Protein in brief
The question "where do you get your protein?" is all too familiar for many of us following a plant-based lifestyle. While the power of plant-based foods is on the rise, protein is often still equated with animal-based foods such as meat, fish, eggs, and dairy. Not only is it possible to get enough protein on a plant-based diet though, it's also relatively easy when enjoying a variety of foods!
Functions of protein
Protein is one of three macronutrients, alongside carbohydrates and fats. It's a source of energy that has important structural and functional responsibilities in the body. Here are a few of proteins roles:
- Structure: proteins such as collagen and keratin play a structural role in muscles and other tissues.
- Hormones: proteins can act as chemical messengers to transmit signals, such as insulin.
- Transportation: proteins help with transportation throughout the body. For example, hemoglobin is a protein that carries oxygen from the lungs to body tissues.
- Immune defence: antibodies and immunoglobulins are proteins that protect the immune system.
- Enzymes: proteins help speed up chemical reactions in the body and partake in several metabolic processes.
The building blocks of protein
Protein is a large structure made up of smaller building blocks called amino acids. There are twenty amino acids that the body needs, eleven of which are "non-essential" and nine which are "essential".
- "Non-essential" amino acids mean that our bodies can make them on their own. Due to this, seeking food sources rich in these amino acids isn't necessary.
- "Essential" amino acids mean that our bodies cannot make them, so we need to consume them from food sources. The nine essential amino acids include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
Understanding protein needs
When it comes to protein needs, we can consider both the quantity and quality of protein. Let's focus on the quantity side first. How much we need depends on several factors including our age, body composition, activity level, health status, and presence of any illnesses. While it's true that plant-based proteins may be slightly less digestible, meaning they may not be as efficiently absorbed, it's still relatively easy to get enough protein from plants.
The protein needs for an average adult are 0.8g/kg - 1.0g/kg of body weight. For example, if someone weighs 143lbs (143 lbs / 2.2 kg = 65 kg), then their minimum estimated protein needs would be 52 - 65g per day (0.8 g x 65 kg and 1.0 g x 65 kg).
A note on athletes
Another common misconception is that everyone who works out needs to load up on protein. While it's true that athletes who train at an elite level have higher needs of about 1.2g-2.0g/kg of body weight, most of us who exercise recreationally don't need quite as much. The average adult who enjoys regular exercise can generally get enough protein from regular meals and snacks without having to drastically increase protein intake.
Other populations to consider
Protein requirements are higher for young children, elderly populations, and pregnant individuals. it's always best to speak with a healthcare professional, such as a dietitian for personalized nutrition requirements, especially in these populations.
Food sources of protein
Protein is found in a wide variety of legumes, grains, vegetables, nuts, and seeds. There are loads of plant-based food sources, below is a list of just a few top sources with approximate grams of protein per serving.
- Tempeh (½ cup) - 17 g protein
- Tofu (½ cup) - 13 g
- Edamame (½ cup) - 9 g
- Beans (most varieties) (½ cup) - 8 g
- Rolled oats, uncooked (½ cup) - 5 g protein
- Quinoa, cooked (½ cup) - 4 g
Nuts and seeds
- Hemp seeds (¼ cup) - 13 g protein
- Pumpkin seeds (¼ cup) - 11 g
- Peanuts (¼ cup) - 9 g
- Chia seeds (¼ cup) - 8 g
- Peanut butter (2 tbsp) - 8 g
- Almond butter (2 tbsp) - 7 g
- Tahini (2 tbsp) - 5 g
- Green peas, cooked (1 cup) - 8 g protein
- Artichoke, cooked (1 cup) - 5 g
- Spinach, cooked (1 cup) - 5 g
Plant-based milk products
- Soy yogurt (¾ cup) - 6 g protein
- Soy milk (1 cup) - 6 g
As mentioned earlier, there are nine essential amino acids that we need to get from foods. This is where the quality of protein comes into play. If a food item contains all nine amino acids in sufficient amounts, it's called a "complete protein". Soy is the main plant-based source of complete protein. Other plant-based protein sources are lower in a few essential amino acids, namely lysine and methionine.
For example, most grains tend to be high in methionine but low in lysine, while most legumes tend to be high in lysine but low in methionine. This is where the idea of protein combining emerged. It was thought that if a person combined these "complementary" proteins in the same meal, they would optimize the availability of amino acids as one food group would "make up" for the lack of particular amino acids in the other food group. We now know that we don't necessarily need to consume these complementary foods in the same meal. Simply having them within the same day has the same effect. By consistently consuming a varied diet from all food groups, we'll likely have our bases covered.
In any case, we may find that many commonly eaten foods are already complementary, for example:
- Toast with nut butter
- Hummus with pita bread or whole-grain crackers
- Rice and beans, in a nourish bowl, wrap, or taco
- Stir fry with tofu or edamame served over rice or with noodles
A closer look at protein absorption
Plant-based protein often faces criticism for not being as efficiently absorbed, but the research is conflicting. Researchers sometimes use protein scoring systems to give us insight into how our bodies absorb different types of protein. Two of these systems include the Protein Digestibility-Corrected Amino Acid Score (PDCAAS) and the newer Digestible Indispensable Amino Acid Score (DIAAS). While these scoring systems are helpful they have limitations, especially when applied to plant-based proteins. For example, these scoring systems don't consider that cooking and processing some plant-based foods can make them easier for our bodies to digest. In any case, there are some tips to optimize the absorption of nutrients from plant-based foods.
Tips to optimize protein absorption
- Soaking and sprouting: There are many benefits to soaking foods like nuts, seeds, beans & grains, including making them easier to digest.
- Embrace variety: Enjoying different foods helps provide us with a variety of different nutrients, including amino acids.
- Include protein at each meal: Aiming to have some form of protein in our meals can ensure we consistently have protein to maximize our intake. To learn about creating a nutritionally balanced plate that includes protein, see our plate method article.
Protein powder & supplements
Here at PUL, we aim to promote food first where possible. The same goes for protein. It's absolutely possible to obtain adequate levels from food alone, even as an athlete.
If our requirements have been determined to be very high or we're unable to meet our needs from food alone, we may choose to supplement with a powder. Some plant-based sources include soy protein, pea protein, hemp protein, flax protein, chia protein, and brown rice protein. When looking to purchase protein powders, we can try to aim for brands that aren't heavily sweetened and have been assessed for contaminants.
In Canada, for example, once a department of the government has assessed a product and decided it's safe and of high quality, it issues a product licence along with an eight-digit Natural Product Number (NPN), which must appear on the label. Before choosing to buy a supplement in Canada, we could check to make sure it had an NPN number. It may be worthwhile to see if our local government has similar regulations, and if a brand meets those regulations, it may be one to consider.
- Obtaining adequate levels of protein is achievable when consuming a varied plant-based diet. Supplementation isn't necessary, as having a variety of different plant proteins and adequate overall energy intake is usually enough.
- The average adult who exercises recreationally needs at least 0.8 g - 1.0 g of protein per kg body weight. Requirements can vary for different populations, especially differ for children, the elderly, pregnant individuals, and higher intensity athletes.
- Elite endurance and strength athletes require higher levels of protein, at about 1.2 g - 2.0 g per kg of body weight. It's still possible at these ranges to obtain sufficient protein from food sources first, before supplements.
- The best plant-based sources of protein include legumes and grain products such as tofu, tempeh, edamame beans, lentils, peas, beans, quinoa, and buckwheat. Other great sources include nuts, seeds, soy milk, and soy yogurt. Aim to choose whole plant foods over processed vegan substitutes if possible, as these may contain higher levels of sodium and saturated fat.
- Focus on obtaining protein from food first, before turning to supplements.