What is the importance of having protein in your diet? How much protein do you need per day?

The human body is made up of approximately 20% protein, including brain cells, muscle, skin, hair and nails. Protein is an essential nutrient, meaning your body doesn’t store protein well, so it’s important to get enough from your diet each day.

There are 20-22 different amino acids commonly found in plant and animal proteins. The body can only manufacture some of these amino acids in which the rest must be supplied by the diet. Foods contain varying amounts of the essential amino acids and the role these amino acids play in the body are to build connective tissue, cell membranes and muscle cells. They are also important to make enzymes, hormones and neurotransmitters and act as transport vehicles and a minor fuel source during exercise.

Bottom line: without protein, life as we know it would not be possible.

The amount of protein you require in your diet on a daily basis depends on your weight, age, health status and activity levels. As a rough guide, the recommended dietary intake (RDI) for protein (measured in grams per kilogram of body weight) for different population groups are as follows:

  • 75 g/kg for adult women
  • 84 g/kg for adult men
  • 07 g/kg for men aged over 70
  • 94 g/kg for women aged over 70
  • Around 1.0 – 1.1g/kg for pregnant and breastfeeding women, and for men and women over 70 years.
  • Protein needs of children, adolescents and teenagers who are still growing and developing, are higher and vary depending on age and weight.
  • Elite endurance athletes: 1.6 g/kg
  • Resistance athletes (early stage): 1.5-1.7 g/kg
  • Resistance athletes (steady state): 1.0-1.2 g/kg
  • Football, power/contact sports: 1.4-1.7 g/kg

What is the difference between animal and plant protein?

The main difference between animal and plant protein is their amino acid profiles. The amino acid profile of animal proteins is closer to that found in humans and are considered to be complete proteins, which means they provide all the essential amino acids in the right ratios compared to the incomplete proteins found in a majority of plant sources. For example, some key plant proteins are often low in methionine, tryptophan, lysine and isoleucine. This also means that the proteins in animal foods are used more readily and rapidly by the body.

Is it possible to get enough protein on a plant-based diet?

If you avoid animal foods, then it may be slightly more challenging to get all the protein and essential amino acids that your body requires, especially if your diet lacks variety. As mentioned above, animal protein provides all the essential amino acids in the right ratio for us to make full use of them compared to plant-based proteins.

However, vegetarians and/or vegans can obtain enough of all the essential amino acids by eating a variety of different types of plant foods including legumes, grains, nuts, seeds, soy products and vegetables. One essential amino acid may be difficult for vegetarians and vegans to obtain is lysine as only a few vegan foods contain lysine in large amounts i.e. tempeh, tofu, and legumes. Therefore, if you avoid these foods in your diet due to an allergy, intolerance or for other reasons then you are at risk of protein malnutrition.

There may be some circumstances where a plant-based protein supplement is beneficial. For example, populations who require higher intakes of daily protein or struggle to meet their daily requirements such as athletes, injured or chronically ill, the elderly and those with a low appetite or fussy eaters may be encouraged to add plant protein powders into their diet.

The best plant-based sources of protein 

Some good sources of plant-based protein include:

  • Legumes – such as chick peas, lentils, kidney beans, borlotti beans, soy beans, peanuts. Not only a great source of protein but also contain good amounts of fibre, carbohydrate, vitamins and minerals.
  • Nuts – such as almonds, walnuts, pecans, cashews, Brazil nuts and nut butters. These foods are also a good source of fibre, iron, vitamin E, selenium and zinc, which is important for immunity and prostate health, and healthy fats that are good for heart health.
  • Seeds – such as sunflower seeds, chia seeds, flax seeds, sesame seeds, chia seeds, hemp seeds, pumpkin seeds are all mineral rich and contain healthy fats such as omega-3s
  • Quinoa, buckwheat and amaranth – these ancient grains are gluten free and also a good source of fibre and low glycaemic index (GI) carbohydrate.
  • Tempeh/organic tofu/edamame – These foods contain soy and are considered complete proteins (containing all amino acids). These foods also contain good amounts of fibre and healthy fats.
  • Non-dairy milks – such as nut, soy and rice milks.
  • Protein powders – such as hemp, pea and rice are good additions to the diet if you are at risk of a low protein intake.

Please note that the quality and quantity of plant-based sources of protein needs to be taken into consideration when assessing your total daily protein intake.