Vegetables are known for their health-boosting powers, including lowering high blood pressure. But which veggies might help it drop the most?
According to a recent study published in BMC Medicine, cruciferous veggies like broccoli and kale lower blood pressure levels better than their root counterparts, such as sweet potatoes and carrots.
The results suggest that cruciferous vegetables may be a healthful choice for people with high blood pressure, which includes about half of the adults in the United States. High blood pressure means having an elevated blood pressure of greater than 130/80 or taking an antihypertensive medication, according to the American College of Cardiology and American Heart Association.
“Hypertension has long been referred to as ‘the silent killer’ as the vast majority of people do not have any symptoms of high blood pressure, yet it contributes to an increased risk for heart disease and stroke,” Brian Downey, MD, director of General Cardiology Services at Tufts Medical Center, told Health.
While the study suggests that cruciferous vegetable intake may help blood pressure regulation, the study authors said more research is necessary to inform potential recommendations that could “reduce the public health burden of CVD [cardiovascular disease].”
The research team had already shown a link between cruciferous vegetables and a lower risk of cardiovascular disease outcomes, but those studies were “observational in nature and hence have limitations in residual bias and confounding factors that are unable to be accounted for,” Lauren Blekkenhorst, PhD, and Emma Connolly, study authors and researchers at Edith Cowan University Nutrition and Health Innovation Research Institute, told Health in an email.
For this most recent study, the researchers wanted to use more rigorous research methods to study the effect of vegetable intake on blood pressure.
To do this, they recruited 16 women and two men aged 56 to 72. The participants all had mildly elevated blood pressure levels. Their systolic blood pressure, which is the top number and measures how hard blood pushes against artery walls, ranged from 120 to 160 millimeters of mercury (mmHg). Their diastolic blood pressure, the bottom number, was less than 100 mmHg.
Participants were randomly categorized into either the active or control group to complete a four-week dietary intervention, separated at the midway mark by a two-week washout period, during which they returned to their regular diets.
During the four weeks, participants in the active group consumed four servings (around 300 grams) of soup containing 40% broccoli, 25% cauliflower, 25% cabbage, and 10% kale. Two servings were eaten at lunch, and the other two were consumed at dinner.
Meanwhile, control group members consumed the same amount of soup containing 40% potato, 30% pumpkin, 20% carrot, and 10% sweet potato at the same time of day as the other group. The soups were formulated to mimic each other in macronutrient content.
Participants in each group ate the same lunch and dinner—which included between one and four servings of vegetables—and consumed their usual breakfast and snack foods.
Members of both groups wore ambulatory blood pressure monitors, with levels checked at the beginning and end of each two-week period.
“We found that consuming cruciferous vegetables resulted in significantly lower systolic blood pressure compared to root and squash vegetables in these adults,” Connolly and Blekkenhorst said.
On average, the group who ate cruciferous vegetables had a 2.4 mmHg reduction in SBP, which could translate to a 5% lower risk of major cardiovascular events. Meanwhile, those in the root vegetable group lowered their blood pressure by an average of 0.7 mmHg.
The authors noted several study limitations, however, including that the study was small and included primarily white women, which means the results may not apply to a broader population. Furthermore, only 72% of participants complied with the instructions. Participants also may have figured out their group assignment due to the color and flavor of the veggie soups, which could have biased the results.
Kristen Carli, MS, RD, owner of Camelback Nutrition & Wellness, told Health she found the study “interesting,” given that the amount of nutrients she’d expect to be beneficial for blood pressure, like fiber and potassium, “are not radically different between the groups.”
“However,” Carli said, “these veggies also contain vitamins C, E, and K, which provide antioxidant and anti-inflammatory benefits that support blood pressure regulation.”
It’s also possible that the phytonutrients, or plant compounds found in cruciferous vegetables, are responsible for the findings. Previous studies have discovered blood pressure-lowering effects of glucosinolates and isothiocyanates, two phytonutrients found in cruciferous veggies. However, many of these were conducted in animals or showed inconsistent findings in humans.
The benefits of cruciferous veggies may extend beyond regulating blood pressure: Research suggests they can also support gut health, blood clotting, and the immune system.
While boosting your broccoli and kale intake could help lower your blood pressure, that’s not the only recommended strategy.
According to Connolly and Blekkenhorst, the Dietary Approaches to Stop Hypertension (DASH) diet can also be a helpful tool for people with elevated blood pressure. The diet revolves around prescribed daily servings of healthy, anti-inflammatory food groups, such as fruits, vegetables, whole grains, and poultry.
Carli suggested that people with normal blood pressure levels aim for less than 2,300 milligrams (mg) of sodium daily, while those with high blood pressure shoot for less than 1,500 mg.
Aside from diet, lifestyle factors can also reduce blood pressure. The American Heart Association suggests that people with hypertension avoid smoking or drinking excessive alcohol and exercise regularly. That means getting 150 minutes of moderate-intensity cardio, 75 minutes of vigorous aerobic activity, or a combination of both.
“Chronic stress can also raise blood pressure, so managing stress through techniques like deep breathing, meditation, yoga, or mindfulness practices is crucial,” Carli added.
You should also strive for seven to nine hours of sleep daily, experts said, and having a consistent bedtime, limiting screen time, and avoiding caffeine late in the day can help.