Nitrates are chemical compounds, a common form of nitrogen found throughout the natural world. These molecules are present in soil, water, and living organisms, and understanding them involves recognizing their chemical makeup and environmental interactions.
What is a Nitrate Molecule
A nitrate molecule consists of one nitrogen atom bonded to three oxygen atoms, forming an ion with a negative charge (NO3-). This charge allows nitrates to readily dissolve in water, facilitating their movement through the environment. This structure contributes to their widespread presence and reactivity.
Nitrates in Nature and Our Diet
Nitrates occur naturally as part of the nitrogen cycle, a process that moves nitrogen through the atmosphere, soil, and living organisms. Plants absorb nitrates from soil and water. Significant dietary sources include leafy greens like spinach, lettuce, and arugula, along with root vegetables such as beets and celery. Processed meats, including bacon, ham, and hot dogs, also contain nitrates (specifically sodium nitrate or potassium nitrate), which are added as preservatives to inhibit bacterial growth and enhance flavor. Nitrates can also be present in drinking water, with levels varying due to agricultural runoff and and other environmental factors.
How Nitrates Transform in the Body
Once ingested, nitrates undergo transformations within the human body. Bacteria in the mouth and gastrointestinal tract convert a portion of these nitrates into nitrites, which are molecules with one nitrogen atom and two oxygen atoms (NO2-). These nitrites can then convert into nitric oxide (NO), a molecule beneficial for various bodily functions. However, under certain conditions, particularly in the presence of specific proteins and high temperatures, nitrites can also form compounds known as nitrosamines.
Health Effects of Nitrates
The health effects of nitrates are diverse, with both beneficial and potentially harmful outcomes depending on their transformation. When nitrites convert into nitric oxide, this molecule promotes vasodilation (widening of blood vessels), helping regulate blood pressure and support cardiovascular health. This improves blood flow and may enhance athletic performance by increasing oxygen delivery to muscles.
However, concerns exist regarding nitrosamine formation from nitrites, especially in processed meats. When cooked at high temperatures (e.g., frying or grilling), nitrites can react with amino acids to form nitrosamines, some of which are carcinogenic. Another concern is methemoglobinemia, a condition primarily affecting infants, where nitrites interfere with the blood’s ability to carry oxygen, sometimes called “blue baby syndrome.” To address risks, the U.S. Environmental Protection Agency (EPA) has established maximum contaminant levels for nitrate in drinking water, typically 10 mg/L, to protect public health.