You may have seen articles that claim that modern crops are less nutritious than the crops our ancestors raised due to depletion of nutrients from the soil.
This claim seemed plausible to me, so I had accepted it as true.
However, a recent conversation led me to this review article which suggests that such claims are misleading at best.
My take aways:
* It's incorrect to compare nutritional tables from the distant past to those in the present due to the impossibility for controlling for relevant variables (sampling technique, etc)
* When you compare modern soil samples to archived historical soil samples using the same modern techniques, there is no significant difference in soil composition.
* Crop samples _do_ show a decline in mineral content as a percentage of mass. However, those percentages declines are dwarfed by natural variation.
* Much of the apparent decline can be explained by the dilution effect--modern crops have the same mineral content as older varieties, but higher carbohydrate yields. So the mineral content is diluted by the carbohydrates.
Here's the article abstract:
"Reports of apparent historical declines in mineral nutrients of vegetables, fruits and grains, allegedly due to soil mineral depletion by agriculture, triggered this critical review. Comparisons of food composition data published decades apart are not reliable. Over time changes in data sources, crop varieties, geographic origin, ripeness, sample size, sampling methods, laboratory analysis and statistical treatment affect reported nutrient levels. Comparisons with matching archived soil samples show soil mineral content has not declined in locations cultivated intensively with various fertilizer treatments. Contemporaneous analyses of modern versus old crop varieties grown side-by-side, and archived samples, show lower mineral concentrations in varieties bred for higher yields where increased carbohydrate is not accompanied by proportional increases in minerals – a “dilution effect”. Apparent declines, e.g., the extreme case of copper from −34% to −81%, represent small absolute changes: per 100 g dry weight vegetables have 0.11–1.71 mg (1555% natural range of variation), fruit 01–2.06 mg (20,600% range), and grains 0.1–1.4 mg (1400% range); copper composition is strongly subject to the dilution effect. The benefits of increased yield to supply food for expanding populations outweigh small nutrient dilution effects addressed by eating the recommended daily servings of vegetables, fruits and whole grains."
https://www.sciencedirect.com/science/article/pii/S0889157516302113
This claim seemed plausible to me, so I had accepted it as true.
However, a recent conversation led me to this review article which suggests that such claims are misleading at best.
My take aways:
* It's incorrect to compare nutritional tables from the distant past to those in the present due to the impossibility for controlling for relevant variables (sampling technique, etc)
* When you compare modern soil samples to archived historical soil samples using the same modern techniques, there is no significant difference in soil composition.
* Crop samples _do_ show a decline in mineral content as a percentage of mass. However, those percentages declines are dwarfed by natural variation.
* Much of the apparent decline can be explained by the dilution effect--modern crops have the same mineral content as older varieties, but higher carbohydrate yields. So the mineral content is diluted by the carbohydrates.
Here's the article abstract:
"Reports of apparent historical declines in mineral nutrients of vegetables, fruits and grains, allegedly due to soil mineral depletion by agriculture, triggered this critical review. Comparisons of food composition data published decades apart are not reliable. Over time changes in data sources, crop varieties, geographic origin, ripeness, sample size, sampling methods, laboratory analysis and statistical treatment affect reported nutrient levels. Comparisons with matching archived soil samples show soil mineral content has not declined in locations cultivated intensively with various fertilizer treatments. Contemporaneous analyses of modern versus old crop varieties grown side-by-side, and archived samples, show lower mineral concentrations in varieties bred for higher yields where increased carbohydrate is not accompanied by proportional increases in minerals – a “dilution effect”. Apparent declines, e.g., the extreme case of copper from −34% to −81%, represent small absolute changes: per 100 g dry weight vegetables have 0.11–1.71 mg (1555% natural range of variation), fruit 01–2.06 mg (20,600% range), and grains 0.1–1.4 mg (1400% range); copper composition is strongly subject to the dilution effect. The benefits of increased yield to supply food for expanding populations outweigh small nutrient dilution effects addressed by eating the recommended daily servings of vegetables, fruits and whole grains."
https://www.sciencedirect.com/science/article/pii/S0889157516302113