What is protein: amino acids, food, sources

What is protein: amino acids, food, sources

What is dietary protein and how do you get enough?

Protein is an essential macronutrient found throughout the body—in muscles, bones, skin, hair, and almost every other body tissue.

Many foods contain protein, but not all food sources are created equal. The available evidence suggests that the source of protein, not the amount of protein, is likely to be important to your health.

Some food proteins are “complete,” meaning they contain all of the more than twenty types of amino acids needed to make new proteins in the body.

Others are incomplete, lacking one or more of the nine essential amino acids that our bodies cannot produce.

Learn what protein is and how to add healthy protein foods to your diet.

What are proteins?

Proteins are macronutrients – Macronutrients are nutrients that we need in larger amounts that provide us with calories and include protein, fat and carbohydrates.

Proteins are made up of chains of amino acids, the building blocks of proteins.

Nine amino acids – histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine – known as essential amino acids, must come from food.

11 of these are known as non-essential amino acids that your body can produce. The human body produces them in two different ways: from scratch or by changing others.

When we digest proteins from food or drink, they are broken down into amino acids. The body then builds all the different proteins it needs from these amino acids.

At least 10,000 different proteins support you and make you who you are as a whole.

What do proteins do in the body?

There are thousands of different proteins in the body that play a huge variety of roles in our organs, such as the brain, heart and liver, antibodies in our immune system, and hemoglobin, which carries oxygen in our blood.

Protein is important for a baby’s muscles and bones as they grow, as well as for keeping our muscles and bones healthy throughout life.

How much protein do we need?

It is often recommended that adults consume at least 0.8 grams of protein per kilogram of body weight per day, or about 7 grams for every 10 kilograms of body weight.

Some people, such as athletes or the elderly, may have higher protein needs.

The recommendations of the Bulgarian Ministry of Health regarding the amount of protein (protein) you should consume are as follows:

age Recommended protein intake – grams per day
men women
0 – <6 months 5.5 – 10.2* 5.2 – 9.2*
6 – <12 months 9.7 – 12.0* 9.3 – 11.5*
1-<2 years 13.0 12.5
2-<3 years 13.6 12.8
3-<4 years 14.4 13.7
4-<5 years 15.6 15.3
5-<6 years 17.8 17.2
6-<7 years 20.3 19.8
7-<8 years 22.7 22.2
8-<9 years 23.9 24.1
9-<10 years 26.7 26.9
10-<11 years 30.0 30.4
11-<12 years 32.4 35.3
12-<13 years 36.5 39.9
13-<14 years 42.8 43.3
14-<15 years 47.4 45.0
15-<16 years 53.0 45.0
16-<17 years 54.6 44.5
17-<18 years 57.6 44.0
18-<19 years 55.6 44.2
19–29 58.1 46.5
30–59 59.7 49.8
60–74 65.6 49.8
75+ 56.4 45.6

Table 1 (how much protein per day)

What foods provide protein?

Many different foods and beverages provide protein. In the healthy eating model, the foods that provide protein are as follows:

  • legumes
  • eggs
  • fish
  • meat
  • milk and dairy products
  • other proteins

Dietary sources of protein are divided according to whether they are animal or plant-based.

Below we take a closer look at the different dietary sources of protein. Tables 2 and 3 show the protein content of some common foods.

Animal sources of protein

Many animal foods in the diet provide protein and are an important source of vitamins and minerals.

Type of food Protein content per 100g
meat chicken breast
Pork steak
Beef stake
Lamb steak
fish Tuna
The heat
He’s trying
Seafood crabs






eggs chicken egg 14.1
Dairy Products Whole milk
Semi-skimmed milk
Skimmed milk
Cheddar cheese
Cottage cheese
Plain yogurt
Low-fat yogurt

Table 2 (what is protein – sources of protein)

Fish and shellfish

Fish provides protein and B vitamins, iodine and zinc, while crustaceans such as shrimp, crab and clams contain selenium, zinc, iodine and copper.

Fatty fish such as salmon, mackerel or sardines are excellent sources of vitamin D and are high in long-chain omega-3 fatty acids, which can help prevent heart disease.

Some studies also show that eating fish is associated with a reduced risk of heart disease and stroke.

It is recommended to eat two portions of fish every week, one of which should be fatty. Fish that is steamed, baked, or grilled is a healthier choice than deep-fried fish.


Eggs are a good source of protein and also provide omega 3 fats, vitamin A, B vitamins, vitamin D and selenium.

There is no limit to how many eggs you can eat as part of a healthy, varied diet (unless your health care provider advises you to limit eggs due to a specific medical condition).


Meat and poultry are good sources of protein and various vitamins and minerals. Birds like chicken provide B vitamins, phosphorus and selenium and can be low in fat if you choose skinless chicken breasts.

Red meats such as beef, lamb and pork provide B vitamins, phosphorus, potassium and zinc, beef is a source of iron and pork is a source of selenium. Red meat can be high in saturated fat, but you can reduce it by choosing lean cuts and removing excess fat.

Processed meats such as ham, bacon, salami and other products are usually high in saturated fat and salt, making them a less healthy choice.

Dairy foods

Dairy foods such as milk, yogurt and cheese provide protein as well as calcium, B vitamins and iodine.

It is recommended to choose lower-fat versions of milk, cheese and yogurt most of the time, as dairy foods contain saturated fat, which should be eaten less.

There is some debate about the effects of saturated fat from dairy products, and there is some evidence that saturated fat from milk, yogurt, and cheese may not raise cholesterol as much as expected.

But in general, it’s a good idea to choose lower-fat versions of dairy products, as they are still rich in nutrients but lower in calories.

Plant sources of protein

Switching to a more plant-based diet is a good direction, but we don’t have to completely eliminate all animal products in order to eat foods that provide us with the nutrients we need.

legumes Red lentils
Bob Tofu




grains Wheat flour
Walnuts almonds

Table 3 (what are proteins – plant protein sources)

Bean crops

Legumes such as beans, chickpeas and lentils are plant-based sources of protein.

It is recommended to eat more of them, as they are a cheap source of protein, fiber and vitamins, and have a low fat content.

They contain thiamin and folate and are foods rich in iron and other minerals.

Nuts and seeds

Nuts and seeds, including peanuts, almonds, sunflower seeds, as well as nut butters or seed spreads such as tahini, provide protein.

They also contain vitamins and minerals such as vitamin E, B vitamins, selenium, iron and zinc.

Nuts are also high in fiber and a source of healthy unsaturated fats.

However, they are high in calories, so it’s a good idea to watch your portion sizes to help with weight management, such as eating a small handful of nuts or about a tablespoon of nut butter as a snack.

Other plant sources of protein

A range of other plant-based protein sources are available, including soy foods such as soy mince or tofu, a range of mycoprotein foods (Quorn – a non-animal protein derived from Fusarium venenatumwhich is a type of fungus) and new sources of alternative proteins such as pea protein.

There are many products designed as a plant-based alternative to meat products, such as vegetarian sausages or burgers.

These may be healthy choices, but they aren’t always. It’s a good idea to check nutrition labels and choose those that contain less saturated fat, salt and sugar.

Is animal or plant protein better for your health?

You may have read about the debate over animal and plant sources of protein and their impact on health and the environment.

In terms of where to get your protein from, the recommendations are to eat more beans and pulses, eat two portions of fish a week and eat no more than 70g of red or processed meat a day.

For many people, eating more beans, lentils, nuts, and other plant-based proteins would be a healthy way to get some of the protein they need, as well as fiber and other nutrients.

This doesn’t mean you have to give up meat or other animal foods, but find ways to eat a variety of foods that provide protein.

If you decide to go vegetarian or vegan, you need to make sure you eat plenty of plant-based protein foods.

Most vegetarians get enough protein in their diet, but it’s important to include a variety of foods to provide protein and other vitamins and minerals.

Although protein from animal sources is considered “higher quality” than protein from plant sources (meaning that it contains the full range of all amino acids in the proper amounts that the body needs), provided you eat a varied diet, you should get all the protein and the amino acids you need, including from plant sources.

Need protein supplements or shakes?

If you exercise intensely, your protein needs may be higher, but you can still get enough protein from food.

Evidence shows that if you’re training at a high level (like a professional athlete), eating protein soon after exercise can help you rebuild your muscles.

For people who train intensely with a busy schedule, taking protein supplements, shakes or bars can be a convenient way to meet their protein needs, although it’s better to try to do it through food if possible. , seeds, low-fat dairy products (yogurt, milk, cheese), legumes (beans, lentils), fish, poultry, eggs.

Read more: When should we take protein, before or after exercise?

Can Eating More Protein Help You Lose Weight?

High protein diets for weight loss have been around for many years in various forms.

Most people think of protein intake to build muscle, but protein intake for weight loss can also help you lose extra pounds.

However, high-protein diets aren’t necessarily better than other types of diets, such as low-fat diets or fasting, but they can be effective for some people – it just depends on what works best for you.

Note that diets high in red and processed meat are not recommended due to the link between these foods and bowel cancer.