Protein Quality: Animal- vs Plant-Based Protein

Protein is made up of the important building blocks, amino acids. There are 20 different types of amino acids, but only 9 of them are considered essential and must be obtained through your diet. The remaining 11 are non-essential because they can be manufactured within your body.

When measuring the quality of protein it’s important to take into account how well the amino acid profile of the protein source matches the requirements of the human body. The other two factors to measure are digestion and absorption of the protein.

Digestion is the chemical breakdown of food into small fragments that can be accessed by digestive enzymes. These enzymes subsequently break the food down into molecules that can be absorbed by the body to be used as fuel. 

WHAT PROVIDES A HIGHER QUALITY PROTEIN?

Protein found in meat tends to be of higher quality than protein from plant sources because meat contains a higher percentage of essential amino acids. Plus its amino acid profile tends to be more similar to the human requirement.

But fear not vegetarians; you can still obtain all your essential amino acids through plant-based proteins. You just have to eat more of them, in greater variety, in order to do so. Of all plant sources of protein, soy is widely accepted as the most complete. In fact, proteins from soy and quinoa are both classified as complete proteins because they contain all the essential amino acids, much like the proteins from animal-based foods.

Note from Luke: Below you'll find that while soy is a complete protein, it has a lower biological value, meaning it is not absorbed well by the body compared to animal proteins and other plant proteins.  I do not recommend soy as a normal protein source because of it's poor absorption rate and tendency to affect estrogen levels.

The best way to obtain your daily protein requirement, however, is to consume a balanced diet that includes a mixture of plant and animal products.

MEASURING QUALITY: BIOLOGICAL VALUE

The biological value is a means of measuring protein quality by calculating the nitrogen used for tissue formation divided by the nitrogen absorbed from food. The biological value is then translated into a percentage to express the total percentage of nitrogen utilized.

In other words, the biological percentage is measuring how efficiently the body utilizes protein consumed in your diet – or how efficiently it is absorbed.

Foods with a greater supply of essential amino acids tend to have a higher biological value. Therefore animal sources generally have a higher biological value, since they are richer in essential amino acids (makes sense).

Biological value is not a perfect measurement of protein quality, however. In fact, it fails to take into consideration several factors that influence the digestion absorption process. In any case, it is a good starting point to consider when selecting rich protein sources for your diet.

The chart below shows the quality ranking of popular sources of protein by biological value aw well as several other protein rating scales. (Remember: the higher the rating, the more efficiently the protein is utilized by the body)

RISKS AND BENEFITS

As with anything, there is a good and a bad side. There are potential issues that may come with eating meat while ingoring other foods as well as not eating meat. For example, while animal foods are considered a higher quality protein, we don't want to eliminate vegetables and carbohydrates because the fiber, antioxidants and nutrients provide some health benefits that protein does not.  As always, choosing one food at the exclusion of all others is usually a bad idea.

Note from Luke: Some research claims there are potential health risks with eating meat. But the reason research makes these claims is because, on a whole, people who eat meat tend to also eat more calories, smoke cigarettes and participate it other higher-risk health behaviors.  So it comes down to understanding the mentality:  Are you a grass-fed beef type of person or a fast food burger kind of person?  When we remove other connected behaviors, there are NO science-backed risks with eating animal protein.

And a problem many vegetarians face is a lack of adequate dietary protein or iron. But again, applying some mindfulness and making intelligent choices has a profound impact on the outcome of your diet.

There are also positives with each. Most animal-based proteins (with the exception of dairy) contain very few carbs – meaning you get a high percentage of your total calories from protein. Many protein-rich, animal-based proteins like red meat, egg yolks and dark-meat poultry, are also rich in zinc and heme iron, which is more readily absorbed in your body than the iron in plant based proteins.

But, when you consume protein from plant-based foods, you’re more likely to have an increased fiber intake and variety of vitamins not found in meat.

Luke's final suggestion?  Falling to either end of the spectrum with lots of animal protein and not many plants or tons of plant proteins and no animal proteins can bring potential issues.  The problem with most nutrition approaches is working in extremes.  Research can be tweaked or highlighted to reinforce just about any nutrition point you'd like to make.  But we find time and again, the benefit of including lots of animal proteins from high quality sources in conjunction with high fiber plant foods is an excellent approach.  The real benefits come from eating adequate protein, controlling calories, eating enough fiber and consuming a varied diet.  

Want to cut out all animal protein or eliminate all plant proteins?  Be prepared to put in some extra work to make intelligent food choices. Make sure your complete protein needs are met, fiber is at least 15g per 1000 calories and you are not over eating calories. 

Below is a list of high quality proteins from both animal and plant sources:

Animal Proteins:

• Eggs
• Meat
• Chicken
• Poultry
• Seafood
• Dairy

Plant Proteins:

• Plant protein blends (with pea protein)
• Quinoa
• Limited whole Grains or high protein sprouted grain bread and wraps
• Legumes and beans
• Nuts and seeds

How Much Protein You Need

Research backs up that for the average person participating in strength training that 0.8 to 1 gram of protein per pound is optimal.  If you eat 4 meals per day that means the average women is going to consume 25-35g protein per meal and the average male 35-50g.  A little bit more is OK (protein is forgiving like that). That ends up being about 4oz cooked protein for women and around 6oz cooked protein for men per meal.

You also have the convenience of downing a shake, some eggs, greek yogurt, cottage cheese or other non-meat options to meet those numbers.  Just aim for the rough window of protein grams and you'll be meeting your needs in most cases.

In case you're wondering what is "too little" protein for a meal, I categorize a serving of protein that's under 20g as a snack.  Lets be honest, 2oz of chicken or 1/2 cup yogurt is hardly a meal anyway so make sure you are honest about your portions. Then stay consistent and note how you feel.  Having fewer blood sugar swings, improved satiety, better recovery and sense of well-being?  You're probably on the right track!

If you fall behind on protein or have a hard time meeting the daily goal, boost it with higher protein snacks like low fat string cheese, a scoop of whey, a protein bar, beef jerky or a smaller serving of low-fat cottage cheese or greek yogurt.  In this day and age you can get those foods almost anywhere so there is no reason not to hit your protein.

Sources:

Boundless. “Digestion and Absorption – Boundless Open Textbook.” Boundless. Boundless, 26 May 2016. Web. 22 July 2017.

Campbell, PhD T. Colin. “Animal vs. Plant Protein.” Center for Nutrition Studies. N.p., 05 Oct. 2015. Web. 22 July 2017.

Hoffman, Jay R., and Michael J. Falvo. “Protein – Which Is Best?” Journal of Sports Science & Medicine. Assist Group, Sept. 2004. Web. 25 July 2017.

L.D., Erin Coleman R.D. “Animal Protein vs. Vegetable Protein.” LIVESTRONG.COM. Leaf Group, 08 Feb. 2014. Web. 22 July 2017.

“Protein Quality – Why Some Proteins Are Better than Others.” Expert Nutrition. N.p., n.d. Web. 22 July 2017.