Where Do I Get My Protein on a Plant-based Diet?

Lucia Tiffany MPH July 11, 2018

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Where do I get my protein on a plant-based diet?

This seems to be one of the most ubiquitous questions asked any one who suggests they might stop eating meat, milk, eggs and cheese. It seems to be rooted in the now thoroughly Western idea that we need meat in the diet to make sure we get our protein.

There are 3 closely related questions to consider in looking at protein requirements –

How much (quantity) protein do I need?
How do I judge quality of protein?
Where do I get this protein?

Let’s look a little bit at the history of protein recommendations before answering these questions.

Back in the late 1800’s, scientists were beginning to understand a little more about macro nutrients (protein, fats, and carbohydrates). A German scientist by the name of Dr. Justus von Liebig determined that human muscles were made of mostly protein. Another man that was working under him, named Dr. Voit, observed coal miners who were strong and very muscular. As these men were eating around 120 gms of protein every day, he decided, based on his observations, that this must be the ideal amount of protein that we need to consume every day. This appears to be the basis of modern day concern in regards to whether or not we are eating enough protein.

How Much Do I Need

So how much protein do we really need? According to Davis and Melina, vegans on a mostly whole food diet need about .9g per kg of body weight. If you weigh 135 lb. that works out to 55 g of protein/day. The National Academy of Sciences sets the recommended daily allowances (RDA) for macro and micro nutrients. In English units, that recommendation is .35 gm/pound of body weight. Interestingly, modern scientific studies show that adults actually only need around 30 gms of protein each day. This is because our bodies are very efficient at recycling protein and only losses that are not available for recyling need to be replaced. This would be losses in the form of hair, skin, and finger and toenails. So the RDA is actually set quite a bit higher than the 30 gm studies show are actually needed. Even so, the average American today consumes 70-100 gm of protein a day, about twice the RDA criteria.

This is even more concerning when we realize that since the 1930’s, we have multiple studies done on laboratory animals that consistently show that high protein diets speed up the rate of growth and development but also shorten lifespan. We seem to be observing these effects in humans in our society today.

There are certain conditions which will increase your need for protein. These include growth and development of children, pregnancy and lactation, athletes that are body building, and those recovering from serious injuries such as burns. Anytime extra muscle or body tissue is being built will increase protein requirements.

Where Can I Find It?

So let’s take a look at an example of where people are getting their protein. We’ll start by looking at someone on a Standard American Diet.

A breakfast consisting of a 3 egg omelet, hashbrowns, 2 pieces of toast with butter and jelly and a glass of orange would provide 55 gms of protein. Lunch of a Big Mac, French fries, and milkshake would give you 40 more gms. A dinner of fried chicken, salad and dressing, baked potato with sour cream, peas, and milk would would give you 75 gms for a total of 170 gms. of protein that day.

Someone on the optimal plantbased diet might have a day that looks more like this:

Breakfast of cooked cereal, milk, toast, banana and an orange for a total of 25 gms protein. For lunch they might have pita bread stuffed with tomatoes, sprouts, cucumbers, a three-bean salad, and split pea soup with barley for 30 gms. Then for dinner they could have spaghetti with marinara sauce, a tossed salad, broccoli flowerets, two slices of bread with humuus, and a baked apple stuffed with walnuts for a total of 30 gms.

So by the end of the day this person would have consumed 85 gms of protein, still way more than is required. In addition they will avoid many problems generated by animal proteins that are NOT a problem with plant-sourced proteins.

Finding Quality Protein

So what determines protein quality? It helps to understand that proteins are made up of 22 amino acids or building blocks. Nine of these must be supplied in the diet and so are called essential amino acids. If you have adequate amounts of these essential amino acids, our bodies can formulate all the other thousands of combinations needed to build the proteins that compose body tissues, that work as catalysts, and that are used in other body functions. As it turns out, on a whole food plantbased diet, as long as you are eating a variety of foods and receiving enough calories to maintain your weight, you will have all the essential amino acids that you need in adequate categories.

So back to our first question, Where can I get my protein on a plant-based diet? The answer is short and simple – the same place I get all my other nutrients, from plants. That’s because all whole plant foods have protein. In fact, if you could eat enough lettuce to maintain your weight (granted that would be a fairly large quantity and is not realistic) you would have all the protein you need.

This is not only true for humans. Other mammals, including elephants and gorillas, have no problem building and maintaining plenty of muscle on a completely plant-based diet. Many athletes today are finding that they have better endurance and strength by switching to plant sources of protein.

So I believe it’s time to put the protein myth to rest – not only is it easy to get enough, but in the case of animal sourced proteins, too much of a good thing is a bad thing.