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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 latrobe.edu.au CRICOS Provider 00115M
Structure of alcohol CH 3 CH 2 OH (ethanol) Methyl group H H Atwater Factor 1g = 29kj H C C OH Carboxyl group H H * Cannot be stored in body & Toxic See Chapter 7 pp.238-247 Whitney and Rolfes Understanding Nutrition 29
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 30
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) 32
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 33
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 34
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 muscle coordination 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) 35
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 36
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) 37
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 38
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) http://www.alcohol.gov.au/internet/alcohol/publishing.nsf/content/guidelines Source: NHMRC 2009 39
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 40
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 41
Standard alcoholic drinks? Beverage (% alcohol) Volume (ml) Alcohol content (g) Beer (4-5%) 2/3 can (250mL) 10 380 Low alcohol beer (2-3%) Wine (8-14%) Fortified wine (18-20%) Spirits (40%) Coca Cola or any softdrink or fruit juice Bacardi and coke 1 small can (375 ml) 10 380 Energy (kj) 100mL 10 400 (sweet white) 60mL 10 300 30mL (1 nip) 10 280 1 can (375mL) 900 250mL 10 700 42
Number of Australian standard drinks in common containers Volume No of standard drinks Medium Light beer (3.5%) 1 can 1 Regular beer (4.9%) 1 can 1.5 Wine (9.5-13%) 750 mlbottle 7-8 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 Pre-mixed spirits (around 5%) 1 can 1.5 Spirits 1 nip (30 ml) 1 One drink isn't always one standard drink 43
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 44
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/b83ad1f91aa632adca25718e0081 F1C3/$File/nas-06-09-1.pdf 45
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