Plant Protein vs Animal Protein. Are all proteins created equal?
I sometimes hear the phrase “animal protein” used as a derogatory term, as if there’s something inherently bad about them.
But, are memes like this perpetuating an ethical paradigm or belief system rather than promoting human health or sustainability?
Is there any difference between ‘animal protein’ and ‘plant protein’?
Or are amino acids just more concentrated in animal sources?
What you will learn from this article
- Getting adequate protein while moderating energy from carbs and fat is critical to managing your appetite and satiety, optimising body composition and avoiding the many diseases related to metabolic syndrome.
- Unless you are eating a LOT of vegan protein powders, a “plant-based” diet sourced from industrial agriculture is a good way to ensure you are always hungry and will consume a lot more energy to get the nutrients you need, including protein.
- Meat and seafood contain more protein per calorie and per gram (especially when you consider bioavailability).
- If you are following an exclusively plant-based diet, it will be much harder to absorb the protein you require without consuming excess calories and/or a massive volume of food!
Comparison of amino acids
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 per calorie, it’s hard to make much sense of this chart.
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 do we need to be afraid of “animal proteins”? Are they valuable, and what do they do for us anyway?
Lysine is an amino acid that is plentiful in fish (e.g. halibut, haddock, shrimp and prawns) and meat (e.g. beef, chicken and turkey).
It is an essential building block for all the other proteins in your body and plays a significant role in calcium absorption.
Lysine is critical 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 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 growth, this seems to be mitigated when we get adequate glycine in our diet. It’s also worth noting that there are a LOT of things that are associated with cancer, including obesity.
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.
Interest in a “plant-based” diet has been growing in popularity lately, spurred on by Netflix films What the Health (2017) and Game Changers (2019). You can see the spikes in searches for ‘plant based diet’ on Google Trends around the release of these two films.
However, rather than promoting more fruits or vegetables, the overarching message of these films is that eating animal products is bad and should be avoided.
The USDA Economic Research Service data indicates that less than3% of calories in the American diet comes from fruits and vegetables. The popular version of the ‘plant based diets is not about to increase this. Hence, we’ve also looked at scenarios where we don’t eat vegetables (which are typically not a focus of the “plant-based” narrative).
This next chart shows a comparison of the plant-based approaches (ND = nutrient-dense) 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 stands out from this analysis is that it is much more challenging to get all amino acids when we exclude animal-based foods, particularly if we aren’t eating a lot of veggies or focusing on nutrient density.
Without a focus on a lot more vegetables, switching to a “plant-based” diet will increase your intake of grains and oils and reduce your protein to energy ratio!
Focusing on the most nutrient-dense plant-based foods does give us a better chance of getting adequate protein. However, just going plant-based means we need to eat for or five times as many calories to get the same amount of protein!
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 Game Changer’s director James Cameron’s vegan pea protein company) you will struggle to get the optimal level of protein without consuming a lot more calories with a massive amount of volume!
Rather than any difference in amino acid profile, what really stands out from this analysis is that any of the dietary 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 (see Why Does Protein Suppress Your Appetite?).
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 United States Department of AGRICULTURE‘s “nutritional guidance” which has primarily focused on replacing animal products with refined “plant based” grains and oils.
The increase in energy has mainly come from added fats and flours and cereals (i.e. high-profit margin “plant-based” products of industrial agriculture).
This additional excess energy in our diet has mainly come from industrial agriculture which has a devastating effect on the ecosystem and degrades the quality and quantity of our topsoil. They are also heavily reliant on synthetic fertilisers that inject limited fossil fuel energy into the food system and then into our bodies (with very few nutrients).
It’s going to be hard to get enough protein (to promote satiety, build muscle or avoid sarcopenia) on a plant-based diet without supplementing with processed protein powders.
The result is that we will consume a LOT more food if we try to eliminate animal products entirely from our diet. Once we exclude animal products, rather than increasing our vegetable intake, 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 the quality of our food system and rewind the clock, so we all consumed 1000 calories less per day as we did 50 years ago!
It’s hard to say if the different amino acid profiles make much of a difference. 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. If we simply consume more protein, our overall energy intake increases.
It’s not about eating more protein, but rather moderating the 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 the formulae for the hyperpalatable comfort foods (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 focus on getting more nutrients in their diet) is 28%.
Not many people can 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 (i.e. 1 g/kg LBM) or more.
The average protein intake of Optimisers is 2.0 g/kg LBM or 1.5 g/kg body weight.
We’ve built a super-simple macro calculator here that you can use to calculate how much protein you need based on your goals, activity, weight and body fat.
But beyond protein, it’s also essential to consider the vitamin, mineral and essential fatty acid content of your preferred way of eating.
The chart below shows the essential micronutrients provided, on average, by 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 reasonably 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 (e.g. omega 3, B1, B3, magnesium, calcium and selenium). Foods that contain more essential nutrients per calorie also contain a much higher percentage of protein! Protein comes along for the ride with nutrient-dense food.
This next chart shows the nutrient profile of all 2,800 animal foods in the USDA database. While the nutrient score is better than the average of all foods, we still struggle to get enough nutrients like K1, C, A, omega 3 and folate (shown towards the top of this chart).
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). The good news is that we get a nice boost in nutrient density score; however, some nutrients tend be to harder to find in optimal amounts.
For comparison, this next chart shows the nutrient fingerprint of the four thousand or so plant-based foods (excluding those fortified with synthetic vitamins). If we define our dietary approach as “plant-based”, we’re going to struggle to get not only enough protein but also omega 3 and B12 (which strict vegans tend to supplement with) 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 reach optimal levels of omega 3, B12, selenium, vitamin A and zinc.
If you don’t eat animal products or a LOT of vegetables (which are not emphasised do by the current “plant based” narrative), you’re going to struggle to get enough nutrients!
Without vegetables, you can boost things a little by focusing on nutrient density, but it’s still far from optimal.
Comparison of nutrient density
To summarise, 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 only 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 is an important first step. Actively avoiding protein or “going plant-based” will make it a lot harder to get sufficient 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 ingest 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 a range of different foods to ingest 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 of protein compared to the cod.
|food||calories||protein (eaten) (g)||weight (g)|
But if you don’t eat a lot of vegetables and instead 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 particular nutrient that we can digest and absorb into our system. This is particularly important when it comes to protein.
The bottom line is that 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 bioavailability 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!
|1||casein (milk protein)|
|1||whey (milk protein)|
|0.89||pea protein concentrate (isolate)|
|0.78||chickpeas and Edamame|
|0.59||cereals and derivatives|
|0.25||wheat gluten (food)|
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).
The charts below show this graphically. Making intelligent choices when it comes to where you get your protein is critical to help you manage your appetite, not having to eat too many calories and not having to eat massive quantities of food!
While there are many benefits in consuming nutrient-dense plant-based foods, relying on them as your primary source of protein may be problematic if you don’t want to have to consume too many calories or don’t have the appetite to eat 4.8 kg of spinach, 5.8 kg of broccoli or 7.3 kg of rice per day!
- A higher % protein is critical to satiety. You will continue to eat more calories until you get the micronutrients you need, particularly amino acids that are vital for life.
- 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 dependent 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.
- The bioavailability of plant-based sources of protein typically less than animal-based sources, so you will need to eat a lot more plant-based proteins to absorb an equivalent amount for use by your body.