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].
2. Keil U, Liese A, Filipiak B, et al. Alcohol, blood pressure and hypertension. Novartis Round Symp 1998;216:125–44 [review].
3. Campbell NR, Ashley MJ, Carruthers SG, et al. Lifestyle modifications to prevent and control hypertension. 3. Recommendations on alcohol consumption. CMAJ 1999;160(9 Suppl):S13–20.
4. Rachima-Maoz C, Peleg E, Rosenthal T. The effect of caffeine on ambulatory blood pressure in hypertensive patients. Am J Hypertens 1998;11:1426–32.
5. Jee SH, He J, Whelton PK, et al. The effect of chronic coffee drinking on blood pressure. A meta-analysis of controlled clinical trials. Hypertension 1999;33:647–52.
6. Hodgson JM, Buddey IB, Burke V, et al. Effects on blood pressure of drinking green and black tea. J Hypertens 1999;17:457–63.
7. Wakabayashi K, Kono S, Shinchi K, et al. Habitual coffee consumption and blood pressure: a study of self-defense officials in Japan. Eur J Epidemiol 1998;14:669–73.
8. Salvaggio A, Periti M, Miano L, et al. Association between habitual coffee consumption and blood pressure levels. J Hypertens 1990;8:585–90.
9. Cappuccio FP, Elliott P, Allender PS, et al. Epidemiologic association between dietary calcium intake and blood pressure: a meta-analysis of published data. Am J Epidemiol 1995;142:935–45.
10. Gavras I, Manolis A, Gavras H. Genetic epidemiology of essential hypertension. Hypertens 1999;13:225–9 [review].
11. Ward R. Familial aggregation and genetic epidemiology of blood pressure. In Hypertension: Pathophysiology, Diagnosis, and Management. Laragh JH, Brenner BM (eds.), New York, NY: Raven Press; 1990:81–100 [review].
12. Alberti KG. Impaired glucose tolerance: what are the clinical implications? Diabetes Res Clin Pract 1998;40:S3–8 [review].
13. Corry DB, Tuck ML. Glucose and insulin metabolism in hypertension. Am J Nephrol 1996;16:223–6 [review].
14. Ferrannini E, Santoro D, Manicardi V. The association of essential hypertension and diabetes. Compr Ther 1989;15:51–8 [review].
15. Mizushima S, Cappuccio FP, Nichols R, et al. Dietary magnesium intake and blood pressure: a qualitative overview of the observational studies. J Hum Hypertens 1998;12:447–53.
16. Sacks FM, Appel LJ, Moore TJ, et al. A dietary approach to prevent hypertension: a review of the Dietary Approaches to Stop Hypertension (DASH) Study. Clin Cardiol 1999;22(7 Suppl):III6–10 [review].
17. Shaper AG. Obesity and cardiovascular disease. Ciba Found Symp 1996;201:90–103[review].
18. Pouliot MC, Després JP, Lemieux S, et al. Waist circumference and abdominal sagittal diameter: best simple anthropometric indexes of abdominal visceral adipose tissue accumulation and related cardiovascular risk in men and women. Am J Cardiol 1994;73:460–8.
19. Stevens VJ, Corrigan SA, Obarzanek E, et al. Weight loss intervention in phase 1 of the Trials of Hypertension Prevention. The TOHP Collaborative Research Group. Arch Intern Med 1993;153:849–58.
20. The Trials of Hypertension Prevention Collaborative Research Group. Effects of weight loss and sodium reduction intervention on blood pressure and hypertension incidence in overweight people with high-normal blood pressure. The Trials of Hypertension Prevention, phase II. Arch Intern Med 1997;157:657–67.
21. Stamler J, Caggiula AW, Grandits GA. Relation of body mass and alcohol, nutrient, fiber, and caffeine intakes to blood pressure in the special intervention and usual care groups in the Multiple Risk Factor Intervention Trial. Am J Clin Nutr 1997;65:338S–65S.
22. Whelton PK, He J, Cutler JA, et al. Effects of oral potassium on blood pressure: meta-analysis of randomized controlled clinical trials. JAMA 1997;277:1624–32.
23. Burgess E, Lewanczuk R, Bolli P, et al. Lifestyle modifications to prevent and control hypertension. 6. Recommendations on potassium, magnesium and calcium. CMAJ 1999;160(9 Suppl):S35–45.
24. Page LB, Damon A, Moellering RC Jr. Antecedents of cardiovascular disease in six Solomon Islands Societies. Circulation 1974;44:1132–46.
25. Stamler J. The INTERSALT Study: background, methods, findings, and implications. Am J Clin Nutr 1997;65:626S–42S [review].
26. MacGregor GA, et al. Double-blind study of three sodium intakes and long-term effects of sodium restriction in essential hypertension. Lancet 1989;ii:1244–7.
27. Weinberger MH. Salt sensitivity of blood pressure in humans. Hypertension 1996;27:481–90.
28. The Trials of Hypertension Prevention Collaborative Research Group. Effects of weight loss and sodium reduction intervention on blood pressure and hypertension incidence in overweight people with high-normal blood pressure. The Trials of Hypertension Prevention, phase II. Arch Intern Med 1997;157:657–67.
29. Blair SN, Goodyear NN, Gibbons LW, et al. Physical fitness and incidence of hypertension in healthy normotensive men and women. JAMA 1984;252:487–90.
30. American College of Sports Medicine Position Stand. Exercise and physical activity for older adults. Med Sci Sports Exerc 1998;30:992–1008 [review].
31. Kelley G, Tran ZV. Aerobic exercise and normotensive adults: a meta-analysis. Med Sci Sports Exerc 1995;27:1371–7.
32. Markovitz JH, Matthews KA, Kannel WB, et al. Psychological predictors of hypertension in the Framingham Study. JAMA 1993;270:2439–43.
33. Markovitz JH, Matthews KA, Wing RR, et al. Psychological, biological and health behavior predictors of blood pressure changes in middle-aged women. J Hypertens 1991;9:399–406.
34. Schnall PL, Schwartz JE, Landsbergis PA, et al. Relation between job strain, alcohol, and ambulatory blood pressure. Hypertension 1992;19:488–94.
35. Matthews KA, Cottington EM, Talbott E, et al. Stressful work conditions and diastolic blood pressure among blue collar factory workers. Am J Epidemiol 1987;126:280–91.
36. Perini C, Müller FB, Bühler FR. Suppressed aggression accelerates early development of essential hypertension. J Hypertension 1991;9:499–503.
37. Beilin LJ, Burke V. Vegetarian diet components, protein and blood pressure: which nutrients are important? Clin Exp Pharmacol Physiol 1995;22:195–8.
38. Sacks FM, Appel LJ, Moore TJ, et al. A dietary approach to prevent hypertension: a review of the Dietary Approaches to Stop Hypertension (DASH) Study. Clin Cardiol 1999;22(7 Suppl):III6–10 [review].