Blood pressure is a term we may hear often but that many of us may not understand fully. So, what exactly is blood pressure, and why is it important to keep it in check? First, blood pressure is the pressure blood exerts on the walls of blood vessels/arteries as it’s pumped through the body by the heart (1;2). When this pressure is consistently too high, we have high blood pressure or hypertension, and our heart has to work harder to pump blood (2). Globally, more than 1 in 4 men and 1 in 5 women have high blood pressure (1). High blood pressure is dangerous because it puts us at a greater risk for developing and dying from diseases of the heart, kidney, and brain, to name a few (2).
Our diet, so what we eat and drink regularly, can affect our blood pressure (2;3-10). Consuming an unhealthy diet, such as one that’s low in fruits and vegetables and high in salt, increases our chance of developing high blood pressure (2). On the other hand, healthier diets are associated with a lower risk of developing high blood pressure. Vegetarian and vegan diets, in particular, have been placed under the microscope and studied for their impacts on blood pressure (3;9-10). However, plant-based diets go beyond these two diets. They include a wide variety of dietary patterns, some of which allow for an often-limited amount of meat and other animal products (3).
Let’s dive deeper into the world of plant-based diets by familiarizing ourselves with some common types in the table below.
|Lacto-ovo vegetarian diet||Promotes consumption of fruits, vegetables, legumes, nuts, seeds, and whole grains, and cuts out meat, fish, and poultry but allows dairy and eggs|
|Vegan diet||Emphasizes eating whole plant foods, is generally low-fat, and doesn’t allow for the consumption of any animals or animal products|
|Mediterranean diet||Focuses on the consumption of fruits, vegetables, whole grains, olive oil, eggs, nuts, legumes, dairy, and a limited amount of meat|
|Healthy Nordic diet||Encourages the consumption of more plant-based foods, as well as fish, eggs, and vegetable fat; while reducing the consumption of meat-based goods, dairy, alcohol, and sweets|
|High-fruit and vegetable diet||Promotes more fruit and vegetable intake|
|High-fiber diet||Endorses increasing the consumption of foods that are high in fiber, such as legumes and whole grains|
|Dietary Approach to Stop Hypertension (DASH)||More heavily restricts the consumption of sodium, saturated fat, and sweets, and supports eating low-fat dairy products, whole grains, fruits, vegetables, nuts, and seeds|
This is a lot of information to take in, and with so many options available, it can be hard to know what diet to follow to reduce our blood pressure. A recent systematic review aimed to help by investigating these diets further and laying out the evidence (3).
What the research tells us
Of the seven plant-based diets studied within the review, only three show the potential to positively impact both systolic and diastolic blood pressure. These are the DASH, lacto-ovo vegetarian, and healthy Nordic diets. The Mediterranean diet may also have blood pressure lowering effects, but only for systolic blood pressure. Overall, the diets that were effective in reducing one or more aspects of blood pressure often encouraged the consumption of fruits, vegetables, whole grains, legumes, nuts, seeds, and a limited amount of animal products. The remaining three diets—the high fruit and vegetable, high fiber, and vegan diets—do not appear to lower any aspect of blood pressure. It's worth mentioning that the vegan diet was the only plant-based dietary pattern studied that completely eliminates the consumption of animal products. These results are important because they imply that diets that are much less restrictive show promise for success.
With that said, the certainty of the evidence that these results are based on ranges from very low-to-high and differs depending on what diet and aspect of blood pressure you're looking at. The DASH diet is the only diet whose findings are based on high certainty evidence across the board; this means that future research likely won’t change the finding that it reduces both systolic and diastolic blood pressure. The same can be said for the lacto-ovo vegetarian diet’s impact on systolic blood pressure, specifically. As for the other findings, we are less confident that the results wont change as more research comes out (3).
There you have it, plant-based diets may hold blood pressure benefits, but not all diets that fall under this category are equal. If you're interested in making a lifestyle change through your diet, speak with your health care team about what dietary pattern is the best fit for you and how to safely make this change.