Sunday, July 12, 2009

Nutritional Value of Veggies: Dropping!

Loss of flavor in grocery store produce is one reason many people have started growing their own, most notably tomatoes, which are especially awful from the grocery store in winter. The flavor loss seems to be a side effect of improved keeping qualities and transportation survivability. These improvements are part of the overall goals of industrial agriculture over the last several decades: making food more abundant, affordable, and available year round. It’s hard to find fault with those very worthy goals, but, like all changes, some bad has come along with the good. Flavor is one quality that many eaters notice, but it turns out that flavor isn’t the only quality our food has lost over the years.

The June/July issue of Mother Earth News contains a summary article about a scientific study concerning nutritional content of veggies, past to present. The study is really a review article. Instead of reporting the result of one specific experiment, it pulls together the results of many experiments from a long period of time to show the trends of a particular area of research. The study, “Declining Fruit and Vegetable Nutrition Composition: What is the Evidence?” was written by Donald R. Davis and published in the Feb. 2009 issue of HortScience.

Apparently, over the last sixty or so years, the nutritional quality of our food has been dropping.

I do not have a copy of the original article to check, but according to the summary in Mother Earth News, Davis reported that a loss of nutritional value has occurred, especially in terms of mineral content, and this is due in part to breeding for higher production and partly to agricultural practices that reinforce that higher level of production.

Forcing growth through use of higher levels of fertilizers and irrigation has resulted in higher yields, but in lower mineral and protein content and increased carbohydrate content for at least some crops.

The summary article includes the idea that older varieties, specifically the lower yielding heirloom varieties, may be more nutritious than newer varieties that have higher yields. A plant may be taking up and distributing to its fruits the same amount of minerals, but these minerals are spread among fewer fruits in heirloom varieties, resulting in higher content per fruit.

Another consideration is that organic farming practices that utilize fertilizers in more complex states, like manures and compost, that are slower releasing, may also result in more nutritious, though lower yielding, crops, than the more readily -available -to -plants NPK formulations in most commercially available fertilizers.

Gardeners hoping to improve their families’ nutrition may want to consider these factors in planning next year’s garden. This may include plans to expand garden area, to make up for lower yields.

I am not sure whether this was addressed in the original study or not, but it is my thought, based on the summary article, that slower-maturing varieties may also have higher nutritional value because of the longer time they spend taking up minerals from the soil. At least, that seems reasonable to me.

2 comments:

  1. I found your blog through a comment you left over at Casaubon's Books.
    I'm so glad I clicked through. Though I've had gardens other places we've lived, I'm just learning how to garden here in NW Georgia. The planting schedule is so different than I'm used to, not to mention the growing season is so much longer. So I'm looking forward to reading through your archives to see what I can learn from your experiences.

    Right now I'm trying to figure out what should be planted next and when.

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  2. Hi Supermom!

    Hope you find something useful here. It is a bit of a shock, gardening here after gardening elsewhere. It took me a while to get the hang of it, and the growing conditions still sometimes throw me for a loop!

    Some useful information can be found through the UGA Ag-publications link near the top of the sidebar. That site has a search function that brings up information on many garden-related subjects.

    Hope your garden is doing well this summer!

    -Amy, NW of Atlanta

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