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A New Take on Plant Protein Quality

Sharon Palmer

It seems that everyone is talking about protein these days, and sure enough, this nutrient is a necessary part of any well-rounded diet. When you follow a plant-based diet, such as a vegan, vegetarian, pescatarian, or semi-vegetarian diet, it’s important to obtain adequate amounts of protein from plant foods to meet your needs. But there is a lot of confusion on the quality of plant proteins compared to animal proteins, which has led nutrition experts to take a more modern approach to evaluating plant proteins in order to further support the health and environmental benefits of plant-based eating.

Green Goddess Buddha Bowl

Understanding Amino Acids

You may be asking yourself, what is an amino acid and why is it important in determining the quality of protein in my food? Well, amino acids are basically the building blocks of proteins. There are nine essential amino acids—essential meaning that the human body is unable to make them, therefore we must obtain them from food. While we need a regular supply of all nine essential amino acids for the body to function properly, using amino acids to solely characterize the protein quality of foods remains questionable and the demand for a new definition has come to light.

The quality of protein in food is currently measured by the FDA using the Protein Digestibility Corrected Amino Acid Score (PDCAAS), which analyzes the amount of amino acids present in a food and its digestibility, as opposed to the effect that those foods may have on overall health and the environment.

Savory Steel Cut Oats with Spinach, Mushrooms, and Tofu

What is Protein Quality?

Animal sources of protein including meat, seafood, and dairy have been viewed as having higher protein “quality” than plant sources. This is largely due to the high digestibility and presence of nine essential amino acids, making it a “complete” protein. Plant proteins partially impair digestion and usually lack high levels of one or more of the essential amino acids, making them an “incomplete” protein. However, using amino acids to identify protein quality in this way is an outdated metric, though the eligibility of foods for protein content claims are still made based on this principle. Unfortunately, this can negatively influence consumer’s behavior and perception of products.

Protein content claims may sound like a new concept, but you have likely seen this on food labels found in your local supermarket. For example, a food item may state that it contains a “good” or “high” source of protein, drawing consumers to believe this item is better than others. This can be very misleading because, while these items seem to be a smart choice containing an adequate source of protein, the remainder of the nutrient content in the food could be unhealthy, in time leading to poor overall health consequences.

Kimberly Doughty, MPH, PhD, a leading expert from True Health Initiative states, “I think it’s pretty clear that we have the wrong approach to defining protein quality, when processed meats and frozen dinners that are laden with sodium and saturated fat can be labeled ‘good sources of protein.’ That these claims can be made to help sell foods known to be associated with chronic disease risk to consumers who already consume more than enough protein is perverse.”

Because this concept is unknown to most consumers, the importance and implementation of protein foods in the American diet continues to increase, incorporating many unhealthy sources. In fact, 50% of Americans state that they have a form of protein at every meal, in most cases well exceeding their daily recommended intake. This growing popularity would be of less concern if the protein choices of individuals did not pose a potential risk to their overall health. Recent findings have shown that more than 60% of protein intake in the U.S. comes from meat, which includes 58% from red meat and of that, 22% is processed—high intake of these sources has been linked with higher risk of chronic diseases.

Nourish Lentil Bowl

Protein Misconceptions

This consistently high intake of animal protein could be due to Americans misunderstanding of protein sources in general, as well as their health effects. Approximately one-third of U.S. consumers believe that those who avoid animal protein are deficient in some nutrients, and 30% believe that animal protein is associated with positive health effects. According to the Dietary Guidelines of Americans, people should consume more plant-based foods and less meat. Not only can this switch to a more plant-based diet decrease the amount of saturated fat and sodium consumed, but it can also help to diminish the risk of many chronic diseases associated with high meat consumption, including cardiovascular disease, type 2 diabetes, and cancer.

This may seem like a confusing change to make, due to the widespread belief that following a plant-based diet can make it very difficult to meet protein requirements, and that in order to do so you must consume “complementary plant proteins” at every meal. Good news: This is no longer the case! A new study has found no evidence supporting these claims, and as long as energy needs are met and a variety of protein food sources are consumed, a vegetarian or vegan diet can meet protein needs and be healthy for the whole family without adding in any foods from animal sources.

The Benefits of a Plant-Based Protein Focus

The Academy of Nutrition and Dietetics considers a well-balanced vegetarian and vegan diet to be “healthful and nutritionally adequate”, because it may help prevent chronic diseases often linked with the consumption of high amounts of animal foods. The benefits of consuming a plant-based diet may vary person to person, but, overall, vegetarians and vegans have been shown to have lower weights compared with nonvegetarians, as well as improved blood lipid profiles and glycemic control.

Plant protein is actually thought to provide many important nutrients, compared to animal proteins. Those who eat plant-based tend to have higher intakes of omega-3’s, healthy fatty acids, folate, vitamin C, vitamin E, and potassium and lower intakes of sodium and saturated fat often found in animal proteins. Not only can you feel good about what you are putting into your body when eating plant-based, but it can also have a very positive impact on the environment. There is considerable evidence that following a vegetarian or vegan diet helps to conserve resources and is overall less-damaging to the environment, reducing greenhouse gas emissions by up to 29% compared to those following a nonvegetarian diet.

Sesame Tempeh Buddha Bowl

A New Definition of Plant Protein Quality

True Health Initiative has put forth a new definition of protein quality, which not only measures the amino acid composition in protein items, but looks at both the health outcomes and environmental impacts, something previously not taken into consideration. Kate Geagan, MS, RD, an expert from True Health Initiative, states, “This ‘protein fix’ is long overdue: consumers deserve an updated definition that better reflects the actual impact of dietary protein sources on public health, aligns with the latest scientific evidence, and helps eaters make the best choices to match their budget and their health goals. It’s rare to find a single switch that holds this kind of potential to help solve some of our most urgent public health crises, but ‘protein quality’ is one of them.”

Consumers depend on accurate nutrition information to make food choices therefore, it is imperative that future protein content claims actually assist individuals in choosing foods that will promote health, not confusion.

Fitting Plant-Based Protein into Your Daily Routine

Whether you want to become healthier, help the environment, or just try something different, it is easy to meet your daily protein needs from plant-based sources with foods that are both healthy and exciting! Switching from animal to plant protein at meal times opens up the door to many new flavor combinations and textures.

Plant Protein Tips:

  • Instead of animal protein at meals, try tofu which provides 10 grams of plant-based protein per ½ cup, or beans (kidney, black, etc.) which provides 8 grams per ½ cup.
  • Incorporate nutrient and protein dense whole grains in place of other starches, such as white rice. Quinoa contains 4 grams of plant-based protein in ½ cup cooked, and is also gluten-free.
  • If milk is a staple in your household, consider plant-based options, such as soy milk which contains 7 grams of protein per cup.
  • Changing your snacking habits can also be a great way to include plant-based protein. You could easily add in a serving of nuts per day, such as one ounce of pistachios or almonds to provide 6 grams of plant-based protein.
  • Try chia seeds in place of eggs to make a delicious pudding, smoothie, or salad topper—each 2 tablespoon serving contains 4 grams of plant-based protein.

Regardless of your schedule or preferences, plant-based protein sources can enhance your daily eating pattern, making it both delicious and nutritious! Here are some great plant-based protein recipes to try at every meal.

Burrito with Refried Beans and Corn

Breakfast

Burrito with Refried Beans and Corn = 11 grams plant-based protein

Moroccan Chickpea Sorghum Bowl

Lunch

Moroccan Chickpea Sorghum Bowl = 17 grams plant-based protein

Miso Green Beans and Tofu

Dinner

Miso Green Beans and Tofu = 14 grams plant-based protein

Side Dish

Easy Cumin Brown Rice = 4.5 grams plant-based protein

Super Berry Soy Chia Pudding

Dessert

Super Berry Soy Chia Pudding = 6 grams plant-based protein

Written by Clara Paternite, Dietetic Intern with Sharon Palmer, MSFS, RDN on July 22, 2019; updated on November 2, 2020.

Sources

David L Katz, Kimberly N Doughty, Kate Geagan, David A Jenkins, Christopher D Gardner, Perspective: The Public Health Case for Modernizing the Definition of Protein Quality, Advances in Nutrition, https://doi.org/10.1093/advances/nmz023.

For other resources on plant proteins, check out the following: 

How to Power Up on Plant Proteins
Plant-Based Protein Tips
Pulses, Cornerstone of the Mediterranean Diet

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