Proteins: Dietary Sources and Requirements

Proteins are essential macronutrients for the human body. They serve as vital structural materials, such as keratin and collagen, and functional proteins, like enzymes and hormones.

The primary sources of protein include meat, eggs, fish, and milk. These sources provide complete proteins containing all the essential amino acids.

Legumes and cereals, except soybeans, contain incomplete proteins that lack some essential amino acids, but consuming them with grains can offer all the essential amino acids.

Adequate protein intake ensures the presence of all amino acids in the cells in proper quantities for protein synthesis.

It also maintains a healthy nitrogen balance, indicating equal rates of protein synthesis and breakdown.

A positive nitrogen balance signifies tissue growth and repair, while a negative balance indicates protein breakdown due to stress or poor diet.

Excess protein intake in a caloric surplus can lead to obesity. Animal protein diets may include saturated fats, increasing atherosclerosis risk, while plant-based proteins like legumes and nuts are linked to lower cardiovascular risk.

Conversely, inadequate intake may cause weight loss, retarded growth, anemia, and edema.