Protein forms 20% of our body weight. It is second only to water in our body’s make-up and has many vital roles in the body.
- primary building material for muscles, hair, skin, nails, eyes, internal organs and our brain
- forms antibodies in our immune system
- most of our hormones are proteins
- haemoglobin in our blood is a protein
- helps to maintain fluid/salt balance in our cells
- helps to maintain sodium-potassium balance (important for nerve signalling)
- helps to maintain our acid-alkaline balance in the body
It’s no wonder that, of all the nutrients, protein is the one that people always think about first.
Proteins are very complex molecules made up of different combinations of building blocks called amino acids.
Currently in nutrition we focus on 22 standard amino acids. The body can make most amino acids but there are 8-9 (different experts have different opinions on the number) that the body cannot make and we must get from the diet. When we must get a nutrient from food we call it ESSENTIAL.
Protein starts to be digested in the stomach – unlike carbohydrates where digestion starts even while it is still in the mouth before it reaches the stomach. Our stomachs have an enzyme called PEPSIN whose job it is to start the digestion of protein. Pepsin is activated by stomach acid. Digestion of protein carries on in the small intestine.
It is important to note that if you have any compromise to your digestive health this will affect your ability to digest all nutrients including protein.
Because protein is the nutrient most people focus on it is useful to get a picture of how much we actually need.
Protein requirements differ from person to person based on age, health status and activity levels but, as a general guide, around 15-20% of your daily calories should come from protein. This means that if you were on 1800 calories per day then around 270-360 calories should come from protein. As one gram of protein contains 4 calories this means your diet should have 67.5-90g of protein.
Calculating your Requirements
There is a formula you can use to more closely calculate your requirements.
Choose a factor between 0.8 and 1.8:
- in good health and sedentary – choose 0.8
- pregnant or recovering from illness – choose somewhere between 1.0 and 1.8
- involved in consistent and intense weight or endurance training – choose somewhere between 1.0 and 1.8
It is also worth noting that elderly people often have higher protein needs, partly because they often consume less calories (for various physical, emotional, social and economic reasons) and partly because they absorb protein less efficiently.
Do the calculation:
weight in kg x chosen factor = grams of daily protein
70kg male, regular exerciser, lifts weights as part of a regular routine
70kg x 1.5 = 105g of protein per day
68kg female, sedentary desk job, no weight or fitness routine
68kg x 0.8 = 54g of protein per day
Eating the Numbers
If you consider that 1 cup of chicken breast contains around 45g of protein it is easy to see that reaching sufficient daily intake is not difficult.
If our sedentary female in the example above had 1 cup of milk with breakfast (9g), 1 yoghurt as a mid-morning snack (10g), 1/2 cup of chicken with her salad at lunchtime (20g), 2 tablespoons of peanut butter as a mid-afternoon snack (8g), and 1/2 cup of fish with her dinner (19g) she will have consumed 66g of protein through the day, more than sufficient for her needs.
And, don’t forget, it’s not just the obvious foods. Nearly all foods including fruits, vegetables and grains contain some protein.
In truth, industrialised countries tend to over-consume protein and people regularly eat in excess of the daily recommendations. Doctors rarely have to deal with protein deficiency conditions but they do regularly have to deal with obesity, cardiovascular diseases, cancers and other degenerative diseases.
Protein is crucial for our health and has important roles in the body but it is no more important than carbohydrates, healthy fats, vitamins and minerals. It is very easy to reach protein requirements in a day and it is actually over-consumption that can cause stress on the body and lead to some health issues. Getting enough protein is not the problem. Focus on the quality of your protein, not the quantity.
Vegetarians, Vegans and Protein
… but where do you get your protein from?
Most vegetarians and vegans would tell you that they would a dollar for every time someone asks them where they get their protein from.
Remember that I said proteins are made from building blocks called amino acids. In nutrition we focus on 22 amino acids and 8-9 of them are essential which means they must come from the diet. COMPLETE proteins contain all the essential amino acids and proteins that come from animal sources are complete proteins. INCOMPLETE proteins are missing one or more of the individual essential amino acids and proteins that come from plant sources are usually, but NOT always incomplete.
Unfortunately, over time, complete and incomplete have become confused in people’s minds with superior and inferior. In fact, as long as a vegetarian is not following the cheese and chips diet, but is combining different plant proteins from different sources they will most likely be getting enough protein.
- grain + legume – such as black beans and rice
- nuts and seeds + legume – bowl of lentil soup with a handful of almonds on the side
- corn + legume – pinto beans in a corn tortilla
- whole wheat toast + peanut butter
- bean soup + whole grain crackers
Quinoa grain is one of the unique plant foods that is a complete protein.
A vegetarian or vegan whose diet includes legumes, whole grains, nuts and seeds will be getting adequate protein. Additionally vegetarians who consume dairy and eggs don’t need to be concerned at all.
It used to be thought that the combinations had to occur at each individual meal but, with better understanding, we now know that as long as a range of foods are eaten over a period of time the body will just pool the amino acids to use as required to build different proteins.