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Beating high blood pressure with beets

Previously demonized in the form of nitrate food preservatives, nitrates are now being researched for heart disease protection.

Study under review: Dietary nitrate provides sustained blood pressure lowering in hypertensive patients: a randomized, phase 2, double-blind, placebocontrolled study

Introduction

“Eat your greens” is very reasonable advice for improving health, but it is also vague, especially for people following a reductionist approach to their food. We know that carotenoids are beneficial and are found in yellow-red foods, anthocyanins are found in the red-blue spectrum, and copious other polyphenolics are found in fruits and veggies. Greens, however? What could explain the benefits found in these veggies?

It turns out that the leafy greens, even humble lettuce, are great sources of the small nitrogen-containing molecule nitrate. Nitrate (NO3-) forms the starting step for one of the major ways the body can get nitric oxide, a small yet potent signalling molecule that relaxes blood vessels and improves blood flow. Strangely, the route for nitric oxide production from veggie consumption involves saliva, as seen in Figure 1. After nitrate is ingested, the intestines digest the compound and then it’s secreted into saliva, where various mouth bacteria digest the nitrate (NO3-) into nitrite (NO2-) for eventual reabsorption in the digestive tract on an as-needed basis. Nitrite is then converted into nitric oxide throughout the body’s tissues by a wide variety of compounds.

Figure 1: Conversion of nitrates and nitrites in the body

This pathway from nitrate, to nitrite, and finally to nitric oxide can be a major player in reducing blood pressure. This process doesn’t require the nitric oxide synthesizing enzyme found in blood vessels, which is known as endothelial nitric oxide synthase (eNOS). While eNOS also plays a major role in reducing blood pressure, its role in regard to health is preventative, and it works best when maintained, rather than being forced to work harder. eNOS regulation is generally not modulated by supplements. While problems with eNOS would likely increase blood pressure, providing a dietary supplement of the amino acid that eNOS uses (L-arginine) would be a very unreliable way to improve circulation.

Due to its potency, reliability, and safety, nitrate from beetroot juice was tested in this clinical trial. It had already been investigated as a single dose treatment in previous trials. This is the first trial to examine a sustained usage of this supplement and its effects on hypertensive subjects of all ages, regardless of medication.

Nitric oxide (NO) relaxes blood vessels and can reduce blood pressure. It is synthesized in a couple of ways in the body. One of those ways uses nitrate (NO3-) from food sources.

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The big picture

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Other Articles in Issue #05 (March 2015)