Maybe you’ve heard recently that many of the fruits and vegetables produced have experienced a decline in their levels of nutrients. In fact, reports from both the U.S. and U.K. governments revealed that the levels of iron, zinc, calcium, selenium, and other nutrients have experienced a double-digit decline in the last few decades. The primary cause, I’ve read in the past, has to do with the depletion of soil nutrients making them less available for plants.
The report I just read by Brian Halweil entitled Still No Free Lunch: Nutrient levels in U.S. food supply eroded by pursuit of high yields, explains that the issue is much more complicated than soil alone. For example, much has to do with the new breed of crops that have been engineered to produce higher yields. Today, three times more corn can be harvested per acre than in the 1940’s.
And while the overall nutrients produced per acre may not have changed, the nutritional value per ear of corn has gone down since there are less nutrients available per plant. In fact, the higher the yield, the lower the protein content. This is true for many high-yield crops, including wheat, tomatoes, and broccoli, and beans. For example, high-yield soybeans have less protein and a lower oil content, and tomatoes have lower levels of vitamin C, lycopene, and beta-carotene. On the flip side, growing organic can increase the density of vitamins, minerals, antioxidants, and phytochemicals, and reduce the amounts of starches, sugars, and water, although this produces smaller fruits and vegetables.
Next is the heavy use of fertilizers and irrigation that lead to atrophied roots on the plants that cannot take up as many micronutrients. There’s no reason for aggressive growth of roots if the nutrients are on the surface of the soil. Also, because of the abundance of nutrients from fertilizers, the plants will put more energy into producing starch and low-quality storage proteins rather than producing protective phytochemicals and absorbing nutrients. On the other hand, organic matter in the soil helps to buffer water and possibly nutrients against extremes in either. The heavy use of pesticides also discourages the synthesis of phytochemicals as well and weakens the plant.
It’s not all positive with regard to growing organic versus conventional and the author gives an example that may produce conventionally-grown strawberries with higher levels of antioxidants than organic berries grown nearby.
Then there’s the fact that so much produce travels thousands of miles to get to your store, which means it’s picked early. Apples and apricots picked early have little or no vitamin C and unripe blackberries have only ~25% of the anthocyanins as ripe berries.
So what do we do to ensure we’re getting the most nutrition possible from our produce?
Buy local - This will ensure you’re getting the freshest fruits and vegetables produced from a small farm. You can always ask your local farmers about their growing practices.
Buy in season - Produce purchased in season is easier to find local.
Eat whole foods - Many of the high-yield crops go into processed and fast foods. By eating whole foods and cooking from scratch as much as possible, you’re more likely to get an abundance of nutrients.
Grow your own if possible - Nothing tastes better than a tomato that’s just been picked from your backyard. When you’re living at the source of your food, you have the freshest produce available. You can also choose the growing methods, i.e., organic versus conventional.
