Written by Katinka Lennemann, Data Evaluation Intern
Why is our produce less nutritous?
Studies have found that the produce that we grow today has less nutritional value than produce of the past. In other words, the apple your grandma was eating probably had more nutrients than the ones you could acquire today. What is the source of this trend, and what can we do today about it?
A 2009 study from HortScience of produce from the United States and the United Kingdom found inverse relationships between crop yield and how much nutritional value they had. In other words, the researcher found that the higher the amount of a certain crop harvested, the less nutrients it had—the “dilution effect”. Comparisons to historical food composition data found median declines from 5% to 40% of various minerals, which indicate that these declines aren’t just minor fluctuations. 
These findings are significant because although getting calories and macronutrients (proteins, carbohydrates, and fats) is important, it’s also critical to make sure that the body is getting adequate amounts of vitamins and minerals, or micronutrients. These micronutrients help keep the body running smoothly and protect against various diseases such as cancer, diabetes, and heart disease.  Although there are many supplements and vitamin pills that people can take to ensure the inclusion of these nutrients in one’s diet, there’s no research suggesting that pills have any particular advantages over simply eating nutritious whole foods such as fruits and vegetables.
As such, thinking about the nutrition profile of our produce is important to consider. One commonly cited explanation for this decline in nutrients is the degrading quality of soil from overfarming, otherwise known as soil depletion. An article from 2013 for instance analyzed magnesium and found that a reduction in the amount of magnesium in soil was reflected in less magnesium that plants could absorb and grow with.  Given this issue, practices such as crop rotation can help the soil regenerate nutrients because different plants interact with the soil and deposit certain nutrients over others, but such practices are not necessarily widespread in farming. 
However, this article from the NYTimes notes that declining nutritional value of crops could be more strongly attributed to changes in cultivated varieties that farmers choose to grow.  Indeed, the 2009 study backs up this suggestion, suggesting that when farmers grow crops, they mostly select crops that maximize the amount produced rather than assessing the micronutrient array of a certain variety. Therefore, the crops grown are more likely to be ones that prioritize higher yields rather than how much vitamins, minerals, and proteins they have, resulting in overall trends of dropping micronutrients in vegetables and fruits crops. 
How can I get more nutritious produce?
More research is needed to better understand the relationships between soil depletion, produce nutrition, and farming methods. Either way though, one way to circumvent this issue is growing your own vegetables and fruit. Home grown produce can sometimes be more nutritious than those from a supermarket, which sometimes must be picked early which lowers their potential nutrient profile.  Given the other advantages to home gardening such as mental health benefits and fresh produce in one’s diet, declining fruit and vegetables composition simply provides another angle by which to support urban gardening within communities.