Can eating more beans and tofu reduce your risk of high blood pressure?

If you’re fond of beans, you may have noticed headlines claiming eating them can cut your risk of developing high blood pressure (hypertension) by a third.

The stories were based on a study published in BMJ Nutrition, Prevention & Health, which looked at whether people who eat more legumes and soy foods are less likely to develop high blood pressure. But do the findings support those headlines?

What did the researchers investigate?

Researchers wanted to understand if there is a link between eating more legumes and soy foods and a lower risk of developing high blood pressure.

Legumes include:

• beans
• lentils
• chickpeas
• and peas.

Soy foods include:

• tofu
• edamame
• soy milk
• tempeh.

Previous studies have suggested these foods may be linked with a lower risk of cardiovascular disease (CVD), but the results for high blood pressure have been inconsistent.

To investigate further, researchers carried out a systematic review and meta-analysis.

This involves gathering multiple studies and analysing the findings as a whole. This gives a more reliable picture of the evidence instead of relying on a single study.

The team examined data from 12 prospective studies with more than half a million participants.

They were followed for a minimum of 3 years and a maximum of 16 years to see who developed high blood pressure and whether there was a link with the quantity of legumes and soy foods they ate.

The people who took part were from the UK, Europe, the United States and Asia and included a mix of men and women.

What did the study find?

When it came to legumes, the research found those who ate the most were 16 per cent less likely to develop high blood pressure than those who ate the least.

Eating 170g of legumes every day had the biggest effect, lowering the risk of hypertension by 30 per cent.

For soy foods, people who ate the most were 19 per cent less likely to develop high blood pressure than those who ate the least.

Having 60 to 80g a day was linked to a 28 to 29 per cent drop in hypertension risk. Eating more than this had no extra benefit.

What do the researchers say?

The researchers conclude that regularly eating legumes and soy foods may help reduce the risk of developing high blood pressure.

They say this could be because these foods are rich in fibre, plant protein, potassium, magnesium and other nutrients that may help support healthy blood pressure levels.

The authors also note that legumes and soy foods often replace foods that are higher in saturated fat, such as processed and red meats. This may contribute to better overall cardiovascular health.

How good is the research?

This study has several strengths, including that it combines data from multiple studies involving many participants.

The researchers only included prospective studies, which follow people over a certain time period. This design is generally more reliable than measuring diet and health outcomes at a single point in time.

But there are some important limitations.

All the included studies were observational. This means researchers identified a link between eating legumes and soy foods and the risk of high blood pressure, but they cannot prove these foods directly lowered the risk.

It’s possible people who regularly eat beans, lentils and soy products also have other healthy habits, such as being physically active, not smoking or eating more fruit and vegetables.

Researchers try to account for these factors, but it is impossible to rule them out.

The studies also relied on people reporting what they ate, and the participants may not have accurately remembered how much they consumed.

The researchers noted they could not fully account for some differences between the studies, including the types of legumes eaten and the way they were prepared.

The authors declare the study was funded by an advocacy group called Plant-Based Health Professionals UK, and that 3 of the authors are affiliates of the organisation. While this is a potential conflict of interest, the authors state that the funder had no role in the study design, analysis or interpretation.

How good was the media coverage?

Several news reports accurately reflected the main findings of the study and highlighted that legumes include foods such as beans, lentils and chickpeas.

However, some headlines concentrated on the risk of high blood pressure dropping by a third in people who ate 170g of legumes or 60g to 80g of beans every day.

The overall comparison between people with the highest and lowest intakes found more modest risk reductions of 16 to 19 per cent.

The coverage also tended to overlook that this was observational research, and it cannot prove cause and effect.

The BHF’s verdict

This study adds to growing evidence that eating more plant foods, including beans, lentils, chickpeas and soy products, may help support healthy blood pressure levels.

High blood pressure is one of the biggest risk factors for heart attack and stroke, so it is important to find dietary patterns that help reduce risk.

While this research cannot prove that legumes and soy foods directly lower the risk of developing high blood pressure, the findings are consistent with what we already know about heart-healthy eating.

Legumes are naturally high in fibre and low in saturated fat and salt. They also provide potassium and magnesium, minerals that help support healthy blood pressure, making them a nutritious addition to meals. They can also be an affordable way to add more plant protein to your diet.

Rather than focusing on a single food, it’s best to think about your overall eating patterns.

A heart-healthy diet limits foods that are high in salt, sugar and saturated fat and includes plenty of:

• vegetables
• fruit
• wholegrains
• beans
• pulses
• nuts
• seeds.

If you’re looking to eat more legumes, here are some simple changes you can try to increase your intake as part of a balanced diet: 

• Add lentils to soups.
• Use chickpeas in salads.
• Swap some beans for meat in stews and curries.
• Try hummus as a spread instead of butter or mayo.

For the biggest benefit, it’s also important to look at the whole lifestyle picture: alongside a heathy diet, staying active, maintaining a healthy weight and limiting alcohol can all help to lower blood pressure.

It’s a good idea to know what your blood pressure is. You can measure your blood pressure at home if you have a monitor, or you can get checked in your local pharmacy. It’s a simple test and takes about 5 minutes.

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