We often hear people say, “Protein is protein, right?” Well… not quite. Yes, both plants and animals contain protein. But the way your body digests, absorbs, and uses that protein is very different.
Let’s break it down simply.
Amino Acids: Your Body’s Building Blocks
Your body needs 20 amino acids.
Out of these, 9 are Essential Amino Acids (EAAs) meaning your body cannot make them. They must come from food.
These EAAs are critical for:
- Muscle growth
- Recovery
- Hormones
- Enzymes
- Immune function
Animal proteins naturally contain all 9 EAAs in the right amounts. Most plant proteins… don’t.
That’s the real difference.
Animal Proteins: Complete & Easy for Your Body
Proteins from chicken, eggs, fish, meat, and dairy are called complete proteins. You digest them easily, and your body uses them efficiently.
They also have plenty of leucine, the key amino acid that switches on muscle protein synthesis (MPS) through the mTOR pathway. Think of leucine as the “START” button for muscle building.
Animal proteins press this button strongly.
Plant Proteins: Incomplete & Tougher to Digest
Many plant proteins are low in:
- Methionine
- Lysine
- Sometimes leucine
Because of this, to trigger the same MPS response, you need much larger quantities of plant protein.
That’s not always practical—especially on a low-carb lifestyle where most plant protein sources also come packaged with high carbs.
On top of that, plant proteins contain anti-nutrients, which make digestion even harder.
Why DIAAS Replaced PDCAAS (A Big Update You Should Know)
The old PDCAAS scoring system used to say plant and animal proteins were “similar”. But it wasn’t accurate. So the scientific community moved to DIAAS, which measures:
- Real amino acid availability
- True digestibility
- How much protein your body actually uses
And this is where animal proteins shine. Chicken, eggs, pork, and dairy consistently score much higher than pea, soy, wheat, or rice proteins.
The Anti-Nutrient Problem in Plant Proteins
Plant proteins come with naturally occurring compounds that make digestion more difficult.
Let’s look at the big three:
- Trypsin Inhibitors
These block the digestive enzymes your body uses to break down protein. This means you absorb less protein, even if you eat a lot of it.
Continuous exposure forces the pancreas to work harder. Animal studies show stress on the pancreas, although the link to pancreatic cancer in humans is not confirmed.
The good news?
Proper cooking and fermentation reduce most trypsin inhibitors.
- Phytates
Phytates are like “nutrient magnets.” They grab onto:
- Iron
- Zinc
- Calcium
- Magnesium
…and stop your body from absorbing them.
They also reduce Pepsin, a stomach enzyme needed for protein breakdown. So again, even if you eat the protein, your body may not use it.
- Lectins: Lectins can stick to the gut lining and irritate it. In sensitive people this can lead to:
- Gas and bloating
- Inflammation
- Increased gut permeability (“leaky gut”)
- Poor nutrient absorption
If gut inflammation continues, it may worsen insulin resistance which is a lectin–gut–IR cycle.
In genetically sensitive individuals, lectins can also aggravate autoimmune conditions through molecular mimicry.
The Heavy Metal Issue in Plant Protein Powders
This is a concern many people are not aware of. Multiple independent lab tests have found high levels of heavy metals in plant protein powders, especially:
- Pea
- Rice
- Hemp
- Blended plant proteins
Plants absorb metals from soil, pesticides, industrial pollution, and groundwater.
During protein extraction, these metals become concentrated.
Animal proteins (whey, egg, collagen) do not accumulate heavy metals the same way.
This is why their contamination risk is much lower.
Long-term daily consumption of contaminated plant protein powders can lead to slow heavy-metal buildup in the body.
Can We Reduce Anti-Nutrients? Absolutely.
Traditional food practices already had the solutions:
✔ Fermentation
- Reduces phytates up to 80%
- Breaks down lectins and trypsin inhibitors
- Boosts digestibility
Examples: Idli, Dosa, Dhokla, Tempeh, etc.
✔ Soaking & Sprouting
Helps reduce phytates and lectins naturally.
✔ Pressure Cooking
Excellent for destroying lectins in beans and lentils.
These methods make plant proteins much easier on your gut but they don’t remove everything.
So, Which Protein Is Better?
Animal Protein
✔ Complete amino acids
✔ Highly digestible
✔ High DIAAS score
✔ No lectins, no phytates, no trypsin inhibitors
✔ Minimal heavy metals
✔ Best for muscle, hormones, metabolism
Plant Protein
✔ Great for fibre, polyphenols, antioxidants
✔ Better for the environment
✘ Lower digestibility
✘ Anti-nutrients reduce absorption
✘ Higher heavy metal risk (especially powders)
✘ Not ideal as your only protein source
Final Takeaway
Plant foods are amazing for fibre, antioxidants, vitamins, and overall health.
But relying only on plant protein especially powders can lead to:
- Lower protein absorption
- Mineral deficiencies
- Gut irritation
- Higher heavy-metal exposure
Animal proteins remain unmatched in:
- Bioavailability
- Amino acid completeness
- Muscle protein synthesis
- Metabolic efficiency
The best approach?
Enjoy plants for their nutrients — but let high-quality animal proteins be the foundation of your protein intake, especially if you care about muscle, metabolism, longevity, and overall health.
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