Myths About Wheatgrass
Proponents claim that wheatgrass is higher in protein than eggs, but numbers can be misleading. Nutrition Diva reveals the truth.
Monica Reinagel, MS, LD/N, CNS
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Myths About Wheatgrass
Yikes. It doesn’t take much to discredit you in Julie’s book. Even though her email was kind of harsh, I emailed her back to tell her she was right. Vegetables do contain small amounts of protein, so I was incorrect to say that vegetable juice contains “no protein.” I should have said that it contains “very little protein.” For example, you’d have to drink about a quart and a half of wheatgrass juice to get the same amount of protein as one serving of chicken.Â
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Is Wheatgrass High In Protein?
Apparently, Julie was surprised to get an email back from me (and if that’s the kind of email she typically sends to public figures, it’s not surprising that she doesn’t get a lot of responses). In any case, old Julie was willing to give me a second chance. “I confess I’m frustrated by not knowing how to find reliable information,” she wrote. “I was trying to find protein sources and read online that wheatgrass contains 20% percent protein, while eggs only 12%. How do I know what to believe?”
Related Content: How to Find Reliable Sources
Seeing as we were now friends, I responded again and explained to Julie that expressing a nutrient as a percentage can be misleading without necessarily being untrue. Confusion about the difference between percentages and absolute amounts leads to all sorts of nutritional myths and misunderstandings. And, believe me, marketers take full advantage of that fact when trying to spin the advantages of their products! You may or may not be interested in wheatgrass as a source of protein—but it’s as good an example of this phenomenon as any, so let’s take a closer look at the numbers Julie came across.
How Marketers Spin the Numbers
The source Julie cited seems to be comparing the percentage of protein by weight. For example, 100 grams of wheatgrass juice powder contains about 20 grams of protein, while 100 grams of eggs contains only 12 grams of protein. Now this is a little sneaky because they’re comparing dehydrated wheatgrass juice to whole eggs. Once you reconstitute the powder back into juice, the percentage of protein by weight goes down to about 3%.
But another way to compare these two foods would be to look at the percentage of calories from protein. Because water has no calories, the fact that we’re comparing wheat grass powder to whole eggs won’t distort the picture. If we do that, we get a different picture: About 35% of the calories in wheatgrass come from protein, which is comparable to whole eggs.
A third way to compare the protein in these two foods is to look at the amount of protein per serving. When we do that, we find that a 2-ounce shot of wheatgrass juice contains about 1.5 grams of protein, while a large egg (which also weighs about 2 ounces) provides 6 grams of protein, or four times as much.
So, we have 3 true statements about the amount of protein in wheatgrass versus eggs:
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Wheatgrass powder is 20% protein and eggs are only 12%Â (% protein by weight)
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Wheatgrass is 35% protein, the same as eggs (% calories from protein)
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Eggs contain four times as much protein as wheatgrass juice (protein per serving)
The website Julie sited was selling wheatgrass powder. Which set of numbers do you think they chose? The take home lesson here is that percentages don’t always tell the whole story. When comparing different food sources, be sure to take into account the absolute amount of protein (or whatever nutrient you’re interested in) per serving as well.
And here’s a bonus take home lesson: Don’t believe everything you read online—especially when the person writing about something is also trying to sell it to you.
Relative vs. Absolute Risks
There’s another way in which percentages cause a lot of confusion. Health researchers often report their findings in terms of relative risk. This can make for very eye-catching headlines, but it also creates a lot of confusion among the general public and reporters—most of whom, sadly, do not listen to the Math Dude’s podcast and, as a result, are not as numerically literate as we might hope.
Let’s say that researchers find that people who eat Brussels sprouts on a weekly basis have an increased risk of developing a rare condition in which their eyelashes fall out. It’s no mere correlation—they’ve actually done a huge, controlled, double blinded experiment that definitively proves that a weekly serving of Brussels sprouts triples your risk of spontaneous eyelash-opecia. The researchers write up their findings, submit them for publication, and the university’s press office writes up a press release. Stop the Presses: Eating Brussels Sprouts Increases Risk of Bald Eyelids by 300%.
Now what? Brussels sprouts are one of my favorite vegetables and I know they are otherwise very good for me. But I’m also rather fond of having eyelashes—and a 300% increase in risk sounds pretty scary. Fortunately, before emptying the crisper drawer into the compost, I decide to check out the details of this new study. When I read the entire paper, I learn that eyelash-opecia normally afflicts one in every 3 million people. A weekly serving of Brussels sprouts increases my risk of bald eyelids from 1-in-3-million to 1-in-1-million. When you put it that way, it doesn’t seem quite as risky. In fact, given the nutritional benefits of Brussels sprouts and my fondness for them, it’s a risk I can live with.
All kidding aside, here’s what I want you to remember next time you see a big scary headline about health risks: A big increase in relative risk doesn’t always translate into a big risk. Something can be 300% more likely and still be very, very unlikely. So before you make any big decisions (or purchases), be sure to ask what the absolute risk is. It may very well put things into a very different light.
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If you questions or comments, please send a (friendly) email to nutrition@quickanddirtytips.comcreate new email. You can also post comments and questions on my Nutrition Diva Facebook Page. I answer a lot of listener questions in my free weekly newsletter, so if you’ve sent a question my way, be sure you’re signed up to receive that.
Wheatgrass Juice image from Shutterstock
About the Author
Monica Reinagel is a board-certified licensed nutritionist, author, and the creator of one of iTunes’ most highly ranked health and fitness podcasts. Her advice is regularly featured on the TODAY show, Dr. Oz, NPR, and in the nation’s leading newspapers, magazines, and websites. Do you have a nutrition question? Call the Nutrition Diva listener line at 443-961-6206. Your question could be featured on the show.Â