Three nutrients that produce energy

“I answer 20,000 letters a year and many couples have problems because they do not get adequate protein and vitamins.”

Barbara Cartland, English novelist.

The Observer (London) “Sayings of the Week” (August 31, 1986).

There are three nutrients that produce energy: carbohydrates, proteins, and fats. These nutrients are written on the following lines.

1. Carbohydrates. Carbohydrates generally provide most of the energy in a normal diet, but no single carbohydrate is an essential nutrient in the sense that the body needs it but cannot make it itself from other nutrients. If your carbohydrate intake is less than 100g per day, ketosis is likely to occur.

2. Fats. With their high caloric value, fats are useful for people with a high energy expenditure; In addition, they are useful for cooking and making food palatable. Although rats need linoleic or arachidonic acids in their diet, essential fatty acid deficiencies are rare in man. It has been shown in patients who have been fed intravenously for prolonged periods without fat emulsions. They develop squamous dermatitis and eicosatrienoic acid accumulates in plasma lipids. Essential fatty acids are precursors of prostaglandin synthesis.

3. Proteins. Protein provides about 20 amino acids, of which eight are essential for normal protein synthesis and for maintaining nitrogen balance in adults. These essential amino acids are methionine, lysine, tryptophan, phenylalanine, leucine, isoleucine, threonine, and valine. Histidine and perhaps arginine are also necessary for the growth of babies.

The “biological value” of different proteins depends on the relative proportions of essential amino acids that they contain. Proteins of animal origin, particularly from eggs, milk and meat, are generally of higher biological value than proteins of plant origin that are deficient in one or more of the essential amino acids. However, it is possible to have a diet of mixed plant proteins with high biological value if the principle of supplementation is used. For example, cereals, for example wheat, contain about 10% protein and are relatively deficient in lysine. Vegetables contain around 20% protein that is relatively deficient in methionine. If you mix (or eat) two parts of wheat with one part of legume, you get a food that contains 13% of a protein of high biological value. This happens because cereals contain enough methionine and legumes enough lysine to supplement the other component of the mixture.

The usual recommended amount for an adequate protein intake is 10% of total calories, that is, approximately 65 g for the average adult. The minimum requirement is less than about 40 g per day of protein of good biological value for an adult.

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