By Dr. Luke Tolley,
Summary
- Proteins need to be digestible and have the right amino acids for you to use them effectively
- The best number to indicate protein usability is called PDCAAS
- A PDCAAS of 1 means that the protein is 100% usable
- Most plant proteins have a PDCAAS of less than 1
- The Blue Unicorn bar uses a protein blend that has a score of 1
Not All Proteins Are Created Equal
Most people are surprised to learn that there can be huge differences in how effective proteins are for your health even when the same number of grams are listed on the nutrition label. If you want the protein that you eat to be as effective as possible, it’s important to learn about digestibility and essential amino acids.
Unsurprisingly, it turns out that some proteins are much easier for your body to use than other proteins. One reason for this is that many proteins don’t contain the right amino acids, which are what proteins are made from. Your body can make many amino acids, but there are 9 of them that you must get from your diet, called essential amino acids. Proteins that don’t contain these essential amino acids are still useful in a way, but you have to combine them with different proteins that have the missing amino acids. This is something to particularly watch out for with plant proteins since most of them are lacking in a few of the essential amino acids.
Another reason why you might not get much benefit from some proteins is digestibility. A protein might contain great amino acids, but if your body can’t digest it to get those nutrients then it doesn’t do you any good. A common example is hair or feathers. These are made of keratin, which is a protein, but not one that you can digest so there’s no usable nutrition. Seriously, don’t eat hair or feathers.
Proteins and Their PDCAAS
Let’s look at the PDCAAS values for several proteins:
Whey protein - 1
Egg protein - 1
Canola protein - 1
Beef - 0.92
Pea protein - 0.8–0.9
Peanut protein - 0.7
Rice protein - 0.5
Wheat protein - 0.42
Collagen - 0
While it’s true that you can combine different proteins to boost the PDCAAS score, it’s still an eye-opener to see that some of these proteins aren’t nearly as useful to your body as others, particularly when it comes to plant proteins. The real shocker for most people is that big zero after collagen. Collagen is interesting enough, though, to deserve its own article, so you’ll have to wait to find out about that.
Blue Unicorn's PDCAAS
By Dr. Luke Tolley, PhD in Chemistry (North Carolina) and former professor, Southern Illinois University
We get lots of great comments and questions about the Blue Unicorn bar. Many of these are along the lines of “How do you make it taste so good?” and “How can it only have 120 calories?”. The answer to the first question is magic, of course, and the second one is what we’ll talk about today.
What are calories?
In the simplest terms, calories are a unit of energy. Each calorie represents a certain amount of energy that is in your food. Sounds simple, right? The reality is a little more complicated but not too bad.
To measure calories they originally would basically burn the food and see how much heat it gave off. This does tell you how much energy there is, but the problem is that your body can’t take advantage of all of the sources of energy. For example, this method says that wood has plenty of calories because it burns great. Though the energy is there you can’t take advantage of it, so for humans it basically has zero calories. More modern methods do a much better job of figuring out how much energy you can actually get out of the food, but it can be a bit tricky.
Calculating Calories
Calculating the calories in food is pretty simple. This method won’t give you exact numbers, but it will get you close enough. After I explain the method then I’ll go through the numbers for the Blue Unicorn bar for a real-world example.
Start with the fat. Fat has about 9 calories per gram of fat so you can just multiply the total fat on the label by 9. Don’t worry about how much of it is saturated or not because that doesn’t really matter to calories.
Next go to the protein, which is probably the easiest one. Protein has 4 calories per gram, so you multiply this next and add it to your fat calories.
Carbohydrates are the trickiest. Normal carbs have 4 calories per gram, just like protein, but you usually can’t just multiply the total carbs by 4. Fiber is the first thing that messes up your calculation. You can’t digest fiber, but the bacteria in your gut can digest some of it. This is why most fiber is called a pre-biotic – it feeds the bacteria. Because of this complicated relationship that you have with your bacteria, many fibers will effectively have 1 - 2 calories per gram. Some of the sweeteners used also have fewer calories than normal carbs. For instance, allulose and erythritol provide less than 0.4 calories per gram. Usually there isn’t enough of these to make much of a difference in your calculations, but they can. Other sugar alcohols still do have the full 4 calories per gram. So here’s what you have to do for carbs. Figure out the net carbs by taking the total and subtracting out the grams of fiber, erythritol, and allulose. Multiply this number by 4. If there’s lots of fiber in the product then go ahead and add the grams of fiber (assuming 1 calorie per gram). These two numbers together will give a good estimate of the carbohydrate calories.
The final category for calories is alcohol, which hasn’t shown up in protein products yet. I’m just including it here for completeness. Pure ethanol has almost as many calories per gram as fat, so you take the grams of alcohol and multiply by 7.
Calculating Blue Unicorn Calories
Here’s how this all works for the Blue Unicorn bar:
4 g fat x 9 calories/g = 36 fat calories15 g protein x 4 calories/g = 60 protein calories
15 g total carbs - 7 g fiber - 4 g allulose = 4 g net carbs
4 g net carbs x 4 calories/g + 7 g fiber x 1 calorie/g = 16 + 7 = 23 carb calories
Total calories = 36 + 60 + 23 = 119 calories
This method won’t give you exact numbers because some ingredients will have slightly different calories per gram, but we can get close enough to make sure that the label is accurate. Hopefully now you can understand where the calories in the Blue Unicorn bar come from and the only question remaining is “Where did they get the magic from?”
