Contemporary Dietary Recommendations and Food Sources of Nitrate and Nitrite

by: Penny Kris-Etherton

A healthy dietary pattern is recommended for health, well-being and the prevention of chronic diseases (1). It features vegetables, fruits, grains, dairy, protein foods, and vegetable oils, and is low in saturated fat, added sugars and sodium (1).  The three food-based healthy eating patterns (shown in Table 1) that have been recommended in the 2015-2020 Dietary Guidelines for Americans include:  the Healthy U.S.-Style Eating Pattern, the Healthy Mediterranean-Style and the Healthy Vegetarian Eating Patterns (1).

Table 1.  Three Healthy Eating Patterns (2000 Calories)

Food Group Healthy US Style Eating Pattern Healthy Mediterranean-Style Eating Pattern Healthy Vegetarian Eating Pattern
VEGETABLES 2 ½ c-eq/day 2 ½ c-eq/day 2 ½ c-eq/day
Dark green 1 ½ c-eq/wk 1 ½ c-eq/wk 1 ½ c-eq/wk
Red and orange 5 ½ c-eq/wk 5 ½ c-eq/wk 5 ½ c-eq/wk
Legumes (beans and peas) 1 ½ c-eq/wk 1 ½ c-eq/wk 3 c-eq/wk
Starchy 5 c-eq/wk 5 c-eq/wk 5 c-eq/wk
Other 4 c-eq/wk 4 c-eq/wk 4 c-eq/wk
FRUITS 2 c-eq/day 2 ½ c-eq/day 2 c-eq/day
GRAINS 6 oz-eq/day 6 oz-eq/day 6 ½ oz-eq/day
Whole grains ≥ 3 oz-eq/day ≥ 3 oz-eq/day ≥ 3 ½ oz-eq/day
Refined grains ≤ 3 oz-eq/day ≤ 3 oz-eq/day ≤ 3 oz-eq/day
DAIRY 3 c-eq/day 2 c-eq/day 3 c-eq/day
PROTEIN FOODS 5 ½ oz-eq/day 6 ½ oz-eq/day 3 ½ oz-eq/day
Seafood 8 oz-eq/wk 15 oz-eq/wk
Meats, poultry, eggs 26 oz-eq/wk 26 oz-eq/wk 3 oz-eq/wk (eggs)
Nuts, seeds, soy products 4 oz-eq/wk 4 oz-eq/wk 14 oz-eq/wk
OILS 27 g/day 27 g/day 27 g/day
Limit on Calories for Other Uses
(% of calories)
270 kcal/day (14%) 260 kcal/day (13%) 290 kcal/day (15%)

 

The food-based recommendations for these three eating patterns are very similar, especially for vegetables, fruits, grains, dairy products and vegetable oils.  They differ in the type and amount protein foods recommended.  As would be expected, the Healthy Vegetarian Eating Patterns recommends mostly plant foods as a protein source (i.e., nuts, seeds and soy products).

The current recommendation for fruits and vegetables is 4 ½ to 5 cup equivalents per day (for 2000 calories per day), which is equal to approximately 9 to 10 servings per day.  Current intake data clearly indicate that Americans 19 years of age and older are woefully under-consuming recommended amounts of fruits and vegetables.  For fruits, females consume between 0.9 to 1.3 cup equivalents and men consume 0.9 to 1.4 cup equivalents (1).  For vegetables, females consume 1.4 to 1.8 cup equivalents and males consume 1.8 to 1.9 cup equivalents (1).  As is apparent, major increases in intakes of fruits and vegetables are needed to meet current dietary recommendations.

In addition to providing many essential nutrients, i.e., dietary fiber, potassium, vitamin A, vitamin C, vitamin K, copper, magnesium, vitamin E, vitamin B6, folate, iron, manganese, thiamin, niacin, and choline fruits and vegetables are also a source of nitrate and nitrite [precursors for nitric oxide (NO) synthesis in blood and tissues).   Fruits and vegetables vary considerably in their nitrate content (presented in Table 2).

Table 2.  Classification of some Fruits and Vegetables According to Nitrate Content

Nitrate content (mg/100 g) fresh weight Vegetables and Fruits
Very low, <20 Artichoke, asparagus, broad bean, eggplant, garlic, onion, green bean, mushroom, pea, pepper, potato, summer squash, sweet potato, watermelon, apple sauce, banana, orange
Low, 20 to <50 Broccoli, carrot, cauliflower, cucumber, pumpkin, chicory, tomato
Middle, 50 to <100 Cabbage, dill, turnip, savoy cabbage
High, 100 to < 250 Celeriac, Chinese cabbage, mustard greens, endive, fennel, kohlrabi, leek, parsley
Very high, > 250 Celery, cress, chervil, lettuce, red beetroot, spinach, collard greens, rocket (rucola)

From reference #2.

In addition to variation in nitrate content among different fruits and vegetables, there also is variability due to geographic marketplace and agricultural production practices.  Nunez de Gonzalez et al. (3) conducted a national survey of nitrate and nitrite concentrations in conventional and organic vegetables at retail.  A notable finding was that both nitrate and nitrite concentrations varied appreciably among different cities surveyed in the U.S.  For example, the mean nitrate concentration of spinach sold in Chicago was 647 ± 69 mg/Kg of fresh weight whereas in Raleigh it was 3155 ± 145 mg/Kg.  Interestingly, for celery there was an approximate 10-fold difference in the amount of nitrate depending on the city surveyed.  The authors also noted that there were few differences in the nitrite content of conventional and organic vegetables in five different markets surveyed (3).  There were some differences in the nitrate content of conventional versus organically grown vegetables with the latter being lower.  The authors suggested that the differences in the amount of nitrates and nitrites in the same vegetable from different geographic retail markets were likely due to different production practices, seasonal differences, soil type, among other factors.

Collectively, the research indicates that there is considerable variation in the content of nitrate and nitrite in different vegetables and fruits, as well as within a specific vegetable/fruit.  It is apparent that even in individuals who meet current recommendations for fruits and vegetables, there could be marked variability in nitrate and nitrite intake, depending upon which vegetables/fruits were included in the diet and where they were purchased.  To illustrate this point, Hord et al. (2) developed two hypothetical dietary patterns that met current dietary recommendations for fruits and vegetables with either high nitrate or low nitrate vegetables and fruits.  The authors reported that nitrate concentrations ranged markedly from 174 to 1222 mg.  Based on the marked variability in nitrate and nitrite as discussed above, it is challenging to have reliable estimate of intake over time in either individuals or the population.

Conclusion

Meeting current dietary recommendations for vegetables and fruits will improve the nutrient quality of the U.S. diet and also increase nitrate and nitrite intake.  The specific fruits and vegetables that are included in the diet will affect both the nutrients consumed, as well as the intake of nitrates and nitrites.  A key public health goal is to close the gap between dietary recommendations and current intakes in the U.S. for fruits and vegetables to improve the health of Americans.

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References

  1. US Department of Health and Human Services/US Department of Agriculture. 2015-2020 Dietary Guidelines for Americans. 8th ed. December 2015. Available at: http://health.gov/dietaryguidelines/2015/guidelines/.
  2. Hord NG, Tang Y, Bryan NS. Food sources of nitrates and nitrites:  The physiologic context for potential health benefits.  Am J Clin Nutr. 2009;90:1-10.
  3. Nunez de Gonzalez MT, Osburn WN, Hardin MD, Longnecker M, Garg HK, Bryan NS, Keeton JT. A survey of nitrate and nitrite concentrations in conventional and organic-labeled raw vegetables at retail. J Food Sci. 2015;80:C942-C949.

 

Author

Penny Kris-Etherton, PhD RD

Dr. Penny Kris-Etherton is the Vice-Chair of the AHA Council on Lifestyle and Cardiometabolic Health, past Chair of the American Heart Association (AHA) Nutrition Committee, and a Distinguished Professor of Nutrition at Penn State University. With a research program focused on exploring how nutrients and other bioactive constituents affect established and emerging risk factors for cardiovascular disease, her connection to HumanN is apparent. Dr. Kris-Etherton has published over 150 scientific papers, 10 book chapters and co-authored four books. Her research program has been funded by the National Institutes of Health, USDA and the private sector. She has also served on many national committees and review panels including the 2005 Dietary Guidelines for Americans Advisory Committee, the National Academy of Sciences Panel on Macronutrients, the American Heart Association Nutrition Committee as Chairperson, NIH’s Nutrition Study Section, the National Cholesterol Education Program Second Adult Treatment Panel, and WomenHeart.

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