Fact or Fiction: Vegetable Protein Edition

The above image depicting the protein differences between beef and broccoli has come across my news feeds several times. And every time I see it, I cringe. Now, this is not because I have anything against vegan or vegetarian diets but because of the misinformation it spreads.

Let me be clear in saying that this critique is not of plant-based diets.  Vegetarian and vegan diets can be a healthy choice, just as omnivorous ones can be. There are a wide variety of plant-based proteins available to easily reach individual protein needs, without the need for meat. In fact, I typically encourage ample intake of plant-based proteins due to their associated health benefits. This is also not a commentary on the ethics of eating meat. This is about nutrition and the biochemical properties of proteins. 

I decided to look a little deeper into the facts presented on this image. After all, maybe my assumption that broccoli couldn't possibly have more protein than beef was incorrect. My philosophy is to always keep an open mind and be receptive to the thought that our long held beliefs may not be correct. This is especially important with nutritional science as our understanding of nutrition and the body is always improving, and becoming more refined.  

Let's now go through the information provided on this image. First and foremost, this image claims that broccoli has more protein than beef. My knee jerk reaction is "no, never!", but let's see what the data says. According to the USDA Nutrient Database, a well accepted source of nutrient information, broccoli does not, in most cases have more protein per 100 calorie portion than beef. Notice that I said "in most cases"...

Let's look at the numbers: 

It does appear that, after searching the USDA directory, there is a 100 calorie portion of broccoli that does have the stated 11 grams of protein. And although I was unable to find the sample of beef with 6.4 grams of protein, I was able to find two 100 calorie beef portions, ground beef and porterhouse steak, that have less than 11 grams of protein per 100 calories. So they weren't exactly lying, I'll give them that. If only the information source had been cited in the image, we could find out exactly which type of beef they used in their comparison. 

Okay, so I admit that the numbers in the image could be correct. Broccoli can have more protein than beef in certain circumstances. Especially, if you pick and choose your examples to make a point...so if anything, although these facts could be true, they suffer from a selection bias. Comparing the type of broccoli with the highest amount of protein to the beef with the lowest is very deceptive way to convince people to drop meat from their diet. 

In my opinion, if the type of beef used is not going to be specified, it would have been more acceptable to compare an average amount of protein per 100 calories of each food. From my random (okay, random-ish) samples above, the average protein in a 100 calories portion of beef is 12.7 gram, while in broccoli is 8.9 grams. But...I guess doing this wouldn't benefit the image publisher's agenda, would it?

Now that we've discovered that a 100 calorie portion of broccoli can have more protein than that of beef, we're done right? Right? Well, not exactly. There's more to the protein picture than just the amount of protein a sample contains.  Two other aspects that really should have been addressed clearly are portions sizes and protein quality

The issue I have with defining protein quantity in terms of 100 calorie portions is that it does not give any indication of the volume of the portion size. And while this image doesn't exactly state that the fork full of beef and broccoli pictured have the amount of protein listed on the ad (they don't), some people may incorrectly infer that they do.

This picture doesn't give us any clues as to how much, volume wise, 100 calorie portions of beef and broccoli are. This is deceiving. Most people don't know what 100 calorie portions of most foods look like on a plate. We can make educated guesses but most of us don't have little calorie counting computers in our brains to automatically know what 100 calories looks like. If we did, my job would be so much easier.  

When you look at the beef and broccoli sample data taken from the USDA, you'll notice that the sizes of 100 calories portions vary quite a bit. To get about 100 calories of beef, you need anywhere between 1.3 to 2.2 oz. For those of you not too savvy in your portion sizes, a good rule of thumb is that cooked meat the size of a deck of cards is about 3 oz. Therefore, 100 calories of beef will range in size from about 1/3 to 2/3 the size of standard playing cards. These portions are not very big and are pretty easy to obtain. 


A "handy" guide to portion sizes.  photo Source

A "handy" guide to portion sizes. photo Source

Now 100 calorie portions of chopped broccoli range from just shy 2 cups to just over 3 cups, depending on whether the broccoli is raw, cooked, or cooked from frozen. In terms of vegetable portions, this is 4 to 6 portions (one veggie portion = 1/2 cup). 

Cooked, chopped frozen broccoli was found to have the most protein, beating out the 100 calorie portion of porterhouse steak and ground beef, but it also registers the most weight among the broccoli samples indicating that the 100 calorie, 2 cup sample is more densely packed than the other broccoli samples. If you've ever cooked with frozen broccoli, you know that the consistency is different than that of freshly cooked broccoli. 

If you compared, side to side, the actual portion sizes in 100 calories of beef and broccoli you would see that you would be eating a lot more broccoli than beef. And while some individuals may have no problem eating 2 to 3 cups of broccoli, there are some people with small appetites (including children, the elderly and those with appetite-suppressing illnesses) that would find such a task impossible. And to top it off, the amounts of protein alluded to in the image (6.4 g and 11.1 grams) are just a fraction of your daily protein needs. For example, a 68 kg (or 150 lb) person requires about 55 grams of protein under the current protein recommendations.  If you do choose to obtain your protein solely through vegetables (which no nutritionist would recommend...more on that next), you would have to eat a giant pile of vegetables to reach your estimated protein requirements.  

Not all protein sources are equal with respect to satisfying amino needs.  photo Source

Not all protein sources are equal with respect to satisfying amino needs. photo Source

My last beef (pun intended) with this image is that it does in no way explain protein quality. The image insinuates that the protein in broccoli is of equal quality to that of beef. It's not. Even the most devoted vegan has to admit that when you compare the two samples, of beef and broccoli, the protein quality (with respect to human needs) of beef is much better than that of broccoli. 

Now what is protein quality? Essentially, proteins are made up of amino acids. And there are several of these amino acids, referred to as essential, that cannot be produced by the human body. This means we must obtain them from dietary sources. Animal-based proteins (e.g. from meat, eggs, dairy) have all the amino acids we need, including the essential ones, in sufficient amounts. Plant-based proteins for the most part (and there are a few exceptions, I know) are either low or lacking in one or more of these essential amino acids. 

I took a deeper look into the 9 essential amino acids contained in 100 calorie samples of beef (round eye) and broccoli, frozen (cooked). Without going into too much detail (if you'd like more detail, I can send you my calculations), I found that the amount of essential amino acids in the beef contains 37-81% (average 64%) of the essential amino acid targets for a 70 kg adult, while the broccoli sample contains only 9-28% (average 18%). As you can see, beef does a much better job of satisfying our essential amino acid needs. 

This is not to say that you can't obtain all the protein (and amino acids) you need from plant-based sources but when you compare the quality of the two, beef protein will always win out over vegetable proteins, including that of broccoli. In the hypothetical, and highly unrealistic, situation where one only eats beef or broccoli for their protein needs, the broccoli-muncher will not satisfy their amino acid needs, even if the total amount of protein ingested seems to meet required protein amounts.

If an organization is going to try to promote plant-based diets, they should do so in the right way, explaining that protein (and amino acid) needs can be met by choosing a diet rich in fruits, vegetables, nuts, legumes and grains, and not by insinuating that vegetables have all the amino acids needed to satisfy one's protein needs.  If you want to educate someone about plant-based diets, do so correctly. Deception and misinformation should not be part of the strategy

Inspiring people to make better dietary choices works better than using misinformation. There are lots of wonderful vegetarian recipes out there, like this  one.

Inspiring people to make better dietary choices works better than using misinformation. There are lots of wonderful vegetarian recipes out there, like this one.

A better approach could have been to show two different balanced meals, one with meat and one with plant-based proteins that both contain the same amount of protein, including essential amino acids. Many people could benefit from choosing more vegetarian meals but are unsure of how to plan them correctly. Why not show how easy, delicious, and satisfying a vegetarian meal plan can be? There are plenty of health benefits from choosing plant-based proteins, and no one with any degree of nutrition knowledge can deny that.

Trying to elicit dietary change via half-truths and deception isn't the answer.  We should all aim to make people excited about trying healthy, new foods, and not resorting to making people feel guilty and shamed for their dietary choices. 


What to learn more about protein? Check out Nutrition 101: Protein