What are the first things that come to mind when you think about protein? Meat? Cheese? Muscle? Weight lifters? All quite understandable, but protein is an integral part of a healthy diet. So how much do we really need?
Dietary protein supplies the bricks and mortar of the human body, for the development and maintenance of organs, teeth, nails, muscles, brain and nerves. Protein contains organic compounds called amino acids, of which there are 22 in total. The body uses eight of the amino acids as building blocks, breaking them down and converting them into the other 14. These eight are therefore deemed ‘essential’; without even one of them, the spectrum of 22 can’t be completed.
If a food contains all eight essential amino acids, it is labelled a ‘complete protein’; if any are missing, ‘incomplete’. In broad terms, protein derived from animal sources, such as poultry, meat and fish, is always complete, while some vegetarian sources — such as grains — can be complete but often aren’t. Quinoa is a complete protein; rice isn’t. Getting sufficient complete protein can be a problem for vegetarians and especially vegans; but a mix of vegetarian sources will usually have the full eight in it somewhere.
Extracting energy and nutrients from food is down to the digestive system, and as carbohydrates are quite readily processed they are the preferred source of fuel. Protein takes far longer to break down, and this can be to our advantage. Simply ensuring that you eat some protein with every meal and snack and combine it with fibre-rich complex carbohydrates (granary breads rather than white, for example) should result in steady levels of glucose in the blood. This combination is a smart way to manage energy levels and appetite without having to follow a strict diet with lots of rules.
It is possible to have too much protein: the side effects are constipation, bad breath and potential loss of bone density. There has been some conjecture in the past about high protein intake causing kidney damage, but this seems to be the case only for people who already had some kidney problems, or who have type 2 diabetes.
Men and women have different protein requirements. The Food Standards Agency recommends that girls of 11 to 14 have 42g daily, increasing to around 45g for adult women. In pregnancy, protein requirements increase to around 75g. Men need around 55g, especially in the teenage years, when they’re growing quickest.
If you are thinking that 55g of protein doesn’t sound much, remember that the food you eat contains fat, carbohydrates and water too. A 100g chicken breast will contain anywhere from 20 to 35g of actual protein. Why such a range? The reasons can help us understand the role of protein more generally. A chicken raised in a confined space won’t develop much muscle, but will increase its fat stores instead. A free-range chicken with access to a chicken run is going to be more active, with more muscle and hence more protein.
In the same way, an active person requires more protein than someone who is inactive, which explains why protein shakes, powders and supplements are so popular in gyms. Protein powders are useful after exercise as they deliver concentrated levels of amino acids that help effectively repair exercised muscles, adding to their bulk.
Common signs of having too little protein in your diet are fatigue, increased appetite and cravings for sugar and the like; thinning hair, poor muscle tone and vertical ridges on finger and toe nails. Obviously these can have other causes but if that sounds familiar, then try adding a little protein to each meal and snack and check your progress.
Where the protein is
|Protein per 100g|
A menu for 55g of protein a day
Breakfast: Medium bowl of porridge with walnuts and almonds, topped with berries. 7g of protein
Snack: Oatcake with tablespoon hummus. 2g
Lunch: Tinned tuna (small can) or 80g tofu salad with avocado, leaves, peppers and pumpkin seeds. 22g
Snack: Plain yogurt with fresh fruit. 2g
Dinner: Vegetable soup with chickpeas. Chicken or Quorn stir fry with mixed vegetables and cooked quinoa and butter bean mash. 22g