Higher Yields Trade-off
One reason for this decline can be attributed to genetic engineering (GE) of plants and vegetables to produce higher yields. The trade-off between higher yields is lower nutrients. Faster growing and higher yielding GE seeds and plants do not develop the root systems that plants used to have. A shorter root system does not allow the plants to absorb as many nutrients from the soil as they used to. This is also true with hybrid vegetables and plants.
Hybridization is pollination that’s carefully controlled to ensure that the right plants are crossed to achieve the desired combination of characteristics, such as bigger size, early maturity, better yield and longer shelf life. Even with organic produce, you can have nutrient depletion as hybridization is looking to create produce with favorable traits that you’d find at a supermarket. The nutritional tradeoffs are not visible, but can usually be tasted. Speaking of taste, modern fruits and vegetables are also genetically modified to increase their sugar content, not their nutrient value. As a result, most of the common fruits and vegetables are high in sugar and lower in key nutrients.
Healthy soil is important. Improper farming practices like monocropping deplete the soil of nutrients is another reason. When plants are repeatedly grown on the same land, the soil loses nutrients faster than can be replaced organically. Plants get much of their nutrients from the soil, so the loss of nutrients in plants starts with the loss of nutrients in the soil. Chemical fertilizer applied by farmers contains just enough nutrition for the plant to survive until harvesting, but not enough to support human health.
In addition, most plants are not harvested fresh. They sit on transport trucks, grocery shelves, and kitchen counters for weeks before being eaten. Over time, the nutrient content of these plants decreases. Certain vitamins including vitamin A, B2, B6, B12 and folic acid all experience nutrient degradation due to long exposure to light and oxygen after they’ve harvested.
Organic Farming Methods
Organic farming methods, on the other hand, use manure to provide nutrition to crops, have more balanced mixtures of nutrients, and tend to release the nutrients slowly, forcing plants to develop more robust root systems that more aggressively absorb nutrients from the soil profile, and produce crops with higher concentrations of valuable nutrients. Organic food may have as much as 20 percent higher nutritional content for some minerals, and 30 percent more antioxidants on average, than conventional produce.
A University of Texas study of 43 plants found that nutrient values have decreased in the last 50 years. This study found nutrient losses ranged from 6% for protein and a 38% loss of riboflavin. Another study done by the USDA (United Stated Department of Agriculture) reported a decline in food quality in 12 common garden vegetables. These included broccoli, cabbage, carrots, cauliflower, collard greens, kale, mustard greens, onions, parsley, turnip greens, and watercress. The decline averages in food quality over the last 50 years were in the following nutrients:
- 28% Riboflavin loss
- 20% Vitamin C loss
- 16% Calcium loss
- 15% Iron loss
- 9% Phosphorus loss
- 6% Protein loss
Despite these concerns, it’s still critically important to eat lots and lots of fruits and vegetables, and these developments shouldn’t discourage us from a healthy diet. It would be excess to say that the tomato you eat today has very little nutrition in it—but it is true that fruits and vegetables grown decades ago were much richer in vitamins and minerals than the varieties most of us get today from the grocery store. As a consumer, you do have a choice to eat higher nutrient foods. You can eat nutrient dense foods by growing your own vegetables whenever possible and buying from organic and local farmers.