D.1

Question 1

what are nutrients?

Answer 1

• Nutrients are substances that are used by the body, and are usually found in food.

Question 2

what are non-essential nutrients?

Answer 2

• Non-essential nutrients are those that can be made by the body or other nutrients serve the same purpose including glucose, starch and other carbohydrates.

Question 3

what are essential nutrients?

Answer 3

• Essential nutrients are those that come from the human diet including some amino acids, some unsaturated fatty acids, some minerals, calcium, vitamins and water.

Question 4

what is Ascorbic acid?

Answer 4

• commonly known as vitamin C.
• It is needed to synthesise collagen fibres that form body tissues including skin and walls of blood vessels.

Question 5

synthesising vitamin c

Answer 5

• Most plants and animals can synthesise their own vitamin C through a series of enzyme-catalysed pathways that convert monosaccharides such as glucose or galactose into vitamin C.
• Unlike most mammals, some primates including humans, chimps and apes are unable to synthesise their vitamin C.
• A series of mutations to genes have resulted in the diminished ability to produce a protein necessary to make vitamin C

Question 6

what happens when we dont have enough vitamin c?

Answer 6

• Vitamin C deficiency in diets can lead to a range of symptoms that are collectively known as scurvy.
• The symptoms of scurvy can be alleviated with dietary intake

Question 7

how was scurvy found and fixed?

Answer 7

• found using guinea pigs
• fed them lemon and cabbage and they were better

Question 8

what are minerals?

Answer 8

• Minerals are a micronutrient needed in the diet at relatively small quantities (mg or ug per day).
• Minerals can be distinguished from vitamins by their chemical nature.
• Minerals are inorganic, maintain their chemical structure, and usually in an ionic form e.g. calcium is needed in the form of Ca2+

Question 9

what is deficiency?

Answer 9

• When a mineral is lacking from the diet, a deficiency disease will result.
• Despite the quantities needed are very small, the deficiency disease may be very serious.

Question 10

what is a common deficiency?

Answer 10

• iodine deficiency
• Iodine is used by the thyroid gland to synthesise the hormone thyroxin that is needed to stimulate the metabolic rate and ensure that there is sufficient energy released in the body.
• Iodine deficiency disorder (IDD) in pregnant women can lead to foetal brain damage, and IDD in children will result in impaired mental development and intelligence.

Question 11

how to reduce IDD?

Answer 11

• table salt is mixed with small quantities of iodine,
  this is called iodised salt; thus iodine is added to the diet.
• Since the 1920’s, it is thought that the iodisation of salt might be the world’s simplest and cost-effective measure to improve health; and it costs US$0.05 p person each year.
• However, in recent years, more people try to reduce salt intake from their diet and this has caused increasing incidences of IDD.

Question 12

what are vitamins?

Answer 12

• micronutrients that are needed by the body in very small quantities.
• Vitamins cannot be synthesised by the body and must be obtained in the diet.
• Vitamins are organic molecules that can be broken down when it is exposed to heat, oxygen or acid.

Question 13

what do vitamins do?

Answer 13

• Vitamins serve a number of roles in the body including as co-factors for enzymes, antioxidants and hormones.
• Vitamins are chemically diverse as some contain amino groups (-NH2), some are hydrophobic with hydrocarbon rings or chains (e.g. vitamin A) and some contain nitrogen
  rings (e.g. vitamin B2).
• Vitamins can be categorised as fat-soluble or water-soluble.
• Water soluble vitamins must be consumed constantly due to loss in urine whereas fat soluble vitamins can be stored in the body.

Question 14

what is vitamin d?

Answer 14

• Vitamin D is an important nutrient as it aids in the absorption of calcium from food in the intestines, and so the symptoms are similar to calcium deficiency.
• Vitamin D can be synthesised by the skin when sunlight (or UV light 290-310nm range) hits the skin.
• If teenagers and adults spend sufficient time outside, vitamin D is not required in the diet.
• Children, pregnant women and elderly people should supplement with ~10g per day in their diet from different sources such as oily fish, eggs and liver.

Question 15

what happens when you dont have enough vitamin D?

Answer 15

• UV light exposure has damaging consequences including mutations that lead to skin cancers.
• Darker skin provides good protection against cancer but reduces vitamin D synthesis.
• Vitamin D deficiency is becoming more common in some countries like Australia as more people tend to protect from skin cancer with sunscreen.
• In children, vitamin D deficiency is seen in the development of skeletal deformities such as rickets (weak/soft bones).

Question 16

what are essential amino acids?

Answer 16

• Essential amino acids include: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, tryptophan, valine, threonine (if phenylalanine is absent from diet) and arginine (babies).

Question 17

what are fatty acids as essential amino acids?

Answer 17

• The other half can be made from simpler nitrogen compounds.
• Some omega-3 and omega-6 fatty acids are essential in the diet as they cannot be synthesised.
• The name of the fatty acids, omega-3 and omega-6, refers to the position of the double bond in the molecule.
• Some fatty acids e.g. alpha-linoleic acid and linoleic acid, are needed in the biosynthesis of other compounds, for the development of the brain and eye.