Episode 72 – Nutrition For Reducing Blood Pressure

Key Topics Covered

 Background 

The main reason this matters is because high blood pressure can contribute to the risk of CVD complications and kidney conditions. 

1. Reduce sodium intake if it is high – avoid going excessively low sodium though

  • If you have high blood pressure, it is prudent advice to reduce sodium intake.  
  • Looking at the research, a 2019 review covering the majority of the research of the topic clearly concluded that reducing sodium intake decreases blood pressure on average and reduces morbidity and mortality from cardiovascular diseases. 
  • The mechanism involves a few things. But mainly it is that sodium increases water retention and increases arterial stiffness. 
  • An RCT identified that dropping from 3700mg per day to 2000mg per day reduced systolic blood pressure by 7.1mm Hg on average. 
  • For context, the average person consumes ~3500-5500mg per day 

Criticism of the reducing sodium advice 

  • Criticism of the advice to decrease sodium usually revolves around these arguments: 
  1. Sodium sensitivity not effecting everyone 
  2. J-Shaped curve of sodium and CVD outcomes 
  3. Athletes having higher needs 
Elderly patient with bp, heart rate, digital pulse check equipment for medical geriatric awareness in stroke systolic high blood pressure, hypertension, hypotension and cardiovascular disease in aged senior older woman person

1)  Sodium-mediated hypertension is a thing.  

  • Statistically, a large percentage of people who have HTN also are sensitive to sodium. So it still remains prudent advice to limit sodium to a moderate level.  
  • There is currently no validated test to confirm whether people do or do not have this.

2) The J-Shaped Curve thing is real too.  

  • The J shaped curve seen when looking at sodium intake and CVD risk tells us that going excessively low sodium appears to increase risk of CVD outcomes too.  
  • BUT This is simple to overcome – just don’t go excessively low. 

3) The athlete’s point is relevant too. But HTN is less common amongst athletes too.  

  • OVERALL A safe guide is to aim for >1000mg and <2000mg per day if you have HTN.
    • But this needs to be individualised.  
    • And the specific numbers do not need to be tracked or overly focused on – it’s just a ballpark.  

2. Implement aspects of the DASH diet

  • DASH stands for “Dietary Approaches to Stop Hypertension“. 
  • It is specifically high in foods that contain a lot of magnesium, potassium and calcium
  • It contains a lot of fruits, vegetables, nuts, seeds, whole grains and dairy. It also has a moderate amount of healthy fats added and some lean meats. 
  • It has been shown to reduce blood pressure significantly even without reducing sodium or body weight. One study under those conditions found an average reduction of 11.4mm Hg in systolic and 5.5mm HG diastolic blood pressure. 
  • It is clearly effective without even reducing sodium, but other research has found it is even MORE effective when sodium 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. 

3. Increase potassium intake

  • 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. 
  • 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.
    • Research on urinary excretion rates, indicates that those with the highest sodium intake and lowest potassium intake typically have the highest blood pressure in the research.  
  • 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. 

Two caveats: 

  • For those with kidney conditions, it is worth checking with your healthcare team to see if you have restrictions on potassium intake.  
  • I have not seen much evidence or support for supplementing potassium individually. Instead, I would just focus on getting in more through food
    • Leafy greens, beans, nuts, dairy foods, and starchy vegetables are particularly rich sources. 

4. Reduce your body weight (only if you have excess weight to lose) 

  • Higher body weight is clearly linked with higher blood pressure on average 
  • A meta-analysis found that every 1kg loss correlated with an average decrease of systolic blood pressure of 1mm Hg. 
  • Body fat is a bit more correlated with blood pressure than muscle mass. But the research has still shown that those who are at higher body weight are more likely to have higher blood pressure, even if they have a relatively lower body fat percentage for their size. So that is still worth being aware of if the goal is to reduce blood pressure. 

5. Reduce cholesterol if it is high 

  • Higher cholesterol levels are linked with higher blood pressure 
  • There are potential explanations such as plaque build-up increasing blood pressure 
  • Either way, reducing cholesterol has been linked with reducing blood pressure. 
  • Cholesterol is found in animal based foods such as higher fat meat products, eggs & dairy  

6. Eat nitrate-rich food  

  • Nitrates dilate blood vessels, helping blood flow more easily. 
  • Concentrated beetroot juice is typically the easiest way to do this. 
  • On average adding beetroot juice daily has been shown to reduce systolic blood pressure by 5mm Hg. 
  • This can be another contributor for why the DASH diet helps. 

7. Reduce alcohol consumption

  • Indirectly, alcohol contributes by adding calories. It could also potentially effect other factors such as sleep or other food intake. 
  • A review found that those who consume high amounts of alcohol (6+ drinks per day) and decreased their intake by 50%, there was a reduction in systolic blood pressure of 5mm Hg. 
  • The type of alcohol does not appear to play a role either e.g. red wine does not have any special beneficial effects. 

8. 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.  
  • Average increase of blood pressure ranges from 3-15mm Hg in those who are not habitual consumers. This persists for a few hours. 
  • So while it does not matter much long term, it is worth being aware of for people who are not habitual consumers. 

Summary 

  • Reduce sodium intake if it is excessively high – but don’t go excessively low either 
  • Implement elements of the DASH diet where possible  
  • Increase potassium intake through potassium rich fruit, veg, legumes, nuts, seeds and dairy 
  • Reduce your bodyweight if over weight 
  • Reduce cholesterol intake, if it is high  
  • Eat nitrate rich foods – nitrates are found in a range of foods, and maybe consider supplementing with concentrated beetroot juice 
  • Limit alcohol consumption  

Related Links/ Resources

Studies Mentioned:

Related Blog Posts: