Week 2 : Types of studies, macronutrients and micronutrients

Question 1

What is the significance of cell line/animal studies, since scientists are mainly concerned with studying how the human body works in nutrition?

Answer 1

Cell line studies allow scientists to formulate hypothesison how biological systems work and animal studies confirm the hypothesis. Only then, verification of effects and observation of side effects can be done in human studies

Question 2

What are the 3 kinds of observational studies?

Answer 2

1. Case-control
2. Cross-sectional
3. Cohort

Question 3

What kind of conclusions can we draw from observational studies?

Answer 3

Correlation

Question 4

What are the 2 kinds of interventional studies?

Answer 4

1. Randomised, double-blinded, placebo controlled intervention studies
2. Clinical studies

Question 5

What kind of conclusions can we draw from interventional studies?

Answer 5

Cause-effect

Question 6

What is the difference between case-control, cross sectional and cohort studies?

Answer 6

Case-control (past) : checks the subject’s history
- “There is a correlation/association of vitamin X intake in people with hair loss compared to people without hair loss”

 - Case : group with disease
 - Control : group with no disease 

Cross sectional (present) : collecting information of a current population to make a conclusion
- “ 5% of the population has hair loss”

Cohort (future) : follow subjects in time to establish a correlation
-“5% if healthy subjects develop hair loss over time. The intake of vitamin X is a risk factor that correlates to hair loss”

Question 7

What is a good placebo?

What is a potential limitation of placebos which are food items?

Answer 7

The placebo should have the same characteristics as the treatment given to participants

• e.g. for vitamin pills, placebo should be of the same : shape/colour/size/texture

Limitation : it is very hard to find a placebo for food products

Question 8

In a good intervention study, there should not be any placebo effect. True or False?

Answer 8

True

Question 9

For carbohydrates, what are the 3 kinds of carbohydrates?
How many calories does each kind of carbohydrate give?

Answer 9

Digestible sugars
1. Simple sugars (mono and disaccharides) : 4 cal/g
2. complex carbs (polysaccharides) : 4cal/g

non-digestible sugars
3. Complex carbs (aka dietary fibre) : 0-2cal/g

Question 10

Which of the following are reducing sugars?
1. Sucrose
2. Fructose
3. Lactose
4. Galactose
5. Glucose
6. Maltose

Answer 10

Reducing sugars are aldehydes and ketones

• Only sucrose is not a reducing sugar as both anomeric carbons are used for bonding, carbonyl group not available
• Though ketones can’t be oxidised further and reduce others. as long as there is free avaiable ketone group, they can undergo isomerisation into aldehyde (e.g. fructose can isomerise into glucose)

Question 11

___ is the storage form of glucose in muscles of animals.

Answer 11

Glycogen

Question 12

How much energy do fats give us?

Answer 12

9cal/g

Question 13

What are the 3 types of dietary fats?

Answer 13

1. Triglycerides
2. Free fatty acids (some are essential to body)
3. Dietary cholesterol

Question 14

what fraction of cholesterol is produced by liver, and what fraction of cholesterol is obtained through our diet/

Answer 14

2/3 produced by liver
1/3 obtained from diet

Question 15

What is the difference between high density lipoproteins (HDL) and low density lipoproteins?

Answer 15

HDL : good cholesterol
- scavenges cholesterol, delivers it back to the liver

LDL : bad cholesterol
- delivers lipids around the body, and may deliver to arteries and block them

Question 16

How can we try to reduce cholesterol intake (LDL and HDL)?

Answer 16

LDL : Reduce saturated fat intake

HDL : reduce dietary cholesterol intake but reduction may not be significant

Question 17

How much energy do proteins give us?

Answer 17

4cal/g

Question 18

Does animal or plant protein have higher protein quality?

Answer 18

Animal protein as it contains all essential AA

Question 19

Micronutrients are not essential to us since they do not contain calorie and do not provide us with energy. True or False?

Answer 19

False, they are essential. Deficiency may lead to disease

Question 20

What are the water-soluble vitamins, and the fat-soluble vtamins?

Answer 20

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

Question 21

Does deficiency in water-soluble vitamins or fat-soluble vitamins take a longer time to develop? Why?

Answer 21

Fat-soluble vitamins, since the body can still utilise the previously stored vitamins in fat cells before a person becomes deficient

Question 22

Consuming excess water-soluble vitamins is detrimental for health. True or False?

Answer 22

False, they are excreted out

Question 23

What is so special about Vitamin D? What is its function?

Answer 23

Our body can synthesise vitamin D, unlike other vitamins. Vitamin D can be synthesised through exposure to sun and body will stop synthesising it when it is present in sufficient amounts

Function : Helps in absorption of calcium and phosphorous, thus maintaining bone integrity.

Question 24

What is the function of vitamin C?

Answer 24

1. Fight infection and repair wounds

Question 25

What is the main function of minerals?

Answer 25

Minerals: mostly metal ions

Most of them function as cofactors, which binds to the apoenzyme (protein portion) in order for the enzyme to get activated and function.

Question 26

What are the 3 factors in evaluating the healthiness of foods? Explain what they mean.

Answer 26

1. Energy-dense : food relatively high in levels of calories per unit weight of food
2. Nutrient-dense : food with relatively high amounts of nutrients (mainly micronutrients) compared to their calorie value
3. Empty-calorie : foods with excess calories in relation to nutrients (mainly micronutrients)