Kathy Kolassa: Nitrates and a healthy diet
Tuesday, December 4, 2018
Dear readers, in time for you to read and think about before making New Year’s resolutions, find your personal physical activity recommendations at https://health.gov/paguidelines. Only 2 in 10 Americans get the physical activity needed to manage their weight, reduce risks for some chronic diseases and to feel great. The guidelines are clear that doing something is better for your health than not moving at all. You don’t have to belong to a gym or have fancy exercise clothes to move. Some is better than none, but adults obtain the maximal benefits of physical activity by regularly performing 150 to 300 minutes per week of moderate-intensity or 75 to 150 minutes of vigorous-intensity activity.
Q Why are nitrate rich green leafy vegetable like arugula, spinach and collard greens considered to be good for heart health, but bacon and other processed meats with added nitrates are considered to be unhealthy? WR, Greenville
A That’s a great question. Brooke Dempster, an ECU dietetic student worked hard to answer your question. Here is what she wants you to know.
The food that we eat is made up of a lot of chemicals and it can sometimes be confusing to figure out the risks or benefits of them to our health. In a food science class, you would learn that nitrates and nitrites are naturally occurring compounds commonly found in vegetables and in additives in processed meats. These two compounds are different based on the number of oxygens attached to the central nitrogen with nitrate having three and nitrite having two.
I won’t try and give a chemistry lesson, but when nitrates are consumed, they are converted to nitrites by bacteria and enzymes produced by salivary glands in your mouth. Further into digestion when nitrites reach the stomach, they have the ability to convert into either nitric oxide or nitrosamines.
The source of the food we consume determines the pathway of the conversion it will take within the body. Nitrates derived from plant products are converted to nitric oxide, a signaling molecule that has many beneficial properties including the protection of cells and the control of cardiac rhythm.
Nitric oxide promotes good heart health because it is a strong vasodilator, meaning it improves the amount of blood flow to and from the heart by increasing the width of blood vessels. This helps improve health conditions like prehypertension and hypertension, also known as high blood pressure by lowering blood pressure resistance. Nitric oxide also protects against plaque build-up in arteries, strokes, and heart attacks. Improving blood flow allows the body to deliver oxygen and nutrients to the body’s many tissues and organs while removing carbon dioxide and waste products. Dietary sources with a considerably high amount of nitrates for the production of nitric oxide include lettuce, spinach, arugula and beets.
On the other hand, nitrites derived from processed meats have the ability to convert to harmful nitrosamines when mixed with stomach acid or when they come in contact with high temperatures. This conversion occurs due to the proteins and iron found in the meat. Nitrosamines are considered carcinogenic due to their association with gastrointestinal, colorectal and rectal cancers and also because of their capability to produce tumors in high amounts.
Nitrates are added to the meat for the purpose of fixing the color and contributing to the overall flavor. They also increase the shelf life of meat by inhibiting the growth of microorganisms within the meat. Nitrates control the oxidation of fat, which means they prevent the meat product from becoming rancid and developing a spoiled off taste and an ammonia like smell.
Nitrites derived from vegetables have the ability to inhibit the conversion to nitrosamines that can promote cancer because they contain a variety of antioxidants, including Vitamin C, Vitamin E, and phytochemicals. This is why it is important to consume fruits and vegetables high in nitrates in order to promote good heart heath and the lower the risk of cancer.
I want to give a shout-out to Dr. Mike Wheeler, chair of ECU’s Department of Nutrition Science who helped us get the message right.
Professor emeritus Kathy Kolasa, a registered dietitian, nutritionist and Ph.D., is an Affiliate Professor in the Brody School of Medicine at ECU. Contact her at email@example.com.