This story is one that will hold a lot of value for almost everybody, but especially for those plant-based-oriented ones who need to be more watchful about their protein intake as well as physically active individuals with higher protein requirements than the average one.
Let’s dig a bit deeper to understand what kind of structures proteins are, their function in our body, and how much protein we should be getting through food daily.
What is a protein?
Proteins in our body are not only forming our muscles, but they are essential for many other different functions.
Collagen, the component of connective tissue that makes up structures like tendons, ligaments or cartilage, is the most abundant one in our body.
Insulin and glucagon are proteins with a hormonal function that regulate the sugar levels in our blood.
Haemoglobin, found in our red blood cells, transports oxygen through our body, and it also happens to be a protein.
As you can see, proteins are everywhere, and our body needs a sufficient quantity of them on a daily basis to support all these complex systems.
But what is actually a protein? On a molecular basis, protein is a chain of amino acids connected by peptide bonds. The order in which these amino acids are linked determines the protein’s function in our body.
And how does our body know in which order to place amino acids? That is a good question! The information for each of these sequences is safely stored in our DNA.
All proteins present in food and inside our bodies are a specific combination of 20 different amino acids.
Amino acids – the protein building blocks
From these 20 amino acids, our body can synthesise some of them alone, but we need to obtain several of them from the food we eat. These are called essential amino acids, and there are nine of them: tryptophan, valine, histidine, phenylalanine, leucine, methionine, lysine, isoleucine and threonine.
For a protein like collagen to be synthesised, our body needs all the amino acids (essential and non-essential) to be present. If one of these amino acids is missing, the protein won’t form.
It is almost like doing a puzzle; each piece has its specific spot, and if one of these pieces is missing, you won’t be able to finish the puzzle.
How does our body use proteins?
Now it is clear why we need to obtain protein from food. The pure purpose of that is to secure all the required amino acids for new proteins in our body to form.
Once we ingest them from various food sources, our body will break them down into amino acids, the building blocks. Only then, by following orders from above (DNA), will it start placing those amino acids into chains to form new proteins, which our body will use for nutrient transport, fighting against infection, building muscles, and many more.
Where can we find protein in food?
Proteins are present in almost all our food and show great variety among different food groups. Grains like wheat have gluten, while the main proteins in dairy products are casein and whey.
These proteins are present in various amounts and have different amino acids present. Also, because of their specific surroundings, they will be digested more or less easily.
If proteins found in a particular food have a full range of all the essential amino acids in sufficient amounts, they are considered complete. On the other hand, if these proteins are lacking at least one essential amino acid, they are incomplete.
The easiest way to divide protein sources is into two groups: those of animal origin and those of plant origin.
Proteins of animal origin are, in principle, considered complete proteins, meaning they have all the essential amino acids in sufficient amounts. The only protein of animal origin lacking one essential amino acid (tryptophan) is collagen.
Some great animal-based sources are eggs, meat, poultry, fish, seafood and dairy, like cheese or yoghurt.
On the other side, most of the proteins of plant origin are considered incomplete, which means they lack at least one of the essential amino acids.
Legumes lack methionine and tryptophan, while cereals lack lysine and isoleucine. Luckily, combining these food groups can provide complete protein, a notion known as the complementing concept.
Previously it was thought that the complementing concept needs to be satisfied in each meal; now, we know that it is enough if we achieve it throughout the day.
To give you some more ideas, here are some of the best complementing concept combos:
Grains + legumes: rice with beans or lentils, barley with peas, bread with a beans stew
Grains + dairy products: pasta with cheese, rice with milk
Legumes + seeds: chickpeas + sesame (hummus), peas + pumpkin seeds
So, if you have a cereal-based breakfast and a beans stew for lunch, you’ve implemented the complementing concept.
This concept especially benefits vegans and vegetarians who eliminate entirely or lower their animal protein intake.
But the story doesn’t finish here! A few proteins of plant origin are also complete, like animal protein! And you should definitely know about them!
Soy protein is considered a high-quality protein with all essential amino acids in sufficient amounts. Before, it was supposed to lack methionine because the tests were made on rats with higher needs (50%) for this particular amino acid than humans. When it comes to its digestibility, it is very close to egg or meat protein. It is definitely one of the best sources of complete protein in the plant kingdom.
Proteins from quinoa, amaranth and buckwheat are also considered complete and have digestibility comparable to other high-quality protein sources.
Quinoa, amaranth and buckwheat are commonly called pseudo-grains because they are used in our diet as grains, but they are actually seeds. Since they are not related to grasses like wheat, they are also gluten-free.
Plant-based proteins are generally 10-30% harder to digest than animal-based ones due to their lower availability of digestive enzymes in our gut.
How much protein is enough?
Our needs for protein change during our lifetime, and they highly depend on our physical activity levels.
The average recommended daily intake for adults with a sedentary lifestyle is set to 0,8 g/ kg body weight (b.wt.). That means that if you weigh 70 kg, you will need 56 g of protein daily.
Multiply your weight by 0,8, and you will get the amount of protein in grams you should get every day through food. Did you already calculate your needs?
Due to the lower digestibility of plant-based protein, vegans and vegetarians should have a 10-30% higher protein intake than their omnivore peers. That would mean that their recommended intake should be, on average, 1 g/ kg b.wt.
For people over 40-50 years old, which is the age when muscle loss starts to arise, the intake should be around 1-1,2 g/ kg b.wt.
If, until that point, you needed 56 g of protein, your requirement will increase to 70-84 g of protein per day.
If you are a physically active individual, you will need a higher amount of protein than that. For people who exercise regularly and focus on endurance training, that amount will climb up to 1,2-1,4 g/ kg b.wt.
On the other hand, for people exercising regularly but base it on strength training, the recommended intake will be even higher, 1,2-1,7 g/ kg b.wt.
Can you take too much protein?
Contrary to what you may think, our body doesn’t have an infinite ability to increase protein synthesis in response to increased protein and energy intake. If that were so, we would all look like Hulk.
Once our body gets the necessary amount of protein, it can use the excess for energy production, store it in the form of fat or excrete it through urine.
That means that above a certain level, our bodies can’t use that protein the way we would maybe like to.
An amount of protein above 2 g/ kg b.wt is considered too much and can negatively affect our bodies.
Potential adverse effects of too much protein:
- Increased calcium loss through urine can deplete calcium storage in bones, increasing the risk of osteoporosis.
That can be prevented with a ratio of calcium (mg) to protein (g) intake of more than 20:1, but in that case, the diet needs to be well-planned.
- It can harm our kidneys, but only if our kidney function is already weakened.
For example, a study on well-trained athletes showed no negative impact on kidney function for protein intake lower than 2,8 g/kg TM.
- Potential dehydration due to higher urine excretion.
- Lowering testosterone levels.
When should you consume protein?
The next question is how you should spread that recommended daily protein intake throughout the day.
Studies show that one meal’s ideal amount of protein ranges from 15 to 30 g. More protein than that in one go doesn’t show any benefits.
Imagine you have a meal with 60 g of protein that your body will break down into amino acids. If, at that point, your body doesn’t need a certain amount of these amino acids, it won’t store them in that same form for later. As previously explained, it will use it for energy production or simply excrete it.
That would mean that it is much better to disperse the total amount o protein throughout the day than to try to fit it all into one meal.
A person that weighs 70 kg and needs 1,2 g/ kg b.wt will need 84 g of protein. That person can easily fit that daily recommendation into three meals with 28 g of protein each without any losses.
Now, you are probably asking yourself how much 28 g would look in the form of a meal. The following list of great animal and plant-based protein sources with a high nutritional value and low to moderate fat will hopefully give you a better idea of what 28 g looks like.
How much is 10 g of protein?
Animal-based sources:
35 g cooked beef, pork or lamb
40 g cooked chicken
50 g cooked white fish/ tuna/ salmon
1 cup or 240 ml milk or yoghurt
30 g or 1-2 slices of cheese
70 g cottage cheese
2 eggs
Plant-based sources:
4 slices of bread
1 cup cooked pasta
3 cups cooked whole grains
3 cups cooked rice
¾ cup cooked legumes (lentils, beans)
120 g firm tofu
1 cup or 240 ml soy milk
60 g nuts or seeds
We could be talking about proteins for days. The topic is so broad and complex that it is hard to say everything necessary in one story. Still, I hope you enjoyed scratching the surface.
I also hope you acquired some new tools to help you meet your daily protein needs and spread them more evenly throughout the day.
Tell me in the comments below if you found this article useful. If you have more questions on this topic, don’t hesitate to ask! I would be more than happy to help!
