Calculating Vegetable Proteins

I recently posted an infographic about vegetable proteins on Facebook and it confused some people, even outraged some. Does spinach really contain 49% protein?  Let me explain.

This chart represents proteins as a percentage of calories. Why would you want to know this? To get a balanced diet we ideally want to balance the ratio of carbs, fats, and proteins. Generally this number is 50% carbs, 30% fats, and 20% proteins. You can find more information on calculating your ratio in this article on Sparkpeople.

It is commonly thought that vegetables are low in protein, therefore vegetarian diets are lacking in nutrition. Of course this is not true.

If we measure our veggie proteins in percentage of calories, we begin to see that they contain good ratios of protein. Now let me say this: in order to get the same number of grams of protein from spinach as from meat, you would need to consume a lot of spinach. That is why we juice and blend our veggies folks!

So how do we know that the above chart is accurate and how do we calculate proteins as percentage of calories? The chart was created using the following illustration contained in the book Diet for a New America, by John Robbins:

And John Robbins calculated his information from the Nutritive Value of American Foods in Common Units in the USDA Agriculture Handbook.

From my calculations, the above charts are fairly accurate. I did determine a few to be a little higher and a few to be a little lower, but I am confident in using the charts as a general guideline to knowing the protein ratios in vegetables.

How to Calculate Proteins as Percent of Calories

We will use raw, shredded red cabbage as an example. According to the Nutritive Value document (linked above), one cup contains 19 calories and 1 gram of protein.

1. Each gram of protein provides four calories. To find the number of protein calories we multiply 4 x P (grams of proteins). Using the example 4 x 1 = 4 protein calories

2 Divide the protein calories by the total number of calories. 4 ÷ 19 = .2105

3. Multipy the answer in step 2 by 100 to get the percentage. .2105 x 100 = 21.05%

For our example this means that 21.05% of the calories contained in raw shredded cabbage are protein calories. It doesn’t change if you eat one cup, two cups or four cups of cabbage. 21.05% of those calories are from protein.

Here’s another example.
One whole cucumber contains 34 calories and 2 grams of protein. 4 x 2 grams of protein = 8 calories from protein. 8 ÷ 34 = .2352. Multiplied by 100 = 23.52% of the calories in cucumbers are protein calories.

Why This is Useful

We tend to have a fixation on how many grams of protein we consume in a day, but it is also important to know if we are eating a balanced ratio of proteins to carbs and fats. Eating a balanced diet promotes good health. You may use the formula above to calculate the percent of proteins you’ve consumed in an entire day. You will need to know the total number of grams of proteins consumed, and the total number of calories consumed.