At any grocery store in North America right now, there are shoppers cruising isles, making thoughtful choices about their family's nutrition. Armed with latest information about health, choosing foods high in nutrition is a primary goal. Unfortunately, no matter how carefully one shops, there is often little nutrition in foods we consume. In fact, it is nearly impossible to consume adequate nutrients through diet alone in our modern world.
What causes our foods to be devoid of nutrition? There are many causes, primarily modern farming, storage, and preservation methods of food. Let's take a look at why this happens.
First, it is widely acknowledged that soils in North America have been depleted of many nutrients since 1930's due to loss of topsoil and reliance on chemical fertilizers. Farmers replace nitrogen, potassium and phosphorus depleted by agriculture in order to achieve optimum plant growth. However, little attention is paid to replacing trace minerals lost in soils.
Consumer demand for attractive produce also plays a role. This demand has resulted in plant breeding for appearance and storage longevity, ignoring nutritional quality. Fruits and vegetables are often picked in green stage, ripening in transit to store. Again, this prevents production of nutrients which often occurs in ripening stage while on plant itself. One example of this is seen in fruits, where cartenoid levels increase as fruit ripens naturally.
Produce now travels an average of 1500-2000 miles from farm to market, often in refrigerated trucks. There have been few studies done on effects of storage on produce, especially in area of overall phytonutrient levels. However, what we do know is most fresh vegetables steadily loose nutrients when stored in cold, dark conditions. Some types of produce are more vulnerable to these losses than others, losing fifty percent or more of phytonutrients in as little as five days storage.
Food preservation methods often play a role in nutrient depletion. When properly blanched prior to freezing, most-but not all-foods retain more nutrition when frozen as compared to canning methods. Interestingly, container used in canning also makes a difference. Foods preserved in cans often retain more nutrients than those in glass or plastic containers as many nutrients are depleted by exposure to light.