Nitric oxide, which should not be confused with the anesthesia gas nitrous oxide
, is produced naturally in the body. The body's production of nitric oxide is critical in the protection of cardiovascular tissues and helps to protect the heart against infarction, tissue death due to a lack of oxygen, and ischemia, a decrease in blood flow which leads to decreased oxygenation of tissues and organs. According to Nobel Prize-winning pharmacologist Louis Ignarro
“In the heart, nitric oxide is the body’s way of protecting against cardiovascular disease. The arteries make nitric oxide to lower blood pressure and improve blood flow to organs because it is a vaso-dialator, which means it widens or relaxes the arteries so that more blood can flow through, therefore lowering the pressure within the arterial system.”
Nictric oxide is produced through the synthesis of two amino acids, L- Arginine and Citrulline. Both of these amino acids can be found in food sources. L-Arginine is found in fish such as tuna, shrimp, scallops and anchovies. It can also be found in pine nuts, almonds, pistachios, oats and wheat germ. Citrulline can be found in vegetables called cucurbits, such as cucumbers and cantaloupe. Watermelon contains the highest level of natural Citrulline. Natural, whole food sources of both L- Arginine and Citrulline can also be found in some nutritional supplements.
Although nitric oxide has long been known to be beneficial to the heart, Evgeny Nudler, PhD, a Julie Wilson Anderson Professor of Biochemistry at NYU Langone Medical Center, says a new study shows that nitric oxide can also prolong the life span of organisms, fortifying them against environmental stress. The study, entitled A Little Molecule’s Remarkable Feat: Prolonging Life
, showed when roundworms commonly used in laboratory studies of aging were fed bacteria that produced nitric oxide, they lived "significantly longer".
Nudler points out that as we age, our levels of nitric oxide decrease. He believes the new study supports the theory that supplementing the body with bacteria that produces nitric oxide may provide a "healthy boost" to humans as well, saying
"In worms, we now know that bacteria can use nitric oxide not only to their own advantage but also to provide their host with a beneficial response, and the same thing could be true in a human gut. It may well be the case that our commensal bacteria control some of our genes, at least in the gut, to protect those cells against stress and age-related decline.”
The study showed that the lifespan of the worms increased by nearly 15 percent when fed the bacteria capable of producing nitric oxide.
According to Nudler, the nitric oxide produced by the bacteria penetrated the tissues within the worm and activated a set of 65 different genes, some of which had previously been associated with stress resistance, immune response and increased longevity. He went on to say
“What we found is that nitric oxide gas produced in bacteria inside the worms diffuses into the worm tissue and activates a very specific set of genes acting through two master regulators, hsf-1 and daf-16, resulting in a high resistance to stress and a longer life. It’s striking that a small molecule produced by one organism can dramatically affect the physiology and even lifespan of another organism through direct cell signaling.”
Since the worms used in the study were not capable of producing nitric oxide on their own, the nitric oxide producing bacteria was required before the worms could receive the health benefits. Humans ingesting similar bacteria may also receive benefits. It is also possible that eating foods high in both L- Arginine and Citrulline would provide benefits as well.
The study has promising implications, not only presenting the potential of additional heath benefits not previously known, but also possibly providing an alternative means of boosting nitric oxide levels in humans who have seen a decline in the chemical due to aging.