Eat a handful of walnuts a day to lower your blood pressure, study suggests

Eating a handful of walnuts a day could reduce your blood pressure, lower weight gain and in turn cut the risk of diabetes and heart disease, a new study finds.

Scientists at the University of Minnesota un-earthed the miraculous potential benefits of the nuts after monitoring the diets of 3,300 people for more than 25 years and giving them several health check-ups.

Walnuts are the only nuts that contain Omega-3 alpha-linolenic acid (ALA), which the scientists said may explain the benefits. The fatty acid has previously been linked to improved heart health. They say more studies are needed to confirm the findings, though.

Previous research has linked walnuts to lower blood pressure, and suggested they prevent diabetes and heart disease. However, these results are yet to be backed up by a rigorous clinical trial.

Scientists at the University of Minnesota suggested walnuts lowered blood pressure because they contained Omega-3 (stock image)

Scientists at the University of Minnesota suggested walnuts lowered blood pressure because they contained Omega-3 (stock image)

In the study — published Wednesday in the journal Nutrition, Metabolism and Cardiovascular Diseases — the scientists analyzed data from 3,341 Americans who were about 45 years old.

Participants had taken part in the Coronary Artery Risk Development in Young Adults (CARDIA) study run by the University of Alabama between 1985 and 2015.  

They were initially interviewed about their diets, and followed up with at years seven, 20 and 25 of the study.

What is high blood pressure? What are the risks?

High blood pressure, or hypertension, rarely has noticeable symptoms. But if untreated, it increases your risk of serious problems such as heart attacks and strokes. 

The only way to find out if your blood pressure is high is to have your blood pressure checked.

Blood pressure is recorded with two numbers. The systolic pressure (higher number) is the force at which your heart pumps blood around your body.

The diastolic pressure (lower number) is the resistance to the blood flow in the blood vessels. They’re both measured in millimetres of mercury (mmHg).

If your blood pressure is too high, it puts extra strain on your blood vessels, heart and other organs, such as the brain, kidneys and eyes.

Persistent high blood pressure can increase your risk of a number of serious and potentially life-threatening conditions, such as:

  • heart disease
  • heart attacks
  • strokes
  • heart failure
  • peripheral arterial disease
  • aortic aneurysms
  • kidney disease
  • vascular dementia

Of those involved, the 340 who ate walnuts consumed about 0.6 ounces (19 grams) a day on average — the equivalent of seven walnut kernels. 

These people were more likely to be female, white and be highly educated.

At year 20, they were invited back for a health check-up where their BMI was measured, alongside their activity levels and blood pressure.

Results showed that those in the walnut-eating group had lower blood pressure than those that did not eat the nuts.

Blood pressure measurements are shown as two figures, as the systolic pressure — or pressure on artery walls when the heart beats — and diastolic pressure — or pressure on artery walls in–`between beats.

Among those that did not eat walnuts their blood pressure score was 117.2/73.6 millimeters of mercury (mmHg).

But for those who did eat the nuts it was 116 / 71 mmHg.

The scientists said the diastolic blood pressure, or second figure, was significantly lower in people who ate walnuts.

But neither figure was in the unhealthy range, which the Centers for Disease Control and Prevention (CDC) says is anything higher than 120 / 80 mmHg.

About 20 percent of walnut eaters in the study had high blood pressure, compared to 22 percent of those who did not eat them. 

The scientists also suggested that walnuts led to lower weight gain and a higher quality diet. 

They found that those who did not eat nuts had a BMI of 29.7, putting them in the upper end of the overweight range, and 39 percent were obese.

But among those who did have walnuts the BMI was barely lower at 29, while 35 percent were obese.

Those who ate the nuts also had a higher activity score in the paper than those who did not.

Scientists also claimed walnut-eaters had significantly lower fasting glucose levels, a better heart disease risk profile and a higher quality diet.

So-Yun Yi, a PhD student in public health at the university who was involved in the research, said the study supported claims that walnuts are ‘part of a healthy diet’.

‘Interestingly, walnut consumers had a better cardiovascular disease risk factor profile such as a lower body mass index… compared to other nut consumers,’ they said.

The scientists said walnuts could help the heart because they are the only nut to have Omega-3, which has been linked to heart benefits.

They also contain a variety of other nutrients, including protein, fiber and magnesium, that may also support heart health.

But researchers added that their results were observational, and that clinical trials should be carried out to confirm the results.

It was not clear whether other nuts were having an impact because walnut eaters tended to eat more nuts generally, compared to those that did not consumer them.