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BS - Gastrointestinal System pt.1 > Introduction to Nutrition > Flashcards

Introduction to Nutrition Flashcards

1
Q

What 3 things will a healthy diet supply?

A
  1. energy
  2. building blocks for metabolism
  3. essential nutrients
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2
Q

what types of diets can lead to disease?

A

diets which fail to meet or significantly exceed an individual’s needs

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3
Q

What type of pattern is shown by dietary intake?

What does the graph look like?

A

a normal distribution

x axis - nutrient requirements
y axis - number of people

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4
Q

What is the EAR and where would it be found on the dietary intake graph?

A

estimated average requirement

it is in the centre of the normal distribution graph

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5
Q

What is described by the EAR?

A

Half of the population usually needs more than the EAR, and half needs less

The EAR is sufficient for 50% of the population

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6
Q

What is the LRNI and where would it be found on the dietary intake graph?

A

Lower reference nutrient intake

This is 2 standard deviations below the EAR (mean)

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7
Q

What is described by the LRNI?

A

LRNI is sufficient for 2.5% of the population, who have low needs

It does not meet the needs of 97.5% of the population

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8
Q

what is the RNI and where is it found on the dietary intake graph?

A

Reference nutrient intake

It is 2 standard deviations above the EAR (mean)

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9
Q

What is described by the RNI?

A

This is sufficient for around 97.5% of the population

The risk of deficiency is very small if the average intake of the population is the RNI

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10
Q

What is meant by the ‘safe intake’?

A

This is the safe upper limit for vitamins and minerals where an excess may be harmful

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11
Q

Why is safe intake used?

A

It is a range for which there is not enough information to estimate RNI, LRNI and EAR

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12
Q

Why is energy balance important?

A

it is the key to maintenance of a healthy weight

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13
Q

What is the “equation” for energy balance in someone of a healthy weight?

A

energy intake = energy expenditure

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14
Q

What does energy intake depend on?

A

Energy intake varies depending on age and gender

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15
Q

Why do people tend to gain weight as they get older?

A

In young adults, there is little change in requirements for energy intake

As you get older, requirements begin to decline

If you carry on eating as much as you used to, you will begin to gain weight with age

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16
Q

what does energy expenditure depend on?

A

Basic metabolic rate and the amount/intensity of physical activity

basic metabolic rate depends on age, weight and sex

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17
Q

What are macronutrients?

A

Macronutrients include fats, carbohydrates and proteins

They can be used immediately for energy generation

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18
Q

How are excess fats and carbohydrates stored?

A

Excess fats are stored as triacylglycerols in the adipose tissue

Excess carbohydrates are stored as glycogen

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19
Q

What is the main source of energy?

A

Fat stores provide 80-90% of total energy

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20
Q

Why is there no storage of protein?

what happens if there is a need for protein?

A

Amino acids cannot be stored

In starvation, muscle tissue can be metabolised for energy or to provide amino acids for other reactions

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21
Q

How much protein is required by an average adult daily?

A

an average adult requires 0.75g protein per kg of body weight

A typical 75kg man needs 50g protein daily

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22
Q

How much protein would be required by an athlete/bodybuilder daily?

A

1.2-1.7 g per kg of body weight

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23
Q

why are proteins not stable?

A

They are constantly being synthesised and degraded

If a muscle is not used, it is rapidly degraded

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24
Q

How do proteins vary in their rate of turnover?

A

Enzymes have a rapid turnover and a half-life in terms of seconds

Structural proteins (e.g. collagen) have a half-life in terms of tens of days

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25
what is the equation for nitrogen balance in a healthy individual?
nitrogen intake = nitrogen excretion
26
When does negative nitrogen balance occur?
when nitrogen intake is less than nitrogen excretion This occurs during fasting and illness
27
what happens if insufficient amino acids are taken in through the diet?
the body begins to break down proteins for energy it secretes more ammonia in the urine (in the form of urea) than is being taken in
28
When does positive nitrogen balance occur?
When nitrogen intake exceeds nitrogen excretion This happens during growth, pregnancy and after major surgery as the body is building new tissue
29
How many essential amino acids are there? What is meant by an essential amino acid?
There are 9 essential amino acids These cannot be synthesised by humans and must be obtained from the diet
30
what are the 9 essential amino acids and how can they be remembered?
``` Methionine Valine Histidine Leucine Phenylalanine Tryptophan Isoleucine Lysine Threonine ``` (Many Very Happy Little Pigs Take Iced Lemon Tea)
31
What is an example of an amino acid which is only required in the diet under certain conditions?
Arginine it can be synthesised by the body, but during pregnancy the body struggles to synthesise enough
32
what is the difference in the kcal provided by fat and carbohydrate/protein? How does this relate to the need for triacylglycerols?
Triacylglycerols are needed for energy 1g of fat provides 9 kcal 1g of carbohydrate/protein provides 4 kcal
33
What is the difference in the way in which carbohydrates and lipids are stored?
The body can store an unlimited amount of triacylglycerols in adipose tissue The amount of glycogen that can be stored is limited
34
what type of molecules are cholesterol and fatty acids important precursors for?
Hormones and prostaglandins Prostaglandins are involved in inflammation and smooth muscle contraction Cholesterol is a precursor for vitamin D and steroid hormones
35
Other than triacylglycerol storage, what are the functions of adipose tissue?
1. protection of vital organs | 2. giving shape to the face and body
36
what are the typical properties of saturated fatty acids?
1. they have no double bonds 2. they are solid at room temperature 3. they are typically found in meat and dairy products
37
What are the properties of monounsaturated fats?
1. they have one double bond 2. they are fluid at room temperature 3. they are found in olive and peanut oil
38
What are the typical properties of polyunsaturated fats?
1. they contain more than one double bond 2. they are fluid at room temperature 3. they are found in corn and sunflower oil
39
What are the typical properties of trans (hydrogenated) fats?
1. they contain trans double bonds, opposed to cis double bonds 2. they are found in cakes, biscuits and pastry
40
What is the consequence of trans fats having a trans double bond?
It makes them more solid This increases the risk of heart disease
41
What is the recommended % of dietary intake that should come from different types of fat?
saturated fats - 11% monounsaturates (cis) - 12% polyunsaturates (cis) - 6% trans-fats - <2% total fat - <35% (30% is desirable)
42
What is the typical fat consumption of an average person?
They tend to consume low levels of trans-fats (0.7%) but a higher than ideal amount of saturated fat (12.5%)
43
What are the 2 classes of essential fatty acids? What are they needed for?
Omega 6 and Omega 3 They are needed for the synthesis of hormones
44
How are the bonds in Omega 3 and 6 counted?
From the opposite end of the molecule to the carboxyl group
45
why is it advised that 2 portions of oily fish should be eaten each week?
they are a good source of omega 3 polyunsaturated fatty acids this helps to decrease the risk of heart disease
46
What are the 4 categories of carbohydrates?
1. polysaccharides 2. disaccharides 3. monosaccharides 4. non-starch polysaccharides
47
what are polysaccharides?
most of our intake comes from polysaccharides this is mainly starch from plant tissue but also glycogen from animal tissue
48
What is our main source of disaccharides?
sucrose (sugar)
49
what are the main monosaccharides in the diet?
glucose and fructose these are the constituents of sucrose
50
What is meant by a non-starch polysaccharide? Why are they needed?
This is dietary fibre It prevents constipation
51
What are the recommended intakes for carbohydrates?
Free sugar - < 5% Intrinsic and milk sugars, and starch - 39% Total carbohydrate - 50% Dietary fibre - 18 g per day
52
What are intrinsic sugars?
naturally occurring sugars
53
What is a typical average adult's consumption of free sugar like?
There has been a slow decline in free sugar consumption It is still around twice the recommended value
54
What are the risk factors associated with a high intake of free sugar?
1. diets high in sugar are high in calories - increases risk of obesity 2. high levels of fructose are linked to insulin resistance, metabolic syndrome and type 2 diabetes
55
What are the most common sources of free sugar?
1. sugar/preserves 2. sweetened soft drinks 3. biscuits, cakes, buns, pastry, etc. 4. alcoholic drinks 5. fruit juice 6. sweetened milk products 7. chocolate and confectionary
56
What are micronutrients?
Vitamins and minerals
57
What are vitamins?
Organic compounds required for normal metabolic function, which cannot be synthesised by the body
58
How are vitamin deficiencies treated?
By giving the deficient vitamin to restore appropriate levels
59
What are the 2 types of vitamin? How much is needed daily?
Fat-soluble and water-soluble They are required in small amounts - micrograms/milligrams
60
How can you remember which vitamins are water and fat soluble?
All B vitamins and vitamin C are water-soluble
61
what are the water-soluble vitamins?
1. B1 (thiamin) 2. B2 (riboflavin) 2. B3 (niacin) 4. B5 (pantothenic acid) 5. biotin (B7) 6. B6 (pyridoxal phosphate) 7. B9 (folic acid) 8. B12 (cobalamin) 9. Vitamin C (ascorbic acid)
62
What are the fat-soluble vitamins>
E, K, A, D
63
What are the majority of vitamines converted into?
Molecules that act as coenzymes Except for A, D, E
64
How do Vitamins A, D and E work?
They enter the nucleus and alter the level of transcription This alters the amount of proteins which are produced
65
What is thiamin (B1) needed for and what is the effect of a deficiency?
it is a cofactor in decarboxylation reactions which release CO2 deficiency leads to Beri-Beri this is muscle weakness, nerve damage, can affect heart
66
What is riboflavin (B2) needed for and what is the effect of a deficiency?
it is a constituent of cofactors (e.f. flavin adenine dinucleotide, FAD) it is involved in many aspects of the metabolism of fats, carbohydrates and proteins deficiencies are very rare as the cofactors bind very tightly to the enzymes
67
What is niacin (B3) needed for and what is the effect of a deficiency?
It is a constituent of cofactors e.g. NADH | Deficiency leads to pellagra diarrhoea, depression, dermatitis, death
68
What is pantothenic acid (B5) needed for and what is the effect of a deficiency?
it is a constituent of coenzyme A - which is needed in energy and fat metabolism deficiency is unknown as it is found in almost all foods
69
What is biotin (B7) needed for and what is the effect of a deficiency?
it is a prosthetic group that acts as a carrier for CO2 in carboxylation reactions deficiencies are very rare
70
What is pyridoxal phosphate (B9) needed for and what is the effect of a deficiency?
cofactor in enzymes involved in protein metabolism, haem synthesis, neurotransmitter synthesis, modulation of steroid hormone action deficiency leads to depression, confusion, inflammation of tongue or mouth
71
What is folic acid (B9) needed for and what is the effect of a deficiency?
1-C transfers, particularly in DNA synthesis Deficiency leads to neural tube defects e.g. spina bifida, anencephaly, macrocytic anaemia
72
What is cobalamin (B12) needed for and what is the effect of a deficiency?
methionine synthesis and fatty acid metabolism deficiency leads to macrocytic anaemia and irreversible neurological damage
73
What is vitamin C needed for and what is the effect of a deficiency?
collagen synthesis and role as an antioxidant deficiency leads to scurvy where symptoms are caused by weakened collagen
74
What is vitamin A needed for and what is the effect of a deficiency?
vision (rod cell function) and as a transcriptional regulator deficiency causes blindness and an excess can cause birth defects
75
What is vitamin D needed for and what is the effect of a deficiency?
bone formation and maintenance, immune regulation, cell differentiation, muscle function deficiency leads to rickets in children and osteomalacia in adults
76
What is Vitamin E needed for and what is the effect of a deficiency?
it is an anti-oxidant which prevents lipid oxidation in membranes deficiency causes neurological problems and is found in those who have difficulty absorbing fats
77
What is Vitamin K needed for and what is the effect of a deficiency?
cofactor for enzymes that​ activate blood clotting proteins, involved in bone maintenance deficiency in newborns causes bleeding, rare in adults

BS - Gastrointestinal System pt.1 (22 decks)

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