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Chandalia M, Garg A, Lutjohann D, von Bergmann D, Grundy SM, Brinkley LJ.
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Diabetes and Alcohol LINDA CARTER AND JOANNE BOYLE Charing Cross Hospital, London, UK
INTRODUCTION
Studies in the general population show an improvement in mortality and morbidity from light to moderate ingestion of alcohol.
This improved mortality was greatest amongst those individuals with the highest risk of ischaemic heart disease (1).
The definition of light to moderate intake is, however, confusing and varies between researchers from one to three drinks per day, 3, 4 units for men and 2, 3 units for women per day, 0.5, 1.0 g/kg body weight, or ‘moderate drinking is the level below which overall net harmful effects are seen in population surveys, about three drinks per day.
Thus less than three drinks per day is moderate or lighter drinking and heavy drinking is three or more drinks per day’ (2).
Recommendations have generally been determined from epidemiological and retrospective data where the problem of evaluating thresholds is complicated by the underestimation of alcohol consumption.
Drinking more frequently or larger measures than reported can lead to a lower apparent threshold of alcohol-related effects.
For people with diabetes, recommendations for alcohol intakes are complicated by the well-established risks of alcohol ingestion such as increasing blood pressure, increasing triglycerides and contributing to obesity versus the benefits of reducing the risk of ischaemic heart disease through increasing HDL cholesterol, increasing insulin sensitivity and the contribution of antioxidant nutrients. (The effect of alcohol ingestion on these individual risks and benefits is discussed later in this chapter.)
Nutritional Management of Diabetes Mellitus. Edited by G. Frost, A. Dornhorst and R. Moses & 2003 John Wiley & Sons, Ltd. ISBN 0 471 49751 7
202 NUTRITIONAL MANAGEMENT OF DIABETES MELLITUS
NUTRITIONAL RECOMMENDATIONS
For the general adult population ‘sensible’ limits are 21 units per week or 2, 3 units per day for men and 14 units per week or 1, 2 units per day for women.
This remains the recommendation by the Royal College of Physicians despite the Department of Health increasing the recommended number of units to 28 and 21 units per week, respectively (3).
The current European nutritional recommendations for people with diabetes (1999) state ‘For those who choose to drink alcohol, intakes of up to 15 g for women and 30 g for men are acceptable’ per day (4,5).
This equates to one small (125 ml) glass of wine (12% abv) or 1.5 units for women per day and two small glasses of wine (12% abv) for men, which equates to 3 units.
However, many wines have a higher alcohol content and many people would regularly drink a larger measure.
The present consensus outlined in the European and American nutritional recommendations for people with diabetes concludes that there are benefits (unless medically contraindicated) from light to moderate alcohol intakes taken with a carbohydrate-containing meal.
Moderate intakes of wine, especially red wine, which contains non-nutrient flavonoid and phenolic compounds, which have antioxidant properties, may confer greater benefit than consumption of spirits or beer (6).
Much of the evidence from studies is based on weekly intakes of alcoholic drinks, but considering that the beneficial effects of moderate drinking on fibrinolytic factors (7) and blood pressure (8) are transient, it is most beneficial to have light to moderate daily intakes.
Health professionals should be cautious when advising on intakes because many people underestimate their alcohol consumption.
Practical recommendations should be explained in terms of drinks and units to avoid confusion.
Table 13.1 shows the alcoholic content and number of units contributed by commonly consumed alcoholic beverages.
PRACTICAL RECOMMENDATIONS
Provided alcohol intakes are not contraindicated (see below), for most people with diabetes it is healthiest for men to drink 2, 3 units and women to drink 1, 2 units per day.
Higher intakes, even taken occasionally, will have an impact on blood pressure and triglycerides and will increase the risk of hypoglycaemia and ketoacidosis.
It is especially important that people with diabetes who are treated with insulin or sulphonylureas should eat a carbohydrate-containing meal and take their medication before drinking and have a bedtime snack (and long-acting insulin if prescribed) before going to sleep.
They should also be aware that prolonged and severe hypoglycaemia can occur up to 36 h after binge drinking and this can be mistaken for intoxication.
For those inclined to drink more
DIABETES AND ALCOHOL 203
Table 13.1 The alcoholic content and number of units contributed by commonly consumed alcoholic drinks
Drink Measure No. of units Alcohol (g)
Beers, lagers and cider 3, 5% abv 250 ml (0.5 pt) 0.75, 1.25 7.5, 12.5 500 ml (1 pt) 1.5, 2.5 15, 25 6, 8% abv 250 ml (0.5 pt) 1.5, 2.0 15, 20 500 ml (1 pt) 3.0, 4.0 30, 40 Wine 9, 11% abv Sm glass (125 ml) 1.0, 1.4 10, 14 Med glass (175 ml) 1.1, 2.0 11, 20 Lg glass (250 ml) 2.25, 2.75 22.5, 27.5 1 bottle (750 ml) 6.75, 8.25 67.5, 82.5 12, 14% abv Sm glass (125 ml) 1.5, 1.75 15, 17.5 Med glass (175 ml) 2.1, 2.45 21, 24.5 Lg glass (250 ml) 3.0, 3.5 42, 49 1 bottle (750 ml) 9.0, 10.5 90, 105 Fortified wines (sherry/port) 16% abv 50 ml glass 0.8 8 Spirits (vodka/gin/rum, etc.) 40% abv 25 ml 1.0 10
than the recommended intakes advice should be given on how to minimise the risk of hypoglycaemia.
This might include eating carbohydrate-containing snacks that might not be particularly healthy, e.g. savoury snacks like crisps and peanuts or alternating alcoholic drinks with sugar-containing soft drinks or fruit juice.
The normal precautions for alcohol intakes still apply with regard to drinking and driving, but it is obviously very important to minimise the risk of hypoglycaemia.
There is no specific benefit for people with diabetes to consume low- carbohydrate beers/lagers or low-alcohol drinks; it is total alcohol intake, how rapidly it is consumed and whether it is consumed with or after food that will determine its effect.
CONTRAINDICATIONS
People with diabetes who should abstain from drinking alcohol include those with a history of alcohol abuse, pancreatitis, liver disease, gastritis and women during pregnancy. Also intakes should be restricted for those who have hypertriglyceridaemia, hypertension, neuropathy and frequent hypoglycaemia and hyperglycaemia.
204 NUTRITIONAL MANAGEMENT OF DIABETES MELLITUS
People with DM who also take antiepileptics and tranquillisers should seek advice from their doctor or pharmacist before drinking alcohol because of possible drug interactions.
METABOLISM OF ALCOHOL
The liver metabolises alcohol at an average rate of 0.1 g/kg body weight per hour.
Thus an average 70 kg man will require 2 h to metabolise 24 g alcohol, the equivalent of 1.5 small glasses of wine.
The total quantity and the rate of alcohol ingestion determines its effect (9).
Some of the alcohol in the stomach is metabolised by the enzyme alcohol dehydrogenase, which is present in the gastric mucosa.
Women have less gastric alcohol dehydrogenase activity than men, so their blood alcohol concentration rises more markedly.
Once absorbed the alcohol spreads rapidly into the body water and the smaller size and greater fat content of women amplifies the rise.
Alcohol is metabolised in a series of reactions to acetyl Co A which, in most extra-hepatic tissues, is then channelled into the TCA cycle.
Here, it is oxidised and this generates most of the ATP from ethanol oxidation.
A small proportion of the acetyl Co A that remains in the liver and that is present in the adipose tissue may act as a precursor for the biosynthesis of fatty acids and glycerol.
OXIDATION OF ETHANOL TO ETHANAL (ACETALDEHYDE) Most of the absorbed alcohol is taken up by the liver. Here, three separate enzyme reactions oxidise the ethanol to ethanal. CH3CHO Ethanal
NADH+H+
1) Alcohol Dehydrogenase NAD+
2) Microsomal Ethanol CH3CHO 3) Catalase Oxidising System CH3CHO Ethanal Ethanal
H2O2 NADPH+H++2O2 NADP++H2O2 2H2O
Figure 13.1 Pathway as described by Newsholme and Leech 1990. Reproduced with permission of John Wiley & Sons Limited
DIABETES AND ALCOHOL 205
Alcohol Dehydrogenase The reaction catalysed by alcohol dehydrogenase is the most widely known. This enzyme is also present in much smaller amounts in the gastric mucosa, kidney and adipose tissue.
Microsomal Ethanol Oxidising System This enzyme system uses NADPH and oxygen to catalyse the reaction to ethanal. The enzyme cytochrome P450 is involved in this reaction and also in the detoxification of many drugs. Alcohol competes with these drugs for the enzyme site and its presence, therefore, can lead to higher circulating levels of drugs which may reach toxic levels (10).
Catalase In the liver peroxisomes, the enzyme catalase reduces H2O2 to H2O concomitantly as it oxidises ethanol to ethanal.
OXIDATION OF ETHANAL TO ACETATE This reaction is catalysed by aldehyde dehydrogenase
CH3 CHO þ NADþ þ H2 O ! CH3 COO þ NADH þ 2Hþ
CONVERSION TO ACETYL Co A Most of the acetate escapes from the liver and is converted to acetyl Co A in extra-hepatic tissues by the enzyme acetyl Co A synthetase: CH3 COO þ ATP4 þ CoASH ! CH3 COSCoA þ AMP3 þ PPi3 The acetyl Co A is then oxidised via the TCA cycle which generates ATP.