Energy and Dietary Fats

Question 1

What are the two main nutrient classes and what are included in them?

Answer 1

1. macronutrients (proteins, carbohydrates, Fats).
2. Micronutrients (vitamins, minerals, trace elements)

Question 2

Energy units

Answer 2

Energy is measured in kcal or kJ.
Fat has 9 kcal (37.7 kJ)/g
CHO has 4 kcal (16.7 kJ)/g
Protein has 4 kcal (16.7 kJ)/g
Alcohol has 7 kcal (29.3 kJ)/g
1 kcal = 4.18 kJ
1000 kJ = 1 MJ

Question 3

Why is energy required?

Answer 3

Voluntary activity
Maintenance of life (BMR)
- body temperature
- breathing
- heart beat
- brain function
Growth
- children
- pregnancy
- body builders

Question 4

Energy requirement depends on:

Answer 4

Body size and composition
Age
Activity
Basal Metabolic Rate (BMR) is estimated using equations based on metabolic studies.
The henry equations are used to estimate BMR

Question 5

BMR estimation: Henry Euqations

Answer 5

BMR = weight coefficient X weight (kg) + height coefficient X height (m) + constant

for values in kcal:
for males aged 18-30
weight coefficient 14.4
height coefficient 313
constant is 113

for females aged 18-30
weight coefficient 10.4
height coefficient 615
constant -282

Basal Metabolic Rate is: _____

Question 6

Estimating energy requirements

Answer 6

energy requirement is then estimated from BMR multiplied by an activity factor ‘physical activity level, or PAI’

PAL ranges from 1.2 (bed rest) to 2.2 (very active or heavy occupational work).

PALs of 1.75 and above are consistent with good health.

For pregnant women in third trimester add 191 kcal per day.

For lacatating women for first 6 moonths of breastfeeding

Question 7

What are dietary fats?

Answer 7

1. Primarily composed of triglyceride (glycerol and 3x fatty acids)
2. fatty acids are saturated, mono-unsaturated or polyunsaturated
3. saturated (no double bonds) are mostly found in animal and dairy fats.
4. Monounsaturated (MUFA) (one double bonds) are found in olives and nuts.
5. Polyunsaturated (PUFA) (several bonds) are found in plant oils, seed oils and fish oils.

Question 8

What are the functions of dietary fats?

Answer 8

1. provision of energy
2. component of memrbanes
3. precursors of prostaglandins
4. precursors of cholesterol
5. absorption of fat soluble vitamins
6. essential fatty acids (linoleic and alpha linolenic) -> found in nuts, seeds, and their oils.

Question 9

What is omega 3 fatty acids?

Answer 9

• Double bond 3 carbons from methyl end of fatty acid chain
• Docosahexanoic acid (DHA)
• Eicosapentanoic acid (EPA)
• α-Linolenic acid (converts to EPA in body)
• Form prostaglandins of the 3 series that alleviate inflammation
• Negative association with cardiovascular disease
• Possible role in preventing periodontal disease
• Oily fish are the richest source of DHA and EPA
• Flaxseed, walnuts, canola oil are rich sources of α-Linolenic acid

Question 10

Trans fatty acids

Answer 10

• Double bonds may be ‘cis’ or ‘trans’
• Trans fats are found in animal products naturally
  (butter cheese meat)
• Manufactured - hydrogenated oils and cooking at
  high temperatures
• Increase LDL cholesterol and decrease HDL
  cholesterol
• Intake is strongly linked with cardiovascular disease
• WHO recommends limiting TFA to <1% energy intake

Question 11

Summary: Energy and
dietary fats

Answer 11

• Energy is provided from all the macronutrients
• Energy requirements may be calculated using the
  Henry equations
• Fat provides energy, components for cell
  membranes and precursors for prostaglandins
• The only essential requirements for fat are for
  Essential Fatty Acids and vitamin absorption
• High intakes of saturated fat and trans fatty acids
  are associated with non-communicable disease