Protein
Proteins are composed of intercoiling strands, in turn composed of amino acids.
- The proteins function to regulate specific steps in metabolism – one step, one protein. Hence, many proteins are needed.
- The variety of protein structures is made possible by the order and arrangement of the amino acid building blocks.
- At any time, body protein is being both synthesized and degraded, an inefficient process which leads to urinary loss of the breakdown products of the amino acid building blocks.
- This loss is obligatory and necessities regular replenishment – hence the nutritional necessity for protein in the diet.
Carbohydrate
Carbohydrate are composed of sugar molecules, single, paired or in long strands. Dietary carbohydrates are predominantly starch, with some sucrose and lactose.
- Starch is digested to glucose units, which are observed to be used for energy or for the synthesis of fats.
- Rising blood glucose levels after a meal stimulates insulin release which disposes of this load. Falling blood glucose levels stimulates glucagon, which maintains a basic minimum level of glucose in the blood.
- Although sucrose is well tolerated, lactose is poorly tolerated by many people who lack the enzyme to digest it. Both these substances yield glucose or glucose-like compounds on digestion.