PLANT-BASED ATHLETE SERIES: PROTEIN QUALITY & QUANTITY MATTERS
Updated: Feb 2
By Annie Bothma, 12 November 2022
Before you swap out the meat or chicken for beans and lentils in your meals, here are a few things you need to take in consideration to make sure you are still getting all the essential amino acids in your diet and meeting your total protein requirements for the day as a plant-based athlete.
WHY PROTEIN MATTERS
Proteins perform a host of very important cellular functions within the body such as participating in biochemical reactions, transporting and storing substances, maintaining structural integrity, signaling between and within cells, and producing movement. For athletes, protein is very important for recovering between sessions, building lean body mass and adapting from hard training.
“Everything we do, everything we are and everything we become depend on the actions of thousands of different proteins.” Houston (2006)
Similar to how glucose subunits form to make glycogen, proteins are formed out of amino acids (the building blocks of protein). The body requires 20 different amino acids, allowing a vast number of possible protein combinations to be formed; with 50,000 different protein containing compounds existing in the body. Of these 20 different amino acids, the body can only synthesize 11, thus, the remainder nine amino acids as essential, and required from the diet.
The current updated index for scoring protein quality is referred to as the ‘digestible
indispensable amino acid score’ (DIAAS). This measures the ideal digestibility of a given protein source. It provides an estimate of the amount of proteins that make their way to the end of the small intestine (Phillips et al. 2016).
Animal-based protein sources have a digestibility score >90%; compared to plant-based protein sources such as soy, wheat, rice, and potatoes show digestibility scores ranging from 45-80% (Food and Agriculture Organization, 2011).
Protein sources such as dairy, are almost completely digested and absorbed in the small intestine. In contrast, poorer quality sources, such as soy, have a greater amount of their amino acids taken up via the gut and as a result, are less available for their contribution to the synthesis of new muscle proteins (Tang et al. 2009). Thus, the digestibility of plant-based protein appears to be remarkably less than those of animal products, which might need to be accounted for when designing a vegan diet.
It has been suggested that vegetarians might need to consume more protein than meat-eaters to compensate for the inferior digestibility of plant-based sources. Values of up to 1.0 g/kg of body-weight per day has been recommended for a vegetarian population, who might consume eggs and dairy products in addition to plant-based proteins in comparison to the RDA of 0.8 g/kg of body-weight that have been suggested for non-athletic populations. However, due to the absence of all animal proteins in a vegan diet, it might be ideal for these athletes to aim for protein intakes towards the higher end of the protein recommendations of 1.4 to 2.0 g/kg of body-weight per day.
Plant foods commonly contain a lower concentration of essential amino acids and leucine content, as well as a reduced digestibility compared to animal proteins and are therefore inferior for increasing rates of muscle protein synthesis (MPS) compared to animal protein sources (Gorissen & Witard 2018).
Muscle protein synthesis (MPS) is the metabolic process that describes the incorporation of amino acids into bound skeletal muscle proteins. Building skeletal muscle requires a daily rate of MPS that surpasses the increase in muscle protein breakdown. In the hours following exercise, an increase in MPS that ensures a positive protein balance is dependent on the ingestion of protein (Rennie & Tipton 2002). In addition, the rate and availability of essential amino acids, and the leucine content of the protein source are key factors that determine the magnitude of MPS post-exercise.
Animal-based proteins have a greater biological value due to the presence of all essential amino acids in the food. in comparison, plant-based protein sources are often incomplete, missing important essential amino acids, and typically contain less Branched Chain Amino Acids (BCAA) than their animal-based equivalents. Leucine appears to be a primary trigger of muscle, and plays an important role in promoting recovery and adaptation from exercise.
Vegan athletes appear to consume less protein than their omnivorous and vegetarian counterparts. This is why optimizing protein intakes for vegan athlete requires that attention is paid to the quantity and quality of protein consumed.
Common examples of the limiting amino acids in plant-based proteins include lysine, methionine, isoleucine, threonine and tryptophan. Of these, lysine appears to be to be most commonly absent, particularly from cereal grains. However, foods such as beans and legumes are rich sources of lysine and leucine can be obtained from soy beans and lentils. Other BCAAs can be found in seeds, tree nuts and chickpeas, meaning that these amino acids can be obtained by consuming a variety of protein-rich, plant-based foods in a vegan diet.
It is advised to consume a mix of plant based foods such as grains, legumes, nuts and seeds on a vegan diet to ensure that all essential amino acids are present throughout the day, and that adequate BCAA's are consumed to support recovery and adaptation from training.
VEGAN PROTEIN SOURCES
Meat, poultry, and fish have a high protein content by weight, meaning you can get a significant amount of protein from a relatively small portion. Protein from animal sources also has high bioavailability, meaning more of the protein in the food is absorbed into the body compared to protein in plant-based foods. While this is good news for athletes who eat meat, it does not just mean vegetarians and vegans are at risk of protein deficiency. Athletes on plant-based diets can absolutely get adequate protein to support support their training and health if they are able consume enough protein in their diet.
Although beans may have protein content, but in order to get a 25 g serving of protein you need to eat an entire can of beans! Beans are also very high in fiber, so they are filling and will increase satiety. A lot of plant-based athletes rely on beans and legumes for a significant amount of their protein intake, but don’t realize how many beans you actually need to get enough protein or the amount of fibre it adds to their diet. For those athletes trying to manage bodyweight, high fiber foods can be a good way to feel full sooner and reduce caloric intake from a meal or an entire day, but for those who have a high energy demand and struggle to meet their caloric intake for the day it can be problematic.
Peanut butter or other nut butters is a favorite amongst plant-based and omnivorous diets, but to get enough protein from peanut butter you add a significant amount of calories to your diet. Half a cup (or 7 tablespoons) of peanut butter will give you a 25 g serving of protein. But it will also add 685 calories and significantly increase the fat content of your meal, which may not make it the most effective way to try meet your protein requirements. However, a few tablespoons of peanut butter can contribute to your daily intake without having to fulfill an entire 25 g serving. In practical terms, you’re not likely to rely on one protein source for an entire 25-g serving all the time.
Here are some plant-based foods that are high in protein and the amount of grams of protein you would get if you consume a 100 g portion of a given food. Take note just like the peanut-butter example with some of these foods, like pumpkin seeds or almonds, it may not be realistic to eat a whole 100g serving all at once. However, these foods can certainly contribute to your overall-daily protein intake. This list is just to give an illustration just how much food you actually need to eat to get enough protein from plant-based foods.
HIGH VEGAN PROTEIN SOURCES (Protein per 100 grams)
Pumpkin seeds (dried, uncooked) - 30.2 g
Lentils (red, split, uncooked) - 24.6 g
Black beans (uncooked) - 21.6 g
Almonds (raw) - 21.2 g
Tempeh - 20.3 g
Tofu (calcium set) - 17.3
Oats (rolled) - 16.9 g
Quinoa (uncooked) - 14.1 g
PLANT-BASED PROTEIN SUPPLEMENTS
Common plant-based protein supplements include soy (and soy isolate), pea, rice, hemp and blended protein products. For athletes who are struggling to meet their protein intake incorporating a protein supplement, especially during hard training phases, may help be helpful. Emerging data are beginning to support the efficacy of plant-based protein powders at improving recovery from training and improving muscle hypertrophy as part of a resistance training program. Protein supplements are convenient protein-source and ideal for athletes who are traveling or have a busy life style.
GETTING MORE ESSENTIAL AMINO-ACIDS ON A PLANT BASED DIET
1. COMBINE PROTEINS SOURCES
Try combining soy and pea proteins (low in methionine/high in lysine) with corn, hemp and brown rice proteins (high in methionine/low in lysine) to ensure a full complement of essential amino acids is present to fully stimulate MPS.
2. INCREASE YOUR QUANTITY
Consume a higher quantity of plant-based proteins per meal and at snacks (compared to animal-based proteins) to compensate for reduced digestibility and low biological value.
3. EAT MORE FREQUENTLY
Consume 20-40 gram protein doses at meals and snacks throughout the day is a practical way to ensure a full spectrum of essential amino acids is available within circulation to support MPS. This should include pre-sleep feeding in the evening, as recovery and muscle protein synthesis continues through the night.
4. INCLUDE A PRE-BEDTIME PROTEIN-RICH SNACK
Pre-sleep protein is an opportunity to meet daily protein recommendations and enhance recovery by supporting overnight muscle protein synthesis. Strive for a 25-40 g dose of protein high in essential amino acids and leucine.
5. CONSIDER ADDING A SUPPLEMENT
Supplementing with a mixed blend or isolated form like soy or pea, vegan-based protein powder that contains sufficient leucine (40g of vegan protein = 30g protein, 2.85g of leucine).
6. RECOMMENDED DIALY TOTAL PROTEIN-INTAKE FOR PLANT-BASED ATHLETES
Aim for 1.4 to 2.0 g of protein per/kg of body-weight per day of total protein.
Each post in this series will include a recipe from Leozette Roode's new cook book: THE SOUTH AFRICAN VEGAN COOKBOOK to inspire you to bring more color into your plate.
FEATURED RECIPE: MULTIGRAIN SALAD
By Leozette Roode
Cooking Time: 45-minutes
1 cup cooked red quinoa
1 cup cooked buckwheat
1 cup brown lentils, cooked
1/2 cucumber, cubed
1 tomato, cubed
1/2 red onion, chopped
2 tablespoons parsley
For the dressing:
3 tablespoons tahini
5 tablespoons lemon juice
1/4 cup water
2 tablespoons white-wine vinegar
1 teaspoon Ina Paarman's Garlic & herb Seasoning
Pinch of Salt
Cook the quinoa and buckwheat according to instructions on the packet.
Mix the grains with the lentils, cucumber, tomato, red onion and fresh parsley.
Place all the dressing ingredients in a mixing bowl and mix until smooth.
Pour the dressing over the salad and mix through.
WHY I LIKE THIS RECIPE
One cup cooked provides about 8 grams of protein and unlike some plant proteins, quinoa is a complete protein, meaning that it contains all nine essential amino acids that our bodies cannot make on their own. Combining the quinoa with the buckwheat and lentils will also increases the total protein content of the meal making an ideal option for a vegan or plant-based athlete.
KEY TAKE AWAYS
Getting enough protein on a plant-based diet can be done, but it certainly requires a lot more planning and preparation to make sure you are getting an adequate amount of essential amino acids in your diet. Combine plant-based protein sources whenever possible to ensure the full spectrum of amino acids are present in your meals. Consume 20-40 gram protein doses at meals and snacks throughout the day and include a pre-bedtime protein-rich snack. Consider supplementing with a plant-based protein if you are struggling to meet your total daily protein requirements.
Remember, regardless if you are following a plant-based diet or not, protein quality and quantity matters for all athletes who are striving to maximize speed-up their recovery, maximize their training adaptations and improve their performance.
Vegan diets: practical advice for athletes and exercisers, (2017), By David Rogerson
Sport Nutrition, Third Edition. (2019) by Asker Jeukendrup, Micheal Gleeson