The human body is remarkably complex. Countless proteins with intricate structures and origami-like foldings perform amazing feats in the body on a routine basis. But occasionally the human body makes use of the simplest tools to accomplish important functions. Nitric oxide (NO) is an excellent example. It’s a small, simple, two-atom, gaseous molecule that persists for mere seconds.
Can You Hear Me Now?
NO is among the few gases the body harnesses for use in signaling. As the name implies, signaling molecules are compounds that help transmit messages, triggering reactions throughout the body. NO is among the smallest signaling compounds. But its function is hugely important.
NO signals tiny involuntary muscle cells to relax. These cells surround our blood vessels, allowing them to expand or contract as needed. In times of emergency—during fight or flight scenarios, for example—hormones are released that trigger responses designed to prepare you to survive. Among other things, these hormones act to signal smooth muscle cells to contract. As a result, blood vessels are squeezed and blood pressure rises—sometimes dramatically. This in turn ensures that adequate blood will be shunted rapidly to major muscles.
That’s all well and good when you are running for your life. But afterward, it’s important for things to return to normal. And that’s where NO comes in. NO can be generated right in the tissues lining the blood vessels, then released as needed. NO signals the smooth muscle cells lining the blood vessels to relax. In response, the blood vessels expand, blood flow slows, and blood pressure returns to normal, at least until the next crisis. This adaptability is built in, and it serves an obvious, beneficial purpose; it helps keep us alive in a crisis. It’s an adaptive response to stress.
Unresolved Stress and the Cardiovascular System
In the modern age, many of us experience low-grade, unrelieved stress more or less constantly. Threats may be more psychological than physical, and may lack any easy resolution. This—combined with poor diet, inadequate exercise, and too many readily available high-calorie foods—can foster high blood pressure (hypertension).
Hypertension is a major risk factor for heart disease and stroke. If you have been diagnosed with mild to moderate hypertension, it’s crucial that you take steps (and follow your physician’s advice) to lower your blood pressure. Exercise, weight loss, and even medications can all help. But the role of proper diet should never be underestimated.
Take NO, for example. Where does it come from? Also known as endothelium-derived relaxing factor (EDRF), the body generates NO from slightly more complex molecules, called dietary nitrates. The endothelium is a delicate, specialized tissue that lines the interior of blood vessels. Nitrates to make NO can also be obtained through the diet. A diet rich in nitrates from plant foods supplies plenty of raw materials so the body can generate all the NO it needs. Having a ready supply of raw materials from which to make NO facilitates the body’s ability to signal blood vessel muscles to relax, which helps reduce blood pressure. No wonder, then, a high intake of nitrate-rich foods has been linked to a reduced risk of cardiovascular disease.
Dietary sources of nitrates include raw beets, spinach and some other healthful whole plant foods, such as arugula. These and certain other foods can provide ample dietary nitrates to boost blood levels of heart-protective nitric oxide.