Primitive societies exposed to very little salt suffer from little or no hypertension. Salt (sodium chloride) intake has also been definitively linked to hypertension in western societies. Reducing salt intake in the diet lowers blood pressure in most people. The more salt is restricted, the greater the blood pressure-lowering effect. Individual studies sometimes come to differing conclusions about the relationship between salt intake and blood pressure, in part because blood pressure-lowering effects of salt restriction vary from person to person, and small to moderate reductions in salt intake often have minimal effects on blood pressure—particularly in young people and in those who do not have hypertension. Nonetheless, dramatic reductions in salt intake are generally effective for many people with hypertension.
With the prevalence of salted processed and restaurant food, simply avoiding the salt shaker no longer leads to large decreases in salt intake for most people. Totally eliminating salt is more effective, but is quite difficult to achieve. Moreover, while an overview of the research found “There is no evidence that sodium reduction presents any safety hazards,” reports of short-term paradoxical increases in blood pressure in response to salt restriction have occasionally appeared. Therefore, people wishing to use salt reduction to lower their blood pressure should consult with a doctor.
Vegetarians have lower blood pressure than do people who eat meat. This occurs partly because fruits and vegetables contain potassium—a known blood pressure-lowering mineral. The best way to supplement potassium is with fruit, which contains more of the mineral than do potassium supplements. However, fruit contains so much potassium that people taking “potassium-sparing”diuretics can consume too much potassium simply by eating several pieces of fruit per day. Therefore, people taking potassium-sparing diuretics should consult the prescribing doctor before increasing fruit intake. In the Dietary Approaches to Stop Hypertension (DASH) trial, increasing intake of fruits and vegetables (and therefore fiber) and reducing cholesterol and dairy fat led to large reductions in blood pressure (in medical terms, 11.4 systolic and 5.5 diastolic) in just eight weeks. Even though it did not employ a vegetarian diet itself, the outcome of the DASH trial supports the usefulness of vegetarian diets because diets employed by DASH researchers were related to what many vegetarians eat. The DASH trial also showed that blood pressure can be significantly reduced in hypertensive people (most dramatically in African Americans) with diet alone, without weight loss or even restriction of salt. Nonetheless, restricting salt while consuming the DASH diet has lowered blood pressure even more effectively than the use of the DASH diet alone.
Sugar has been reported to increase blood pressure in animals and humans in short-term trials. Though the real importance of this experimental effect remains unclear, some doctors recommend that people with high blood pressure cut back on their intake of sugar.
Right after consuming caffeine from coffee or tea, blood pressure increases briefly. In trials lasting almost two months on average, coffee drinking has led to small increases in blood pressure. The effects of long-term avoidance of caffeine (from coffee, tea, chocolate, cola drinks, and some medications) on blood pressure remain unclear. A few reports have even claimed that long-term coffee drinkers tend to have lower blood pressure than those who avoid coffee. Despite the lack of clarity in published research, many doctors tell people with high blood pressure to avoid consumption of caffeine.
Several double-blind trials have shown that adding 6.5–7 grams of fiber per day to the diet for several months leads to reductions in blood pressure. However, other trials have not found fiber helpful in reducing blood pressure. The reason for these discrepant findings is not clear.
Food allergy was reported to contribute to high blood pressure in a study of people who had migraine headaches. In that report, all 15 people who also had high blood pressure experienced a significant drop in blood pressure when put on a hypoallergenic diet. People who suffer migraine headaches and have hypertension should discuss the issue of allergy diagnosis and elimination with a doctor.
Reusing vegetable oils for frying, especially oils with high concentrations of unsaturated fatty acids (such as sunflower or safflower oil) has been associated with an increased risk of high blood pressure. Presumably, this increased risk is due to some of the degradation products (such as lipid peroxides or polymers) that result from the excessive heating of these oils. Frying with more stable oils, such as olive oil, is not associated with an increased risk of high blood pressure.
Exposure to lead and other heavy metals has been linked to high blood pressure in some, but not all, research. If other approaches to high blood pressure prove unsuccessful, it makes sense for people with hypertension to have their body’s burden of lead evaluated by a healthcare professional.
In a double-blind trial, supplementation with a tomato extract significantly lowered both systolic and diastolic blood pressure, compared with a placebo, in people with hypertension. The amount of extract used was 250 mg per day (providing 15 mg per day of lycopene plus other carotenoids) for eight weeks.
Lifestyle changes that may be helpful:
Smoking is particularly injurious for people with hypertension. The combination of hypertension and smoking greatly increases the risk of heart disease–related sickness and death. All people with high blood pressure need to quit smoking.
Consumption of more than about three alcoholic beverages per day appears to increase blood pressure. Whether one or two drinks per day meaningfully increases blood pressure remains unclear.
Daily exercise can lower blood pressure significantly. A 12-week program of Chinese T’ai Chi was reported to be almost as effective as aerobic exercise in lowering blood pressure. Progressive resistance exercise (e.g., weight lifting) also appears to help reduce blood pressure. At the same time, blood pressure has been known to increase significantly during the act of lifting heavy weights; for this reason, people with sharply elevated blood pressure, especially those with cardiovascular disease, should approach heavy strenuous resistance exercise with caution. In general, people over 40 years of age should consult with their doctors before starting any exercise regimen.
Most people with high blood pressure are overweight. Weight loss lowers blood pressure significantly in those who are both overweight and hypertensive. In fact, reducing body weight by as little as ten pounds can lead to a significant reduction in blood pressure. Weight loss appears to have a stronger blood pressure-lowering effect than dietary salt restriction.
Eric R. Braverman, M.D.
Dr. Braverman is a Summa Cum Laude and Phi Beta Kappa graduate of Brandeis University and NYU Medical School, did brain research at Harvard Medical School, and trained at an affiliate of Yale Medical School. He is acknowledged worldwide as an expert in brain-based diagnosis and treatment, and he lectures to and trains doctors in anti-aging medicine.