Nitrite and Nitrate Benefits

Study Finds That Nitrites and Nitrates Offer Cardiovascular Health Benefits
Editor: Jay B. Wenther
July 1, 2009

Nitrate and nitrite intake can play a valuable role in reducing blood pressure for those following the well-regarded Dietary Approaches to stop Hypertension(DASH) diet, according to a new study published in the American Journal of Clinical Nutrition.

Approximately 80% of dietary nitrates are derived from vegetable consumption; sources of nitrites include vegetables, fruit, and processed meats. Nitrites are produced endogenously through the oxidation of nitric oxide and through a reduction of nitrate by commensal bacteria in the mouth and gastrointestional tract. As such, the dietary provision of nitrates and nitrites from vegetables and fruit may contribute to the blood pressure-lowering effects of the DASH diet.

Michigan State researcher Norman G. Hord collaborated with University of Texas Health Science Center researchers Yaoping Tang and Nathan Bryan in qualifying levels of nitrites and nitrates in high-nitrate or low-nitrate vegetable and fruit choices based on the DASH diet. According to their analysis, the nitrate concentrations in these patterns - deemed healthy and even theraputic - ranged as high as 550 percent above the World Health Organization's (WHO) acceptable daily intake for an average adult.

About 93% of human dietary nitrate comes from vegetables and saliva. Nitrate in vegetables like spinach, lettuce and beets are converted to nitrite in the mouth. Nitrite is used as a curing ingredient in meat to stabilize color and flavor and to prevent rancidity. However, cured meats contribute less than five percent of total human nitrite intake, other studies show.

"These data call into question the rationale for recommendations to limit nitrate and nitrite consumption from plant foods; a comprehensive re-evaluation of the health effects of food sources of nitrates and nitrites is appropriate," the authors wrote.

"The DASH diet forms the basis for public dietary health recommendations in the United States (e.g, MyPyramid.gov) and is widely recommended by private health agencies, such as the American Heart Association. Taken together, the data considered here support the conclusions of the European Food Safety Authority that benefits of vegetable and fruit consumption outweigh any preceived risk of developing cancer from the consumption of nitrate and nitrite in these foods," the researchers wrote. "The strength of the evidence linking the consumption of nitate and nitrite containing plant foods to beneficial health effects supports the consideration of these compounds as nutrients."

The study was funded by the Michigan Agricultural Experiment Station, Michigan State University, and the American Heart Association. The complete study is available for your review through AAMP's website at www.aamp.com.

Source: Food sources of nitrates and nitrites: the physiologic context for potential health benefits
Authors: Norman G. Hord, Yaoping Tang, and Nathan S. Bryan
American Journal of Clinical Nutrition - 2009;90:1-10. 2009 American Society for Nutrition