Friday, June 26, 2015

Wild Greens Nutrition Comparison

You might be getting tired of all our posts this spring extolling the virtues of wild greens, but we wanted to do one more before giving it a rest for a while.  In particular, we were curious to see how the nutrition of the greens we forage stacked up against the greens we grow, so we made a spreadsheet (of course) to compare.  And as long as we were answering our own questions, we figured we might as well write it up into a blog post!

It's a bit of a challenge to get an apples-to-apples comparison because not all "weeds" have nutrition info readily available, and of the ones we were able to find, not all of the same metrics were available for each (for example, some were missing vitamin K or some of the B vitamins).  On top of that, some of the benefits of eating wild greens are attributed to factors that aren't quantified in normal nutritional analyses, such as content of phenolics, flavonoids, and mucilaginous substances. But, for what it's worth, we can make a few legitimate comparisons.

And fortunately, there's enough data to make some charts and graphs!

First up, Vitamin A.  Actually, first we should say that the reported serving sizes vary widely across our source materials (linked at the end of the post), so we had to do some normalization.  Everything here is based on 100 g of fresh leaves, rather than a one-cup serving.  But back to vitamin A: just about all of these greens will give you a good dose of it, but if you're foraging and feeling deficient, aim for dandelion, lambsquarter, and stinging nettle greens.  These three, along with kale, are well over the 100% RDV.  Interestingly, several sources claim that mallow is a good source of vitamin A, and although 28 RDV% is nothing to sneeze at, it hardly measures up to most of the other greens.

However, those same sources claim mallow is rich in vitamin C, and the only quantitative measure we could find put it at about 1% RDV. (Although the flowers have a lot more than the leaves.)  But it looks like we'll have to shoot for dandelion, sorrel, or lambsquarter greens if we catch the scurvy and there's no kale around.

Protein is where the wild greens really start to shine, and finally find a metric where they can beat kale, at least for lambsquarter and stinging nettle.

Similarly, for calcium, the wild greens do well compared to typical cultivated greens.  Stinging nettle blows everything else out of the water, but lambsquarter and dandelion are also higher than anything normal gardeners grow intentionally.  Even the lowly mallow is right up there with kale.

Most of the rest of the items that show up on a nutritional label didn't have data across all eleven species, but if you want to take a look at the spreadsheet, you can find it here.  Also, recommended daily values (RDVs) were based on a 2000 calorie diet.  The RDVs we based our calculations on can be found here.

It would be a shame to spend all this time talking about greens and nutrition and leave you hanging with no evidence of them actually prepared!  So we leave you with this: the dandelion-sorrel quiche we made a few weeks ago should be an excellent source of vitamins A and C!

Did we miss your favorite wild or cultivated leafy green?  Let us know in the comments section below!

Now, the sources of the numbers, in case anyone is interested:

Dandelion, lambsquarter, purslane, and all the cultivated greens came from the nutrition facts database.  In the spreadsheet, when figures were available for cooked greens, we used the 'no salt' option.

Sorrel came from the USDA national nutrient database.

Mallow came from this paper and this paper, using the moisture content to back calculate nutrient content in the fresh leaves.  For the second paper, the moisture content was listed as only 2.8%, which is not typical of fresh green biomass!  So the moisture content from the first paper was used in back calculations of the mineral contents.  Also, vitamin A proper was not given, so the total carotenoid content, which provides an upper limit on the possible vitamin A content, was used.  Also, some interconversion between mg and IU was required for vitamins A and E, which we got from here and here.  Finally, note that the two papers analyze different species of mallow (Malva sylvestris in the first and Malva neglecta Wallroth in the second), so there is some uncertainty in the numbers reported here.  This paper also appears to have the data we're after, but only for a price.

Stinging nettle came from this paper, using the spring data because in the fall, there are so many other things to eat.

EDIT 10/19/15: A recent article (covered also here) took a more sophisticated approach, but came up with chard and spinach ranking much higher than kale, which was on par with dandelion greens.  Evidently, they were able to find more complete nutritional data than we did, but they also mention that their ranking system is similarly limited by lack of data on things like phytochemicals.  But we also wanted to mention that watercress, which topped their list, is an excellent wild green, too!  Now if only they had included some of our other favorite wild greens, they would have a perfect article...

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