Leafy crops like spinach generally have higher nitrate concentrations. Photo: Racool_studio/Freepik
Australian biomedical research is once again at the forefront with innovative work on nitrates, which is once again provoking controversy about its role in human health. On the other hand, nitric oxide (NO*) shows a cardiovascular benefit; on the other hand, nitrates are considered carcinogenic elements in certain foods.
Therefore, it is not surprising that the researchers of Edith Cowan University (Australia), led by Professor Catharina Bondonno, wrote their study in this way: Nitrate: Dr. Jekyll and Mr. Hyde of human salvation? (Nitrate: Dr. Jekyll and Mr. Hyde of human health?).
For the authors of this work, which appears in Trends in Science & Technology, the basic aspects can be summarized as follows: nitrate, through NO*, seems to be beneficial to humans, but through carcinogenic N-nitrosamines, although not. it is more fully supported by evidence; It is uncertain whether the binomial damage is the same as the source of nitrate in vegetables, meat and water.
For more than half a century, these Australian researchers recall, the nitrate content of the three main sources of purity (vegetables, meat and water) was widely, regulated and monitored due to public health concerns about the risk of cancer.
On the other hand, an effective and growing body of evidence indicates that pure nitrate, especially from vegetables, protects against cardiovascular and other chronic diseases.
This evidence for the protective effect of nitrates is consumed from the potential of nitrates to form carcinogenic nitrosamines.
They recall that definitive studies examining the beneficial or harmful effects of nitrates, according to the source, have not yet been completed.
Studies with better exposure assessment and accurate characterization of the factors affecting endogenous nitrosation are also necessary to draw conclusions about the risk of cancer from pure nitrate intake.
Since nitrate is part of the nitrogen cycle, it plays a major role in plant nutrition and functioning.
Bondonno’s team suggests that the variation in nitrate content of food plants is due to genetic, environmental and cultural factors, as well as post-harvest conditions, including storage and processing methods.
This scientist can lay the key to the origin of nitrates and states that they are obtained from three main sources of purity: food, water, and vegetables. “Nitrate starvation as a health threat goes back to the 1970s, when two studies showed that it can form N-nitrosamines, which are highly carcinogenic in laboratory animals,” he recalls.
“However, no studies in humans – he adds – have confirmed its potential risks, but our clinical and observational studies support that nitrate prevents cardiovascular diseases if it is of plant origin.”
Finally, he emphasizes that “the possible connection of nitrates with cancer was raised fifty years ago; now is the time for a deep analysis to distinguish reality from fiction.
Despite his youth, Dr. Bondonno is President of the Perth Regional Group of the Australian Nutrition Society and a member of the Australian Academy of Sciences. She is associate editor of Food & Function and co-editor of the Asia Pacific Journal of Clinical Nutrition.
Nitrates, naturally in the environment
According to the Spanish Agency for Food Safety and Nutrition, nitrates are compounds that are naturally present in the nitrogen cycle, but can be altered by various agricultural and industrial activities.
Nitrates are widely found in foods. The main source of human exposure to nitrates is the consumption of vegetables and, to a lesser extent, drinking water and other foods.
Some plant species accumulate nitrates in their green parts. Therefore, leafy greens like lettuce and spinach usually have higher concentrations of nitrates. They are also used in agriculture as fertilizers and in food processing as a common fuel additive.
Nitrate itself is relatively non-toxic. Its toxicity is determined by conversion to nitrite. Nitrate can be converted to nitrite by bacterial reduction both in food (during processing and storage) and in the body itself (in saliva and the gastrointestinal tract).
Nitrites in the blood oxidize iron in hemoglobin producing methemoglobinemia, unable to transport pain, most common in children exposed to concentrations of nitrates in food (Blue Baby Syndrome).