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Dietary Requirements

Role Of Carbohydrates And Lipids In The Body

Starch and Sugar

Provide ≈80% of total chemical P.E.
Breast-fed infants obtain ≈40% of their chemical P.E. from lactose

Non-starch polysaccharides (e.g. glycogen)

Control appetite
Low levels in diet may cause appendicitis, cancer of colon, haemorrhoids, constipation


Source of chemical P.E.
Phospholipids are essential for plasma membranes
Essential fatty acids are precursors of other important substances

Simple Laboratory Techniques For Estimating Energy Content Of Different Foods

Role Of Proteins In The Body

Nucleic acid

Genetic info

Cells and tissues

Growth and repair

Enzymes and hormones

Essential role in metabolic pathway

Mineral ions

Synthesis of compounds;
Carrying out functions;
Transmitting nerve impulses

Essential amino acids

Cannot be synthesised and must be present in diet

Non-essential amino acids

Can be synthesised from essential amino acids by transamination in the liver


Role Of Vitamins With Respect To Vitamin D And Of Inorganic Ions Illustrated By Fe And Ca


Provided in fresh vegetables, meat, fish, eggs, fruit
Decrease appetite / minimises risk of constipation

Vitamin D

Involved in metabolism of calcium
Essential in the diet but required in small amounts


- In bones, teeth, small amounts in tissues, body fluids
- Important for synapses
- During lactation, women tend to eat more → automatic increase in calcium intake


Synthesis of Hb, used by enzymes
≈30% in the body can be stored

The Path Of Iron Through The Body

People Who Are Vulnerable To A Deficiency Of Iron:

Dietary Requirements Concept Of Basal Metabolic Rate BMR

Protein Requirement

Glycogen Loading And The Enhancement Of Athletic Performance

Concept Of A Balanced Diet And Problems Which Arise From Vegetarian And Weight-Loss Diets

Table 16-5-1: Dietary demands in pregnancy and lactation





Growth of fetus, placenta, uterus, breasts

High amino acid content of milk for growth of baby


For fetal Hb and increase in mother's Hb and blood volume

Synthesise of baby's Hb


Growth of fetal teeth and bones

Growth of baby's bones (and teeth)

Influence Of IUDs And Oral Contraceptives On Menstrual Loss Of Iron

Table 16-5-2: Sample calculation

Conc of Hb ≈ 13g per 100cm3

13 * 41/100 = 5.3g Hb lost

5.3g Hb = 18.4g Fe over a 28-day cycle

0.7mg day-1 of Fe lost

0.8mg day-1 Fe lost from other causes

Total loss of Fe = 1.56mg day-1