“Broccoli has more protein than steak”—and other crap

Of all the asinine things that I read about nutrition—and let me tell you, I read a lot of them—this one has got to be the asininniest: Broccoli has more protein than steak.

I’ve seen this idiotic meme repeated many times, but the primary source of this stupid—see also: delusional, ludicrous, and absurd—notion seems to be Dr. Joel Furhman. My mom—bless her little osteoporotic soul—keeps his books down at the beach cottage. I don’t think she does it to taunt me, but you never know. I was a bad kid, and payback may be in order. My family has forbidden me to read Dr. Furhman’s books, to pick them up, or to even glance at the covers because the resulting full-on nutrition-rant kills everybody’s beach buzz.

However, as of last week, I have officially maxed out my tolerance for just ignoring this nonsense. So, note to my family: Read no further, it will kill your beach buzz.

According the Dr. Furhman’s book, Eat to Live, a 100-calorie portion of sirloin steak has 5.4 grams of protein, and a 100-calorie portion of broccoli has 11.2 grams of protein. This is rubbish. According to the USDA’s Agricultural Research Service’s Nutrient Data Laboratory database, 100 calories of broiled beef, top sirloin steak has exactly 11.08 grams of protein and 100 calories of chopped, raw broccoli has exactly 8.29. I’m not sure what universe Dr. Furhman lives in, but in my universe, 8.29 is less than 11.08.

I can explain the discrepancy in numbers by the simple fact that Dr. Furhman and I used different sources for our information. Dr. Furham wrote his book—the one that contains the piece of drivel under consideration—in 2005, but he chose to reference a nutrition book written in 1986 (Adams, C. 1986. Handbook of the Nutritional Value of Foods in Common Units, New York: Dover Publications). Just to put things in perspective, in 1986, the internet and DVDs had not yet been invented, no one knew who Bart Simpson was, and it would be another couple of years before Taylor Swift even draws her first ex-boyfriend-bashing breath.

Here’s what I can’t explain: Why, oh why did he dig up a reference nearly two decades old and not just use the USDA internet database, which is—and has been since the 1990s—available to anyone with a library card and a half a brain? While I do not wish to speculate on exactly which of these tools Dr. Furhman might be lacking, suffice it to say that it would take less than 10 minutes for any blogger interested in the truth of the matter to find a more recent source of information—assuming of course that bloggers who perpetuate this particular fiction are interested in the truth.

But wait—before you foam at the mouth too much, Adele—8.29 grams of protein is fair bit of protein.  There is only a difference of a couple of grams of protein between broccoli and steak.  Yes, I would agree, those numbers are a lot closer than you might expect, and this might actually be nutritionally important, if—Big If—all protein were created equal. Which it isn’t.

While I am a big fan of coming at nutrition from an individualized perspective, and I am aware that nutrition scientists don’t have any monopoly on truth, we have managed to nail down a few essential things that human must acquire from the food that they eat. In terms of essentiality, after calories and fluid comes protein—or more specifically, essential amino acids (there are more essentials, but they are not the topic of this particular rant). Because these amino acid requirements are so important (a particular form of starvation, kwashiorkor, involves not overall calorie deprivation, but protein deficit in the context of adequate or near-adequate calories), the World Health Organization has established specific daily requirements of the essential amino acids that are necessary for health.

Let’s see how similar caloric intakes of steak and broccoli stack up when comparing how these two foods provide for essential amino acid requirements. A 275-calorie portion of steak (4 ounces) has 30.5 grams of protein and comes very close to meeting all the daily essential amino acid requirements for a 70 kg adult. A 277-calorie portion of broccoli is not only way more food—you’ll be chewing for a long time as you try to make it through 9 ¼ cups of broccoli—exactly NONE of the daily essential amino acid requirements for an adult are met:

EssentialAmino acids (g) Daily requirement 70 kg adult (g) Essential amino acids (g) in 275 calories of steak (4 oz or 113.33 g) Essential amino acids (g) in 277 calories of chopped, raw broccoli (9.25 cups)
histidine 0.70 0.975 ( +0.275) 0.48 (-0.22)
isoleucine 1.400 1.391 (-0.009) 0.643 (-0.757)
leucine 2.730 2.431 (-0.299) 1.05 (-1.68)
lysine 2.100 2.583 (+0.483) 1.099 (-1.001)
methionine 0.70 0.796 (+0.096) 0.309 (-0.391)
cysteine 0.28 0.394 (+ 0.114) 0.228 (-0.052)
threonine 1.050 1.221 (+0.171) 0.716 (-0.334)
tryptophan 0.280 0.201 (-0.079) 0.269 (-0.011)
valine 1.82 1.516 (-0.304) 1.018 (-0.802)

In reality, it takes twice that much broccoli, or over 18 cups, containing nearly twice as many calories, in order to get anywhere near meeting all essential amino acid requirements.  While I’m willing to concede that individual amino acid requirements may vary considerably, I am not willing to concede that similar caloric amounts of steak and broccoli provide a similar supply of those requirements.  I’m no broccoli basher (it’s sooo yummy baked with cheese & a little bacon on top), but as a protein source, even a lot leaves a lot to be desired.

Oh yeah? Well then, “how on earth do animals like elephants, gorillas and oxen get so big and strong eating only plants? A diverse plant-based diet can obviously support a big, powerful body.” Sure it can. If you’re an elephant or a gorilla or an ox.

In general, human bodies don’t work very efficiently without a regular dietary supply of all essential amino acids: “It would be difficult to find a protein that did not have at least one residue of each of the common 20 amino acids. Half of these amino acids are essential, and if the diet is lacking or low in even one of these essential amino acids, then protein synthesis is not possible” [Emphasis mine; reference: Campbell & Farrell’s Biochemistry, 6th edition]. Protein synthesis allows us to grow, heal, reproduce, and function in general. One of the specific outcomes of protein deficiency in humans is stunting, i.e. where humans who would otherwise grow bigger, don’t.

Dr. Furhman seems to think that those of us who “believe” that food from animals provides a more biologically complete source of protein than food from plants “never thought too much about how a rhinoceros, hippopotamus, gorilla, giraffe, or elephant became so big eating only vegetables.” Hmmm. I have to say, I’m thinking the same thing about Dr. Furhman. Maybe he is unaware that humans aren’t really all that much like rhinoceroses, hippos, gorillas, giraffes, or elephants. But then maybe he just hangs out with a different crowd than I do.

Once again, armed with a library card and half a brain, it is not too difficult to figure out—assuming you did think about how those animals got so big eating only plants and didn’t just mindlessly parrot Dr. Furham’s poorly-researched blather—that, as Gomer Pyle would say, surprise! surprise! Humans and other large mammals ARE different.

While non-ruminants (like humans) must get their essential amino acids from their diet, ruminants (like giraffes) “may also acquire substantial amounts of these amino acids through the digestion of microbial protein synthesized in the rumen” (see: Amino Acids in Animal Nutrition, edited by J.P. Felix D’Mello). This may come as a bit of a shock to Dr. Furhman and his readership, but humans don’t actually have rumens and utilizing this particular approach to the acquisition of essential amino acids from plant matter ain’t gonna work for us.

You can get plenty of protein from a plants-only diet by eating like a hippo.

Other non-ruminant grazers—see elephants, rhinos, and hippos—have a different eating strategy. They “eat for volume and low extraction.” In other words, the relatively low availability of protein in the food is overcome by the high volume consumed. In that regard—assuming you aspire to an elephant-like, rhino-like, or hippo-like bod—it may be possible to get sufficient protein from a strictly plant-based diet. If you don’t mind eating all the time. And pooping. Less than half of what is consumed by the high-volume grazers is utilized by the body; the rest—like a handsome stranger—is just passin’ through (see: Nutritional Ecology of the Ruminant, by Peter J. van Soest). If the idea of literally flushing over half of what you eat down the toilet doesn’t bother you, then this strategy actually might work.

ooooh! Can we? Please?

So what about gorillas? This particular primate-to-primate comparison has been tossed all around the internet. Why can’t we just eat plants like gorillas do? Gorillas, although not so good at Jeopardy, are big and strong and they’re vegans, so we should all be vegans too, right? Aside from the fact that we don’t really know exactly what gorillas are eating much of the time, it does seem that they eat a lot of bugs along with their plants. So unless you have a particularly fastidious gorilla, some dietary protein won’t be vegan. Compared to humans, gorillas also have a much larger proportion of the gut devoted to fermentation—again, another source for microbes to contribute to the nutritional completeness of a plants-only diet. And, again, a high volume of food is consumed to compensate for the low nutritional value of it. You won’t have to worry about half your food going down the toilet, though. Those who want to live like gorillas can just eat that poop instead of flushing it. This provides the body with another opportunity to extract nutrition from the substance formerly known as food and may also help explain the willingness of Dr. Furhman’s readers to swallow what he’s shoveling.

I have nothing against a plants-only diet—in whatever form it takes—if that’s what a person want to do and it makes him/her happy. I have no more interest in converting a vegan to omnivory than I do in having a vegan attempt to convert me to swearing off bacon. I am also aware that there is more—much more—to food choices than the nutritional content of the food chosen.

But I’m afraid this is just one of those situations where ideology has been sent to do the work of science. Ideology has its place, and science has its flaws. Truth, facts, and beliefs can be hard to define and harder still to separate. I get all that. But – to quote Neil deGrasse Tyson – “The good thing about science is that it’s true whether or not you believe in it.” Unfortunately, for all those gorilla-wannabees out there, the reverse also applies: Believing in something doesn’t make it true. You can believe all you want that broccoli is a better source of protein than steak, but your ribosomes don’t have access to a keyboard and they might vote differently.

Now, dear readers, if you ever run across some library-card-challenged blogger out there perpetuating Dr. Furhman’s little myth, you have a link to help spill some sunshine on the matter.

Advertisements