Nutrition for Reducing Blood Pressure: A Comprehensive Guide

High blood pressure (hypertension) is well known for increasing the risk of complications like heart disease and stroke. There are many options for how to reduce it, which in turn can reduce the risk of a lot of health complications. 

One thing I want to address with this article is to provide a relatively comprehensive guide, while also keeping it relatively easy to read.

Somebody recently asked me if I had any good resources to send them on how to reduce blood pressure. Although I had not yet written anything personally, I did not think it would be hard to find. 

Unexpectedly though, pretty much everything I found was either super basic and brief, or scientific papers taking a deep dive in a way that might be less practical for people.

Ideally, this post is something in between those that I can use as a resource to send to people going forward.

Why Is High Blood Pressure “Bad?”

High blood pressure can be defined in many ways, but the table below is a good representation of the current consensus. 

The main reason high blood pressure is detrimental is that it can lead to cardiovascular events and contribute to kidney issues. 

A few other issues can also occur due to high blood pressure. Keeping it simple though, most people would agree that it is beneficial to address hypertension.

Sodium 

One of the most common recommendations in relation to blood pressure is to reduce sodium/salt intake.

Less common, but still prevalent is criticism of that advice, suggesting that it either does not help or is actively detrimental. 

This conflicting information can be confusing. 

My baseline starting advice is that if you have high blood pressure, you will likely benefit from reducing your sodium intake. But I need to add context around that.

The Case for Reducing Sodium Intake

Starting with the basics – there is a reason why most public health organisations recommend reducing sodium if you are looking to reduce your blood pressure. It is genuinely the current consensus based on the research on the topic.

A 2019 review covering the majority of the research on sodium and hypertension concluded that a reduced sodium intake not only decreases blood pressure but also reduces morbidity and mortality from cardiovascular diseases.

That is a compelling statement.

The main contributing factor is that high sodium intake can increase water retention in the blood and increase arterial stiffness, amongst other things, which increases blood pressure. 

In terms of how effective this is, a randomised controlled trial identified that reducing from an average of ~3700mg per day down to ~2000mg per day reduced systolic blood pressure by 7.1mm Hg on average.

For context, the average person appears to consume 3.5-5.5g per day and the World Health Organisation recommends limiting sodium intake to 2g per day.

The Case Against Reducing Sodium Intake

There are 3 main arguments against reducing sodium intake that I see, which I will address individually:

1. If you do not have high blood pressure and you are fit and healthy, you probably do not need to worry about reducing sodium. In fact, if you are an athlete, you might even benefit from increasing sodium.
2. There is a thing called sodium sensitivity, or sodium-mediated hypertension. Mainly those who are sensitive to the effect of sodium on hypertension need to worry about sodium intake.
3. There is a J-Shape curve. Going too high sodium causes issues and going too low sodium causes issues.

There is validity in all of these.

With the first one, there is truth to that aspect. But I am targeting this article toward people who DO have high blood pressure. And if you are an athlete who sweats a lot but also has hypertension, then the discussion about the 3^rd one will be relevant to you, just with higher amounts of sodium.

With the second point, there is some truth there too. 

Sodium sensitivity appears to exist. Stating the obvious though, those with hypertension are more likely to be sodium sensitive than those who do not have hypertension.

We know from all the research on reductions in sodium that on average reducing sodium reduces blood pressure. So, we know on average, reducing sodium helps people with high blood pressure.

But what if you are not sensitive to sodium? 

The first question is – how do you know? The short answer is that there does not appear to be a validated tool for figuring this out. 

One simple option can be to test yourself. You can reduce your sodium intake and see if it reduces your blood pressure. It is not a perfect system, but since there is no consistently reliable tool for identifying this, it is not as bad of an idea as it sounds. 

The J-Shape curve aspect is based on research highlighting that going high sodium leads to issues, but so does going low. 

Solving this issue is simple. Just avoid going excessively low. 

A safe guide for most people would be to aim for >1000mg and <2000mg daily. This needs to be individualised based on your needs. For example, athletes might benefit from more. 

It is also worth highlighting that you should not be obsessive about this and actively track your intake every day. These are just ballpark ranges to strive for. 

Potassium

Potassium plays a large role in our blood pressure as well.

It is arguably as important for the average person with high blood pressure to increase their potassium intake as it is to reduce their sodium intake, although it is far less commonly spoken about.

High potassium intake is also potentially a large factor in why the DASH diet is so effective for managing hypertension.

Theoretically, this is because potassium increases sodium excretion and relaxes the walls of blood vessels.

Based on urinary excretion rates, it appears that those with the highest sodium intake and lowest potassium intake typically have the highest blood pressure in the research. Every gram increase in potassium leads to an average reduction of 1mm Hg of systolic blood pressure. 

For context, the RDI for potassium is 3800mg for men and 2800mg for women, but approaches such as the DASH diet recommend 4800mg. The average person consumes significantly less than these numbers.

There can be downsides of excessive potassium intake for those with kidney conditions. And since kidney conditions are more common amongst those who have high blood pressure, that is worth mentioning. If this is the case, you would need to speak with your healthcare team for individualised advice.

I have not seen much evidence or support for supplementing potassium individually. Instead, I would just focus on getting in more through food.

Weight Management

It is well established that being at a higher body weight increases the likelihood of having elevated blood pressure.

The Nurse’s Health Study identified that those with a BMI of 22 were 6x less likely to have higher blood pressure than those who had a BMI of 29 or above. 

Obviously, there are flaws in BMI that have been discussed at length in other places. It is just being used in this case as an overly simplified tool to establish that higher body weight is on average associated with higher blood pressure.

Other research has identified that on average, every 4.5kg increase in weight leads to an increase in 4mm Hg of systolic blood pressure.

More importantly, it has been shown that even small weight losses have a dramatic improvement in blood pressure. A meta-analysis on the topic identified that on average, every 1kg loss of body weight was associated with a 1mm Hg drop in blood pressure.

The mechanisms explaining why this happened are related to changes in insulin resistance, vascular structure and function, sodium retention and a variety of other systems. It is very multifactorial. But basically, all we need to know is whether it is effective.

A Note on BMI vs Body Composition

A major criticism of BMI is that it only assesses body weight in relation to height. It does not assess how much muscle somebody has. 

Theoretically, you can have a higher BMI while remaining at a relatively low body fat percentage. 

Having a lower body fat percentage is beneficial for reducing blood pressure. But higher BMIs are still associated with elevated blood pressure, even when higher levels of muscle mass are factored in. 

Some research even indicates that BMI can be a better predictor of blood pressure than body composition. This is surprising, but it is worth mentioning. 

It makes sense to focus on improving body composition and still paying a bit of attention to your total body weight too if reducing blood pressure is your goal.

If looking to lose body fat, I have another post covering that in detail. 

DASH Diet 

The DASH Diet is specifically designed for reducing blood pressure. DASH literally stands for “Dietary Approaches to Stop Hypertension.” 

It is specifically high in foods that contain a lot of magnesium, potassium and calcium.

The diet looks like the following:

The DASH diet has been shown to reduce blood pressure significantly in the research even without reducing sodium intake or body weight. One study under those conditions showed a reduction of 11.4mm Hg in systolic and 5.5mm HG diastolic blood pressure.

These positive findings have been consistently repeated in many different trials under different conditions too. 

It is clearly effective without even reducing sodium, but it is even MORE effective when that is reduced too.

A lot of people question the inclusion of certain aspects of the diet, such as the high wholegrain and dairy aspects. But a review of 28 studies found that increasing wholegrain and dairy intakes significantly reduced the risk of hypertension.

Potentially Easy Win – Beetroot Juice and Other Nitrates

Beetroot juice is a novel option that is often touted to help reduce blood pressure.

The main mechanism through which it does this is due to the nitrate content leading to the vasodilation of blood vessels. As these blood vessels are vasodilated, blood pressure is reduced. 

Based on this, you can get this effect from any foods that are high in nitrates. Concentrated beetroot juice just happens to be the easiest way to get a sufficient dose.

On average, daily beetroot juice seems to reduce systolic blood pressure by ~5mm Hg and diastolic blood pressure by ~2mm Hg. That is my own interpretation of the research since obviously, the outcomes are variable based on the dosage, duration and situation.

Other people have highlighted that the effects of beetroot juice might be short-lived since improvements appear to be larger within a few hours of consumption.

That is definitely true with one-off dosages. The argument falls apart a little bit with the meta-analyses highlighting those studies involving >14 days of duration showed better outcomes than those with <14 days duration.

Nitrates can also be another explanation for why the DASH diet is so effective for reducing blood pressure too.

Does Cholesterol Play a Role?

Theoretically, the build-up of cholesterol can narrow the arteries, increasing blood pressure. Higher cholesterol levels are linked with a higher incidence of hypertension.

Research has also found that reducing cholesterol levels could also lead to a reduction in blood pressure.

This is an area that seems to be less of a strong link than other aspects that have been mentioned so far, but if your cholesterol levels are elevated, it is worth addressing that too anyway.

Since that is obviously a large topic on its own, I will direct anybody interested to a separate article I have written specifically on how to reduce cholesterol levels through dietary approaches.

Fibre

There is consistent evidence that increasing fibre intake leads to a small improvement in blood pressure.

One example of this is a review on added psyllium husk showing a reduction of 2mm Hg on average, with large reductions coming from those with particularly high blood pressure.

There are a lot of explanations why, but I would wager the effects are more indirect than direct.

Some of these explanations include:

• Increasing fibre intake could reduce appetite, contributing to weight loss. 
• High fibre foods could also be high in nitrates.
• High fibre foods are often unprocessed foods. Switching from a more processed diet to a more unprocessed diet could mean a reduction in sodium intake.
• Certain types of fibre could also help reduce cholesterol.

Increasing fibre intake is typically a good idea for most people. Unless you already have a particularly high fibre intake, this can be another option worth considering.

Alcohol

Alcohol can impact blood pressure both directly and indirectly.

Small amounts of alcohol (1-2 standard drinks) do not have a significant impact on blood pressure in the short term.

A systematic review found that a reduction from 1-2 standard drinks per day down to near abstinence levels did not significantly improve blood pressure. 

Higher amounts of alcohol clearly increase blood pressure though. For those who consume 6+ standard drinks per day, this same review identified that a 50% reduction in alcohol-reduced systolic blood pressure by an average of 5mm Hg.

Some people claim that the type of alcohol matters. The most common example is people saying that red wine seems to have more beneficial effects. Often this claim is backed up with observational evidence, where those who consume red wine instead of other options typically have lower blood pressure.

The rationale behind this is that red wine is high in antioxidants, particularly polyphenols, which have beneficial compounds.

This claim falls apart a bit when analysed closely though. 

Firstly, you could get those benefits from consuming the grapes wine is made from without the downsides of alcohol.

But more importantly, there is more controlled research on the topic showing that when the alcohol content from beer and wine is matched, both increase blood pressure equally. 

That same research identified that de-alcoholised red wine had no impact on blood pressure. 

Indirect Effects of Alcohol on Blood Pressure

One of the difficult things in writing about blood pressure is that every dietary change has an indirect impact.

With alcohol, beyond the direct impact, it also indirectly impacts things.

Alcohol contains calories. That could contribute to weight gain, which could lead to increased blood pressure.

It also lowers inhibitions, which can change dietary choices towards higher calorie intake.

Having alcohol in your diet could displace other food sources which could have been more beneficial for reducing blood pressure.

Sleep can also be disrupted, which could indirectly impact a variety of things too.  

Caffeine

Caffeine is a substance that has been linked with blood pressure for a long time, mainly due to its acute effects. 

It has the potential to be a vasoconstrictor, which means that it can decrease the size of blood vessels, therefore raising blood pressure.

Reviews of caffeine’s acute effect on blood pressure have shown increases in the ranges of 3-15mm Hg systolic and 4-13mm Hg diastolic. Typically, this occurs within 30 minutes and can persist for more than 4 hours. 

Another review found that 200-300mg of caffeine (the equivalent of 2-3 shots of coffee) led to an increase of 8.1 mm Hg systolic and 5.7mm Hg diastolic on average. 

The authors also highlighted that there was no long-term effect of coffee drinking on blood pressure. 

It is also clear that habitual caffeine intake plays a role. Those who habitually consume caffeine seem to be less likely to experience this acute increase to the same degree.

There is also a difference between consuming caffeine by itself instead of just coffee. Caffeine itself seems to increase blood pressure a bit more than coffee. This is theoretically due to other compounds in coffee, such as antioxidants, having a beneficial effect. 

Beyond the acute effects, the longer-term data is more interesting. A 2017 review found a 9% reduction in the risk of hypertension in those who were consuming 7 cups of coffee per day. 

The current consensus is that those with high blood pressure should exercise caution when drinking coffee, but there is no need to avoid it. 

Practical Summary

There are things that have not been mentioned in this article that could help. But this post includes a lot of aspects, and if you implement these, you will very likely see a significant reduction in your blood pressure.

Below is a summary of things you can do from a nutrition perspective that can help:

• Reduce sodium intake if it is high. Avoid going excessively low sodium though.
• Increase potassium intake.
• Reduce your body weight if you have excess weight to lose.
• Implement aspects of the DASH diet.
• Take action to reduce your cholesterol if it is high.
• Increase your fibre intake if it is low, although the benefits are likely more indirect than direct.
• Eat nitrate-rich food. Concentrated beetroot juice is typically the easiest way to do this.
• Reduce alcohol consumption.
• Be cautious of caffeine. The long-term impacts likely are not that detrimental. Caffeine can lead to an acute increase in blood pressure though, particularly in those who are not habitual consumers of it.