Is your gut the key to lowering blood pressure?

Woman eats a high cholesterol and fatty breakfast consisting of fried eggs, buttered toast, bacon, and orange juice with a salt shaker on the side, while monitoring blood pressure.

Image: Nelz/Bigstock.com

It has long been acknowledged that a Western diet (that is, a diet high in animal products, processed foods and saturated fats) along with a high salt consumption can lead to high blood pressure (hypertension). But new research suggests your gut microbiome might just have a hand in the mix.

Hypertension and diet

Hypertension is the most common of all the conditions of the circulatory system. In fact, a 2014-15 Australian Bureau of Statistics report found approximately 6 million Australians (34%) aged 18 years and over, had high blood pressure and of those, 4 million (68%) had uncontrolled or unmanaged blood pressure.

So, how do you manage your blood pressure?

The National Heart Foundation advocates for the DASH (Dietary Approaches to Stop Hypertension) diet. This is an eating plan rich in plant foods. It emphasises fruits, vegetables, legumes and low-fat dairy products. It also includes wholegrains, nuts, fish and lean poultry but contains only small amounts of red meat.

It is also rich in fibre, potassium, magnesium and calcium. Minerals, such as potassium, help you balance out the sodium (salt) that you eat and help keep your blood pressure low. It has been proven that following the DASH diet can reduce your systolic blood pressure by 8-14 mmHg!

But now there’s more to the story . . .

Hypertension and your gut

Our gut is often termed our ‘second brain’, because like our brain it seems to be linked to many of our body’s functions. Conditions from heart disease and diabetes to anxiety and depression have been linked to the health of our gut microbiome.

The gut microbiome is the collective genes of your microbiota (akin to the human genome, which includes all of our genes) studied using DNA-sequencing. The microbiome is critically important because it’s the bacterial genes that provide instructions for what the bacteria will make (known as metabolites) from the foods you feed them.

These metabolites signal multiple organs in your body. Some metabolites are nasty, promoting inflammation and disease while others are soothing, reducing inflammation and boosting your immune system. While your genome is fixed for life, your microbiome changes over time and is influenced largely by your diet.

The latest research

In the case of hypertension, new research published in the scientific journal Nature has identified the gut as a potential key player in managing blood pressure.

In mouse experiments, researchers have found a high salt diet leads to depletion of good bacteria, specifically Lactobacillus species in the gut, which in turn leads to increases in pro-inflammatory T cells resulting in a rise in blood pressure (and ultimately increased risk of type 2 diabetes and heart disease). The depletion of this beneficial bacteria was identified after just one day, with the lowest abundance on day 14!

The harmful changes to gut bacteria under high salt environments led researchers to consider that adding back lactobacilli as a supplement must help reverse these changes and lower blood pressure. And their results were very promising – daily supplementation of lactobacillus species led to a significant reduction in systolic blood pressure and normalisation of diastolic blood pressure.

In a preliminary salt challenge in humans, these results were repeated. A small pilot in healthy male participants placed on a high-salt diet were shown to have a decrease in lactobacillus species, an increase in pro-inflammatory immune cells and a subsequent increase in blood pressure after just two weeks.

This new research expands our existing knowledge about salt and hypertension and provides a potential new target (the gut) to help counteract salt-sensitive changes. These results suggest that maintaining a healthy gut microbiome will be beneficial in lowering blood pressure and reducing the risk of many chronic conditions, such as heart disease and diabetes.

The identification of lactobacillus species as a ‘natural inhibitor’ of salt-induced immune cells could serve as an exciting nutrition management strategy for people with high blood pressure.

Sue Radd is an Advanced Accredited Practising Dietitian and one of Australia’s leading nutritionists and health communicators. Her most recent book Food as Medicine: Eating for Your Best Health received the Gourmand World Cookbook Award for Best Health and Nutrition Book in the world for 2016.

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Category: Physical Health

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