Measurement of Nutrients

• Individual measurement scan vary based on:

  • Freshness of the sample

  • Variety of the plant or animal (e.g. one type of apple and another)

  • How the item was grown or reared

  • The way the item was preserved, processed or cooked.
• It is a legal requirement for producers to inform consumers about the types and amounts of different nutrients in foods.
• Biological Value: How much of a nutrient in a food is used by the body after the nutrient has been digested and absorbed from the small intestine.
• 1. Protein is broken down into amino acids.

  2. Excess amino acids not used are not stored by the body as they contain

  nitrogen which is toxic to the body.

  3. This is converted into ammonia in the liver, then into urea which is excreted

  through the kidneys as urine.
• Protein consumed – nitrogen in urine = biological value of protein (e.g. retained protein and nitrogen)
• Glycaemic Index: A system for rating foods according to how rapidly and by how much they raise the blood glucose level of a person
• Foods with a high GI score contain rapidly digested carbohydrate, which produces a large rapid rise and fall in the level of blood glucose. In contrast, foods with a low GI score contain slowly digested carbohydrate, which produces a gradual, relatively low rise in the level of blood glucose.
• The GI index runs from 0–100 and usually uses glucose, which has a GI of 100, as the reference.
• Low GI foods are foods with a GI less than 55.

  •Intermediate GI foods are foods with a GI between 55 and 70.

  •High GI foods are foods with a GI greater than 70.
• GI is not completely accurate because:

  • The measurements can vary up to 50% in GI value when measured by different people

  • The time of day the food is eaten will affect the glycaemic response

  • Foods previously eaten will affect the glycaemic response

  • GI values of food vary according to how ripe it is (e.g. fruit) or how it is prepared or cooked, or the size of the pieces

  • Most foods digestion is affected by other foods eaten at the same time e.g. protein and fat slow down carbohydrate absorption in the small intestine.
• Complementary interaction of nutrients:

  This is ways in which nutrients and other natural substances in food all work together in very complex chemical reactions to maintain the body and health

  These can also be negative interactions!

  Too much fibre can affect how much calcium and iron are absorbed by the body!
• Nutritional Values, Nutritional Labelling, Nutrient Density, Biological Value and Glycaemic Index are all ways of measuring nutrients in food.