CHO Essentiality

CHO Essentiality

1. FREE - mono and disacch added to foods by consumer, cook, manufacturer. plus sugars in syrups, juices, honey

2. TOTAL - all mono and disacch other than polyols

3. DIGESTIBILITY

   • High amylose:amylopectin more dense less digestible (resistant starch)
   • High amylopectin:amylose more porous quicker to digest
   • Primary determinant of glucose response

4. GLYCAEMIC INDEX

   • 50g of available CHO in test food vs glucose
   • lots of limitations
     • fructose does not count
   • delay emptying of gastric juices - lower GI
   • GLYCAEMIC LOAD
     • also factors in portion size
     • (g of test CHO x GI) / 100
     • low GI stay full for longer

5. IN THE DIET

   • SACN 2015
     • 50% TEI
     • <5% free sugars
     • 30g fibre
   • without CHO use fat from AT for gluconeogenesis and ketone bodies for CNS

6. MALABSORPTION

   • affects osmolarity
     • diarrhoea and bloating
     • SGLT-1 deficiency
     • impairment of enterocyte function (lower SA) eg coeliac
     • disaccharidase (lactase) deficiency

7. CELLULAR UPTAKE

   • driven by [Na+]
   • Glucose/Galactose with Na+ via SGLT-1 transporter
     • Na+ leaves by Na/K pump (ATP)
     • Glu/Galac leave by Glut-2 transporter
   • Fructose via facilitated diffusion (Glut-5 transporter)
     • Leaves by Glut-2