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Are vegetarians missing out on proteins that can prevent high blood pressure?
Are vegetarians missing out on proteins that can prevent high blood pressure?
Press coverage of a recent study suggested that vegetarians might be more at risk of high blood pressure. But this isn't the full story: we reveal the truth.
Eating a broad range of proteins — from both plant and animal sources — may lower your risk of developing high blood pressure, according to new research published in the online journal Hypertension.
High blood pressure, also known as hypertension, can cause long-term damage to your health if left untreated. However, symptoms can be hard to spot, leaving many people unaware that they have the condition.
Researchers from the National Clinical Research Center for Kidney Disease in China wanted to find out if there was a connection between the types, amounts and variety of protein people ate and whether they developed high blood pressure.
They asked 12,177 people who did not have high blood pressure at the start of the study to report what they ate over three consecutive days and noted how much they ate on average each day of eight different types of protein: whole and refined grains, processed and unprocessed red meat, poultry, fish, eggs and legumes (such as peas, beans and products made from them, like tofu).
They followed participants for an average of six years. During this time, just over a third of them (35 per cent) developed high blood pressure.
Getting more protein from eggs and legumes was linked with a lower risk of high blood pressure, while eating greater amounts of red meat was linked with a higher risk (although smaller amounts were beneficial).
The team also looked at what were the best amounts to eat of the eight different types of each protein - that is, "best" in terms of being linked to the lowest risk of high blood pressure.
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A strength of the study was that it included a large number of people and that it looked at specific types of protein sources (whereas some previous studies only looked at broader categories of protein, such as “meat”).Researchers also adjusted for other factors that could influence the findings, such as how much fat, fibre and salt the participants ate, their body mass index, their level of physical activity, and whether they smoked or drunk alcohol.
A weakness of the research is that it relied on a lot of self-reported information from participants, which can mean less accuracy. For example, participants told researchers what they ate. To assess whether some of the participants developed high blood pressure, they asked participants whether a doctor had ever told you them they suffer from high blood pressure, rather than measuring their blood pressure.
The study also focused on people in China, so the findings aren’t necessarily applicable to people from other nations, where dietary patterns can be different. For example, protein from dairy was not included as part of the analysis, perhaps because relatively little dairy is eaten in China.
The authors of the study themselves conclude that more research is required to confirm and develop their findings. As the work was observational, they are also unable to make claims on cause and effect.
How good was the media coverage?
The study was covered by the Mail Online and the Express.While the Mail story includes quotes from the study author, as well as the British Heart Foundation, it unhelpfully reframes the research as a “warning to vegetarians”. It says, “Vegetarians and vegans may be missing out on important sources of protein which can protect against high blood pressure.” But the study did not specifically compare vegetarian or vegan diets with meat-eating diets. While it found that eating four or more different types of protein in “appropriate amounts” was linked with a lower risk of developing high blood pressure, four of the types were foods that vegetarians can eat: eggs, legumes, whole grains and refined grains.
In fact, when the researchers were looking at the relationship between specific types of proteins and high blood pressure risk, higher intakes of eggs and legumes were linked with a lower risk, while greater amounts of red and processed red meat was linked with a higher risk.
The Mail’s helpfully included the NHS Eatwell Guide infographic, which shares advice on what balanced diets should look like.
The Express, meanwhile, offers some helpful detail on the health complications that are associated with high blood pressure and focuses on the actual findings of the study, that increasing your variety of protein sources could lower your risk of developing high blood pressure.
Yet The Express story does raise reader expectations with its headline that “increasing sources of protein could slash your risk by 66 per cent”, without explaining in the article that this statistic is specifically about a comparison between eating four or more types of protein and only one type.
The BHF verdict
Tracy Parker, Senior Dietitian at the British Heart Foundation (BHF), said: “This study adds to the evidence that eating a moderate amount of protein from a variety of foods is an important part of a healthy diet.“Although this study was observational, it suggests that eating a selection of both plant and animal-based proteins in your diet can help to control your blood pressure and benefit your heart. Further research is now needed to help understand this further, including in different population groups with different dietary intakes.
“To keep your heart healthy, you should focus on eating more fruit, vegetables, fish, pulses and wholegrains, and cutting down on foods high in salt, sugar and saturated fat like cake, biscuits and sweets. Lifestyle factors such as exercising regularly, quitting smoking, and maintaining a healthy weight are also important ways to reduce your risk of heart and circulatory diseases.”
For more information on how to maintain a healthy, balanced diet, read our expert dietitian’s answers to common questions about protein. You can also test your own knowledge of the topic by taking our protein quiz.
If you are following a plant-based diet and you are concerned about your protein intake, read our dietitians’ detailed guidance on how vegetarians and vegans can maintain a heart-healthy diet.
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