Not many people immediately think of onions for blood pressure but like its cousin garlic, onion has many attributes that prove useful in managing high blood pressure.
For one, it's a great source of quercitin, found mostly in the outer layers and the skin of shallots, yellow and red onions, but not in white (apples are also rich in quercitin).
This powerful antioxidant flavonol is linked to a reduced risk of heart disease and stroke and has been shown to reduce high blood pressure.
When people with hypertension took 730 mg. of quercitin a day for 28 days, their blood pressure dropped between 2 and 7 points systolic and 2 to 5 point diastolic compared with no change with a placebo.
Other studies find that just 2 or 3 tablespoons a day of onion essential oil can drop blood pressure by an average of 25 points systolic and 15 points diastolic.
That would, however, translate to a lot of onions - more than anyone who has to be around other people would want to eat in a single day.
I'm sure you can still get good benefits from just one onion or two a day, particularly if you can eat it raw or lightly cooked (onions that are barely cooked seem to reduce blood pressure much more than fully cooked onions).
Both garlic and onion contain a compound called adenosine, which is a smooth muscle relaxant. So by decreasing peripheral resistance it helps the blood to run smoothly in the vessels.
Onions also contain small amount of prostaglandin A1 and E, substances with blood-lowering effects.
Prostaglandins are hormone-like messangers that command the release or shut off of one or another chemical substance in the body.
Aspirin is often used in the treatment of heart disease and works by suppressing the secretion from the cells of certain prostaglandins that turn on processes causing inflammation, pain and platelet aggregation.
In fact, aspirin blocks cells' production of a prostaglandin A called thromboxane that orders cells to start sticking together. Onions do precisely the same thing, without the side effects of continuos use of aspirin.
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FURTHER READING: Health Benefits of Onions
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