Protein: how much you need, how to choose it, and why it is key to maintaining muscle

Hello, I'm Dr. Isabel Viña Bas, physician and Scientific Director at IVB Wellness Lab.

We talk about protein more and more every day. We find it in shakes, bars, yogurts, breads, and all kinds of enriched foods. And it is completely normal for questions to arise: Do we really need that much protein? What happens when we eat it? Does all the protein we consume go to muscle? Are all proteins equal? How much do we need depending on our age or activity level?

To answer these questions, I am joined in this episode by Dr. Juan Viña, a physician, professor of Biochemistry and Molecular Biology, and an expert in protein metabolism.

And there is an idea that will be present throughout the entire conversation: protein is much more than muscle.

Our body needs proteins to maintain tissues, produce enzymes, build hormones, participate in metabolic pathways, and carry out many other essential functions for life.

That's why, when we talk about protein, we need to stop thinking solely about gaining muscle mass and start understanding it from a much broader perspective.

What does our body do with the protein we eat?

When we consume a food that contains protein, our body does not directly use that protein as we have eaten it.

First you need to digest it.

Proteins are made up of chains of amino acids, and during digestion, these structures are broken down into smaller units. Amino acids are absorbed in the intestine, enter the bloodstream, and from there can reach the body's various tissues.

Y aquí encontramos una de las primeras ideas importantes:

the protein you eat doesn't go directly to the muscle.

Amino acids are distributed throughout the body and are used to build different types of proteins.

For example, they can be used to produce:

• Structural proteins.

• Enzymes.

• Defense-related proteins.

• Hormones.

• Proteins required for different metabolic pathways.

Muscle is one of those tissues, but it is not the only one.

Why do muscles need protein?

Muscle needs amino acids to manufacture the proteins that make up its structures.

But it also needs protein so the muscle itself can function properly.

Within muscle tissue, there are different metabolic pathways and enzymes that allow processes such as energy generation and utilization, glycogen storage, or muscle contraction to occur.

Therefore, when we talk about protein and muscle, we have to think about two different concepts:

Protein is used to build muscle, but also so that muscle can function.

And this is especially important as we get older.

Because the goal of maintaining good muscle mass isn't just about having more muscle.

It is about ensuring the muscle remains functional.

That allows us to walk, get up from a chair, climb stairs, carry bags, maintain our independence, and fight against frailty.

Por eso, cuidar el músculo es importante durante toda la vida.

Protein isn't just in muscle

When we think of protein, the first thing that probably comes to mind is muscle.

But protein is practically everywhere.

For example, many hormones are proteins.

Among them we find the insulin, prolactin, growth hormone, and various hormones related to the functioning of the reproductive axis, such as FSH and LH.

Enzymes are also proteins, and they are essential for the various chemical reactions that keep our body functioning.

Therefore, when we consume protein, we are not simply providing "muscle-building material."

We are providing the amino acids that our body needs to produce its own proteins.

Muscle is of special importance because it is a highly active tissue and because its maintenance is directly linked to our mobility and independence, but metabolically speaking, it is not the only tissue that needs protein.

Where does the protein we eat go?

Once proteins are digested and amino acids are absorbed, they reach via portal circulation the liver.

And here we find a key piece.

The liver is the first major organ to receive these amino acids from the gut, using a significant portion of them for its own functions.

Among other things, the liver uses amino acids to make structural proteins and proteins that it subsequently releases into the blood, such as albumin.

But not all amino acids remain in the liver.

A portion continues into the general circulation and can reach other tissues such as the brain, kidneys, heart, or muscle.

Therefore, when we ingest protein, there is an amino acid distribution among different tissues.

And this also helps us understand why liver health is so important when we talk about protein metabolism.

Why is the liver so important for protein metabolism?

Amino acids have a structure containing carbon and nitrogen.

When we consume more amino acids than we need to synthesize proteins, our body has to metabolize them.

El amino group is converted into urea, a process that occurs in the liver, and the urea is subsequently eliminated through urine.

Furthermore, the carbon skeleton of amino acids can be oxidized or transformed into other metabolic products.

Under certain circumstances, it can even contribute to lipid formation.

Therefore, the liver plays a fundamental role in amino acid metabolism.

And this is especially interesting when we talk about people who present metabolic disorders or hepatic fat accumulation.

Does exercise increase protein delivery to the muscle?

Here is one of the most interesting concepts from the episode.

Amino acids are distributed throughout the body, but exercise can help ensure that a greater amount reaches the muscle.

And why?

Through several mechanisms.

On one hand, insulin promotes the muscular uptake of certain amino acids, especially branched-chain amino acids.

Additionally, exercise itself promotes the transport of these amino acids to the muscle.

But there is another very simple mechanism that we often forget:

exercise increases blood flow to the muscle.

If a certain concentration of an amino acid is present in the blood and blood flow to the muscle tissue increases, a greater amount of that amino acid will reach the muscle.

Por eso, si queremos favorecer que los aminoácidos que ingerimos se utilicen para mantener y desarrollar nuestra masa muscular, la combinación tiene mucho sentido:

enough protein + strength training.

It is not just about eating more protein.

You also need to provide the muscle with the stimulus it needs.

How Much Protein Do We Need a Day?

This is probably one of the most frequently asked questions.

For a long time, the figure of 0.8 grams of protein per kilogram of body weight per day.

Pero aquí es importante hacer una distinción:

0.8 g/kg does not necessarily mean it is the optimal amount for everyone.

It is a minimum reference established within a specific context and under certain conditions.

And one person's needs are not the same as another's.

Does not need the same:

• A young person than an older person.

• A sedentary person than a person who trains.

• A healthy person than a sick person.

• A person who is maintaining their weight than someone who is losing weight.

• A 30-year-old person than an 80-year-old person.

Human beings are heterogeneous.

Therefore, we cannot take a single figure and apply it identically across the entire population.

Where did the 0.8 g/kg recommendation come from?

This figure also has an interesting historical context.

The first recommendations were established decades ago, at a time when social and health circumstances were very different.

During World War II, for example, there was a clear concern with determining what the amount was minimum of protein that could be guaranteed under certain circumstances.

Over the years, research has evolved, and so have the methods used to study protein requirements.

Today, we have a greater understanding of individual differences, aging, physical exercise, disease, and protein composition.

Therefore, the figure of 0.8 g/kg may fall short for many people.

As a general reference, the episode suggests an approximate intake of 1.1–1.2 g of protein per kilogram of body weight per day, siempre teniendo en cuenta la calidad de la proteína y las características individuales.

For certain individuals, especially those who are physically active, requirements may be higher.

Do older adults need more protein?

Age is one of the factors we need to consider most.

Over the years, what we know as anabolic resistance.

This means that the muscle may respond less effectively to a given amount of amino acids and to the stimulus of exercise.

A 70-year-old person can consume the exact same amount of protein as a 25-year-old and yet get a different muscle response.

This happens because the body changes with age.

There may be lower efficiency in the absorption of certain nutrients, diseases may coexist, medication consumption may increase, and, above all, physical activity may decrease.

That's why maintaining an adequate protein intake and pairing it with strength training becomes even more important as we age.

The goal is not simply to live more years.

It's reaching those years maintaining our autonomy and our functional capacity.

What is anabolic resistance?

Anabolic resistance can be understood as a lower muscle sensitivity to amino acids and to the stimulus needed to build and maintain muscle protein.

It can appear with age, but it is not exclusive to aging.

It can also be related to:

• Immobility.

• Disease.

• Inflammation.

• Lack of exercise.

• Metabolic disorders.

And here we find a fundamental principle of biology:

for a response to occur, there must be an adequate stimulus.

Eating protein provides the necessary amino acids, but without sufficient muscle stimulation, the response won't be the same.

For this reason, a person who remains immobilized for an extended period can lose muscle mass even if they continue to take in protein.

¿Qué relación existe entre resistencia a la insulina y músculo?

Insulin resistance can also influence the muscle's response to protein.

Among the amino acids especially important for muscle are branched-chain amino acids, such as:

• Leucine.

• Isoleucine.

• Valina.

In order for these amino acids to enter the muscle, there is a relationship with insulin signaling.

If a person has peripheral insulin resistance, muscles may respond worse and absorb certain amino acids less efficiently.

This adds another piece to the concept of anabolic resistance.

And here an interesting relationship emerges between metabolism, body composition, and muscle mass.

How can we improve insulin sensitivity?

One of the main tools is once again the exercise.

Ganar masa muscular puede ayudar a mejorar la sensibilidad a la insulina y, al mismo tiempo, favorecer una mejor utilización de los nutrientes.

Diet also plays an important role.

Among the strategies mentioned in the episode, we find the increase in the consumption of fiber, which can help improve certain metabolic parameters and reduce inflammation.

It also mentions some supplements that can be used as support in certain contexts, including:

• Berberine.

• Coenzima Q10.

• Lycopene.

• Silymarin.

• Gymnema sylvestre.

• Myo-inositol.

But once again, supplements are no substitute for the two main foundations:

movement and proper nutrition.

How much protein can we absorb in one meal?

There is a widespread idea that our body can only absorb a certain amount of protein in one meal.

However, from the standpoint of digestion and absorption, there is no simple limit beyond which the body stops absorbing ingested protein.

Our gut features numerous amino acid transporters and different absorption mechanisms.

Therefore, we should not think that if we consume more than a certain amount in a meal, the rest simply "goes to waste."

What happens after absorption is different.

Once our body has more amino acids than it needs to produce proteins, these can be metabolized.

The amino group is converted into urea in the liver and excreted through urine, while the carbon skeleton can follow various metabolic pathways.

absorbing protein does not necessarily mean using all of that protein to build muscle.

They are different processes.

Are all proteins the same?

No.

And here we need to introduce another fundamental concept: protein quality.

To assess the quality of a protein, it is not enough to simply know how many grams it contains.

We also need to know:

• How much essential amino acids it provides.

• What part of that protein we can digest.

• How much of those amino acids we can absorb and utilize.

Currently, one of the systems used to assess these aspects is the DIAAS, which takes into account the essential amino acid composition, as well as the digestibility and bioavailability of the amino acids.

This allows for a more comprehensive assessment than simply looking at how many grams of protein appear on a label.

Which foods have the highest quality protein?

We can find high-quality protein in both animal- and plant-based foods.

Among the examples discussed in the episode, we find:

• Milk.

• Egg.

• Meat.

• Fish.

• Soy.

• Quinoa.

• Trigo sarraceno.

• Tofu.

• Lupin.

• Pea.

We also find isolated proteins with high protein quality, such as whey, milk, or soy isolates.

And this is important because it dispels another common idea:

It is not necessary to consume animal-based foods to get high-quality protein.

There are plant sources with a good amino acid profile, and we can also combine different foods to improve the overall amino acid profile of our diet.

What is protein complementarity?

Different plant proteins may contain varying amounts of certain amino acids.

However, this does not mean that a plant-based diet cannot provide all essential amino acids.

complementarity.

If a protein contains a lower amount of a specific amino acid, we can combine it with another protein that provides a higher amount.

For example, throughout the day we can combine different foods such as:

• Cereals.

• Legumes.

• Eggs.

• Soy.

• Peas.

• Nuts and seeds.

Not every meal needs to be mathematically perfect.

What matters is the food intake as a whole.

That is why, when assessing protein quality, we must also look at the overall range of foods a person consumes throughout the day.

What role does leucine play in the muscle?

Among the essential amino acids, leucine plays an especially relevant role in muscle.

Along with isoleucine and valine, it is one of the branched-chain amino acids.

Leucine is especially important because it plays a role in signaling related to muscle protein synthesis.

But this does not mean that we can reduce muscle nutrition to leucine alone.

To make a protein, we need all essential amino acids.

Leucine can act as an important signal, but the body needs to have the remaining essential amino acids available to complete protein synthesis.

That's why a complete, high-quality protein makes sense as part of a strategy aimed at maintaining muscle mass.

What happens when we are sick or immobilized?

During an illness, a period of immobility, or a major inflammatory process, maintaining muscle mass can be particularly difficult.

The body can increase the breakdown of muscle proteins and reduce the ability to build new proteins.

In these situations, in addition to trying to maintain a sufficient protein intake and exercising whenever possible, it can make sense to turn to certain supplements.

One of the ones that particularly stands out in the episode is the HMB.

What is HMB and what can it be used for?

HMB is a metabolite derived from leucine.

It is produced naturally in our body, although in very small amounts.

Its main interest in this context is that it can help to reduce muscle protein breakdown, a process known as proteolysis.

This can be especially relevant in situations where muscle is at a higher risk of loss, such as:

• Fragility.

• Immobility.

• Disease

• Major inflammatory processes.

This does not mean that HMB replaces protein or exercise.

In fact, the order of priorities should remain:

sufficient protein + strength training + avoiding immobility.

HMB can be used as support when these tools are not enough or when there are specific situations where maintaining muscle mass is particularly difficult.

Can collagen replace a complete protein?

Collagen is a very important protein.

In fact, it is the most abundant protein in the body

It is essential for tissues such as skin, tendons, and ligaments.

But here we need to differentiate between two concepts.

It is one thing for collagen to be an important protein for our body, and a completely different thing for it to be a good source of complete dietary protein.

Collagen has a different amino acid composition and features very low amounts or an absence of certain essential amino acids, such as tryptophan. In addition, it contains low levels of leucine and methionine.

That is why, collagen should not be used as a substitute for a complete protein.

We can use collagen peptides for other reasons, as there is evidence regarding certain parameters related to the skin, tendons, or ligaments.

However, this does not mean that it can replace foods like eggs, fish, meat, soy, or an isolated protein when our goal is to meet overall protein requirements.

They are different objectives.

Protein and muscle: what should we keep in mind?

After discussing digestion, absorption, protein quality, age, exercise, anabolic resistance, and metabolism, we can draw several key takeaways.

Primero: Protein isn't just for building muscle.

The amino acids we obtain through diet are used to make structural proteins, enzymes, hormones, and many other molecules necessary for the body to function.

Second: quantity matters, but quality does too.

We shouldn't just look at how many grams of protein a food contains. We also need to evaluate its essential amino acids, digestibility, and bioavailability.

Third:

Age, exercise, health status, mobility, and metabolic context can alter our needs.

Bedroom: Strength training is essential.

Eating protein alone is not enough if we want to maintain our muscle mass. Muscle needs an adequate stimulus to respond.

Quinto: anabolic resistance may develop with age.

That is why maintaining a good protein intake and performing strength training becomes even more important as we age.

And, finally, collagen does not replace a complete protein.

It may be of interest for specific fabrics and targeted objectives, but we should not confuse its specific properties with its ability to meet general protein needs.

Because, in the end, when we talk about nutrition and muscle health, there is no single variable that explains everything.

Protein quantity matters. Quality matters. Exercise matters. Age matters. Metabolic state matters. Rest and lifestyle matter too.

Health, once again, does not work in isolated pieces.

Transforming your health is a matter of applying science consistently, day by day.

Hope you like it :)

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