Friday, March 20, 2009

The Good Old Salad Days: Why Vegetables Today Have Less Nutrition

I will confess I am a bit of a science geek. Not totally as I tend to skim all the statistical analysis parts where the nitty gritty details of the methodology are transcribed in excruciating detail (yawn). But I read enough of it to see if the b.s. detector goes off. I have a finely tuned b.s. detector.

So, when I tell you the broccoli you are eating is not what it used to be, well, it’s true. In fact, some 43 most commonly eaten vegetables have between six percent protein and up to 38 percent riboflavin amounts LESS than their 1950 counterparts. And less of other “good stuff” too.

So, are we going to have to eat more than five servings?

Well, most kids are not eating enough anyway, so this is really not good news. Read on.

The study, “Changes in USDA Food Composition Data for 43 Garden Crops, 1950 to 1999,” was published by Donald R. Davis, PhD, FACN, Melvin D. Epp, PhD and Hugh D. Riordan, MD. The research team narrowed suspected causes for this drop in nutrition to a few variables.

One theory was the difference in the environment and soil in which the crops where raised. They concluded while this is plausible (and previously proven that organic methods produce vegetables with more nutrition) the difference between these two was not enough to account for the total difference in nutrition found.

So, it is not just about organic versus industrial growing methods.

It’s actually more about the type, or cultivars, grown. You see, in the last 50 years large-scale growers have been selecting for varieties that grow quickly, grow larger and have higher yield. That, in addition to ones that ship well. Nutrition suffers in the tradeoff for yield (i.e. profit).

It’s kind of like that whole triangle diagram from work, the one where the three points say, “fast, good, cheap” and you can only pick two for a realistic project. In this triangle, however, you can’t pick good and fast or good and cheap. Fast trumps flavor and nutrition, and the only goal the growers have is fast and cheap.

Think of each little head of broccoli like a closed loop with the same amount of nutrition no matter what, it just gets spread thinner when the plant gets bigger faster.

Proof. Slow food really is best. Which can leave a health-minded eater wondering, “Where do I get me some of that 1950 broccoli?”

Your back yard is a good place, just like the Obamas. Or your farmers market if you have the right farmers selling there. However, you will want to be sure that the varieties you are buying are heirlooms. Heirloom varieties by name must be at least 50 years old for the seed origin and must open pollinate. These old varieties of seed are the kinds of things you don’t see on store shelves. Many don’t ship well, or don’t have the high yield that commercial farms require. Heirloom tomatoes are probably the most familiar, sexy, tasty, ugly tomatoes full of flavor and character, and apparently, more nutrition.

Heirlooms are not just tomatoes, however. Take a scan through my favorite seed porn and you will get a glimpse of what you are missing. Early Purple Sprouting Broccoli, Romanesco, Cosmic Purple Carrots. And some old varieties you’ve probably not tried; Amaranth greens, Cardoon, Salsify to name a few.

If you’re still standing in the grocery store produce section, well, you’re missing out on more than just nutrition.

Flavor, variety, new tastes. And nutrients. It’s a lot to miss.

*If you’re curious as to why organic methods produce more nutrition, (fellow geek!) it is because the artificial inputs cause the crop to grow in size and weight more rapidly. The plant doesn’t have enough time to reach its nutrition potential before it gets big enough to get chopped off and shipped.


Chiot's Run said...

I also think that is has to do with giving plants the proper environment. Plants are stronger & I believe more nutritious when they have to fight a little to survive. Since antioxidants are what help protect the plant from disease & insects, it only makes sense that if you give them a perfect environment where they don't have to fight to survive they won't be as nutritious.

This is one reason I try to grow all heirloom veggies in my own gardens. I know my spinach is healthier when I pick it and eat it 5 minutes later.

Rachel said...

That's really interesting, B. I'd read about the nutritional impact of harvesting produce early to send through the retail chain, but I didn't know that the cultivar itself made a difference in nutritional punch. All the more reason, as CR says, to cultivate heirloom varieties.

Paul said...

There is one problem with the assumption that modern farm production methods (ie "organic" versus traditional production practices) is short changing consumers on nutritional benefits. For example, for many decades, wheat producers have known that timing of fertilizer applications on winter wheat effects the protein content of the wheat. The rule of thumb is, top-dress early to get increased yield, topdress late to increase protein. The science behind this rule came from years of on-farm research as well.

Though I'm not disputing your researcher's finding, I am suggesting there are practices, even with currently used plant varieties, that can greatly effect the nutrient content of the food.

Even if one allows for the assumption that heirloom garden plants has more nutritional benefits, most of the reduction in nutrition comes from improper food preparation and cooking. And that happens, with any variety of food products.

Unknown said...

Paul,it's not an assumption, it is tested and proven fact. what to do about it - individual gardeners have only so much impact

ExpatChef said...

Here is a link to just one of many studies on benefits of organic versus conventional for nutrition content:

As far as what to do about it, well, grow your own, support farms that grow heirlooms and sustainable methods, join a CSA. In fact, I plan on sending my CSA farmer extra heirloom seed I don't have room to plant. :)

ExpatChef said...

Ah, and the other point, just don't overcook your veggies. They taste better "tender crisp." Use methods like light steaming for best nutrition, or a quick saute. Some varieties have different nutrition when cooked. Here is a post with details on that.

Paul said...

W, I disagree. As I said earlier, nutritional components are greatly influenced by the timing and quantities of plant nutrients.

Additionally, there is no difference in the molecular properties of nitrogen created by a refinery or organically derived nitrogen, such as manure or that coming from a legume. Same goes for phosphates and potash.

Having said that, the study mentioned in the Epat's post does have a valid point about variety selection that they believe accounts for changes in nutritional values.

However, again, I am saying that environmental and management factors, can influence the nutritional values as well, due to weather, water stress, timing and presence or lack of nutrients in the soils.

It's not a zero sum game, where variety selection, soil nutrition and weather are uniform and non-interactive.

Paul said...

Expat, thanks for the link to the study. However, that study was commissioned and performed by the Tesco Centre for Organic Agriculture based at Newcastle University, UK, hardly an independant, disinterested party. If these results can be corroborated by independant, third party organization that has no political or financial interests in the findings, then, so be it.

Until then, the findings cannot be sceintifically relied upon.

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