bioavailability or nutrient handling

• The British Journal of Nutrition has a very good Supplement on The Nutritional Needs of Children
• BJN 2007, vol 92, pp S 67-S 232 Editors Koletko B, et al

• In deciding how much should of a nutrient be recommended it is important to define Nutrient Handling.
• This is an interesting concept and identifies the different variables when food and its constituents are eaten.

• 1. Dietary intake (of foods or nutrient mixtures); impact of processing and preparation.
• 2. Milieu within the gastrointestinal tract (matrix effects, intraluminal nutrient interactions, gut transit time).
• 3. Mucosal binding.
• 4. Mucosal cell uptake.
• 5. Mucosal export (portal circulation or mesenteric lymphatic transport).
■ 6. Hepatic uptake.
• 7. Organ (including liver) clearance.
• 8. Biliary clearance and excretion.
• 9. Systemic circulation and peripheral distribution.
• 10. Renal clearance and excretion.
• 11. Peripheral tissue utilisation (e.g. metabolic/catabolic use. structural roles) and deposition.
Each nutrient can then be individually assigned one or more of these key steps as being rate-limiting for its utilisation.
Another variable will be age as these variable will be different at different ages of development.
However I was very interest ed to note that a very important variable the speed and length of time spent eating was not mentioned. This is an enormous variable and very neglected, by all but the traditional French eaters.

Martin Eastwood
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