Are Nitrates Healthful?
Is your fruit and veggie rich diet, also high in nitrates? Here's some great information about the nitrates in your food.
A study in the American Journal of Clinical Nutrition from Michigan State University reviewed the DASH diet (Dietary Approaches to Stop Hypertension), and found the consumption of nitrates for those following the diet was up to 550 times that of the World Health Organization’s Acceptable Daily Intake (ADI). Nitrates and nitrites are compounds containing nitrogen and oxygen. The difference is that nitrate contains three oxygens, and nitrite contains two. The body readily converts nitrate into nitrite through the action of naturally occurring bacteria in the saliva.
The DASH diet, known for its dramatic blood pressure lowering effects, promotes the consumption of a variety of fruits and vegetables, whole grains, fish, poultry, nuts, and low-fat dairy products. The DASH diet also limits intake of saturated fats, cholesterol, sweets and sugar-containing beverages. The diet is rich in magnesium, potassium and calcium, as well as protein, fiber, and… apparently nitrates. Could the Michigan State University’s findings shed a new, positive light on nitrates?
Nitrates are natural constituents of plants and are the main source of nitrogen needed for growth. More than 85 percent of a person's daily intake comes from nitrates in common vegetables included in a healthy diet. I.e. green, leafy, or root vegetables, such as lettuce, spinach, beets, cabbage and carrots.
Why add nitrates? Nitrites are added to meat to delay rancidity, stabilize flavor, and establish the characteristic pink color of cured meat. Specifically, sodium nitrite helps prevent the growth of Clostridium botulinum, which can cause botulism in humans. Sodium nitrate is also used as an ingredient in fertilizers, pyrotechnics, as a food preservative, and as a solid rocket propellant, as well as in glass and pottery enamels, and has been mined extensively for those purposes. Sodium nitrate is also used as a color fixative in cured meat and poultry products. Some examples of nitrate containing meats are bologna, hot dogs, and bacon; at most, approximately five percent of our daily nitrate intake comes from cured meats.
Nitrates can do harm…and maybe some good?
During the cooking process, nitrites combine with amines naturally present in meat to form N-nitroso compounds. The formation of these compounds is also suspected to occur in the human stomach. N-nitroso compounds are known carcinogens associated with cancer of the oral cavity, urinary bladder, esophagus, stomach and brain. Nitrites can also react with hemoglobin, the oxygen transporter in our blood, forming a structure that can no longer bind oxygen. The blood’s decreased capacity to transport oxygen results in a reduction of oxygen reaching the body’s tissues. If high enough levels of nitrites are consumed, cyanosis, rapid heart rate, weakness and loss of consciousness can occur due to lack of oxygen reaching critical cells. The harmful effects are thought to result from consuming “added nitrates” in cured meats, and contaminated water. The effects of naturally occurring nitrates in fruits and vegetables have not been extensively studied, but the recent evaluation of the DASH diet reveals the possibility of positive health benefits.
Keep in mind that the source of nitrates and nitrites, whether from its addition to cure meats or its natural occurrence in fruits and vegetables, is most likely what determines its impact on health. As we have discovered about fats, not all nitrates and nitrites are created equal. A diet rich in a variety of colorful fruits and vegetables is ideal, and look for cured meats processed without nitrates, especially during summer grilling season!