We all know that leafy green vegetables are good for us, but do you know why they’re so good? There are plenty of reasons but, when it comes to heart health, the secret is nitrates.
In a paper published in the Journal of Clinical Investigation, researchers from the University of Pittsburgh propose that high levels of dietary nitrate might in part explain the vascular benefits of diets rich in leafy greens.
Since the 19th century nitrates have been administered to patients with angina to dilate their arteries and increase blood flow.
Vascular diseases (disorders of the circulatory system) can lead to heart attacks, strokes and even death. The Pittsburgh researchers pointed out that typical treatments for these disorders, such as bypass surgery and angioplasty, actually induce vascular injury and can lead to an over-proliferation of the cells of the blood vessels in a way that limits blood flow.
According to the researchers, nitric oxide is an important molecule that helps maintain the contractility and health of vascular smooth muscle cells. Multiple studies have linked vascular disease to a decreased level of nitric oxide and it is believed that therapies increasing the availability of nitric oxide could help protect vascular health.
Usually, nitric oxide in our bodies is synthesized from the amino acid L-arginine by an enzyme called nitric oxide synthase. In the University of Pittsburgh research, it was found that when rats sustained blood vessel injury that synthesis was disrupted. However, a secondary process that generates nitric acid from nitrate was activated.
The researchers found that supplementing rats with nitrate before inducing vessel injury significantly limited the extent of the damage, while a diet low in nitrate exacerbated it.
What kinds of greens are best for your heart?
Leafy greens and root vegetables are good sources for nitrates with beetroot, turnips, celery, spinach, lettuces, carrots and radishes generally having the highest levels. Fertilizers used in growing vegetables can boost their nitrate content.
Besides vascular health there are many other good reasons to eat your leafy greens. Greens have a wide range of nutritional benefits. They contain vitamins A, C, E and K as well as prodigious amounts of calcium, iron, potassium, magnesium, phosphorous and zinc, not to mention the fiber, folate, chlorophyll, micronutrients and phytochemicals that protect against disease.
Greens are also rich in cancer fighting antioxidants. Generally speaking, the darker the leaves, the more nutrient dense is the vegetable.
While iceberg lettuce, Boston bibb or even romaine all have a place at the table, it is best to make the effort to add in more of the nutrient dense dark greens. These include serious greens like kale, bok choy, collards, Swiss chard, mustard greens, broccoli rabe, escarole and dandelion. These greens are powerful allies for your body, assisting in purifying the blood, strengthening the immune system, promoting good intestinal bacteria (probiotics) and improving circulation, liver and kidney function.
Give greens a chance. Your body will thank you.
© The New York Times
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