Broccoli beats beets: How cruciferous veggies rule the blood pressure game

By Study Finds

Could eating more broccoli, kale, and Brussels sprouts be the key to lowering your blood pressure? A new study suggests that consuming cruciferous vegetables may have a significant impact on cardiovascular health, particularly for middle-aged and older adults with mildly elevated blood pressure.

Researchers at Edith Cowan University in Australia conducted a clinical trial to investigate the effects of cruciferous vegetables on blood pressure compared to other types of vegetables. Their findings, published in the journal BMC Medicine, indicate that eating about four servings of cruciferous vegetables daily for two weeks led to a notable reduction in systolic blood pressure.

Cruciferous vegetables, which include broccoli, cauliflower, cabbage, and kale, have long been lauded for their potential health benefits. These vegetables are rich in compounds called glucosinolates, which break down into bioactive substances like sulforaphane when the vegetables are chopped or chewed. Previous research has suggested these compounds may have anti-inflammatory and antioxidant properties, potentially contributing to better cardiovascular health.

“Increasing vegetable intake is widely recommended to reduce heart disease risk, and previous observational studies have shown, cruciferous vegetables like broccoli, cabbage, and Brussels sprouts, have stronger relationships with lower heart disease risk than other vegetables,” says study co-author Emma Connolly, a PhD student at Edith Cowan, in a statement. “However, while these vegetables are consumed globally, cruciferous vegetables typically make up a small portion of total vegetable intake.”

In this study, dubbed the VEgetableS for vaScular hEaLth (VESSEL) trial, researchers recruited 18 participants aged 56 to 72 years with mildly elevated blood pressure. The majority of participants were female and of Caucasian descent. At the start of the study, participants had an average systolic blood pressure (the top number in a blood pressure reading) of about 136 mmHg, which is considered elevated but not yet in the hypertensive range.

The study employed a crossover design, meaning each participant completed both the cruciferous vegetable intervention and a control intervention involving root and squash vegetables. This approach allows researchers to compare the effects of different treatments within the same individuals, reducing the impact of individual differences on the results.

During the cruciferous vegetable intervention, participants consumed about 300 grams (roughly 4 servings) of a mix of broccoli, kale, cauliflower, and cabbage daily for two weeks. These vegetables were provided in the form of two soups – one for lunch and one for dinner. For the control intervention, participants consumed an equivalent amount of root and squash vegetables, including potato, sweet potato, carrot, and pumpkin, also in soup form.

The researchers used 24-hour ambulatory blood pressure monitoring to measure the effects of the interventions. This method involves wearing a blood pressure cuff that automatically measures blood pressure at regular intervals throughout the day and night, providing a more comprehensive picture of blood pressure patterns than single measurements taken in a clinical setting.

The results were striking. After just two weeks of consuming cruciferous vegetables, participants experienced an average reduction in 24-hour systolic blood pressure of 2.5 mmHg compared to the control intervention. This effect was even more pronounced during daytime hours, with an average reduction of 3.6 mmHg.

(Credit: American Heart Association)

While a decrease of 2.5 mmHg might seem small, it’s important to understand its potential impact on cardiovascular health. Previous research has shown that even modest reductions in blood pressure can lead to significant decreases in the risk of heart disease and stroke. In fact, the researchers note that this reduction could translate to approximately a 5% lower risk of major cardiovascular events.

Interestingly, the study also found that participants who consumed cruciferous vegetables had lower levels of triglycerides in their blood compared to when they consumed root and squash vegetables. Elevated triglycerides are a risk factor for heart disease, so this finding suggests that cruciferous vegetables may have additional cardiovascular benefits beyond blood pressure reduction.

The mechanisms behind these effects are not fully understood, but the researchers suggest that compounds found in cruciferous vegetables, such as sulforaphane and S-methyl cysteine sulfoxide (SMCSO), may play a role. Previous studies have shown these substances provide various beneficial effects for the cardiovascular system.

While the results are promising, it’s important to note that this was a small study with a limited duration. Larger, longer-term studies will be necessary to confirm these findings and determine whether the blood pressure-lowering effects of cruciferous vegetables persist over time.

Nevertheless, this research adds to a growing body of evidence suggesting that what we eat can have a significant impact on our cardiovascular health. For those looking to manage their blood pressure through dietary changes, increasing intake of cruciferous vegetables may be a simple and effective strategy to consider.

Paper Summary

Methodology

The VESSEL study used a randomized, controlled, crossover design. Participants completed two 2-week dietary interventions separated by a 2-week washout period. During one intervention, they consumed about 300 grams of cruciferous vegetables daily in the form of two soups. In the other intervention, they consumed an equivalent amount of root and squash vegetables, also as soups. Blood pressure was measured using 24-hour ambulatory monitoring before and after each intervention period. The researchers also collected blood and urine samples to measure various biomarkers related to cardiovascular health and to confirm adherence to dietary interventions.

Key Results

The primary finding was a significant reduction in 24-hour systolic blood pressure of 2.5 mmHg after the cruciferous vegetable intervention compared to the control intervention. This effect was more pronounced during daytime hours, with a reduction of 3.6 mmHg. The study also found lower triglyceride levels following the cruciferous vegetable intervention. Markers of oxidative stress and inflammation did not differ significantly between the interventions.

Study Limitations

The study had several limitations. First, the sample size was small, with only 18 participants completing the trial. The majority of participants were female and Caucasian, limiting the generalizability of the results to other populations. The study duration was also relatively short at two weeks per intervention, so it’s unclear if the effects would persist over a longer period. Additionally, while participants were blinded to which intervention was considered “active,” the different soups had clear differences in color and taste, which could have influenced results.

Discussion & Takeaways

The researchers suggest that compounds found in cruciferous vegetables, such as sulforaphane and SMCSO, may be responsible for the observed blood pressure-lowering effect. These compounds have been shown to have antioxidant and anti-inflammatory properties in previous studies. The reduction in blood pressure observed in this study, while modest, could translate to a clinically meaningful reduction in cardiovascular risk if sustained over time. The researchers emphasize the need for larger, longer-term studies to confirm these findings and explore the potential mechanisms behind the effects of cruciferous vegetables on cardiovascular health.

Funding & Disclosures

The study was funded by grants from Edith Cowan University and the Department of Health Western Australia. Several of the researchers were supported by various fellowships and grants from organizations, including the Royal Perth Hospital Research Foundation, the Western Australian Future Health Research and Innovation Fund, and the National Health and Medical Research Council of Australia. The authors declared no competing interests.

Source: Study Finds

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