Just How Much Do We Know About Nitrates & Nitrites?

Articles
June 19, 2009

Just How Much Do We Know About Nitrates & Nitrites?

A study published just this week in the American Journal of Clinical Nutrition from Michigan State University reviewed the DASH diet (Dietary Approaches to Stop Hypertension), and found the human consumption nitrate intake up to 550 times that of the World Health Organization’s Acceptable Daily Intake (ADI) recommendation. Nitrate and Nitrite are compounds containing nitrogen and oxygen, the difference is that nitrate contains 3 oxygens and nitrite contains 2. 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 and fiber…and apparently nitrates! Could these findings of the Michigan State University’s study shed a new, positive light on nitrates?

A study published just this week in the American Journal of Clinical Nutrition from Michigan State University reviewed the DASH diet (Dietary Approaches to Stop Hypertension), and found the human consumption nitrate intake up to 550 times that of the World Health Organization’s Acceptable Daily Intake (ADI) recommendation. Nitrate and Nitrite are compounds containing nitrogen and oxygen, the difference is that nitrate contains 3 oxygens and nitrite contains 2. 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 and fiber…and apparently nitrates! Could these findings of the Michigan State University’s study shed a new, positive light on nitrates?

Nitrates are natural
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 of nitrite comes from nitrate in common vegetables included in a healthy diet and specifically the DASH diet plan. This includes, green, leafy, or root vegetables, such as lettuce, spinach, beets, cabbage and carrots. Vegetable intake analyzed in the study ranged from 174-1222mg, the upper level equivalent to 550 times WHO recommendation.

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 a color fixative in cured meat and poultry products. Some examples of nitrate containing meats are bologna, hot dogs, and bacon; at most, approximately 5 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 cured meats, and contaminated water. The effects of nitrates in fruits and vegetables have not been extensively studied - but the recent evaluation of the DASH diet reveals the possibility of positive health altering benefits.

According to the study’s authors, “The strength of the evidence linking the consumption of nitrate- and nitrite-containing plant foods to beneficial health effects supports the consideration of these compounds as nutrients.” No definite conclusions could be drawn from this study but instead an indication that more research is needed in regards to the health benefits of nitrates and nitrites from plant sources.

Let’s be clear: 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 it 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 recommended, and if you do enjoy cured meats look for those processed without nitrates or nitrites, and if you cannot find them, eat these foods in moderation!