As we work through the segments of the Eatwell plate, hopefully you’re becoming better acquainted with what each segment means, and therefore how much of each food group we should be including in our diets on not just a daily basis, but over the course of weeks and months too!
Today’s segment is focusing on protein and what proportion of your daily nutrient intake it should comprise. It is important to remember that the above segment (which predominantly includes meat, fish, eggs and beans) is not including protein from dairy sources. Consequently total protein intake may differ to the cut out segment seen in the above illustration, so you must also factor in the amount of milk, cheese and yoghurt you consume too. You might have noticed that the combined protein sources i.e. the pink and blue segment combined is just shy of a third, and many think that the purple segment (Food and drinks high in fat and /or sugar) could, and perhaps should be eliminated from the diet completely as they offer no nutritional value i.e. they are empty calories!
What is Protein?
Protein is a key nitrogenous compound that consists of one or more long chains of amino acids. Amino acids are the basic building blocks of every cell in the human body; consequently they are used and replaced at a frequent rate. There are approximately 20 different amino acids that each serve a role in the body in their own right, they can be used for cell structure, they’re needed for cell signalling (neurotransmitters), hormonal response, immune response enabling us to fight disease and infection, they help to control the pH of the body’s blood and water, as well as being integral to muscle contraction (actin and myosin).
Where does Protein come from?
Protein should be obtained from the diet in the form of whole foods such as meat, fish, eggs and beans (as seen on the Eatwell plate), it can also be obtained through dairy sources such as milk, cheese and yoghurt, and it is dairy which is the preferred protein source used in the ever popular protein supplement! Of particular importance are the essential amino acids, and this is because they cannot be synthesised within the body, the non-essential (conditionally essential) amino acids can be.
Essential amino acids include:
Non-essential amino acids include:
(Food Standards Agency, 2008)
Branched Chain Amino Acids (BCAA)
Of the essential amino acids, the BCAA’s are deemed to be the most beneficial amino acids to muscle integrity and contraction. Isoleucine, Leucine and Valine, these are most readily obtained through the ingestion of meat, dairy and legumes such as beans, peas and lentils. The BCAA’s reduce muscle catabolism whenever the body is placed under stress such as during illness or exercise.
What happens if you have too much Protein?
We are often asked, what happens if someone consumes too much protein. Well, basically you get fat and potentially run the risk of placing strain on the kidneys through elevated nitrogenous output. However this mainly occurs at extreme intakes, maybe 2-3 times the recommended daily intake. An average person should aim to consume approx 1-2g protein per kg body weight, but some athletes choose to exceed this maybe consuming 2-3g protein per kg body weight. If too much protein is consumed the body transfers it to glucose via a process known as Gluconeogenesis, literally meaning ‘glucose synthesis’. If glucose is in excess, the body eventually converts this to fat which increases adiposity (stored fat and protein) resulting in the build up of body fat and elevated blood glucose.
Food Standards Agency, (2008). Manual of Nutrition. Amino Acids. 11th Ed. London: TSO.
NHS Choices, your health, your choices, (2010). The Eatwell Plate. Retrieved 24th June, 2013, from http://www.nhs.uk/Livewell/Goodfood/Pages/eatwell-plate.aspx