the power of protein: everything you need to know about this vital macronutrient
Protein is dubbed the “building block of life” for a reason; it’s a fundamental nutrient that plays a crucial role in various bodily functions, ranging from muscle growth and repair to supporting a robust immune system.
In this blog post, I’ll delve into what protein is, why it’s essential to our health (especially as we age), how much you should be getting per day, and why quality matters.
Keep reading to learn more!
MANY WOMEN DON'T GET ENOUGH PROTEIN
Despite its importance, many women fall short on this essential macronutrient. And while dietary preferences, lack of knowledge about daily needs, and calorie restriction could all play a role, I also think that there is a dogma around women and animal products: that eating meat (the most bioavailable sources of protein) is inherently associated with masculinity. I subconsciously subscribed to this belief when I was younger, which resulted in health issues like low muscle mass, iron deficiency, and missing periods.
But, ironically, factors like monthly menstruation and childbirth make it really important for women to eat nutrient-dense foods like animal products that are rich in quality protein and other vital micronutrients, like heme-iron and B12...a reminder that how we nourish our body should never be restricted by gender norms or stereotypes!
WHAT EXACTLY IS PROTEIN?
Protein is one of the three essential macronutrients—alongside carbohydrates and fats—made up of smaller units called amino acids. While amino acids have many functions within the body, they mainly serve as the building blocks for all the body’s tissues, like our bones, skin, and organs; it’s easy to see why this macronutrient is so critical to optimal health!
All of the 20 amino acids found in human proteins fall into two main categories:
(1) Essential: The following nine amino acids are 'essential' (aka we need to get them from our diet) because our body doesn't produce them:
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine
A dietary protein is 'complete' when it contains all nine essential amino acids.
2) non-essential: Our body can make these amino acids, so we don't usually need to get them from our diet. Non-essential amino acids are:
Alanine
Arginine
Asparagine
Aspartic acid
Cysteine
Glutamic acid
Glutamine
Lycine
Proline
Serine
Tyrosine
That said, some non-essential amino acids can become 'conditionally essential' under certain circumstances (like illness, stress, or nutrient deficiencies), in which case we need to get them from food or supplementation. For example, the body needs B6 to make the non-essential amino acid glycine, making it essential if we're deficient in this B vitamin.
THE IMPORTANCE OF ADEQUATE PROTEIN INTAKE
Gym bros and gains usually come to mind when we think of protein. However, this vital macronutrient has many other roles besides muscle growth (although healthy muscles definitely help to support health and longevity).
Here are some of the top functions of protein within the body:
Structural support: As mentioned above, proteins provide structural support to cells, tissues, and our organs, like our lungs, heart and more!
Muscle maintenance & growth: Protein is essential to maintaining/building strong muscles, which are key to metabolic health, balance and quality of life as we age. Protein consumption is especially important with age as we start to naturally lose muscle mass at age ~30.
Bone health: Like our muscles, we reach peak bone mass at ~ 30 and gradually lose more bone than we form as we age (although the rate we lose bone depends on the individual). We usually think of calcium when it comes to bone mass, but protein is also essential for maintaining healthy bones and preventing age-related bone loss.
Enzymes: Many proteins act as enzymes, which enable and accelerate various metabolic processes, like digestion and energy production.
Transport & storage: Some proteins serve as carriers and transport molecules throughout the body. For example, hemoglobin (found in red blood cells) transports oxygen from the lungs to tissues.
Hormones: Some proteins also act as hormones. For example, insulin is a protein hormone that helps regulate blood sugar levels by facilitating the uptake and storage of glucose in cells.
Immune function: Antibodies are specialized proteins that the immune system produces and play a crucial role in the body's defence against infections and diseases.
DNA replication & gene expression: Some proteins are essential for DNA replication, where genetic information duplicates before cell division.
Metabolic Health: Protein requires more energy to digest and metabolize than fats or carbs. As a result, consuming protein-rich meals can increase calorie expenditure and boost our metabolism (which is so much more than our ability to lose weight…thinking of writing an article on this topic soon!).
Blood sugar regulation: Protein plays a significant role in regulating blood sugar levels. When consumed alongside carbohydrates, protein slows down the digestion and absorption of sugars into the bloodstream, preventing rapid spikes in blood glucose levels.
That’s a lot of info to take in, but I think it’s beneficial to see just how many roles protein has in the body and why it's not something we want to skimp on!
PROTEINS IN OUR BODY ARE CONSTANTLY BEING TURNED OVER
The body is constantly breaking down our body’s proteins into amino acids to either (1) make new proteins or (2) to discard old, damaged amino acids via urine. When proteins are broken down, the unused amino acids are stored for future use in an ‘amino acid pool’. The amino acid pool is like a carefully controlled stash of amino acids. It's constantly being managed to make sure we have enough essential amino acids for protein-building and other vital stuff.
Think about it like playing with lego: you can pull individual pieces out of the box to make a new structure and then when you’re done you can break them down into their individual blocks to play with again.
The catch is that there is a protein triage, meaning when we don’t have enough amino acids in the pool our body will prioritize essential functions like maintaining our vital organs, supporting the immune system and repairing damaged tissues to ensure survival. In times of stress or a lack of dietary protein, our body actually breaks down lean muscle mass to use those amino acids to build more essential proteins. And other non-essential functions like muscle and bone building, hormone production, and repairing non-critical tissues (think skin, hair and nails) take a backseat. While these things aren’t necessary for survival, they’re still needed for optimal health.
HOW TO MEET YOUR DAILY REQUIREMENTS
so, how much protein do you need to eat per day?
...this is really the million-dollar question. And, when giving general advice, the answer is always: it depends! Like everything in nutrition, the answer will vary based on the individual and their unique needs, which is why working 1:1 with a Holistic Nutritionist can be so valuable ;).
Health Canada recommends that adults 19 and older consume about 0.8 g of protein per kilogram of body weight. For example, if you're a 150 pound woman, you'll need to eat about 54 g of protein daily.
However, that recommendation is for daily function and doesn't account for other factors like aging, health status, fitness goals, activity levels and stress, etc. A higher range closer to 1.1-2.0 g per kg of body weight per day (up to 110 g for a 150 pound woman) might be more optimal, depending on your health goals.
but make sure to spread it out throughout the day
We can only absorb so much protein at a time, so be sure to spread out your intake throughout the day between your meals and snacks (i.e. ~ 20-30 g per meal and ~ 10 g per snack).
PROTEIN QUALITY MATTERS TOO
Yes, plant-based sources of protein might contain the same number of grams of protein however they may not be equal in quality because of factors like the amino acid composition, digestibility and bioavailability.
amino acid composition
All animal proteins (eggs, dairy, meat) are complete proteins, meaning they contain all 9 essential amino acids in sufficient amounts. On the other hand, most plant-proteins (apart from a few exceptions like soy, quinoa, buckwheat, flaxseeds, hemp seeds, and spirulina) are incomplete proteins.
Why is this important? Research shows that consuming all 9 essential amino acids is needed for protein synthesis in the body (1), And while you can pair a variety of plant-proteins together to create a complete amino acid profile, you need to be incredibly diligent as not all pairings will provide each amino acid in sufficient amounts. And in addition to amino acid composition, there are other factors to consider, including…
digestibility & bioavailability
Just because we are consuming protein, doesn’t mean our body is actually digesting it and utilizing it! That’s why we also need to look at the digestibility and bioavailability of a protein.
According to the Food and Agriculture Organization (FAO) the Digestible Indispensable Amino Acid Score (DIAAS) is the preferred way to determine the quality of protein in food, measuring the amino acid profile and digestibility.
Here is a list of the top proteins and their scores:
Whey Protein: DIAAS score of around 1.0
Casein Protein: DIAAS score of around 1.0
Egg Protein: DIAAS score of around 1.0
Milk Protein: DIAAS score of around 1.0
Beef Protein: DIAAS score of around 0.9
Chicken Protein: DIAAS score of around 0.9
Fish Protein (Salmon, Tuna, etc.): DIAAS score of around 0.8-0.9
Soy Protein: DIAAS score of around 0.9
Pea Protein: DIAAS score of around 0.8-0.9
Lentil Protein: DIAAS score of around 0.7-0.8
Rice Protein: DIAAS score of around 0.5-0.7
Wheat Protein: DIAAS score of around 0.4-0.5
Peanut Protein: DIAAS score of around 0.4-0.5
Almond Protein: DIAAS score of around 0.4-0.5
As you can see, the scores really dip down once we get into the plant-based proteins (apart from soy).
but plant-based foods are important too!
I’m not demonizing plant-based proteins because there are so many other reasons, apart from protein intake, why we might want to eat certain foods! Similar to how animal proteins provide vital nutrients like bioavailable protein, vitamin A, heme-iron and omega-3 fatty acids, plant-based foods also contain health-boosting nutrients like gut-healthy fibre, complex carbs and micronutrients like vitamins, minerals and antioxidants. Legumes, tofu & tempeh, quinoa, and nuts and seeds are all nutritious sources of plant-based protein.
it’s important to look at things holistically
It’s all about using the information available while respecting your unique health needs. For example, consuming dairy simply because it's a good source of protein isn't going to be very health-promoting if you're lactose intolerant. And the importance of protein intake doesn't make carbs and fats any less important—we need those too! (will write posts on these macronutrients as well!)
what about protein powder?
Protein powder can be helpful if you have higher protein requirements, struggle to meet your protein needs through whole foods alone, or have specific dietary restrictions (i.e. if you’re dairy-free, vegan or vegetarian).
That said, you don’t necessarily need to buy expensive protein powders to reach your protein needs! And, often, it can be better to get protein from whole foods when possible to benefit from all the other nutrients these foods offer (since this is such a big topic I’m thinking of writing a part 2, including how to pick a protein powder).
BOTTOM LINE
Protein is a powerful macronutrient that is vital to optimal health. And while animal sources tend to provide more digestible, essential amino acids needed for protein synthesis, eating a variety of animal and plant proteins can help to meet your daily requirements while also providing a variety of nutrients to support robust health.
Not sure if you’re meeting your individual protein needs? I can help you! Click here to book your first 1:1 health coaching appointment.
SOURCES
Volpi, E., Kobayashi, H., Sheffield-Moore, M., Mittendorfer, B., & Wolfe, R. R. (2003). Essential amino acids are primarily responsible for the amino acid stimulation of muscle protein anabolism in healthy elderly adults. The Journal of nutrition, 133(6), 1824S-1830S.
