Protein has steadily become one of the most popular nutrients of the past decade and longer.
- But how much protein do we really need – and why?
- How much can we obtain from natural food sources?
My follow-up post will cover protein needs predominantly in plant-based diets, but for now I will start by exploring the fundamental principles of protein needs and requirements.
Why do we need protein?
Our body is composed of tens of thousands of different types of proteins – all of which are central to our structure, function, well-being and survival. Proteins regulate all biological and metabolic pathways and processes within the body and are the core components of:
- Tissues and organs
- Enzymes
- Hormones
- Neurotransmitters
- Cell signalling proteins
- Transport proteins
Protein is essential to life.
What is protein actually made from?
♦ This bit is really important to all my future posts on plant-based diets! If you just remember one thing from this post – then remember this! Proteins are composed of individual amino acids as described in my earlier blog post amino acids and protein – a closer look.
Don’t get bogged down with the funny names or chemical structures, but it’s useful to become familiar with the essential amino acids.
It is important to recognise that the body is constantly breaking down, synthesising and replacing proteins – in a highly efficient process known as protein turnover.
The amino acids released during the breakdown of body proteins are reused to synthesise new proteins. In this way, protein turnover itself creates little need for additional protein from foods.
However, our body does require sufficient essential and non-essential amino acids to ensure that all its biological needs and processes and are met – and this is precisely where our dietary requirement for protein stems from.
Factors Affecting Protein Requirements
Historically, protein needs and requirements have been extremely difficult to ascertain. This is because there are an enormous variety of factors that can affect an individuals protein requirements, including:
- Age
- Gender
- Past medical history and medical conditions
- Trauma, stress and illness
- Exercise and activity levels
- Certain types of weight-bearing exercise
In addition, protein needs can be affected by:
- Hormone levels
- Sleep and lifestyle
- Overall diet – for example, the levels of carbohydrate intake will differ between individuals (and carbohydrates are protein sparing)
- The rate of protein synthesis and broken breakdown (will vary between individuals)
These are just some of the factors that can influence protein needs and requirements. Unfortunately, establishing individual protein requirements isn’t as easy as throwing some numbers into a formula to calculate! When in a non-clinical setting, at best we can estimate protein requirements, monitor and adjust accordingly.
Estimating Protein Requirements in Adults
In the United Kingdom, daily protein requirements for the population are generally estimated at around 0.75g protein per kilogram bodyweight.
There is a lot of discussion and debate around the accuracy of these values, with many people feeling it’s a little on the low side. At the very least, it provides a good baseline value from which to gain some appreciation of protein needs for the general population.
For men and women (19yrs to 50yrs) average guideline amounts are given as:
- Females: 45g protein per day
Example: A female weighing 60kg x 0.75g = 45g protein per day
- Males: 55g protein per day
Example: A male weighing 75kg male x 0.75g = 56g protein per day
Protein requirements can also be estimated using 1g protein per kilogram body weight. For an average 62kg female – this would equate to around 62g protein per day.
It is worth bearing in mind that for someone who is significantly overweight do to an accumulation of adipose tissue (or body fat) – protein requirements may sometimes, but not always, be overestimated. This is because protein needs do not tend to increase significantly as adipose tissue increases.
Protein intake in the UK tend to be a lot higher than the recommended daily amounts. The typical daily intake for both males and females usually range somewhere between 45g to 90g protein a day. However, levels can exceed 100g protein per day for those who regularly supplement with protein – i.e. intakes of 1.5g or >1.8g protein per kilogram body weight.
What is Protein Quality?
♦ It is important to remember that not all protein-containing foods are equal. Protein quality gives some indication of how ‘bioavailable’ the amino acids are from that particular food source, by taking into account factors such as:
- the precise range and availability of amino acids in that food
- how easy it is for the body to digest, absorb and utilise protein from the food source
Again, this is something I will revisit in my future posts on plant-based diets!
How Much Protein Is In Foods?
I have compiled a very brief list (to be replaced later with a more detailed list!) – with values given per 100g food, and in the some cases – (e.g. eggs and cheese) – per portion.
♦ Remember, these values may vary depending on a number of factors, including where the food is sourced, brands e.t.c.
Protein Ready Reckoner
Average Values given per 100g (cooked) or per portion
Milk and Alternatives
(per 100ml)
Oat Milk Alternative – 0.3g to 1.0g protein
Almond Milk Alternative – < 0.5g
Coconut Milk – < 0.5g
Rice Milk Alternative – 0.1g
Cows milk – 3.5g protein
100g Natural Yoghurt – 4.0g protein
25g portion cheddar cheese – 6.0g protein
Cereals and Grains
40g portion Porridge Oats – 4.0g protein
100g Quinoa – 3.0g to 4.5g
100g Rice – 3.0g
1 medium slice of bread – 4.0g protein
Beans and Pulses
100g Cooked Lentils – 8.0g protein
100g Cooked Chickpeas – 7.0g
100g Variety of Beans Cooked – Between 5.0g to 8.0g
Nuts and Seeds
30g Nuts – Between 4.0g to 7.0g – (depending on variety of nut)
25g Pumpkin Seeds – 7.0g
Green Vegetables
Spinach – 3.0g
Broccoli – 3.0g
Eggs and Poultry
1 medium egg – 7g protein
100g chicken thigh / leg – 25g protein
100g chicken breast – 30g protein
White & Oily Fish / Prawns
100g white fish – 24g protein
100g tuna – 24g protein
100g mackerel – 24g protein
100g salmon – 22g protein
100g Prawns – 14g to 18g protein
Further Reading and Related Posts: