Nutrition

Question 1

How is BMI calculated?

Answer 1

Weight (in kg) / (HeightxHeight) (in m)

Question 2

How is BMI interpreted?

Answer 2

Underweight- less than 18.5
Desirable- 18.5 to 24.9
Overweight- 25-29.9
Obese- 30-34.9
Severely obese- over 34.9

Question 3

Describe the condition of marasmus

Answer 3

energy malnutrition most commonly seen in children under the age of 5. The child looks emaciated with obvious signs of muscle wasting and loss of body fat although there is no oedema. Hair is thin and dry, diarrhoea is common and anaemia may be present.

Question 4

Describe the condition of kwashiakor

Answer 4

protein energy malnutrition. occurs typically in a young child displaced from breastfeeding by a new baby and fed a diet with some carbohydrate but a very low proteincontent. The child is apathetic, lethargic and anorexic (loss of appetite). The abdomen is distended owing to hepatomegaly and/or ascites (accumulation of fluid in the peritoneal cavity). There is generalised oedema due to low serum albumin (osmotic pressure). Anaemia is common.

Question 5

What is 1kcal equivalent to?

Answer 5

4.2kJ, energy required to raise temperature of 1kg water by 1 degree celsius.

Question 6

What are the daily energy requirements of the average person?

Answer 6

70kg male- 12000kJ

58kg female- 9500kJ

Question 7

What is the energy yield of carbohydrates?

Answer 7

17kJ/g

Question 8

What is the average minimum requirement of protein in the diet to maintain nitrogen balance?

Answer 8

35g

Question 9

Which are the fat soluble vitamins?

Answer 9

A,D,E,K

Question 10

What is the energy yield of fats?

Answer 10

2.2x that of carbs and proteins

Question 11

Give an example of an essential fatty acid

Answer 11

linoleic/linolenic

Question 12

What is the unit of food energy?

Answer 12

kJ.

1 calorie (everyday usage)= 1000 calories= energy to raise temperature of water by 1 degree celcius= 4.2kJ

Question 13

Describe some features of carbohydrates

Answer 13

• general formula is (CH2O)n
• carbohydrates are hydrophilic.
• need less oxygen than fatty acids for complete oxidation.
• disaccharides are linked with glycosidic bonds, alpha or beta.

Question 14

How can carbohydrates be classified?

Answer 14

• monosaccharides
• disaccharides
• oligosaccharides
• polysaccharides

Question 15

How are dietary polysaccharides digested?

Answer 15

• alpha 1-4 and alpha 1-6 linkages in starch and glycogen
• Dietary polysaccharides (starch and glycogen) are hydrolysed by glycosidase enzymes. This releases glucose, maltose and leaves smaller polysaccharides (dextrins).
• This begins in the mouth with salivary amylase and continues in the duodenum with pancreatic amylase
• In duodenum and jejunum- disaccharidases attached to brush border membrane of epithelial cells. Lactase, sucrase, pancreatic amylase, isomaltase.
• Monosaccharides actively transported into intestinal epithelial cells and then, via blood supply, to target tissues. GLUT1-GLUT5 transport proteins in cells. Can be hormonally controlled via insulin/GLUT4

Question 16

Why can’t humans digest cellulose?

Answer 16

• glucose monomers in cellulose are joined together by beta-1,4 glycosidic linkages.
• Humans do not posses the enzyme to digest these linkages
• cellulose increases surface areas for substrates to bind to, so enzyme action is increased, increasing digestion

Question 17

What are the essential amino acids? What are conditionally essential amino acids? Why is plant protein considered lower quality?

Answer 17

Isoleucine, Lysine, Threonine, histidine, leucine, methionine, phenylalanine, tryptophan, valine

Some amino acids become conditionally essential in differed physiological states. For example, arginine, tyrosine, cysteine during pregnancy.

Plant protein considered lower quality as it is deficient in one or more essential amino acid.

Question 18

Why are minerals required in the diet? What is IV fluid?

Answer 18

• electrolytes important for ion gradients, signalling, enzyme cofactors
• iron required for haemoglobin
• calcium for teeth and bones

IV fluid is sodium, potassium, chloride and water

Question 19

What conditions can arise from inadequate vitamin nutrition?

Answer 19

Deficiency:

E-Neurological abnormalities
K-Defective blood clotting
A- Xerophthalmia
D- Rickets

Question 20

Where can dietary fibre be obtained and why is it necessary?

Answer 20

Found in cereal foods e.g. bread, beans, fruit and veg

It can’t be broken down but good for GI health and motility. Deficiency linked with constipation and bowel disease. High fibre diet linked to reduced cholesterol (bile salt sequestration).

Question 21

What is BMR?

Answer 21

Maintains resting state of body. It is a big part of total daily energy expenditure, along with DIT and physical activity..

Question 22

What is lactose intolerance?

Answer 22

Primary lactose deficiency= absence of lactose persistence allele

Secondary lactose deficiency= caused by GI injury (e.g UC/Crohn’s etc)

Congenital= rare defect in lactase gene

Question 23

How is glucose uptaken by cells?

Answer 23

-Active transport into intestinal epithelial cells (SGLT1) and then into blood stream via GLUT2 transporter

Glucose transporters (facilitated diffusion):

• GLUT1- foetal tissues, erythrocytes, blood brain barrier
• GLUT2-kidney, liver, pancreatic beta cells, small intestine
• GLUT3-neurons, placenta
• GLUT4-adipose tissue, striated muscle (insulin dependent)
• GLUT5- spermatozoa, intestine

uptake depends on km of transporter and therefore glucose concentration

Question 24

What tissues have an absolute glucose requirement?

Answer 24

• RBC’s as they have no mitochondria
• Neutrophils as they can only undergo glycolysis
• innermost cells of kidney medulla
• lens of eye (poor oxygen supply)

CNS prefers glucose but can utilise ketones