Summer salads,
and how our food has changed in 70 years

One serving of my salad experienced nearly a 1/4 decline in 8 essential micronutrients since 1950. In other words, had I eaten my salad 70 years ago, it would have been 22% tastier.

Jokes aside, this chart highlights the distribution of salad components with regards to changes in micronutrient quantities since 1950. One serving of salad has seen a decline in a whopping 7 out of 8 micronutrients.

This is cause for concern. Micronutrients greatly impact our overall health, with deficiencies causing severe and even life-threatening conditions" according to the WHO. Deficiencies are preventable through nutrition education and proper food consumption -- but what about people who believe they are already eating enough produce to hit their micronutrient requirements?

We can take a look at the distribution of percent changes for each crop to better understand nutrient losses across U.S. produce.

This issue spreads beyond the produce involved in our salad. The 43 crops examined include other berries and fruit, staple crops such as potatoes and corn, leafy greens like spinach or cabbage, root vegetables like carrots, turnips, and parsnips, and many more. For each micronutrient highlighted in this chart, more than half of these crops experienced a decline. In some cases, they experienced a 100% decline, meaning the total loss of that nutrient. Unfortunately, the patterns noticed in the salad mirror overall U.S. trends.

Is it really so much of an issue? After all, we can get micronutrients elsewhere, through dairy or meat products. In fact, key micronutrients like iron or vitamin B2 are primarily found through those sources. Couldn't we just compensate with other foods?

While that may be true for some micronutrients, others are less lucky. Vitamin C experienced an average 28% decrease across the examined crops since 1950 and is primarily found through citrus fruits, berries, and (yes!) potatoes. Other lesser known micronutrients that also have a primary produce source include calcium, vitamin B1, and vitamin A.

Not to mention, many people have some form of restrictive diet that makes them rely more heavily on produce -- as someone with lactose intolerance, I can't rely on dairy for calcium (well, I could, but painfully).

However, things may not be too dire. While all micronutrients are still less present than their 1950 counterparts, we see some recovery, with vitamin A, calcium, phosphorus, and vitamin B2 improving up to 20 percentage points. Furthermore, calcium and vitamin A have produce as a primary source; their improvement means that produce is once again becoming viable way of including them in our diet.

It is particularly reassuring to see such an impressive vitamin A recovery, as vitamin A deficiency is one of the most experienced deficiencies in the U.S. Vitamin A is generally sourced from eggs, dairy products, and leafy, orange, and yellow vegetables -- with more available vitamin A in produce, which is generally cheaper and more accessible than animal products, we can hopefully combat these deficiencies more effectively.

Micronutrients are leached from the soil that the crops grow in, so researchers hypothesize that the decline in micronutrients is due to the aggressive planting and harvesting cycles that grew increasingly popular in the 1960s. By not letting the land rest between harvests, there are simply not enough micronutrients left to maintain the typical micronutrient levels we expect to see in produce.

However, in the late 1970s to early 1980s, new bills regarding regenerative agriculture were passed, leading to greater regulation of the land and crop cycles. Most famously among these reforms is the 1985 "Farm Bill" which amongst other changes introduced penalties for tilling prairie or grassland and converting wetlands to farmland, as well as paid farmers to let old land rest by taking it out of production and planting more native grassland. This was the first (land) conservation bill to be passed in the U.S., and I hypothesize it laid the foundations for the better agricultural practices that allowed some of the micronutrient losses to recover.


We're not out of the woods yet, however. We must still push for greater regenerative practices to be put into place to safeguard our soil for future generations. If we aren't careful, we will lose our crops, our health, and tasty summer salads.

About the data

This narrative was built through R and Adobe Illustrator for DATA1500 with Professor Fischer-Baum at Brown University (great class, definitely recommend!).

The data was sourced from USDA National Nutrition Database for Standard Reference as well as historical data drawn from the Department of Agriculture’s handbook #8 on produce’s nutritional values to the dataset. I used a pre-cleaned dataset from Kaggle for the former, and used this study (Davis et. al, 2004) to extract snippets from the latter.

Code available on GitHub.