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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


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


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)


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


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


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)


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


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)


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


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


Reducing the risk on a single drinking occasion


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


Guidelines for children and adolescents


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


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


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


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


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

http://www.nrv.gov.au/nutrients/protein.htm

http://www.nrv.gov.au/nutrients/protein.htm

http://www.alcohol.gov.au/






































Thank you

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copyright act 1968 · wernickes encephalopathy, korsakoff [s psychosis . la trobe university 37...

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