Last week I wrote about garlic in relation to lowering blood pressure.  Today I wanted to mention potassium and blood pressure.

Firstly I wanted to write a little more about the problem of high blood pressure (hypertension) in the Western world.  For purposes of illustration I am using statistics(1) for England derived from the 2005 Health Survey for England.  However, the trend is general for the UK and beyond.  High blood pressure is not great news!  It increases the risk of heart disease and stroke and is also linked to dementia and eye problems such as age related macular degeneration.

Hypertension is defined as a systolic blood pressure of 140mmHg or over, or a diastolic blood pressure of 90mmHg or over (see last week for definitions and explanations of diastolic and systolic).  The target for the general population is to have a blood pressure below 140 (systolic)/85 (diastolic).

In England 2005:
*The average systolic blood pressure was 134mmHG for men and 128mmHG for women
*35% of men and 28% of women had hypertension or were being treated for hypertension
*59% of men and 44% of women with hypertension were not receiving treatment
*Of the individuals who were being treated for high blood pressure over 50% remained hypertensive (with a high blood pressure)
 

Blood pressure levels increased with age.
*In men aged 16-24 the average systolic blood pressure was 128mmHg compared to 141mmHg in men aged 75 and over
*In women aged 16-24 the average systolic blood pressure was 117mm Hg compared to 144mmHg in those aged 75 and over. 
*Only 1% of women aged 16 to 24 are hypertensive, compared to 42% aged 55 to 64 and around 67% aged 65 to 74.

As the statistics show, high blood pressure is a very real problem, especially as we get over the age of 40.  Thankfully there is plenty we can do to keep our blood pressure in check and lower it if necessary.  Last week I discussed garlic supplementation and today I am looking at potassium.  The British Heart Foundation(1) have a booklet on blood pressure with more detailed information on why blood pressure maintenance is important, the causes of high blood pressure and detailed advice on how to reduce it.  The booklet can be downloaded from their website.

Back to potassium.  A recent review(2) has found that boosting dietary intake levels of potassium may help to lower the risk of developing high blood pressure and may also decrease blood pressure in individuals already suffering from hypertension. 

Vegetables and fruits are great sources of potassium.  The authors of the study point out that a healthy intake of potassium is thought to be one reason why vegetarians and isolated populations have a very low incidence of heart disease.  In areas were diets are low in sodium and high in vegetables and fruits (representing high potassium levels), hypertension affects only 1% of the population. In contrast, the authors note that in industrialized societies, where people consume diets high in processed foods and large amounts of dietary sodium 1 in 3 persons have hypertension.

In addition to potassium the review study looked at calcium and magnesium, minerals which are also important in controlling blood pressure.  The authors conclude that “A high intake of these minerals [potassium, calcium and magnesium] through increased consumption of fruits and vegetables may improve blood pressure levels and reduce coronary heart disease and stroke”

An increase in vegetables and fruits is fantastic general dietary advice.  These super foods are full of essential vitamins, minerals and other phytonutrients (bioactive plant chemicals) as well as fibre and are vital to our health, not just blood pressure.  Getting a minimum of five portions a day is recommended (recently the National Cancer Institute has recommended 5-9 portions a day and the Danish campaign aims at a minimum of 6 a day!).  Potassium supplements are available and limited trial data exists to support their usefulness in lowering blood pressure, however, potassium supplements should not be used as a replacement for fruit, vegetables and a healthy diet.

(1)British Heart Foundation http://www.heartstats.org/homepage.asp, http://www.bhf.org.uk/

(2)Houston MC & Harper KJ.  2008.  Potassium, magnesium and calcium:their role in both the cause and treatment of hypertension.  10:3-11

Written by Ani Kowal