You may have already read or heard that today's foods are less nutritious than those of the past. Have you wondered if this is a rumor, or if it is founded? Should we eat more fruits, vegetables, and grains to have the same nutrients?
Here is what science says about it:
Studies published in the early 2000s compared the seeds used in the past with those of today. These studies report that some of today's foods are indeed less nutritious.
In general, three hypotheses are proposed to explain these nutritional differences:
- the dilution effect
- soil degradation
- climate change.
The dilution effect
The 1960s, with the Green Revolution, led to more productive cultivars. Of course, this allowed more people on the planet to be fed. We thus demand an increase in yield from the soils. Consequently, the increased use of chemical fertilizers has doubled, if not multiplied tenfold, the yield of fruits, vegetables, and grains.
The dilution effect therefore refers to the difference between the increase in crop yield and the nutritional value of these crops, which does not appear to have increased to the same extent. Nutrients become diluted, shared among the different plants.
Soil degradation
The rapid growth of plants, known as intensive cultivation, is very demanding on the soil, with nutrients being extracted very quickly. Additionally, soil compaction caused by agricultural machinery contributes to soil degradation. However, degraded soils have a negative impact on the nutritional value of food, as plants are less able to draw nutrients from degraded soils than from healthy soils.
Farmers therefore add chemical or natural fertilizers to try to restore this balance, but according to Ms. Jacynthe Dessureault-Rompré, agronomist, it is still difficult to achieve good synchronization between the nutrient inputs given to the soils with the different fertilizers and the needs of the crop.
The climate changes
Finally, the increase in CO2 In the atmosphere accelerates the growth of food, which could in itself be good news, but which decreases their nutritional value, as they absorb fewer minerals (e.g., zinc, iron).
It is predicted that if greenhouse gas emissions continue at this rate, the iron content could decrease by 10% in wheat, rice, and soybeans. What is concerning is that a large part of the world’s population relies on these foods in their diet. Deficiencies could be expected.
Current Situation and Recommendations
Can a direct link be made between the decrease in nutrients in food and the fact that many Canadian adults have nutrient deficiencies such as magnesium, calcium, and vitamins A and D? Apparently, not yet. Canadian adults simply do not consume enough of them.
A 2017 study concedes that there is some truth to the idea that the nutrient content of certain foods has decreased.
However, this study supports that the changes are not significant nutritionally, and therefore are unlikely to have an impact on the nutritional health of consumers.
The study concludes by mentioning that the slight decreases in certain nutrients can easily be offset by following the recommendations of the Canadian Food Guide regarding the consumption of vegetables, fruits, and whole grains.
Indeed, only 30% of the Canadian population would follow the guide's recommendations and consume 5 to 10 servings of fruits and vegetables per day.
Future Perspectives
In conclusion, further studies are needed to better understand the causes of these decreases in certain nutrients, particularly climate change and increasingly demanding agriculture on soils, which could exacerbate this phenomenon in the coming years.
Could we add that it is important to take care of our planet. It is our pantry. (See article: What is sustainable food? And how to go about it?)
References:
- https://www.scientifique-en-chef.gouv.qc.ca/impacts/ddr-are-foods-less-nutritious-than-before-what-you-need-to-know/
- Marles, R. (2017). Mineral nutrient composition of vegetables, fruits and grains: The context of reports of apparent historical declines, Journal of Food Composition and Analysis, 56, 93-103.
- https://guide-alimentaire.canada.ca/en/