What is dietary protein?
The amount of protein you need in your diet depends on your weight, age and health. As a rough guide, the recommended dietary intake (RDI) for protein (measured in grams per kilogram of bodyweight) is:
0.75 g/kg for adult women
0.84 g/kg for adult men
People following a strict vegetarian or vegan diet need to choose a variety of protein sources from a combination of plant foods throughout the day to get an adequate mix of amino acids. For example, a meal containing cereals and legumes, such as baked beans on toast, provides all the essential amino acids found in a typical meat dish.
A very high-protein diet can strain the kidneys and liver, and prompt excessive loss of the mineral calcium.
Different foods contain different amounts of amino acids. Generally:
Animal products (such as chicken, beef or fish) contain all of the essential amino acids.
Soy products, quinoa and the seed of a leafy green called Amaranth (consumed in Asia and the Mediterranean) also contain all of the essential amino acids. However, plant proteins usually lack at least one amino acid.
Animal protein sources
Chicken: If you eat it without the skin, the majority of calories in it come from protein. Chicken breast is also very easy to cook and tastes delicious if you do it right.
Protein content: 80% of calories. 1 roasted chicken breast without skin contains 53 grams, with only 284 calories.
Beef: Lean beef is very high in protein, and also tastes delicious. It is loaded with highly bioavailable iron, vitamin B12 and large amounts of other important nutrients.
Protein content: 53% of calories. One 3-ounce (85 g) serving of cooked beef with 10% fat contains 22 grams of protein, with 184 calories.
Fish: It is loaded with important nutrients and tends to be very high in heart-healthy omega-3 fatty acids.
Protein content: Highly variable. Salmon is 46% protein, with 19 grams per 3-ounce (85 g) serving and only 175 calories.
(Tuna) Like other fish, tuna is also very high in various nutrients and contains a decent amount of omega 3 fats.
Protein content: 94% of calories, in tuna canned in water. A cup (154 g) contains 39 grams of protein, with only 179 calories.
Turkey: It consists mostly of protein, with very little fat and calories. It also tastes delicious and is high in various vitamins and minerals.
Protein content: 70% of calories. One 3-ounce (85 g) serving contains 24 grams, with 146 calories.