copyright act 1968 · wernickes encephalopathy, korsakoff [s psychosis . la trobe university 37...
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DTN2PNU Principles of Human Nutrition Lecture: Alcohol Lecture Prepared by: Dr Regina Belski & Associate Professor Catherine Itsiopoulos Department of Dietetics and Human Nutrition
29 La Trobe University
Structure of alcohol
CH3CH2OH (ethanol)
C C OH
H H
H H
H
See Chapter 7 pp.238-247 Whitney and Rolfes Understanding Nutrition
Carboxyl group
Methyl group
Atwater Factor 1g = 29kj
* Cannot be stored in body & Toxic
30 La Trobe University
Metabolism of alcohol
Absorption • Stomach – 20% alcohol if absorbed but is proportional to the amount of food
present • Small intestine – rapid absorption - jejunum • Liver – site of alcohol metabolism 3 Pathways of Alcohol metabolism in the liver: Pathway 1 • Alcohol Dehydrogenase Pathway • NAD Nicotinamide adenine dinucleotide (contains niacin) TPP (thiamin ) co factors in
alcohol metabolism – both B vitamins – high turnover in the energy pathway Pathway 2 • MEOS stands for microsomal enzyme oxidizing system recruited with chronic or
acute excessive intake. Same pathway is recruited for drug, poisons metabolism. • Alcohol is a poison. Activating this pathway effectively makes the liver more efficient
at breaking down alcohol and enhances tolerance to alcohol. Therefore there can be problems giving anaesthetic and other drugs to alcoholics
Pathway 3 • Excretion of 5% alcohol via the lungs in the basis of the breathalyzer
32 La Trobe University
Metabolic effects of alcohol
• Inhibition of glucose metabolism (hepatic gluconeogenesis)
• Competition for thiamin in the glucose pathway
• Increase in lactic acid
• Increase in lipid synthesis (fatty liver/ high triglycerides)
• Decrease in protein synthesis
• Increase in effect of drugs (slowed metabolism)
• Interference with vitamin D and B6 synthesis
• Diuretic effect
Dehydration: the main cause of ‘hangover’ + low blood glucose levels (hypoglycaemia)
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Rate of metabolism of alcohol Fixed rate of alcohol metabolism
Limited by the amount of the enzyme alcohol dehydrogenase present
This enzyme is largely produced by gut bacteria which ferment undigested starches
5-8 g alcohol/h* (approx)= 60-200 mg/kg/h
average of 100mg/kg/h
How long does it take a 65kg male to metabolise 3 standard drinks?
30 g ethanol @100mg/kg/h = 4.6 hours
How long does it take a 50kg female to metabolise 3 standard drinks?
= 6 hours
*NHMRC 2003
34 La Trobe University
Short-term effects of alcohol
Alcohol is a depressant and a narcotic (anaesthetic)
Interferes with REM sleep (deep sleep)
Increase in blood flow to the skin
rosy flush
increase in blood pressure
Increased risk of gouty arthritis
High risk of injury and accidents
35 La Trobe University
Alcohol doses and brain response (short-term
effects)
No. of drinks Blood alcohol (%) Short term effects
2 0.05 Judgement impaired
4 0.10 Control impaired
6 0.15 Loss of musclecoordination
8 0.20 Vision impairment
12 0.3 Out of control
14+ 0.5-0.6 Amnesia /death
Adapted from: Whitney & Rolfes (2002, p. 235)
36 La Trobe University
Long-term effects of alcohol Stomach
alcohol increases acid secretion
Pancreas
pancreatic damage, secondary diabetes
Liver
direct toxin …….cirrhosis (hardening of the liver)
Small bowel
change in morphology of cells - malabsorption
iron overload
Brain
depressant……….sleep disturbance
acetaldehyde acts as a direct toxin
B6 (pyridoxine) & B1 (thiamin) deficiency
Wernicke’s encephalopathy, Korsakoff’s psychosis
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Other complications • Cancer of pancreas and liver
• Foetal alcohol syndrome
• Malnutrition
Folic acid, B6
• Obesity (beer gut)
• Increase in blood pressure and stroke
• Cardiovascular disease
• Diminished libido (lack of sex drive)
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Beneficial effects of alcohol Moderate alcohol intakes
reduction in blood clotting
Low alcohol intakes
anti-spasmodic effect upon blood vessels
Increases High Density Lipoprotein (HDL)
Moderate alcohol (glass red wine with meal) important Feature of Mediterranean Diet:
• 1-2 glasses/day
• Always with meals
• Don’t get drunk
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Reducing the risk of alcohol-related harm over a lifetime
New Australian Guideline 1
No more than 2 standard drinks on any day
No different between men and women
Drink less frequently over a lifetime (weekly rather than daily)
o Reduces risk to 1/100
o Harm proportional to age
» Greatest 15-24 yrs (50% prevalence)
Source: NHMRC 2009
http://www.alcohol.gov.au/internet/alcohol/publishing.nsf/Content/guidelines
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Reducing the risk on a single drinking occasion
New Australian Guideline 2
No more than 4 standard drinks on a single occasion
No different between men and women
Double relative risk (RR) of injury/harm at 4 drinks on a single occasion
Risk increases exponentially with > 4 drinks on a single occasion
Source: NHMRC 2009
41 La Trobe University
Guidelines for children and adolescents
New Australian Guideline 3
Under 15 yrs – greatest risk of harm
15-17 yr – the safest option is to delay the initiation of drinking for as long as possible
Alcohol affects brain development and leads to alcohol related problems in later life
Source: NHMRC 2009
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Standard alcoholic drinks?
Beverage (% alcohol)
Volume (mL)
Alcohol content
(g)
Energy (kJ)
Beer (4-5%) 2/3 can (250mL) 10 380
Low alcohol beer (2-3%)
1 small can (375 mL)
10 380
Wine (8-14%)
100mL 10 400 (sweet white)
Fortified wine (18-20%)
60mL 10 300
Spirits (40%)
30mL (1 nip) 10 280
Coca Cola™ or any softdrink or fruit juice
1 can (375mL) 900
Bacardi and coke
250mL 10 700
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Number of Australian standard drinks in common containers
‘One’ drink isn't always ‘one standard’ drink
Volume No of standarddrinks
Medium Light beer (3.5%) 1 can 1
Regular beer (4.9%) 1 can 1.5
Wine (9.5-13%) 750 mLbottle 7-8
Pre-mixed spirits (around5%)
1 can 1.5
Spirits 1 nip (30 mL) 1
1.8 180ml
Average restaurant serve of Wine 12% Alc./Vol
1.5 375ml
Full strength beer
4.9% Alc./Vol
1.5 375ml
Pre-mixed spirits
5% Alc./Vol
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Summary- Alcohol
Absorbed across walls of stomach
Metabolised using numerous pathways
Main AD
MEOS
Lost through breath
Alcohol content of standard drinks = 10g ethanol
1 ‘glass of wine’, or 1 ‘can’ of full strength beer does not = 1 standard drink
45 La Trobe University
References Whitney, E., Rolfes, SR, Crowe, T., Cameron-Smith, D. & Walsh, A. (2011). Understanding Nutrition:
Australia and New Zealand Edition. South Melbourne, Australia: Cengage Learning Australia.
http://www.nrv.gov.au/ (accessed 22/03/12)
Images courtesy of Microsoft office ‘Clip Art’ unless otherwise attributed
AIHW 2008 the 2007 National Drug Strategy Household Survey, AIHW, Canberra.
NHMRC Australian Alcohol Guidelines to reduce health risk from drinking alcohol. NHMRC 2009
See www.alcohol.gov.au
Deakin V. Alcohol: The legal drug in Sport. Sports Coach 1999; 22 (2):22-23.
NHMRC Dietary guidelines for Australian adults. A guide to healthy eating. NHMRC 2003, p. 151-170. (under revision 2009)
NHMRC Dietary Guidelines for Children and Adolescents in Australia. A guide to healthy eating. NHMRC 2003, p. 151-170. (under revision 2009)
National Alcohol Strategy 2006-2009 Towards safer drinking cultures , Australian Gov Policy
http://www.alcohol.gov.au/internet/alcohol/publishing.nsf/Content/B83AD1F91AA632ADCA25718E0081F1C3/$File/nas-06-09-1.pdf
Thank you
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