Why do we accept that the nitrate content is constantly increasing in our food, and is this a healthy development? The answer is clear. No, and I will try to explain the reason.

Nitrate occurs in minerals, soil, groundwater and the atmosphere. The general view is that nitrate is not harmful. Although we know that the body converts nitrate into nitrite and nitrite can cause health problems. The general view is also the legitimate reason why growers use this easily, because the nitrogen in nitrate helps plants to grow. Plants naturally extract nitrate from the soil, but it is also a common and widely used ingredient in fertilizers. In addition, factors such as light, temperature and season also play a role in the amount of nitrate that eventually ends up in crops. For example, the amount of nitrate in vegetables such as lettuce is seasonal. In winter it is about one and a half times as large as in summer. On average, a country’s head of lettuce contains 3.2 grams in the winter against 2.2 grams per kilogram. There is a lot of talk about the amount of nitrate we receive daily and what is (still) acceptable. What is striking is that globally the nitrate content in lettuce increases. This increase is mainly due to the increased use of synthetic nitrogen fertilizers and animal manure in intensive agriculture. There is now an increase in nitrate in fruit and vegetables, drinking water, meat and fish, cheese and bread. You see that the percentage has increased, especially in industrialized countries. (GEMS Food regional diets WHO, 1998)

The use of nitrate in Europe and America is clearly higher than in other countries. It is remarkable that little research is done into the actual intake of nitrate in the consumer. You have to look carefully for research and that is strange. The most recent survey (Food Standards Agency, 2004) comes from Slovenia and showed the average nitrate concentration of lettuce produced in greenhouses during the summer. This was found to be 2999 mg / kg (range 676-4382 mg / kg,); in the winter the average was 3617 mg / kg (range 1945-5720 mg / kg). The lettuce produced on land contained significantly lower concentrations both in summer (1140 mg / kg on average, 181-2656 mg / kg range) and in winter (1997 mg / kg average, range 810-3100 mg / kg).

Who sets the standard?

If we look at this development historically, we see that governments always adjust the permissible level to the increase in the nitrate content in the vegetables. We know that the use of artificial fertilizer has a clear influence on this. Only it is strange that the level of nitrate in for example lettuce is getting higher and higher. With this, the government consciously accepts that the nitrate burden on our health is also increasing. While they cover themselves with fixed tolerable daily intake (ADI) from 1990 onwards. So we see that in 1976 an average inhabitant of the Netherlands received 110mg of nitrate per day, and that was the norm at that time. In 1990 this was increased to 222mg per day (ministerial decree). Since 1990, the official standard for acceptable daily intake (ADI) nitrate is a maximum of 3.7 mg / kg body weight (EC, 1992). Thereafter, the ADI was retained (in 1995) and reduced an ADI of up to 0.06 mg / kg body weight for nitrite (EC, 1997). In 1990 the ADI was 0-3.7 mg / kg for nitrate and 0-0.07 mg / kg for nitrite. This is in line with WHO recommendations.

But they assume a person of 60 kg; it may consume 216 mg per day. Unfortunately, an average Dutchman (and American) now weighs 84 kg, so that may take 303 mg per day, almost three times the standard of 1976. Nothing shows that the safe standard is based on the amount of fat of a person (same stomach and mouth and body, only more fat). Moreover, this standard is based on the food products and nitrate values used at the time. If you look at the change in permissible standards in lettuce cultivation, we see the following:

These are the changed standards that the government (and EU) allows in the amount of nitrate in lettuce. You can see that in 1990 the lettuce had about 50% less nitrate. So when this is the norm, our nitrate load is now double that of 1990, and even more compared to 1975. Not 221 but about 500 mg per day. Or we should eat less and less of lettuce to avoid exceeding the daily amount of nitrate. But that is at odds with the message from the government, which advises us to eat more lettuce (vegetables) ?!

Further increase nitrate

The question is why we accept that nitrate levels are constantly increasing and whether if this is a healthy development.

It is known that organically-dynamically grown lettuce only contains 372 mg nitrate per kilo and organically grown vegetables have on average half as much nitrate as non-organically grown (Consumer Guide, February 2002). Organic cultivation of vegetables takes place in a soil that is not fertilized with artificial fertilizer; the plants get the time to mature. The nitrate content is remarkably low. The taste of the lettuce is clearly fuller, with the typical soft-sweet taste. The sugar and dry matter contents are higher. This lettuce does not wilt quickly and also keeps its freshness longer outside the fridge. In the self-dissolution test, it is seen that the decay process starts later and the lettuce is not so rotten. Another study (in America) confirms this result.

But it does not stay with an increase in nitrate in lettuce. Unfortunately, we see that after 2004 not only in lettuce but also in carrots, potatoes and other crops the nitrate content rises. Mean NO3 levels in conventional broccoli, cabbage, celery, lettuce and spinach cultivation were 394, 418, 1496, 851 and 2797 mg / kg FW, respectively, while the biological equivalents had marked averages of 204, 552, 912, 844 and 1318 mg / kg FW (2015). In addition, there is and there was a clear difference between different countries in Europe with regard to nitrate levels in food. The lettuce from the Mediterranean region around the turn of the century clearly had less nitrate than that from the Netherlands. It is of course known that the amount of sunlight is of influence, but what is very strange that despite the amount of light, you suddenly see the nitrate level in those countries rise enormously around 2008 (SERD@foodstandards.gsi.gov.uk). Currently, these values are even above the permissible level in the Netherlands. And the world keeps hiding behind the old standard of the WHO. Without taking into account the huge increase of nitrogen fertilizer and hydroponics.


Why then do we accept that increase? Nitrate is absorbed by adults mainly through vegetables and water (in the Netherlands). At least that is the conclusion of an investigation almost thirty years ago. Meanwhile, various forms of nitrate have been added to our food, such as sodium nitrate (E251) and potassium nitrate (E252). These nitrates (E251 and E252) account for approximately 5% of the total exposure to nitrates from all sources in each scenario and for each population group in our daily use (debatable, because a meat eater clearly gets more of this nitrate). Nitrate levels in vegetables vary widely and can vary from 1 mg / kg to 6800 mg / kg. Although leaf vegetables (spinach and arugula) contain the highest content of nitrates, on average 32% of the nitrates are consumed with potatoes and 29% with lettuce. In this article we do not explicitly discuss the development of the rising nitrate level in potatoes (75mg / kg in 1980 – 133 mg / kg in 1991- 200mg / kg in 1995), which has doubled again in recent years.

Different dietary habits, such as a vegan diet and, for example, the frequent eating of our Dutch endive stew with sausage, can lead to the ADI being exceeded. In addition, the changes in nitrate levels can increase to 75% during cooking. For the assessment of dietary intake of nitrate, you must now also consider other nitrate sources. In particular, the influence of food processing on the nitrate content in, for example, vegetables, of which currently insufficient data are published, must be taken into account. Another source is of course the nitrate content of water, which is between 20-50 mg per liter. On average, we drink two liters of tea, coffee and water per day. That is already half of what is permissible. And then we also have to include the air pollution of NO in the total load of our ammonia (NH3) to nitrate (NO3) – nitrite (NO2) to – NO (nitric oxide) load.

General view

The government and “experts” always hide behind the story that a nitrate ion as such is not toxic. But by the action of anaerobic bacteria in the oral cavity and the gastrointestinal tract, 5 to 20% of the nitrate ingested is converted into the much more toxic nitrite, which in turn is converted into nitrosamine in the stomach, which is strongly carcinogenic.

It is true that in the human organism nitrates also play a positive role, but certainly also a negative role. Which of these roles predominates depends mainly on the intake. The positive effect of nitrate on the human organism is in the conversion to NO, which has many positive physiological effects, including the control of blood pressure, improvement of cardiovascular health and support of gastrointestinal and immune function. The strange thing is that the general scientific consensus is that when there are too many nitrates there are apparently no harmful effects on these physiological processes. Nevertheless, the Health Council concludes that an important part of the direct health damage caused by reactive nitrogen is accounted for by air pollution, another part on account of (contamination of) drinking water and food.

The explanation

Nitrate is converted into nitrite in the mouth and then into a nitrosothiol (R-SNO) and this is converted into nitric oxide (NO). This causes small amounts of N-nitrosodimethyl and N-nitrosodiethylamine in the stomach. And here it ends, because N-nitrosamines have carcinogenic properties. In addition, only 4 to 8% of the nitrate in the saliva (total 20%) is converted into the mouth. The danger lies in the fact that nitrite can lead to the formation of methemoglobin (methemoglobinaemia) in both animals and humans, making oxygen transport through the blood more difficult. That is why it is only dangerous in babies. After all, the rest of the nitrate goes out of the body through our blood and urine. This is roughly the story that everyone uses and especially the government. Nothing wrong; that 4 to 8% can be overseen when you stick to the daily amount.

But we have seen that a mouth full of lettuce in 1990 contained half less nitrate than nowadays. So logically, that mouth full of lettuce now contains twice as much nitrate. So the amount of nitrate conversion in nitrite has also doubled. In addition to this lettuce we also consume many other foods, food additives and water with more nitrate, so more conversion to nitrite. For example, a mouth full of food quickly becomes a nitrite bomb.

The real story

1. The conversion of nitrate to nitric oxide is clear. We also know that nitric oxide is a free radical. And free radicals are atoms or molecules with an odd number of electrons that are very unstable and that damage cells in every interaction with healthy cells. So why is nitrate not stressful? A free radical is an extremely sensitive substance that only exists for a fraction of a second, but is capable of causing a lot of physical damage in that short time. It is now quite well known that cells in blood vessels and organs can be greatly affected by free radicals. The connective tissue of the skin is also affected by the free radicals, causing it to lose elasticity and wrinkles.

2. Nitrates are converted into, among other things, the smooth muscle cells of the vessel wall and in the blood in among other, nitric oxide (NO). A small part of the nitrite that is formed in the mouth is also reduced to nitric oxide (NO). Due to the increase in the amount of nitrate, we actually get an excess of nitrogen (NO) in our bodies. And here is the real danger, because nitrogen reacts with the substance peroxynitrite. This is the destroyer of brain and nerve cells, DNA and the surrounding tissue. This substance can even weaken the natural barrier between your blood and your brain so that toxic chemicals (chemicals / heavy metals) can penetrate your brain more easily. It is known that the reaction of NO with superoxide (O2 -) forms the more powerful oxidation substance peroxynitrite (ONOO-). A known and harmful substance (Nitric Oxide and Peroxynitrite in Health and Disease, PMC). Unfortunately, this is not reflected in the arguments to lower the level of nitrate.

Peroxoyitrite damages the mitochondria (power plants) of all cells. Peroxynitrite destroys blood plasma proteins and membranes of red blood cells and platelets. This explains why excessive production of peroxynitrite contributes to disease and aging. In addition, it is known that in several countries a positive relationship has been found between high nitrate intake and stomach cancer. Nitrate is also involved in bladder, ovarian, gastric and liver cancer (tseZou et al., 1996, Mueller et al., 2001, WeYer et al., 2001). In England, an ecological study showed that there was an increased incidence of tumors in adult brain and central nervous system in areas with high nitrate levels in drinking water (Johnson & Kross, 1990). A cohort study of more than 20,000 women found a positive correlation between nitrate water concentrations and bladder and ovarian cancer. Studies in Chinese populations exposed to high concentrations of nitrates in drinking water also suggested a link between nitrate infection and gastric and liver cancer (WeYer et al., 2001).

In other words: It is scientifically known that increased nitrate intake via the process to nitric oxide and peroxynitrite is dangerous for humans. Studies that demonstrate a clear relationship with cancer are again being questioned by other researchers. A well-known phenomenon. Who speaks the truth? But as far as the toxicity of peroxynitrite is concerned, there is no doubt. So the risks of elevated nitrate levels are knowingly and concealed.

Why do I publish this as “Hydroponics-Nederland. The reason for this is that the increased increase in nitrate is due to hydroponics (greenhouse cultivation) because we have been able to see how the differences in traditional, organic and greenhouse cultivation are. It is also a known problem in greenhouse cultivation. But it is a problem that arises from the aim to grow faster and more and to produce more. Growing a head of lettuce within 5 weeks is like rearing a chick within 6 weeks to a chicken. It is a commercial problem. The companies want to make more and faster money. And in the case of lettuce it is completely bad. Because commerce has made lettuce into a vegetable. A vegetable that we have to eat every day, and that was not “vegetables” 50 years ago. (You can read the story about lettuce in the next article.) Hydroponic cultivation is over. It is time for self-reflection and self-criticism. As Hydroponics Netherland I want to kick off here. The next step is to publish the nutrients of the vegetables that comes from this hydroponics greenhouses. Up to now no one wants to make this information public.

We must stand for a more sustainable and small-scale local healthy vegetable cultivation. Hydroponics is a good alternative in agriculture, provided the vegetables can grow fully with the right nutrients. And here the biological hydroponics can play a role.

Especially the Arab countries are flooded with nitrate via the hydroponic systems. An article about this will soon be published

©Ed van der Post