Lecture 10 - Nutrition

The science that interprets the interaction of nutrients and other substances in food in relation to maintenance, growth, reproduction, health and disease of an organism

A component in foods that an organism uses to survive and grow

• nutrients that are required in large quantities by the body to maintain normal metabolic activities Carbohydrates, fibre, fats, protein, and water

• Nutrients that are required in small quantities by the body to maintain normal metabolic activities Vitamins and minerals

Nutrients that are required by the body to carry out/maintain normal metabolic activities but our body is unable to synthesise them. Hence, we need to obtain them from the food we eat/supplements

Assist the enzymes (cofactors to enzyme) that participate in the release of energy from carbohydrate, fat, and protein (enzymes required cofactors to stimulate their functions)

Physical digestion: Teeth breaks down food mechanically Chemical digestion: Lingual lipase breaks down dietary fat/mainly triglycerides into medium or smaller fatty acid chains Salivary amylase breaks down starch into maltose

Stomach acid inactivates amylase and stops the digestion of starch HCL in the stomach activates the enzyme pepsinogen to pepsin. Then the pepsin and HCL helps to break down proteins into smaller polypeptides and amino acids Gastric Lipase in the stomach only hydrolyses a very small amount of fat

Pancreas produce pancreatic amylase through the pancreatic duct into the small intestine, which breaks down starch into smaller polysaccharides and disaccharides. Then, the disaccharide enzymes on the surface of the small intestinal cells hydrolyse the disaccharides into its respective monosaccharides Pancreatic and Intestinal protease hydrolyse polypeptides into tripeptides, dipeptides and amino acids. Then the Intestinal tripeptidases and dipeptidases hydrolyse the peptides into its respective amino acids When fat enters the small intestine, it triggers the release of cholecystokinin, which signals the gallbladder to secrete bile. The bile then emulsifies the fat. This breaks down the fat into smaller fat globules which has a larger surface area for the enzymes to act on to increase the efficiency of digestion. Pancreatic lipase breaks down the emulsified fat (triglycerides) into monoglycerides, glycerol and fatty acids

Active transport requires energy (in the form of ATP) to open the channel in the plasma membrane. Passive transport do not require energy (particles can pass through across the membrane via simple diffusion down a concentration gradient)

Passive transport of materials across the plasma membrane using the transport proteins

Trap fat within a water friendly environment to facilitate the transport of fat within our body)

A small fat globule made from protein and lipid (outer layer is water friendly but the centre is the fat) transfer fat through the blood to be stored in our organs (need to be wrapped within a water friendly medium because fat is immiscible with water)

Reduce blood sugar levels

DHA/EPA (essential as our bodies are unable to synthesise these fatty acids)

alpha-linolenic acid (an omega-3 fatty acid), linolenic acid(an omega-6 fatty acid), DHA and EPA.

When there is insufficient data/evidence of the RDA value

Maximum daily intake that is unlike to cause any adverse health impacts

It includes RDA, AI and UL

A disease affecting people who obtain adequate kilocalories but inadequate protein Characterized by failure to grow and development, edema, changes in the pigmentation of hair and skin, fatty liver, and anaemia The extreme lack of protein causes an osmotic imbalance in the gastro-intestinal system causing swelling of the gut diagnosed as an edema or retention of water

A disease affecting people who do not obtain enough kilocalories Characterized by poor growth, dramatic weight loss, loss of body fat and muscle, and impaired brain development.

Scurvy (Impaired collagen formation) symptoms include bleeding gums

Rickets defective mineralization or calcification of bones) (only in kids with vitamin D deficiency

Night blindness