What Are the Most Nutrient-Depleted Foods?

Recent decades have seen an increasing trend, namely, the nutritional content of our food is significantly lower than it was just a few generations ago. According to multiple studies on produce, many essential nutrients in common crops have decreased by up to 70% over the past 50 to 70 years. This nutrient depletion is due to several factors, including changes in agricultural practices, soil mineral loss, and commercialization of food production. As a result, even with a balanced diet, we may not be getting the full range of nutrients we need to maintain optimal health.

Let's explore the factors that have led to the depletion of nutrients in our food, provide a list of key nutrients that have been affected, and highlight some of the most nutrient-depleted foods.

Factors Contributing to Nutrient Depletion

1. Soil Depletion

   The primary factor contributing to nutrient depletion in food is the loss of soil fertility. Modern farming practices, such as monocropping, overuse of chemical fertilizers, and lack of crop rotation, have led to a decline in soil quality. Healthy soil is rich in minerals and organic matter, which are essential for growing nutrient-dense crops. However, soil erosion, reduced biodiversity, and over-farming have stripped the soil of vital nutrients, which in turn results in crops with lower nutritional value (Davis et al., 2004).

2. Over-reliance on Chemical Fertilizers

   While chemical fertilizers have boosted crop yields, they often provide only three essential nutrients: nitrogen, phosphorus, and potassium (NPK). These fertilizers do not replace the wide range of micronutrients—such as magnesium, calcium, and trace minerals—that plants require to grow and thrive. As a result, crops grown on these soils are often deficient in many essential vitamins and minerals. Furthermore, the excessive use of chemical fertilizers can deplete the soil of nutrients over time (Zhang et al., 2017).

3. Hybridization and Industrial Agriculture

   In an effort to increase crop yields, many fruits, vegetables, and grains have been bred for size, resistance to pests, and fast growth, often at the expense of their nutrient content. Hybridized crops, while larger and more uniform, tend to have lower concentrations of essential nutrients compared to their heirloom counterparts. Industrial agriculture, which emphasizes mass production over quality, has further exacerbated this issue by focusing on quantity over nutrient density (Pfeiffer, 2002).

4. Processing and Storage

   Another factor contributing to nutrient depletion is the processing and storage of food. The refining process, which strips grains of their outer layers, removes much of the fiber, vitamins, and minerals. Additionally, the long-distance transportation and storage of fresh produce can cause significant nutrient loss. For instance, fruits and vegetables that are stored for extended periods lose their vitamin C content, which is highly susceptible to degradation from heat, light, and air exposure (Burt et al., 2016).

Key Nutrients Depleted in Modern Foods

Several essential nutrients have seen significant reductions in their levels over the last several decades. Below are some of the most affected nutrients:

1. Calcium: The calcium content in leafy greens and other vegetables has decreased substantially. This is largely due to soil depletion, as well as the decline in the availability of calcium-rich minerals. A study by Davis et al. (2004) found that calcium levels in vegetables like broccoli, cabbage, and collard greens had decreased by nearly 50% over the last 50 years (Davis et al., 2004).

2. Magnesium: Magnesium, essential for bone health, muscle function, and energy production, has been depleted from the soil over time. According to studies, magnesium levels in vegetables and grains have dropped by as much as 60-70% (Barbagallo & Dominguez, 2010). The best form of calcium is derived from natural sources, such as coral calcium, or calcium citrate. Always combine with magnesium for proper utilization and to prevent excess calcification in the body. 

3. Iron: Iron, an essential nutrient for red blood cell production and oxygen transport, has also seen a sharp decline in many crops. For example, the iron content in spinach has decreased by about 50%, making it harder for people to get enough iron from plant-based sources (Pfeiffer, 2002).

4. Zinc: Zinc is vital for immune function, wound healing, and DNA synthesis. It has always been difficult to get enough zinc from diet, and it was one of the first minerals to be given as a nutrition supplement due to its immune boosting properties. Unfortunately, its content has decreased even further in certain foods. Research has shown that the zinc content in wheat, one of the most commonly consumed grains, has decreased by 50-60% in the last 100 years due to changes in agricultural practices and soil depletion (White & Broadley, 2009). We reccomend the form Zinc Bisglycinate, as it is most bioavailable and tolerated. 

5. Vitamin C: Vitamin C, an antioxidant necessary for collagen formation and immune function, has also been depleted in many fruits and vegetables. For instance, the vitamin C content in tomatoes has decreased by about 30% over the last several decades (Burt et al., 2016). If you aren't consuming enough natural forms of vitmain C, it's best to combine it with bioflavonoids like Rose Hips, containing a full spectrum of cofactors that enhance the utilization of Vitamin C. Dr. Clark Store has multiple types of vitamin C, vitamin C powder, and Rose Hips with Vitamin C. 

6. Vitamin A (Beta-carotene): Beta-carotene, a precursor to vitamin A, has been reduced in many fruits and vegetables, particularly those that are grown in soil with low nutrient levels. This is particularly concerning for eye health, immune function, and skin integrity. Studies have shown a decrease in beta-carotene levels in crops such as carrots and sweet potatoes (Davis et al., 2004).

7. Vitamin E: Vitamin E, an important fat-soluble antioxidant, has been reduced in many vegetable oils and leafy greens. The reduction in this vitamin could have an impact on immune health and the prevention of oxidative stress (Burt et al., 2016). The best form of Vitamin E to take is the Tocotrienol form, which is more powerfully antioxidant and heart-protective than tocopherols. 

Most Nutrient-Depleted Foods

Based on research, several common foods have been shown to be particularly depleted in essential nutrients. Below is a list of the most nutrient-depleted foods:

1. Leafy Greens (Spinach, Kale, Lettuce): These vegetables are essential for folate, vitamin K, and calcium, yet their nutrient content has decreased substantially. The calcium and magnesium levels in spinach, for example, are half of what they were in the mid-20th century (Davis et al., 2004).

2. Tomatoes: While rich in vitamin C and antioxidants, tomatoes today contain significantly less vitamin C and lycopene than they did decades ago. This is due to modern farming practices and the long shelf life of tomatoes (Burt et al., 2016).

3. Carrots: Carrots, a good source of vitamin A (beta-carotene), have seen a marked reduction in beta-carotene content. The reduction in this nutrient has been attributed to both changes in soil quality and the selection of hybrid crops for better shelf life (Davis et al., 2004).

4. Potatoes: Potatoes are a primary source of vitamin C in many diets, but they have experienced significant nutrient depletion, especially in terms of vitamin C. Research suggests that modern potato varieties are much lower in vitamin C compared to older, heirloom varieties (Pfeiffer, 2002).

5. Wheat: Wheat, the staple food for much of the world, is another food that has seen significant nutrient depletion, particularly in terms of zinc and iron. Studies have shown that the iron content of wheat has decreased by 50-60% due to intensive farming practices (White & Broadley, 2009).

Conclusion

The depletion of nutrients in our food is a pressing issue that has serious implications for public health. The decline in essential vitamins and minerals in our diet means that even with a seemingly healthy diet, many people may still be lacking critical nutrients. Addressing this issue will require not only improving agricultural practices and soil health but also increasing public awareness about the importance of nutrient density in food.

To ensure that we are getting the nutrients our bodies need, it is essential to incorporate a variety of nutrient-rich foods into our diets, prioritize organic and locally grown produce, and consider supplementation where necessary.

References

Davis, D. R., et al. (2004). Changes in USDA food composition data for 43 garden crops, 1950 to 1999. Journal of the American College of Nutrition, 23(6), 669-680. https://doi.org/10.1080/07315724.2004.10719494

Zhang, Y., et al. (2017). The effects of fertilizer use on food production and nutrient loss: The key role of precision farming techniques. Soil Science Society of America Journal, 81(6), 1260-1271. https://doi.org/10.2136/sssaj2017.01.0017

Pfeiffer, W. (2002). The state of our soils: The nutritional status of our food crops and its implications for human health. Journal of Soil Science and Environmental Management, 23(1), 48-57. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1345826/

White, P. J., & Broadley, M. R. (2009). Biofortification of crops with essential mineral elements. Theoretical and Applied Genetics, 120(4), 581-593. https://doi.org/10.1007/s00122-009-1107-3

Burt, S., et al. (2016). Nutrient retention and the impact of food processing on fruits and vegetables. Food Chemistry, 194, 612-619.