CHAP 12 : NUTRITION

Question 1

What are biochemical reactions?

Answer 1

Biochemical reactions are chemical reactions that take place inside the cells of living things.

[The field of biochemistry demonstrates that knowledge of chemistry, as well as biology, is needed to fully understand the life processes of organisms at the level of the cell.]

Question 2

What is involved in biochemical processes?

Answer 2

1. Breaking down of food materials into energy and building blocks
2. Usage of produed energy and building blocks for growth and maintenance

Question 3

What are biochemical reactions?

Answer 3

Biochemical reactions are chemical reactions that take place inside the cells of living things.

[The field of biochemistry demonstrates that knowledge of chemistry, as well as biology, is needed to fully understand the life processes of organisms at the level of the cell.]

Question 4

BIochemical processes are part of metabolism.

Give the definition of the biochemical processes stated below and give some examples

1. catabolism
2. anabolism

Answer 4

1. Breaking down of large molecules into smaller molecules. Digestion is an example of a catabolic process.
2. Anabolism – biochemical processes that build macromolecules from small molecules, and these maromolecules are then used for growth, maintenance or stored as reserves.

Question 5

What is the unit for energy in food?

Answer 5

kilocalories (kcaal) or Calorie –> note captial C

Question 6

How many kcal does each of the following chemicals provide :

1. Protein
2. Fat
3. Digestible carbohydrates
4. Fermentable carbohydrates

*5. Alcohol

Answer 6

1. 4 kcal/g
2. 9 kcal/g
3. 4 kcal/g
4. 2 kcal/g
5. 7 kcal (in 1g of ethanol)

Question 7

How many calories does an
1. average female adult
2. average male adult
need?

Answer 7

1. 2000 kcal per day
2. 2500 kcal per day

Question 8

What are the 3 main contributors to energy expenditure?

Answer 8

1. Basal metabolism
2. Physical activity
3. Thermic effect of food

Question 9

What is the definition of :
1. Basal metabolism
2. Thermic effect of food

Answer 9

1. Minimum amount of energy needed to keep body alive while at rest
2. Energy required for the digestion of food

Question 10

List all 3 scenarios of the energy balance (energy expenditure and energy intake) and their effect on weight.

Answer 10

energy expenditure == energy intake : no net change in weight

energy expenditure < energy intake :
gain in weight

energy expenditure > energy intake : weight loss

Question 11

Underweight and malnourishment are predominant in _____ countries where there is food _____

Answer 11

impoverished ; insecurity

Question 12

In poor countries, what are the factors affecting nutrient intake and absorption? [2]

Answer 12

1. Poor access to food
2. Poor sanitation –> prone to foodborne diseases

Question 13

List factors affecting obesity. Explain how these factors lead to obesity. [3]

Answer 13

1. Socioeconomic status
   - Lower SES –> poor access to healthy food ;; low income families spend more time working and have less time to prepare home cooked foods.
2. Culture
   - children may adopt eating and exercise habits of parents
3. Genetics
   - Some people are resistant to obesity, while some people tend to gain weight very easily

Question 14

The most of abundant protein in the body is _____, which is a major component of bone, skin, muscles, tendon and _____

Answer 14

collagen ;; cartilage

Question 15

In young children, protein is needed for _____ and _____. In adults, proteins in the diet provide amino acids for the _____ of proteins in the body that are damaged by _____ and _____.

Answer 15

growth ;; development

replacement ;; wear & tear

Question 16

We tend to think amino acids are the simplest building blocks for proteins, but they can be synthesised from even smaller building blocks. What are the building blocks that amino acids are made of?

Answer 16

Carboxylic acids and ammonia source

Question 17

Non-essential amino acids and essential amino acids : which can be synthesised from simpler building blocks and which cannot be synthesised from simpler building blocks?

Answer 17

Non-essential a acids can be synthesised from simpler building blocks but essential a acids cannot

Question 18

What are CONDITIONALLY essential amino acids?

Answer 18

They can be synthesised by the body from simpler building blovks but the rate of synthesis is insuffiecient to meet the needs of the body during conditions like illlness / infancy

Question 19

What is de novo synthesis?

Answer 19

The ability to synthesise a biomolecule from even simpler building blocks

Question 20

Does animal protein or plant protein contain higher levels of essential amino acids?

Answer 20

Animal

Question 21

Animal protein provides essential amino acids in the _____ that the body requires, hence they are known as _____ proteins. Plant-based foods tend to be _____in some essential amino acids. To make up for this, we can combine ____ and _____ so that we have a sufficient intake of amino acids.

Answer 21

proportion ;; complete
lacking
legumes and grains

Question 22

What are legumes and grains respectively?

Answer 22

Legumes : Family of foods that encompasses beans, peas, and lentils

Grains : Foods made from wheat, rice, oats, cornmeal, barley, or another cereal grain is a grain product

Question 23

DISEASES

What is Kwashiorkor?

Answer 23

It is when a child is deficient in protein intake but consumes sufficient energy.

Question 24

DISEASES

What is Marasmus? What is it characterised by?

Answer 24

When a child is deficient in both protein and energy intake.
- Characterised by severe wasting (A weakening, shrinking, and loss of muscle caused by disease or lack of use.)

Question 25

If protein intake is more than what is required for growth and maintenance, the amino acids can be further _____ _____ to provide _____.

Answer 25

broken down ;; energy

Question 26

What are 2 negative consequences of excessive consumption of protein?

Answer 26

1. Weight gain, increased risk of obesity
2. Higher amount of urea produced places burden on kidneys, for infants and patients with kidney disease (not a problem for adults but a problem)

Question 27

What happens during catabolism of amino acids?

How does excess protein lead to weight gain?

Answer 27

• Amino group is removed as ammonia and converted into urea for excretion.
• The carbon skeleton of amino acids are used to make glucose, fat or oxidised to produce energy, leading to weight gain

Question 28

What are 2 negative consequences of excessive consumption of protein?

Answer 28

1. Weight gain, increased risk of obesity
2. Higher amount of urea produced places burden on kidneys, for infants and patients with kidney disease (not a problem for adults but a problem)

Question 29

What is the function of phospholipids?

Answer 29

increase rigidity and stabilise structure of the cell membrane (w cholestrols embedded in it)

Question 30

Fats are also found in epidose tissues. What are the functions of apidose tissue? [2]

Answer 30

1. A store of energy that is used during periods of fasting
2. Acts as a padding to cushion internal organs from physical damage

Question 31

What are the 3 other functions of fat?

Answer 31

1. Dissolve fat-soluble vitamins so they can be absorbed by intestinal cells
2. provides a waterproof barrier to skin
3. fat, particularly cholesterol, needed to make hormones

Question 32

_____ and _____ fatty acids can be synthesised de novo from building blocks derived from _____ and _____. However, we are unable to synthesise _____ fat de novo

Answer 32

Saturated ;; monousaturated
carbohydrates ;; proteins
polyunsaturated

** synthesised de novo from glucose and a acids (aka building blocks of carbs and proteins)

Question 33

Which 2 fatty acids are polyunsaturated essential a acids that must be obtained from the diet?

Note : these 2 fatty acids serve as building blocks for synthesis of other polyunsaturated fatty acids that the body requires too

Answer 33

Linoleic acid, alpha linolenic acid

Question 34

Animal sources of fat , and tropical oils (coconut/palm) consist of higher levels of ____ fat.Olive oil, rapeseed oil (aka canola) and nuts are higher in _____ fat while vegetable oil such as sunflower seed oil contains more _____ fat

Answer 34

saturated ;; monounsaturated ;; polyunsaturated

Question 35

The negative consequence of consuming excessive fat is that it leads to obesity. How does fat lead to obesity?

Answer 35

Fat increases palatability of food, which may lead to overeating and obesity.

Question 36

Obesity and excessive consumption of _____ fats have been linked to cardiovascular diseases. This is also characterised by dyslipidemia, where there are high levels of total cholestrol, high levels of _____-_____ _____cholesterol, low levels of _____-_____ _____ cholesterol and high levels of triglycerides in the blood.

Answer 36

saturated

Low-density lipoprotein cholesterol (bad cholesterol)

High-desnity lipoprotein cholesterol (good cholesterol)

Question 37

CARBOHYDRATES

In a well-fed state, excess glucose is stored in the _____ as ______. During periods of fasting, ___ is broken down to maintain regular blood glucose, and _____ is the main hormone to signal its breaking down.

Answer 37

liver ;; glycogen ;; glycogen ;; glucagon

Question 38

Amino acids and fatty acids can also be converted into _____ _____, which serves as an alternate fuel source for the brain and other tissue.

Answer 38

ketone bodies

Question 39

What is the downside of production of ketone bodies?

Answer 39

It can lead to ketacidosis, which is a potentially fatal condition where the pH of blood is lowered.

Question 40

What is type 1 and type 2 diabetes?

Answer 40

Type 1 diabetes : due to lack of insulin production
- autoimmune disease, usually develops during childhood or adolescence

Other info :
- Insulin helps blood sugar enter the body’s cells so it can be used for energy. Insulin also signals the liver to store blood sugar for later use.

• An autoimmune disorder occurs when the body’s immune system attacks and destroys healthy body tissue by mistake.
• A chronic condition is a health condition or disease that is persistent or otherwise long-lasting in its effects or a disease that comes with time. (usually last more than 3 months)

Question 41

What are the 3 functions of dietary fibre?

Answer 41

1. Maintain peristalsis and prevent constipation
2. Some dietary fibre is fermented by gut microorganisms, maintaining a healthy gut microflora
3. May bind to toxic compounds (e.g. heavy metals) and prevent absorption

Question 42

Dietary fibre can be further categorised into soluble and insoluble fibre. True or False?

How much energy is provided by soluble and insoluble fibres?

Answer 42

True

• soluble fibres : 2 kcal/g
• insoluble fibres : insignificant

Question 43

How does excessive consumption dietary fibre lead to malnutrition? (esp in young children)

Answer 43

• They are less energy dense. limiting energy intake in young children
• Foods in high dietary fibre associated with anti-nutrients (compounds that lower the bioavailability of nutrients)

Question 44

Low level of alchohol consumption has been associated with health benefits.

The 2020 US Dietary Guidelines recommends no more than how many glasses of wine per day for women and men respectively?

Answer 44

• women : no more than 1 drink
• men : no more than 2

** Note : the dietary guidelines state if you do not have the habit of drinking, it is not necessary for you to start drinking.

Question 45

What 2 categories can vitamins be categorised into?

Answer 45

Fat soluble and water soluble vitamins

Question 46

Which are the fat-soluble vitamins and which are the water-soluble vitamins?

Answer 46

Fat soluble : Vitamin A,D,E,K
Water soluble : Vitamin B,C

Question 47

Some vitamins and minerals function as _____ in enzymatic reactions.

Answer 47

Co-factors

Question 48

What are co factors in enzymatic reactions?

Answer 48

A cofactor is an inorganic / small organic molecule that assists in enzyme activity. They are able to assist in performing certain, necessary, reactions the enzyme cannot perform alone.

Question 49

What are 2 subcategories of cofactors and what is the difference between?

Answer 49

1. Cosubstrates
   - not covalently bonded to the enzyme and are consumed during reaction
2. Prosthetic factors
   - covalently bonded to the enzyme (tightly bound) and do not get consumed during the reaction

Question 50

A lack of vitamin C impairs _____ formation in the body. This in turn manifests as a disease called _____, characterised by bleeding gums, easily bruised skin and wounds that heal poorly

Answer 50

collagen ;; scurvy

Question 50

A lack of vitamin C impairs _____ formation in the body. This in turn manifests as a disease called _____, characterised by bleeding gums, easily bruised skin and wounds that heal poorly

Answer 50

collagen ;; scurvy

Question 51

As vitamins are _____ compounds, they may be destroyed during food processing and storage.

What kinds of processing causes less degradation of vitamins? [2]

Answer 51

organic

• non-thermal processing such as ultrahigh pressure
• processing foods at higher temperatures but for a shorter duration (as compared to processing foods at lower temp for a longer duration)

Question 52

What are some functions of minerals? [2, but may have more]

Answer 52

1. Act as prosthetic factors in proteins
2. Form structural components of the body (e.g. calcium and phosphorous forming bones ;; sodium -potassium pump)

Question 53

In the potassium-sodium pump in cell membranes, sodium is the main ______ cation while potassium is the main _____ cation. Low levels of potassium / high levels of sodium draw fluid to _____ space, thus _____ blood pressure (revisit how the pump works)

Answer 53

extracellular ;; intracellular

extracellular

Question 54

What is the sodium limit of sodium as recommended by the Singapore Health Promotion Board?

Answer 54

2000 mg (2g)

Question 55

Unlike vitamins, minerals cannot be degraded by food processing but it can be lost? By what ways can minerals be lost from food?

Answer 55

Through leaching into the water during blanching, boiling or other similar operations

• Thus, whenever possible water used for boiling foods should be used for other dishes like soup to minimise the losses of minerals in the diet

Question 56

What is bioavailability?

Answer 56

The term bioavailability refers to the proportion or fraction of a nutrient, consumed in the diet, that is absorbed and utilized by the body

Question 57

Plant sources have antinutrients / anti-nutritive factors. What is a kind of antinutrient in plant sources of food?

Answer 57

Indigestible carbohydrates
- Vitamins and minerals may be entrapped behind tough cell walls which are composed of indigestible carbs

Question 58

How do whole grains act as anti nutritive factors?

Answer 58

They contain phytic acid, which chelate s multivalent cations (lie Fe2+ and Ca2+), limiting the absorption of these ions

– chelate : a heterocyclic compound having a metal ion attached by coordinate bonds to at least two nonmetal ions.

Question 59

What are flavonoids (aka bioflavonoids)?

Answer 59

They are polyphenols
- Can be found in foods such as cocoa, green tea, red wine
——————————————————–
are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans

Question 60

What is the OBSERVED benefit of a diet high in flavonoids?

Answer 60

Protect against cardiometabolic diseases such as heart attack. stroke and type 2 diabetes

** note : the exact function of flavonoids is not fully understood as of now

Question 61

The US Academy of Nutrition and Dietetics has issued a guideline that there is moderate evidence that a daily intake of ___ - ___ mg of flavonoids is beneficial to health

Answer 61

400-600

Question 62

DIFFERENCES BETWEEN FOOD SCIENCE AND NUTRITION

What are the underlying principles in food science and nutrition?

Answer 62

Food science is the discipline in which chemistry, biology, physical sciences and engineering are used to study nature of foods, causes of detrioation and principles underlying food processing.

Human nutrition is built on foundation of basic sciences such as biochemistry, physiology, statistics, epidemiology, social sciences –> applied to identify nutrients that affect growth, maintenance of health and prevention of diseases in humans.