Studies such as those by Donald Davies in the United States or by ANSES in France are unanimous: most of our foods (fruits, vegetables, grains) today contain, compared to half a century ago, fewer vitamins and minerals such as calcium, iron, vitamin C, or vitamin B2. Concentration decreases can range from 10 to 50% depending on the variety. The culprits behind this disastrous phenomenon: carbon dioxide pollution and the race for yield.
The concentration of carbon in the atmosphere due to fossil fuels has changed the way plants grow, leading to an increase in their sugar content and a decrease in essential nutrients including zinc.
The degradation of our food quality will cause a hidden famine: people will be able to consume the same number of calories but empty of their essential nutrients for well-being. While rich countries have the means to circumvent this deficiency, the same cannot be said for poorer nations. A study published in the journal Nature shows that by mid-century, an additional one billion people could suffer from anemia caused by iron deficiencies, which are responsible for pregnancy complications, stunted growth, and even death.
The harmful effects of nutrient depletion
It is estimated that immune system disorders linked to zinc deficiency are responsible for nearly half a million additional child deaths each year, due to otherwise treatable diseases such as diarrhea and pneumonia. According to a clinical study involving more than 10,000 pregnancies, women with severe anemia are seven times more likely to experience life-threatening bleeding during childbirth, and their babies are more exposed to health problems.
In 2018, a study by Nature Climate Change covering 150 countries attempted to show how carbon dioxide pollution would disrupt food deficiencies. It demonstrated that by 2050, 175 million people would suffer from problems due to zinc deficiencies and 122 million from protein deficiencies.
In wealthy countries, populations can escape these deficiencies by eating more meat or by taking dietary supplements or products fortified with vitamins or minerals. But these are only stopgap measures.
The best way to correct the effects of “vitamin dilution” is to diversify diets so that the deficiencies of one food are compensated by the richness of another.
Government policies have a role to play. Thus, according to the Washington Post, when the Indian government decided to subsidize rice and flour, there was a significant drop in the consumption of sorghum and millet, which have suffered much less from CO2 pollution! Governments should encourage the most nutritious crops rather than the most profitable ones. And, obviously, the ultimate solution would be to reduce our carbon dioxide emissions.
The causes of nutritional loss
There are three of them:
- Yield at all costs: Modern agriculture selects plant varieties for their rapid growth, disease resistance, and yield per hectare. However, a plant that grows twice as fast or produces larger fruits biologically does not have the time to produce or draw as many micronutrients proportionally to its size. Sugar and water increase but minerals are diluted.
- Soil life and depletion: The intensive use of chemical fertilizers (mainly the Nitrogen-Phosphorus-Potassium trio or NPK) feeds the plant so that it grows but often neglects the soil’s microbial complexes. Microscopic fungi (mycorrhizae) that normally help roots absorb zinc, magnesium, or copper are less active in overexploited soil. If the soil becomes depleted in micro-elements, the plant contains less of them.
- Logistics and harvesting before maturity: A large part of the vitamins (notably vitamin C) is synthesized in the last days of ripening in the sun. To travel long distances, fruits are often picked green. They ripen in warehouses or trucks, developing their pigments but not their full vitamin potential. Moreover, prolonged storage rapidly degrades vitamins sensitive to light and air.
Climate change
It plays a significant role through the increase of carbon dioxide (CO2) in the air. This mechanism, described as “carbon dilution,” modifies the very biology of plants.
- The Junk Food effect of high CO2: Those who oppose efforts to reduce carbon emissions claim that carbon dioxide is “plant food.” But without a corresponding increase in mineral absorption, plants are unable to produce more proteins, acids, and other molecules that make them nutritious. The result is that crops have the potential to grow larger and faster and produce higher yields, but every bite of food will contain more sugar and fewer nutrients than before.
However, mineral absorption by roots does not keep up with this accelerated pace. The result: the plant produces more biomass, but its concentration of essential nutrients drops. Large-scale studies, notably at Harvard, show that when crops are exposed to the levels expected by 2050, significant decreases are observed:
- Zinc and iron decrease by 5% to 10% in wheat, rice, soy, and corn.
- Proteins also drop by 5 to 8% in these same staple cereal crops.
- Between 1988 and 2040, zinc concentration would decline by 40% in chickpeas.
- Disruption of plant transpiration: To absorb minerals from the soil, plants rely on the flow of water that rises from their roots to their leaves, driven by transpiration. However, when there is a lot of CO2 in the air, the plant partially closes small pores on the leaves (stomata) to avoid losing too much water. By closing, the plant transpires less, which slows the movement of water from the soil upward. Soluble minerals like calcium and magnesium then have great difficulty climbing to the leaves and fruits.
- Heat and water stress: repeated heat waves and droughts modify the chemical structure of plants. Under intense heat stress, a plant first seeks to survive, it shuts down its circuits, its photosynthesis slows down, and it consumes its own energy reserves. Fruits and grains harvested after an extreme summer heatwave show degraded nutritional profiles compared to a normal climate year.
