Are carrots becoming less nutritious?

Claims that modern vegetables are significantly less nutritious than those from the 1950s due to depleted soil quality lack robust scientific evidence. While some historical databases show declines in minerals like calcium and iron, retired scientist Robin Marles notes that these records are often inconsistent due to changing analytical methods. However, long-term data from the Broadbalk wheat experiment reveals a genuine 20% to 50% decrease in zinc, iron, and magnesium concentrations since the 1960s. Professor Steve McGrath attributes this to the "dilution effect," where high-yield dwarf grain varieties prioritize carbohydrate production over mineral density. Crucially, this decline is linked to plant breeding and harvest index changes rather than a lack of nutrients in the soil itself. Despite global issues like erosion and carbon loss, there is no evidence that soil nutrients are being "washed out." Maintaining a varied diet remains the most effective way to ensure adequate nutrient intake.