat vegetarian diets typically have lower blood pressure compared to people who eat a standard American diet; this is probably due to multiple components of the vegetarian diet, including low saturated fat, and high fiber, potassium, and magnesium intakes.37 The Dietary Approaches to Stop Hypertension (DASH) diet, which emphasizes fruits, vegetables, low-fat dairy products, nuts, and a low saturated fat and cholesterol intake, has successfully treated people with hypertension, despite inclusion of fish and chicken.38
1. Stamler J. Blood pressure and high blood pressure. Aspects of risk. Hypertension 1991;18(3 Suppl):I95-107 [review].