High blood pressure: 7 lifestyle changes with the numbers to back them

High blood pressure is the quiet one. It has no symptoms most of the time, and in South Africa about 1 in 3 adults has it, with roughly half of them unaware, according to the Heart and Stroke Foundation SA. The good news is that it is 1 of the few health numbers that lifestyle moves quickly and measurably. This guide covers what the big trials actually found, in mm Hg, so you can see which changes are worth your effort, and where medicine still has to do the job.

First, know your number

A blood pressure reading has 2 numbers: systolic (the top, the pressure when your heart beats) and diastolic (the bottom, between beats). Under 120/80 is normal. 140/90 or higher, on more than 1 occasion, is high blood pressure. The band in between is where lifestyle changes pay off most.

A home monitor with an upper-arm cuff costs a few hundred rand at any pharmacy and is more useful than an occasional reading at the doctor. Sit quietly for 5 minutes, feet flat, arm supported at heart height, and take 2 readings a minute apart, morning and evening, for a week. Give your doctor the average, not 1 nervous reading.

What the trials found, change by change

1. Eat the DASH way: about 5 to 11 mm Hg. The DASH trial fed 459 adults a diet rich in vegetables, fruit and low-fat dairy, with less saturated fat, for 8 weeks, keeping salt and body weight the same. Systolic pressure fell 5.5 mm Hg more than the control diet; in the people who started with high blood pressure, 11.4 mm Hg. That is the size of effect you get from a first blood-pressure tablet, and it came from food alone.

2. Cut salt: another 2 to 7 mm Hg, more if your diet is poor. The follow-up DASH-Sodium trial (412 adults) tested 3 salt levels on both diets. Going from high to low salt cut systolic pressure by 6.7 mm Hg on an ordinary diet and 3 mm Hg on the DASH diet. Combined, low salt plus DASH was 11.5 mm Hg lower than high salt plus an ordinary diet in people with hypertension. Most of the salt South Africans eat is already in bread, processed meat, stock cubes, sauces and takeaways, not the shaker, so reading labels matters more than not salting your eggs.

3. Eat more potassium: about 3.5 mm Hg, and fewer strokes. A 2013 BMJ meta-analysis of 22 trials found higher potassium intake cut systolic pressure by 3.5 mm Hg in people with high blood pressure (no effect in people with normal pressure), with no harm to kidney function in healthy adults. The cohort data also showed 24% fewer strokes. Potassium comes from vegetables, fruit, beans, potatoes, dairy and fish. 1 caution: if you have kidney disease or take certain blood-pressure medicines (ACE inhibitors, spironolactone), ask your doctor before adding potassium, including salt substitutes.

4. Swap your salt: proven to prevent strokes. The 2021 Salt Substitute and Stroke Study followed 20,995 older Chinese adults for nearly 5 years. Those who swapped ordinary salt for a 75% sodium / 25% potassium blend had 14% fewer strokes, 13% fewer major heart events and 12% fewer deaths, with no rise in serious high-potassium events. Potassium-enriched salt is sold in SA supermarkets. Same kidney caution as above.

5. Lose weight if you carry extra: about 1 mm Hg per kilogram. A meta-analysis of 25 trials (4,874 people) found an average 5.1 kg loss lowered systolic pressure 4.4 mm Hg and diastolic 3.6 mm Hg; people who lost more than 5 kg gained more. You do not need to reach a "goal weight" to see the benefit, each kilogram counts.

6. Move: 3.5 mm Hg from cardio, and up to 8 mm Hg if you already have hypertension. A review of 93 trials (5,223 people) found endurance exercise cut systolic pressure 3.5 mm Hg overall and 8.3 mm Hg in people with high blood pressure. Resistance training helped too. The surprise was isometric exercise (holding a squeeze or a wall-sit), which showed the largest drop, 10.9 mm Hg, though from only 5 small studies, so treat it as promising rather than proven. The practical version: 30 minutes of brisk walking most days.

7. Drink less, if you drink more than 2 a day: up to 5.5 mm Hg. A 2017 meta-analysis of 36 trials found that cutting back made no difference for people on 2 or fewer drinks a day, but for those on 6 or more, halving intake dropped systolic pressure 5.5 mm Hg. Alcohol is also a common reason blood-pressure tablets seem not to work.

Add them up. These effects stack. DASH eating, lower salt, a few kilograms and a daily walk together can move a borderline reading back into the normal range, and lower the dose someone with hypertension needs. That is the realistic promise: a smaller dose and a lower risk, not always no tablets.

What doesn't have good evidence

• Collagen, bicarbonate of soda, silica and most supplements. None of our products lowers blood pressure, and we won't tell you otherwise. Bicarb is a sodium salt: a teaspoon carries about 1,200 mg of sodium, so if your pressure is high, keep bicarb to the occasional ¼ teaspoon or skip it.
• Garlic, hibiscus, beetroot juice. Small trials show small, short-lived drops. Fine as food; not a treatment.
• Stress reduction. It helps you feel better and sleep better, and poor sleep does raise pressure, but the trial evidence that relaxation techniques lower blood pressure on their own is weak and inconsistent.
• "Natural" in place of prescribed medicine. Stopping blood-pressure tablets because your diet improved is a decision for your doctor, made on your home readings, not a decision to make alone.

Women over 40: 2 things worth knowing

Blood pressure often rises after menopause, as oestrogen falls, and it is easy to miss because it is silent. Check it yearly from 40, and after any new medicine. Second, if you had high blood pressure or pre-eclampsia during a pregnancy, your lifetime risk of hypertension and heart disease is higher; tell your doctor, and check more often.

Frequently asked questions

How quickly do lifestyle changes lower blood pressure?
The DASH trials saw most of the drop within 2 weeks of changing diet. Exercise and weight-loss effects build over 1 to 3 months.

Can I stop my tablets if my readings come down?
Sometimes, yes, but only with your doctor, using a week of home readings. Stopping suddenly can cause a rebound.

Is coffee bad for blood pressure?
A cup raises it for an hour or 2. In habitual drinkers the long-term effect is small. If you are checking your pressure, do it before coffee.

Does bicarbonate of soda raise blood pressure?
It is sodium, so regular use can. People with high blood pressure, heart or kidney disease should avoid it or keep it to the occasional ¼ teaspoon for indigestion.

What's the single most useful change?
For most people, eating more vegetables, fruit and beans while cutting processed food does both the DASH and the salt job at once. If you drink more than 2 a day, cutting back is the quickest win.

The sources

• Appel LJ et al. (1997). A clinical trial of the effects of dietary patterns on blood pressure (DASH). New England Journal of Medicine 336:1117–1124. View →
• Sacks FM et al. (2001). Effects on blood pressure of reduced dietary sodium and the DASH diet (DASH-Sodium). New England Journal of Medicine 344:3–10. View →
• Aburto NJ et al. (2013). Effect of increased potassium intake on cardiovascular risk factors and disease: systematic review and meta-analyses. BMJ 346:f1378. View →
• Neal B et al. (2021). Effect of salt substitution on cardiovascular events and death. New England Journal of Medicine 385:1067–1077. View →
• Neter JE et al. (2003). Influence of weight reduction on blood pressure: a meta-analysis of randomized controlled trials. Hypertension 42:878–884. View →
• Cornelissen VA, Smart NA (2013). Exercise training for blood pressure: a systematic review and meta-analysis. Journal of the American Heart Association 2:e004473. View →
• Roerecke M et al. (2017). The effect of a reduction in alcohol consumption on blood pressure: a systematic review and meta-analysis. Lancet Public Health 2:e108–e120. View →
• Heart and Stroke Foundation South Africa (2019). Hypertension awareness material. View →

Find out more

• How much sugar is too much? Hidden sugars on South African labels
• How to reduce stress naturally: 5 habits that hold up
• How sleep improves your health, and 7 habits that help
• Bicarbonate of soda: facts, benefits and safe use
• 8 ways women's bodies can change after 40
• Health and ingredient guides

This article is general information, not medical advice. If you take blood-pressure medicine, have kidney disease, or are pregnant, talk to your doctor before changing your diet, salt or potassium intake.

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