Ask a Dietitian

There is a lot of confusion around nitrates in our diets. Nitrates and Nitrites are naturally occurring nitrogen compounds with either 3 or 2 oxygen molecules respectively. They are found in soil, water plants and our bodies. Vegetables are the primary source of nitrates in our diets. Nitrates are also used as a preservative. For example, processed meats contain added nitrates/nitrites used to prevent the growth of bacteria causing listeria and botulism. These additives are also used as a means for enhancing colour and flavour. Nitrates are converted to nitrites by bacteria in meats. Research shows that when nitrates in meats are heated above 266 degrees F in the presence of amines (from amino acids in meat), they form nitrosamines, which are carcinogenic. Adding Vitamin C to foods containing nitrates helps prevent the conversion of nitrite to nitrosamine. That’s why you will see deli meats with ascorbic acid in the ingredient list. However, it is not clear if it is the nitrates in processed meats or other characteristics of processed meat that has classified them as a Class I carcinogen. Either way it is a good idea to reduce our consumption of processed meats. Nitrosamines are also produced when nitrites and amines combine in acidic places like the human stomach.

What about the nitrates found in vegetables such as beets, beet greens, arugula, spinach, parsley, fennel and celery seed? These vegetables contain more nitrates than deli meats. Plants pick up nitrates from soil, nitrogen based fertilizers, water and the atmosphere. When we eat nitrates the bacteria in our saliva converts them to nitrites. The vitamin C and antioxidants in fruit and vegetables helps to prevent the conversion to nitrosamine in the acidic environment of our stomach. Nitrites are then stored in our cells until they are converted into nitric oxide. Nitric oxide is known to cause vasodilation (relaxing of the arteries) and reduce blood pressure. Sports Scientists have been researching the effects of nitrate/nitrite supplementation on exercise performance. Studies show that nitrate supplementation from beet roots and beetroot juice can enhance physical performance in high intensity endurance exercise in non-elite athletes. The DASH diet also recommends a high intake of fruits and vegetables in order to lower blood pressure, possibly due to the nitrates in them.

The Bottom Line: Naturally occurring nitrates in vegetables such as leafy greens, beets, radishes and arugula have significant health benefits including vasodilation and reducing blood pressure. Supplementation with beetroot juice and other nitrate containing vegetables can improve physical performance. It is recommended to limit consumption of processed meats, in particular those processed with nitrates and avoid heating at high temperatures to prevent the production of nitrosamines which are carcinogenic.