I have partnered with the National Dairy Council to help promote Dairy. I have been compensated for my time commitment. However, my opinions are entirely my own and I have not been paid to publish positive comments.
It is no doubt that protein is the building block for all of our muscles and body tissues. What isn’t as obvious is the difference between protein quality, types and sources of protein and how they play into sports performance. Today, more than ever, athletes are boasting the benefits of a plant-based diet on their performance. In a recent documentary titled “Game Changers,” Arnold Schwarzenegger among others discusses how times have changed when it comes to promoting animal protein for sports performance. For a full critique of the documentary, check out this article on Men’s Health. Today I’m going to focus on one topic covered – protein – or rather how not all protein sources are created equal.
We need protein in order to survive. Our organs, muscles, bone, nails and hair are mostly made from protein. It is essential for rebuilding, maintaining and repairing body tissues, like muscle or nervous tissue. It is also important for supporting a healthy immune system and to make new cells.
Amino acids are the building blocks that make up protein. There are 21 amino acids. Twelve of the amino acids our bodies can produce making them nonessential. The remaining 9 we cannot make, so we need to get them from our diet, making them essential amino acids. If a food or beverage contains all the 9 essential amino acids, it is considered a complete protein. The more essential amino acids a protein food/beverage contains, the higher quality protein source it is considered.
The Protein Digestibility-Corrected Amino Acid Score (PDCAAS) is a method of evaluating protein quality based on human amino acid needs and their ability to digest the protein. These scores range from 0.0-1.0. For example, egg whites have a PCDAAS of 1.0 while black beans have a 0.53. This does not necessarily mean one is better or worse than the other, it simply means food and beverages consumed must be diversified and, in some cases, increased in order to reap the same benefits of protein from plant-based sources.
Besides the amino acid content, these protein sources all boast different benefits. For example, a 3-ounce serving of cooked beef is rich in vitamin B12, zinc and selenium; milk and yogurt are good sources of calcium, riboflavin and phosphorus; while 1 cup of shelled edamame is rich in vitamin K and folate.
Sources of Protein
When it comes to sources of protein, there are many different types. Animal or plant-based, what should you choose? While protein is essential, not all sources are equal. In order to reap the benefits of protein from a plant-based source, a larger quantity needs to be consumed. For example, in order to consume 25 grams of protein, which is about half of a chicken breast (142 calories) or 1 cup of cottage cheese (220 calories), one would need to eat 3 cups of quinoa (660 calories), 6.5 tablespoons of peanut butter (613 calories), 1 ⅔ cups of black beans (379 calories) or 1 ⅓ cups of edamame (249 calories). This difference is due to a lower presence of amino acids. For a visual depiction of this, check out this infographic created by National Dairy Council.
Dairy has two different types of protein—whey and casein. Whey is easily digestible and rapidly absorbed, making it ideal for a post-workout protein supplement. Casein is also a complete protein source, however it is digested much slower, about 4-6 hours, which is helpful in preventing muscle breakdown and aiding muscle recovery during sleep. Both whey and casein are found in dairy products, because they are only found in milk, while plant-based protein can be sourced from nuts, seeds, legumes and grains.
A position statement from the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine recommends 1.0 g/kg of protein for recreational athletes, 1.2-1.4 g/kg for endurance athletes, 1.2-2.0 g/kg for ultra-endurance athletes, and 1.5-2.0 g/kg for strength athletes. For a 150 lb (68 kg) female marathon runner this means between 82-136 grams of protein per day. Consuming adequate amounts of protein helps to maintain and promote muscle synthesis. This process is due to a positive nitrogen balance. When protein is consumed in the diet it is then broken down into amino acids. These amino acids are then available for muscle hypertrophy.
When it comes to protein, timing is everything. While consuming 20 g of protein after a workout is important, having adequate protein stores (i.e., positive nitrogen balance) throughout the day is best for building and maintaining muscle. In a study conducted by Mamerow et al., it was discovered that spreading intake of high-quality protein sources evenly across three meals was more effective in 24-hour muscle protein synthesis than consuming the majority of one’s protein at the evening meal.1 Achieving adequate protein intake can be difficult, therefore, spreading intake out over meals and snacks can make this more manageable. Consuming 75% of your protein needs at meals and 25% at snacks is a good rule of thumb for protein distribution.
No matter which protein you choose, plant or animal-based, it is important to know the differences and benefits of each. Maintaining a positive nitrogen balance is important for muscle growth and maintenance and consuming a variety of foods is the best way to ensure adequate protein consumption.
How to Put Into Action
Eat a variety of foods. Plant-based diets have their merit in that they encourage the increased consumption of plants. This ensures adequate fiber and micronutrient intake. Including animal proteins like meat and dairy also promote proper amino acid balance and ensure adequate Vitamin D, Calcium, and Phosphorus intake. Including rich protein sources at meals and snacks while consuming a variety of plant foods helps to maintain and increase lean body mass while properly fueling the body with the nutrients that it needs.