What's the best source of Protein?

Everything seems to be labeled “a source of protein” now a days, but not all protein is made equal. Animal vs Plant sources, whey vs pea protein. You get the picture…

Did you know there is actually a protein quality index, a score if you will. This is called the Digestible Indispensable Amino Acid Score (DIAAS). This score rates the amino acid profile of the protein source and its digestibility in the human body.

IN THIS ISSUE:

• 💪 Why Protein Quality Matters

• 🧬 Leucine and Muscle Protein Synthesis

• 🤓 The Protein Quality Scoring System

• 🥗 Vegan Protein Sources

• 💤 Pre Sleep Protein Intake

• ✍️ Key Takeaways and Practical Applications

THE BASICS
Why Protein Quality Matters.

Protein is an essential macronutrient and is made up of 20 amino acids, which are the building blocks of your body. Consuming protein triggers Muscle Protein Synthesis (MPS), which is a metabolic process that helps you recover, build and maintain muscle.

Out of the 20 amino acids mentioned above, 9 are Essential Amino Acids (EEA’s). Of these 9, 3 of them are classed as Branched Chain Amino Acids (BCAA’s) which I’m sure you have came across with supplement companies trying to sell you them.

🚨 Spoiler Alert! If you are consuming enough dietary protein from quality sources, you have no need to pay supplement companies money for EAA’s & BCAA’s, as the protein you are already consuming will meet those needs. It’s like trying to put a fire out with a cup of water when there is a fire engine next to you hosing it down… Your taking part but not doing very much…

YOUR MAIN PLAYER
Leucine And Muscle Protein Synthesis

Arguably the most important of these EAA’s is Leucine. Thats because Leucine is the EAA that acts as a trigger to stimulate mTOR, which in turn then stimulates MPS.

Leucine triggering MPS was subject of a systematic review, which included 29 studies by (Lacerda et al., 2020a). Their findings correspond with the above statement.

How much Leucine? A review published in the Journal of the International Society of Sports Nutrition by (Stark et al., 2012) , states 3-4g of Leucine per meal, to be sufficient to maximally stimulate MPS.

Below is a chart from (Gorissen et al., 2018) of several food sources and human muscle for comparison, showing the percentage of leucine content in relation to total protein.

Although Leucine has the important role of triggering MPS, you still need the other eight EAAs, to actually build the new muscle tissue.

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TELL ME MORE…
The Scoring System

The Food and Agriculture Organization (FAO) and World Health Organisation (WHO) originally recommended the PDCAAS scoring system in 1993, which looks at the content of all 9 EAA’s and the protein digestibility by the human body. Since then the FAO & WHO have recommended using the DIAAS score, which scores based off the ileal amino acid digestibility.

In Short, the DIAAS score basically measures the protein sources amino acid profile and its bioavailability. 

Most animal protein sources (Milk, Whey, Eggs and Beef) have a complete amino acid profile with a digestibility rating of 95-100%, however plant sources usually lack one or more amino acid and have a lower digestibility rating between 70-85% (Tomé, 2023).

An important caveat to note is that the above bar chart is reference to DIAAS scores of proteins being eaten in isolation not in combination with other food sources.

So this brings me to the, everything is labeled as a “good source of protein” statement I mentioned at the start.

Let’s take Peanut Butter for example: yeah it contains protein. But the DIAAS score of peanut butter is 0.46 (Berrazaga et al., 2019) which is regarded as poor. 

This means in a typical 100g serving of peanut butter there is:

• Fat ~49g

• Protein ~28g

• Carbs ~16g

However as it only has a DIAAS score of 46, while consuming ~ 49g of fat, I wouldn’t call it a good source of protein!

I EAT GREENS
Vegan Protein Sources?

Although animal sources tend to have higher DIAAS scores than their plant based counterparts, some plant based sources meet all the EAA requirements and can therefore be considered a good source of protein.

Scoring in the excellent or good range… (I included some of these in the chart above, but lets recap) 👇

• Pea Protein Isolate: Has a DIAAS score of 1.00 (100%), meaning it meets all EAA requirements. (Guillin et al., 2021)

• Tofu: DIAAS = 0.97 (97%)

• Soy Protein: DIAAS = 0.91 (91%)

• Chickpeas: DIAAS = 0.83 (83%)

• Pea Protein Concentrate: DIAAS = 0.82 (82%)

Recommendations for Vegan and Plant based folks: 👇

1. Aim towards to the higher end of the recommended daily protein intake, just in case some of your sources have lower DIAAS scores.

2. Perhaps supplement protein intake with high quality, plant based protein powders (Pea Isolate & Soy Protein).

As stated above, plant based protein sources are usually consumed in combination and not in isolation. This means that one plant based protein source, which may be limited in one EAA (lowering it DIAAS score) may be accompanied with another source to meet the missing EAA requirements. Therefore, elevating your meals overall DIAAS score.

BEDTIME
Consideration To Pre Sleep Protein Intake

Casein Protein is an animal protein source derived from milk, in fact milk protein is 80% casein and is a complete protein source. It’s also digests slower than whey and other protein sources, hence why it is typically consumed before bed as it feeds your muscles with amino acids at lower levels over a more prolonged period of time.

According to the findings of this study (Guillin et al., 2021), Casein Protein has a DIAAS score of 1.45 (145%)! One of the highest scores I’ve came across for any protein source.

A study by (RES et al., 2012) looked at 16 males who performed resistance training and 30 minutes before bed consumed casein protein. The results showed that it was effectively digested resulting in a rise in amino acids in their system which remained throughout the night, increasing full body protein synthesis rates. Showing the idea that it digests slower and provides more sustained at longer supply to the muscles during the night.

The main form you will probably buy to supplement is Micellar Casein.

JUST FOR YOU
Key Takeaways & Practical Applications

• Leucine has the important role of triggering mTOR which signals Muscle Protein Synthesis.

• 3-4g of Leucine per meal is sufficient to maximally stimulate MPS

• Most animal sources have a complete amino acid profile and score in the “excellent” category for protein source.

• Several sources of plant proteins also provide good protein sources.

• Casein protein has the highest DIAAS score thats been studied.

• Studies have shown that pre sleep casein protein raises MPS through the night.

No matter which diet regime you choose to follow, you can meet a high quality protein intake.

Don’t just fall for the whole “good source of protein” marketing trick by companies to sell you their products.

This may be more challenging if you are Vegan / Plant based, but is certainly achievable. Just be mindful and ensure your protein intake is from higher quality sources. Pea Protein and Soy Protein isolate protein powders match the quality of whey protein and are good alternatives.

If most of your protein sources come from animal products, as long as you are hitting your recommended protein intake, the protein quality and leucine content of that protein will take care of itself.