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Blood pressure is simply the pressure of your blood against the walls of your blood vessels (arteries) as it is pumped around your body by your heart. As your heart pumps and relaxes, your blood pressure rises and falls in a regular wave like pattern, so blood pressure peaks when your heart pumps (systolic blood pressure) and falls when your heart relaxes (diastolic blood pressure). Ideally, blood pressure should be less than 120 / 80 mm Hg (millimetres of mercury). High blood pressure (greater than 140 / 90 mm Hg) is a risk factor for having a heart attack or stroke, so ask your doctor to monitor it regularly, or consider buying your own home blood pressure monitor if your doctor advises you too.

Lifestyle factors that help lower blood pressure

As discussed in this Month’s edition of GI News, key dietary factors that influence blood pressure include your salt or sodium, potassium, and calcium intake, and eating too many kilojoules, leading to unwanted weight gain (i.e., excess body fat). Regular physical activity can help reduce your blood pressure.

Low GI and GL diets and blood pressure

In this Month’s Diabetes Care, we discussed research linking high GI diets to raised blood pressure in people with diabetes. There is similarly high-quality evidence that low GI diets lower blood pressure in people without diabetes.

A recent systematic review and metanalysis of randomised controlled trials (14 in total) included 1097 overweight or obese people living in Europe, North America and Australasia. Estimates of GI and GL ranged from an average GI of 40–54 for the lower-GI groups to 53–86 for the higher-GI groups and an average GL of 50 g/1000 Calories (4,200 kilojoules) for lower GL groups compared with 75–120 g/1000 Calories (4,200 kJ) for the higher GL groups. An average reduction in GI of 10 units reduced Systolic Blood Pressure (SBP) by 1.1 mm Hg and Diastolic Blood Pressure (DBP) by 1.3 mm Hg, independent of weight loss. Similarly, a reduction in GL of 28 units reduced SBP by 2.0 mm Hg and DBP 1.4 mm Hg, independent of weight loss.

Therefore, the quality and quantity of carbohydrate in your diet also effects blood pressure in healthy but overweight people.

Read more:

  1. Barclay. Reversing Diabetes. Murdoch Books. 2016
  2. Evans and colleagues. Glycemic index, glycemic load, and blood pressure: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr. 2017
Dr Alan Barclay, PhD, is a consultant dietitian and chef with a particular interest in carbohydrates and diabetes. He is author of Reversing Diabetes (Murdoch Books), and co-author of 40 scientific publications, The Good Carbs Cookbook (Murdoch Books), Managing Type 2 Diabetes (Hachette Australia) and The Ultimate Guide to Sugars and Sweeteners (The Experiment Publishing).
Contact: Follow him on Twitter, LinkedIn or check out his website.