I sometimes hear the phrase “animal proteins” used as a derogatory term, as if there’s something inherently bad about them, but are “plant-based” proteins better? Are all proteins created equal?

Are memes like this perpetuating a belief system rather human health or sustainability?  

But is there really any difference?  Or are they just more concentrated in animal sources?   

What you will learn from this article

• The bottom line of the analysis is that meat and seafood contain more protein per calorie and per gram (especially if you consider bioavailability).  

• Getting adequate protein while moderating energy from carbs and fat is critical to satiety, optimising body composition and avoiding metabolic syndrome.  

• Unless you are eating a LOT of vegan protein powders a “plant-based” diet sourced from industrial agriculture is a sure way to ensure you are always hungry and will consume a lot more energy to get the nutrients you need, including protein.

Comparison of amino acids 

In an effort to bring some clarity to the discussion, this article compares the amino acid profile of the following groups of foods:

• animal only,

• plant only,

• plant only (excluding vegetables),

• nutrient-dense animal-based, 

• nutrient-dense (plant only), 

• maximum nutrient-density.

This first chart shows a comparison of the essential amino acids as a proportion of the Optimal Nutrient Intake per 2000 calories for each approach.  Other than the fact that animal-based foods provide a LOT more protein, it’s hard to make much sense of this chart.   

Animal foods 

Zooming in, to understand how the amino acid profile differs between plant and animal-based foods, the chart below shows the approaches that contain animal-based foods vs the average of all foods.  Animal foods have marginally more methionine and lysine and less phenylalanine than the average of all the other foods. But should we be afraid of these amino acids?

Lysine 

Lysine an amino acid that is plentiful in fish (e.g. halibut, haddock, shrimp and prawns) and meat (e.g. beef, chicken and turkey).  Lysine is an essential building block for all other proteins in your body and plays a major role in calcium absorption.  

Lysine is essential for muscle growth and is used to form carnitine, which helps you use fats for energy.  Inadequate lysine is associated with anemia, fatigue, poor concentration, loss of bone calcium, tiredness and infertility.   

Our satiety analysis of data from Optimisers indicates that lysine has a strong satiety effect once we consume more than around 6 grams of lysine per 2000 calories.  

Methionine 

Methionine is an essential amino acid that is the substrate for other amino acids such as cysteine, taurine and glutathione.  

While there are concerns about excess methionine from muscle meat driving cancer grown, this seems to be mitigated when we get adequate glycine in our diet.  

The most concentrated sources of methionine are eggs and seafood (e.g. cod, shrimp, prawns, haddock).  

Our satiety analysis shows that we get a strong satiety response once we consume more than around 2 grams per 2000 calories of methionine.  

Plant-based foods  

Interest in a “plant-based” diet has been growing in popularity lately, spurred on by the Netflix films What the Health (2017) and Game Changers (2019).   

However, rather than promoting more fruits or vegetables, the overarching message of these films is that eating animal products was bad and should be minimised.  Hence, we’ve also looked at scenarios where we exclude vegetables (which are typically not a focus of the “plant-based” narrative).

This next chart shows a comparison of the plant-based approaches vs the average of all foods.  In contrast to the animal-based foods, we get less methionine, lysine and histidine from plant-based foods. 

But what really stands out there is that it is much more difficult to get adequate protein when we exclude animal-based foods, particularly if we aren’t eating our veggies.  

Without a focus on vegetables, a plant-based diet has a very low protein to energy ratio as it ends up being sourced refined grains and oils!  

Focusing on the most nutrient-dense plant-based foods does give us a better chance of getting adequate protein but just going plant-based means we need to eat four or five times as many calories!

Can you get enough protein on a plant-based diet?  

According to the Game Changers website:

“When it comes to gaining strength and muscle mass, research comparing plant and animal protein repeatedly demonstrates that as long as the right amount of amino acids are consumed, the source is irrelevant.”  

The problem is that without going out of your way to consume a LOT of plant-based protein powders (such as those made by James Cameron’s vegan pea protein company) you will struggle to get the optimal level of protein without consuming a lot more calories! 

Rather than any difference in amino acid profile, what really stands out from this analysis is that approaches that contain some animal protein have a vastly higher percentage of protein.  If you don’t get enough nutrients from your diet (particularly amino acids), your body will upregulate your appetite and you will go in search of enough nutrients to survive.  

Over the past 50 years or so we’ve seen an increase in energy from both fat and carbs in our food system as we’ve followed the guidelines prepared by the United States Department of AGRICULTURE’s “nutritional guidance” which has largely focused on the reduction of animal products.

This increase in energy has mainly come from added fats and flours and cereals (i.e. the “plant-based” products of industrial agriculture).  

This additional excess energy in our diet has come largely from industrial agriculture which has a devastating effect on the ecosystem and degrades topsoil.  They are also heavily reliant on synthetic fertilisers that inject limited fossil fuel energy into the food system and then into our bodies.

It’s going to be hard to get enough protein (i.e. to promote satiety, build muscle or avoid sarcopenia) on a plant-based diet without processed protein powders.  We tend to consume a LOT more food if we try to eliminate animal products. Once we exclude animals most of us end up relying on the products of industrial agriculture.  

Take a moment to consider the impact on our health and the planet if we could modify our food system so we all consumed 1000 calories less per day!  

It’s hard to say if If the different amino acid profiles make much of a difference either way.  But the protein:energy ratio of the foods and the amount absorbed into your body will have a very significant impact!!!

How much protein do you need?

It’s not just about eating MORE protein with no regard for our energy intake.  As we consume more protein our overall energy intake increases.  

It’s not protein, but rather managing the easy energy from fat and carbohydrates while getting enough protein.  The magic of satiety happens when we reduce the amount of easy energy from fat and carbs. Refined fat and non-fibre carbs are basically the formula for hyperpalatable comfort food (aka “junk food”) that we tend to overeat.  

When we reduce the amount of energy from carbs and fat we tend to eat less. 

It’s harder to overeat foods that contain a higher proportion of energy from protein.  When our diet consists of less carbs+fat energy our percentage of energy from protein increases.  The population average intake of protein, the estimated average requirement (EAR) and the recommended daily intake (RDI) align with the lowest satiety response.  

While the population average protein intake is around 12%, the average intake of Optimisers, who are focusing on getting more nutrients in their diet, is 28%.  Not many people are able to sustain more than around 40% of their energy from protein over the long term because it is so satiating. Once you get enough protein your body goes in search of easy energy from fat and/or carbs.

While the minimum protein intake to prevent diseases of deficiency is 0.8 g/kg BW, recent recommendations have raised this target to 1.2 g/kg BW and most people who are active or trying to grow or preserve lean muscle mass tend to aim for 2.2 g/kg LBM or 1 g/lb LBM.  The average protein intake of Optimisers is 2.0 g/kg LBM or 1.5 g/kg body weight.  

Micronutrient profile 

It’s also important to consider the vitamin, mineral and essential fatty acid content of your preferred way of eating.  

All foods 

The chart below shows the essential micronutrients provided in all the foods in the USDA database as a proportion of the Optimal Nutrient Intakes.  The essential amino acids are shown in red.   Unless you go out of your way to avoid animal products, protein tends to be fairly easy to obtain from our food system.

The most nutrient-dense foods

By contrast, the chart below shows the nutrient fingerprint when we emphasise the harder to find vitamins, minerals and essential fatty acids.  Foods that contain more essential nutrients per calorie also contain a much higher percentage of protein! Protein simply comes along for the ride with nutrient-dense food.

Animal-based foods 

This next chart shows the nutrient profile of all 2,800 animal foods in the USDA database.  While the nutrient score is better than average, we still struggle to get enough nutrients like K1, C, A, omega 3 and folate.  

The next chart shows the most nutrient-dense animal-based foods (i.e. the top 1000 foods when we prioritise foods that contain the harder to find nutrients). 

Plant-based micronutrients 

This next chart shows the nutrient fingerprint of the four thousand or so plant-based foods (excluding foods fortified with synthetic vitamins).  If we simply define our dietary approach as “plant-based”, we’re going to struggle to not only get enough protein but also omega 3 and B12 (which most strict vegans tend to supplement) as well as selenium and vitamin A.  

When we prioritise the harder to find vitamins, minerals and essential fatty acids we get a better nutrient score, more protein and a lower energy density.  However, we still struggle to get optimal levels of omega 3, B12, selenium, vitamin A and zinc.  

If you don’t eat animal products or a LOT of vegetables you’re really going to struggle to get enough nutrients! 

Without vegetables, you can boost things a little by focusing on nutrient density, but it’s far from optimal.  

Comparison of nutrient density 

This next chart shows a comparison of the Optimal Nutrient Score for the different approaches.  Just “going plant-based” without focusing on vegetables could have a diabolical effect on your ability to get adequate micronutrients across the board (not just protein)!  An omnivorous diet with a focus on nutrient density will give you a much better chance of getting all the nutrients you need without having to consume too many calories.

The chart below shows a plot of % protein vs the Optimal Nutrient Score.  While it makes sense to optimise your diet by chasing the harder to find nutrients, getting adequate protein can be an important first step.  Actively avoiding protein or “going plant-based” will also make it a lot harder to get adequate vitamins and minerals.  

Another factor to consider is energy density.  While you can get enough protein from broccoli, you will need to eat nearly six kilos or 13 pounds of it to get 2000 calories to fuel you for the day!   

If you can’t imagine yourself consuming that much broccoli you could go for 600 grams of cod with 630 calories and get the same amount of protein as the 2000 calories worth of broccoli.  Focusing on leaner and bioavailable protein sources will give you a much better chance of building and maintaining plenty of lean muscle mass.  

To get the same amount of protein you will need to consume three times the calories and ten times the weight of food from broccoli compared to cod! 

The table below shows a comparison of the amount of broccoli, cod and “plant-based” doughnut to get 100 g of protein.  You’ll need to consume ten times the weight of broccoli and 17 times the calories from the doughnut to get 100 g protein.

But if you don’t eat a lot of vegetables and instead just eat refined flour and vegetable oils you’ll end up with a very energy-dense diet that is easy to overeat with very little protein.  

What about bioavailability?

Bioavailability is the amount of a certain nutrient that we are able to digest and absorb into our system.   Bioavailability is particularly important when it comes to protein. The reality is you will need to consume a lot more plant-based protein to absorb the same amount into your body.  

The table below shows the Protein Digestibility Corrected Amino Acid Score for a range of foods, Dairy and meat are at the top with the highest availability with rice and wheat at the bottom.  Not only will you get a lot less protein from plant-based sources you will also absorb a lot less of it! 

Note:  Soy and pea protein do have a higher PDCAAS than other plant-based sources of protein.  Perhaps James Cameron’s next film will include Arnie downing some pea protein to prevent muscle loss in old age.

The table below shows a comparison of the weight, calories for 100 g of absorbed protein (once we take the PDCAAS into account).  To get the same amount of usable protein in your body you will need to consume thirteen times the weight of broccoli and 66 times the calories from the doughnuts to get the same amount of protein compared to 440 g of cod! 

Summary 

So, in summary:

• A higher % protein is critical to satiety.

• Foods that contain vitamins and minerals tend to contain more protein.

• Without supplementation, you will need to consume a LOT more energy to get the protein you need to thrive on a “plant-based” diet.

• “Plant-based foods” are typically products of industrial agriculture that are highly dependant on non-renewable resources.  Not only will you tend to eat more calories from these foods, but they will also deplete our limited planetary resources at a faster rate as we end up consuming a LOT more food.