Author: Shireen Kassam, Visiting Professor, Health and Wellbeing Research Group, University of Winchester and Dagfinn Aune, Research Fellow, School of Public Health, Imperial College London

nuts

Photo: Fernanda Martinez / Unsplash

More than 1.4 billion people worldwide live with high blood pressure (hypertension). It’s the single biggest metabolic risk factor for early death – driving diseases such as heart attacks, strokes, kidney failure and dementia.

Most of these cases of high blood pressure are shaped by how we live and what we eat. This means that making changes to your diet can have a big impact on your risk of developing high blood pressure.

Even small changes can help, as our latest research shows. We found that adding just one serving of nuts into your daily diet is linked with lower hypertension risk.

It’s well known that eating more plant foods is associated with a lower risk of hypertension – but research on the impact of nuts has been limited to date.

Fruits and vegetables are associated with a lower risk of hypertension, with consumption of 800g (ten portions) per day reducing the risk by 11%.

Whole grains – brown rice, oats, wholemeal bread – are similarly linked to lower risk of hypertension. Our research found that the people who consumed the highest amount of whole grains each day had a roughly 26% lower risk compared to people consuming the least.

We have also shown that legumes and soya are associated with a 16% and 19% lower risk of hypertension respectively.

Our latest analysis published in the British Journal of Nutrition, now shows the clear impact eating nuts can have on hypertension risk.

Our study pooled data from 143,000 people – including 20,665 people who had hypertension. We found that eating around a handful of nuts daily (between 30-35g) was linked with a 26% lower risk of hypertension compared to not eating any nuts.

Why plant foods work

Plant foods share a few key characteristics, which may explain why they’re beneficial for the heart.

They are an excellent source of potassium, which helps to lower blood pressure by shedding sodium and relaxing blood vessels.

Plant foods also provide fibre that feeds gut bacteria so they can produce short-chain fatty acids – compounds that are linked to lower blood pressure.

Many plant foods also contain L-arginine and nitrates, which the body converts into nitric oxide in order to widen blood vessels. Plant foods are rich in polyphenols, which have also been associated with lower blood pressure.

Despite nuts being energy-dense, they’re linked to lower obesity rates – thus helping to mitigate another risk factor for hypertension.

These overlapping mechanisms all nudge blood pressure down, and help explain the link between plant-rich diets and lower risk of cardiovascular diseases.

But as tempting as it might be to call nuts a heart health “superfood,” their real power lies within a broader pattern of healthy eating. While reductions in hypertension risk are observed with intake of even just one daily serving of nuts, a diet built around several whole plant foods may provide even further benefits.

This is exactly what Dash, Mediterranean and plant-based diets prove. They all work because they put these different plant-based foods on the same plate.

However, it’s worth noting that the studies included in our analysis are observational. This means they show that people who eat more nuts tend to have lower blood pressure, but they cannot fully prove that nuts are the cause.

People who consume more plant foods in their diet also tend to follow other healthy lifestyle habits such as regular physical activity. Although our analysis adjusted for many of these factors, we cannot fully rule their impact out.

But the randomised controlled Dash diet trials, where diet is actually changed to include more vegetables, whole grains and lean protein, are what give us confidence the link is real. Similarly, intervention trials, which compared the effects of multiple different plant-based diets, also show benefits for blood pressure reduction.

There are knowledge gaps to note, too. The nut studies we included in our review did not separate salted from unsalted. Since salt raises blood pressure, the true benefit of unsalted nuts may even be larger than reported.

Most of the data also came from Europe, the Americas and East Asia. Little evidence came from Africa and India. More large studies conducted in a variety of regions will help sharpen the evidence base.

The takeaway is practical and affordable. You don’t need supplements or fads. Fill half your plate with fruit and veg, choose whole grains, build meals around beans and tofu and add a handful of unsalted nuts. These are small habits that add up to a significant reduction in one of our biggest health risks. The Conversation

This article is republished from The Conversation under a Creative Commons license. Original article.

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