You may be surprised to hear doctors recommend eating banana for high blood pressure, but that may well become more and more common.
Often you see bananas on the list of foods to avoid if you want to lose weight. But if you do avoid them, what are you missing?
Bananas are packed with nutrients, especially potassium.
An average-sized banana contains more than 400 mg of potassium and only 1 mg of sodium.
Potassium is one of the most important electrolytes in the body, and works with sodium to help regulate heart function and fluid balance - a key factor in controlling blood pressure.
The effectiveness of potassium-rich foods, such as bananas, in lowering blood pressure and protecting against heart disease and strokes is well accepted and supported by considerable scientific evidence, so much so, that the US Food and Drug Administration has just allowed the banana industry to make official claims for the fruit's ability to reduce the risk of blood pressure and stroke.
In one landmark study researchers tracked more than 40,000 American male health professionals over four years to determine the effects of diet on blood pressure. Men who ate diets higher in potassium-rich foods had a substantially reduced risk of high blood pressure and stroke.
According to scientists, two bananas a day can help control high blood pressure offering a cheap alternative to expensive drugs and without their side-effects either.
The finding supports earlier research that potassium-rich food such as bananas could play a role in controlling blood pressure.
A 1997 study carried out at Johns Hopkins University in the US had suggested that people would have to eat five bananas a day to have half the effect of a blood pressure-controlling pill. But let's have a look at what a more recent study on banana for high blood pressure reveals.
According to one study conducted more recently in India, researchers reported that blood pressure fell by 10% in people who ate two bananas daily for a week.
The study involved human volunteers at the Kasturba Medical College in Manipal in southern India.
It followed successful experiments in rats that showed that ripe and unripe bananas have compounds that can lower blood pressure.
Current drugs to lower hypertension, or high blood pressure, are called ACE-inhibitors. They are expensive and may produce side-effects such as dizziness.
How do ACE-inhibitors work?
One of the reasons for high blood pressure can be put down to overproduction of an enzyme - angiotensin converting enzyme or ACE - which causes angiotensin I to be converted into angiotensin II. Angiotensin II is a hormone which causes constriction of blood vessels and an increase in blood pressure.
ACE inhibitors, as the word suggests, inhibit this conversion allowing the blood vessels to dilate causing a decrease in blood pressure.
I'm sure you're not surprised to discover that the pharmaceutical trade in ACE-inhibitors is worth billions of dollars every year, considering the millions of people suffering from high blood pressure.
The Indian scientists report that natural compounds in bananas act in a manner similar to anti-hypertensive drugs in the Indian medical journal Current Science.
The Manipal team studied six popular banana varieties and found that all had ACE-inhibiting properties, though the ripened bananas had a stronger action than unripe ones.
Due to high consumption of processed foods, many Americans, and most people in Western countries, have a potassium-to-sodium (K:Na) ratio of less that 1:2. This means that most people ingest twice as much sodium as potassium. Now, this is woefully inadequate.
Researchers recommend a dietary potassium-to-sodium ratio of 5:1 to maintain optimal health. This means ten times more potassium than the average intake. And even this may not be optimal.
How do you achieve this?
A natural diet rich in fruits and vegetables can produce a K:Na ratio greater than 100:1, as most fruits and vegetables have a K:Na ratio of at least 50:1.
Average K:Na ratio of some common fruits and vegetables:
The estimated safe and adequate daily dietary intake of potassium is between 1.9 to 5.6 grams in the USA and in the UK the RNI (Reference Nutrient Intake) is 3.5 g. for adults and 765 mg for children.
So by including a variety of fruits and vegetables in your diet as well as a couple of bananas a day is quite possible to take in an adequate amount of potassium and reduce the amount of sodium, which will help lower high blood pressure.
In England the recommended daily intake of fruits and vegetables is 5 a day. That's nowhere good enough to provide us with the necessary potassium. A more realistic intake is 9 to 11 servings per day.
How many are you eating?
Have a look at the following article in this series to see how fruits and vegetables can lower your blood pressure.