Proteins are important molecules. They make essential parts of the cells and tissues. Many structures in our bodies, like muscles, are mostly proteins. But other than structural values, they have critical functional roles too. They are regulatory molecules. Enzymes in our bodies are proteins. Antibodies are proteins. Many hormones, chemical messengers, and molecular transmitters are made of proteins. We all need proteins in our diet, but how much protein do we really need?
Structure of proteins
Proteins are huge molecules. Each big molecule of protein is made up of hundreds to thousands of smaller building blocks called amino acids. When we eat proteins, our digestive enzymes break them up into amino acids. All the proteins in our body are made up of about 20 amino acids. Our bodies can make 11 of these amino acids from other nutrients. However, there are nine amino acids that we cannot make within our bodies, and we need to receive them via our diet. We call this group essential amino acids. By essential, we mean that they should be present in our food. Any healthy diet should contain enough proteins to provide us with these essential amino acids. We can not get them from any source other than the proteins in our food.
Dietary allowance
How much protein do we need? The dietary allowance is 0.36 grams per pound or 0.8 g of protein per kilogram of body weight. This is the basic nutritional requirement. So, a 70 kg person will need about at least 56 g protein per day. Each gram of protein has about four calories. This means that If the average, 70-kg-person with a diet of 2000 calories per day gets about 10 percent of his calories from protein, the daily requirement is met. However, not all experts agree with this amount. Some believe that we need more than this. Research on the optimal amount of daily protein intake is going on, and the issue is not settled yet. For now, it seems acceptable if we get 10-35 percent of our daily calorie intake from proteins.
But, the source of protein is as important as the amount of protein. Foods that contain an ample amount of protein, also contain other healthy or unhealthy stuff too. In other words, our proteins come in packages; we should pay attention to the content of this package as a whole. Red meat has protein, but it also contains a lot of saturated fat. Beans have proteins along with many fibres. Processed meat has protein with a lot of salt and fat and fish has protein, somewhat contaminated with heavy metals. These are all considerations that are important in choosing our source of proteins.
Animal vs plant proteins
It does not mean that a vegan diet can not provide us with enough amino acids. It means that vegans should be careful to have different types of plant proteins in their diet. For example, many types of beans lack the essential amino acid methionine. On the other hand, grains lack another essential amino acid, lysine. But a combination of these two, like bean and rice, gives a high-quality protein diet. And remember that this combination need not be done in every meal. What is important is achieving a balance throughout the day with a variety of foods.
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