How do animal and plant proteins affect our bodies differently?

How do animal and plant proteins affect our bodies differently?

What is Protein?


Protein is one of the three macronutrients (along with carbohydrate and fat) that we require in order to remain in good health. Protein is found everywhere in our body and forms the basis for bones, muscles and enzymes; organs which carry out vital functions (e.g hormone regulation, DNA creation). Whilst we can store fats and carbohydrates to be used as energy sources, we cannot do the same for amino acids (the ‘building blocks’ of protein). Thus, we need to replenish our protein supply daily – aiming for an intake of 1-1.5 grams of protein per kilogram of bodyweight. 



Where Can I Get Protein?


Protein can be derived from animal sources (e.g meat, eggs, milk, whey) or plant sources (e.g tofu, beans, pulses), and whilst both can provide adequate amounts of protein, it is important to note that sources are not always equal in terms of their quality. The quality of protein can be deduced by looking at 3 main factors: amino acid quantity, absorbability and cleanliness. 


What are the Differences Between Animal and Plant Protein Sources?


1. Amino Acids

Both animal and plant protein sources contain amino acids, however their ratio of amino acids is different. This amino acid ratio, or content, can be referred to as the amino acid profile. Animal sources generally have better essential amino profiles than plant sources, meaning they contain more of the specific amino acids that the body is unable to synthesise itself (as such, they must come from food). It is widely accepted that animal sources have better quantities of the 9 essential amino acids, whereas plant-based protein sources tend to have less of one or another. It is also important to note that it is often easier to reach our recommended daily intake of protein through animal sources, as they typically contain 2-10 times more protein than plant sources.


2. Absorbility

The absorbability of protein is important to consider when reducing its quality, as if our bodies are unable to properly absorb and therefore digest and utilise the amino acids within the protein, then the protein is essentially useless. Comparing plant and animal protein, the former is generally understood to not be as readily absorbed and used by the body as the latter (i.e animal protein is more absorbable than plant protein). 


3. Cleanliness

‘Clean protein’ is generally viewed as protein which is free of pesticides, antibiotics, genetically-modified organisms and other heavy metals, which can be damaging to the body. For plant sources, this would relate to the pesticides that were sprayed on the crops, or the quality of the soil that the produce grew from. Regarding animal sources, we essentially eat what the animal ate – if they were fed growth hormones, antibiotics or other harmful substances, this would negatively impact the cleanliness of the protein. However, cleanliness can also be impacted post-harvest, in the production process. Beans, pulses, dairy and meat can have preservatives and sodium added to improve palatability and shelf-life, whilst damaging the cleanliness and ultimately, the health benefits. As such, it is always best to aim for organic plant based protein sources, and animal sources that have been fed organic feed (e.g grass).  


I Have Reduced my Meat Consumption.. What’s a Good Alternative? 


Whilst animal protein sources, especially meat, are typically more efficient (in terms of absorbability and protein content), some individuals wish to reduce their meat consumption for various reasons, such as the environment and ethics. 

For such individuals, a good alternative protein source is whey protein. Whey protein has both a high protein content and amino acid profile, and therefore enables individuals to reach both recommended protein and amino acid intakes – facilitating healthy wellbeing. 


Can I Get Enough Amino Acids with Plant Protein Sources?


Plant protein sources are typically lower on their amino acid content comparative to animal protein sources, as such it is more difficult to get enough of every amino acid. However, plant protein can provide all of the amino acids if 2 sources with complementary amino acid profiles are consumed together. 

For instance, chickpeas (garbanzo beans) are a great source of amino acids as they contain 8 of the essential amino acids, apart from histidine. However, combining a portion of chickpeas with a serving of tofu, which contains histidine, will provide individuals with all of the essential amino acids required by the body. When combining foods as such, it is important to know which products provide which amino acids in order to ensure a complete profile is consumed.