In Canada, 1 in 5 (or 20%) of the population has high blood pressure. That’s a lot of people. Hypertension is when the pressure, or force, of the blood pushing against the blood vessels walls is consistently too high and can cause:
- Arterial damage and aneurysm
- Damage to you heart (e.g. Coronary Heart Disease, Heart Failure)
- Kidney failure
- Damage to the blood vessels in your eyes
In 2007 hypertension was the most common reason for seeing a doctor, with 4 million prescriptions for anti-hypertensive medications written each month (yes, you read that correctly...EACH month). While these stats are a decade old, they are likely comparable today (although, I’d love to be wrong in this assumption).
While there are medications for hypertension, there are also dietary factors that can lower high blood pressure. In addition, lifestyle changes such as quitting smoking, reducing alcohol, maintaining a healthy weight and exercising have also been shown to positively influence blood pressure (BP). Ideally dietary and lifestyle changes should be attempted first before medication is prescribed, although there may be cases in which doctors feel medication should be started right away. That being said, even if medications are recommended, it is still encouraged to take steps towards lowering hypertension through diet and lifestyle.
So, let's talk about food and what you can do with diet to lower blood pressure. There are several science-backed foods (or groups of foods) that are associated with lowering blood pressure, including:
I’m sure you’ve heard “eat your greens!” before but there is a reason for this age-old advice. Green veggies are packed with goodness, and this includes blood pressure-lowering goodness. Green vegetables, and especially the dark leafy green ones, are a great source of potassium, calcium, and to a lesser extent magnesium. These three nutrients are major components of the blood pressure-lowering DASH diet, an eating plan that has repeatedly been shown to improve hypertension.
Leafy greens like bok choy, kale, turnip greens and mustard greens are especially good sources of calcium and potassium, while Swiss chard and spinach are stars in the magnesium and potassium department. Other green, non-leafy vegetables that deserve a mention are broccoli, Brussels sprouts, asparagus and okra. All have varying amounts of calcium, magnesium and potassium but inclusion of these, and other green vegetables, will all be helpful in obtaining enough of those blood pressure-lowering nutrients.
Another valuable BP-lowering nutrient abundant in many vegetables, including the green ones, is vitamin C. While most known for its role in preventing scurvy and reducing the duration of colds, vitamin C may also play a role in maintaining healthy blood pressure. I say “may” because the evidence is a bit muddled at this point. While observational studies have not been able to conclusively link vitamin C to lower blood pressure, some smaller randomized controlled trials have shown supplementation with 500 mg of vitamin C does reduce blood pressure in those with normal and high blood pressure. Despite these findings, whether vitamin C actually does lower blood pressure is yet to be proven without a shadow of a doubt. The only reason I bring this up is to further encourage the importance of vegetables in the diet (green and non-green, alike) as they are a source of vitamin C, along with the other valuable blood pressure-lowering nutrients.
Nuts and Seeds
Nuts and seeds are great little powerhouses of blood pressure-lowering nutrients. In fact, a study involving 15 966 participants found an association between nut consumption and lower risk of hypertension (although this relationship seemed to be strongest in lean, rather than overweight or obese individuals).
Like the green veggies mentioned above, nuts and seeds contain the triad of BP-lowering minerals: magnesium, potassium and calcium. However, what separates nuts from green veggies is that they tend to contain a greater percentage of magnesium, a nutrient which is thought to promote smooth muscle relaxation within the vascular system.
Among nuts, Brazil nuts, almonds and cashews contain a significant amount of magnesium and potassium, along with a small amount of calcium. In the seed category, sesame, sunflower and pumpkin seeds are a good source of magnesium and potassium. Sesame seeds are a particularly good source of calcium too, and when ground into tahini paste can be a great way of boosting dietary calcium. Of course, when choosing nuts and seeds, look for unsalted (or as lightly salted as possible) to prevent too much sodium.
Yes, you read that correctly - studies show that a compound in beetroot lowers blood pressure. Beetroot contains a high concentration of inorganic nitrate, a compound which increases production of nitric oxide, a vasodilator (i.e. a compound that works to expand and relax our blood vessels). A meta-analysis found that consumption of beetroot juice lowers blood pressure, particularly that of systolic blood pressure. The effects of beetroot juice appear to be most powerful in the immediate hours following consumption.
It should be noted that the “beetroot hypertension” studies have all used beetroot juice, which has a greater concentration of inorganic nitrate than beetroot alone. Consuming beets on the regular may not have the same effect as seen in these studies but it certainly doesn’t hurt to include them in your diet. If you have access to a juicer, or can find some beetroot juice, try including a ½ cup per day. Who knows? It could help lower that BP.
Herbs and Spices
Although herbs and spices don’t have any blood pressure-lowering powers (that I am aware, at least), they did make this list of foods essential for a healthy BP. My reasoning is sort of a roundabout way of encouraging a lower salt intake. You see, herbs and spices can be used to replace the salt (or salty seasonings) in our food. Time and time again, high sodium diets have been linked to high blood pressure. Studies show that even modest attempts at lowering dietary salt can have a meaningful impact on hypertension. This is where herbs and spices come in. Learning other ways to flavour foods, while ditching the salt shaker and any other salty foods, is a good strategy to reduce dietary sodium.
Lowering dietary salt can be surprisingly challenging for some people. Studies show that the amount of salt we consume shapes our preferences. If we eat a lot of salt, it will cause our body's taste preference for salt increase. In other words, eating salty foods causes us to continually want salty foods. This can pose a bit of a challenge when someone is trying to cut dietary salt - food will taste bland and motivation to continue with a low sodium diet can be compromised. So learning to use flavourful herbs and spices to hide the fact that salt is missing, can be a way to combat this. There is good news, though. Taste preferences adjust to a lower salt diet (just as they at one time adjusted to the high salt diet). Many people find that after changing to a low sodium diet, the salty foods that they once enjoyed have become undesirable. Funny isn’t it?
Legumes, such as beans and lentils, are a great source of complex carbohydrates and plant-based proteins. They are an essential part of a healthy, vegetarian diet. Most legumes are a fantastic source of potassium, boasting 200-400 mg per ½ cup. Three legumes that are particularly rich in potassium are Great Northern beans, soybeans, and lentils.
Legumes are also a fairly good source of those other two blood pressure-lowering nutrients, magnesium and calcium. Great Northern beans, soybeans, black beans and peanuts are a good course of magnesium, containing 15-20% of the mineral’s daily requirement per ½ cup serving. The calcium content is of beans isn’t huge but they do provide a small amount.
Looking past their micronutrient content, there may also be another factor in legumes which plays a role in lowering of blood pressure. Many legumes contain certain proteins, that when broken down into smaller peptides, affect the same blood pressure-lowering pathway as ACE-inhibitor medications (a very common type of medication used for hypertension). A literature review, found that both soybeans and lupin had a high concentration of these blood pressure-lowering peptides, while chickpeas, lentils and dried peas had moderate amounts.
Considering these two factors together (the micronutrient content and BP lowering peptides), making legumes a regular part of your diet is a great idea. If beans are something that you are relatively unfamiliar with check out my article 5 Easy Plant-Based Proteins for the Newbie Vegetarian (and of course, you don’t need to be a vegetarian to start adding legumes to your diet!).
Dairy makes this list of blood pressure-lowering foods due to its excellent calcium content. Although many other foods do contain calcium, the quantity and its ability to be absorbed is much better in dairy foods. In addition to calcium, dairy products are also a good source of potassium. Several studies, including a systematic review and meta-analysis, have found an inverse relationship between dairy consumption and hypertension risk. More specifically, there seems to be a trend towards the consumption of low-fat dairy and a reduced hypertension risk.
Dark chocolate receives an honourable on this list because, well, who doesn’t love seeing chocolate on a list of foods that can improve their health?
In all seriousness though, there is *some* data to back up this claim (so it’s not just wishful thinking). Dark chocolate (and cocoa) contains flavanols. These flavanols are thought to increase the concentration of angiogenic cells, or cells that are needed for maintenance and repair of blood vessels. A review of the literature found that flavanol-rich cocoa products are associated with small (2 mm Hg), short-term decreases in blood pressure.
This may seem like great news but (yes, there’s a ‘but’) many of the studies are smaller studies and are funded, at least in part, by chocolate companies. In addition, most of the chocolate products on the market (i.e. the ones that you and I can buy) are not flavanol-rich. The cocoa or chocolate used in these studies has been altered to concentrate their flavanol content. Considering this, your best bet is to choose dark chocolate (with less ingredients watering down the possible flavanol content) or cocoa nibs (raw pieces of cacao beans).
PUTTING IT ALL TOGETHER
As we review the above list of foods, you may have noticed some similarities between the groups, or at least, trends among them. In general, a dietary pattern that lowers blood pressure contains many whole foods and is low in processed or fast foods, as well as:
- Contains lots of veggies and fruits
- Try to make half your plate veggies at lunch and dinner
- Have at least two vegetables per meal
- Try adding beet or beet juice regularly into the diet
- Includes plant-based proteins, like legumes, nuts and seeds
- Try having 1-2 vegetarian meals each week
- Experiment with adding (low sodium) canned beans to your regular meals (in pastas, soups, or on salads).
- Try cutting ground meats with lentils (a 50:50 mix works well)
- Is low in salt, and salty convenience foods
- Ditch the salt shaker
- Use herbs, spices, vinegar and/or lemon and lime to flavour food
- Look for low sodium food options (read - Salt: Is it a little or a lot)
- Limit restaurant meals and convenience foods
- Includes dairy (if tolerated)
- Boost calcium intake with a few glasses of milk each day
While any one of these factors, or dietary strategies, may only decrease blood pressure by a few points, their cumulative effect could make a significant difference. See, for example, the following image - which shows how different modifiable factors could improve hypertension.
By using a multi-pronged approach (i.e. improving diet and lifestyle), there is potential to make significant changes in blood pressure. Armed with a little knowledge, it is possible to lower blood pressure without medications.
If you could use a little guidance in planning out a healthy blood pressure-lowering diet, consult with a Registered Dietitian.