Author: Doug Cook, RD MHSc CDE
Referred to as the silent killer because you can’t tell if you have high blood pressure by how you feel, high blood pressure remains the number one risk factor for stroke and a major risk factor for heart disease according to the Heart & Stroke Foundation of Canada. Blood pressure refers to the force of blood against the walls of your blood vessels as blood is pumped throughout your body. The 1st number is the pressure within in your blood vessels as your heart contracts; the pressure of the blood leaving your heart causes the blood vessels to expand which can be measured (systolic). The 2nd number is the pressure when the heart relaxes between beats (diastolic).
High blood pressure is defined as consistent readings of 140/90 mm Hg. Normal blood pressure is between 120/80 mm Hg and 129/84 mm Hg with high normal blood pressure being between 130/85 mm Hg and 139/88 mg Hg; a relatively newer definition since those with high normal blood pressure are more likely to go on and develop high blood pressure. In the past, treatment wasn’t started until a person was diagnosed as having high blood pressure but with a high normal category, interventional strategies can be started earlier.
High blood pressure increases the risk for cardiovascular disease, including stroke and heart disease, by damaging blood vessels which, over time, leads to scarring and plaque formation. As plaque develops, it ultimately leads to narrowing, eventually blocking blood flow.
Risk factors for high blood pressure include increasing age, being overweight or obese, male and a member of certain ethnic groups including South Asians and African descent, smoking and a sedentary lifestyle. By now, almost everyone has heard that higher intakes of sodium are associated with high blood pressure and current dietary advice is to lower sodium intake between 1,500 mg to 2,300 mg per day based on individual needs. However, recent research has found that lowering sodium is only part of the equation that there’s a bigger return on effort if there’s a simultaneous increase in the amount of potassium consumed; in fact, the golden ratio seems to be five to one for potassium and sodium. In other words, getting a lot more potassium compared to sodium will provide a greater blood pressure lowering impact.
But it doesn’t end there, magnesium is greatly underappreciated for its role in maintaining healthy blood pressure as well and there’s a lot of room to play with this incredible nutrient. We know from the Canadian Community Health Survey that most Canadians are not meeting the recommended daily intake of magnesium for a variety of reasons including the fact that the magnesium content of food has slowly been decreasing in part due to lower soil levels, and because most of us are eating highly refined foods as well. Refining foods removes much of the magnesium found in different foods. In addition to eating more magnesium-rich foods, consider adding an extra 200 – 300 mg per day from supplements.
The new kid on the block is vitamin D which helps to lower blood pressure in the same way that some blood pressure lowering medications do by balancing the action of rennin, a hormone that acts in the kidney to help maintain normal blood pressure. However, some individuals are very sensitive to the action of rennin which can lead to high blood pressure over time but vitamin D helps to temper this. Because there are very few appreciable food sources of vitamin D, supplementation is essential to get the most as it relates to blood pressure. To increase vitamin D in blood to a level that is associated with better blood pressure control, aim to get 2000 – 3000 IU per day; be sure to check the vitamin D content of your multivitamin too.
For many, preventing high blood pressure, or being able to slow the progression, is not only achievable but desirable. Keeping blood pressure as close to 120/80 mm Hg for as long as possible will help prevent damage to the blood vessels thereby reducing the risk for stroke and heart disease. Prevention includes achieving and maintaining a healthy body weight, increasing physical activity, smoking cessation, and eating more foods with nutrients that have been shown to help reduce blood pressure.
To reduce your intake of sodium, try to focus on fresher, minimally processed foods more often, choose lower sodium or salt-free canned goods and condiments, limit fast food, use fresh or dried herbs, spices, and flavoured vinegars to flavour foods, choose salt-free butter, low sodium seasoning mixes, limit ‘instant’ foods, and rinse canned foods like tuna, or beans for 60 seconds. Don’t be afraid to use a pinch of salt in cooking or at the table, table salt is an important source of iodine. Remember, about seventy percent of your sodium intake is from processed and prepared foods; a pinch of salt is not the problem.
To boost your potassium intake, think fruits, vegetables, pulses [chickpeas, lentils, dried peas and beans] and whole-grains. For magnesium, go for whole grains, pulses, soybeans, dark green, especially leafy, vegetables, tofu set with magnesium [check the label], nuts and seeds. Naturally occurring nitrates in a handful of vegetables have also been shown to reduce blood pressure by helping to relax blood vessels; choose celery, spinach, beet root, radish, lettuces, and leafy vegetables.
Here’s one recipe in particular that’s very low in salt (350 mg per serving) and provides 27% of your recommended daily potassium and 116 % of the magnesium.
For loads more that are lower in sodium – less than 500 mg per serving – visit the Lower Sodium section of the recipe database.