WORLD - ALL

Part II of II

The metabolic effects of alcohol are very important. Dr. H. Pawnall, in an article published recently(9), stated that after an acute dose of alcohol, plasma alcohol levels rise rapidly especially if consumed on an empty stomach. Two drinks can raise plasma alcohol levels to near intoxicating levels (0.05 % = 10 MMOl/L) which in some persons will alter perception and produce some impairment of motor skills. If the alcohol is consumed with fat containing foods, the peak alcohol level is lower but the appearance of the alcohol in the plasma is more persistent; hence the appropriateness of the adage "Don’t drink on an empty stomach".

The consumption of alcohol with high fat meals in an individual with a sedentary lifestyle is associated with increased truncal obesity particularly in women. The interaction of alcohol and dietary fat is interesting for a number of reasons. First, most alcohol is consumed with fat; second, the magnitude and duration of the fat in the blood after an acute dose of saturated fat are increased in several pathologic states. Enhancement of lipemia after meals by preprandial alcohol is most profound when the meal contains saturated fat and can be substantially reduced by substituting poly unsaturated fat in the diet. The effects of alcohol in individuals with hypertriglyceridemic edema are important because of the known association between hypertriglyceridemic edema and pancreatitis. Hypertriglyceridemic patients are generally advised to avoid alcohol even though moderate consumption is cardio protective. 

It is important for a number of reasons to identify the effects of alcohol on lipid metabolism in individuals with type II diabetes mellitus. Cardiovascular mortality in diabetic people is more than three times higher than in age matched non-diabetics. Individuals with type II diabetes frequently exhibit a cluster of lipid risk factors for athreo-sclerosis. The interaction of alcohol and diet is likely to be more complicated than in non-diabetic individuals and must be more carefully managed. 

A series of epidemiologic studies have suggested that one to two drinks a day of any alcoholic beverage provides a protective function in terms of coronary artery disease. Three or more drinks per day can raise blood pressure ( 10). The apparent protective effect is of relatively low strength and raises concern about the influence of confounding variables compared to controls. The latter include physical activity as well as education and economic status. Observations of the protective effects observed in people who only have one drink a month support this view. Further analysis of the population subset among females have revealed that only those with coronary risk factors experience a benefit from low dose alcohol ( 11). Whether or not this benefit is additive to the influence of standard cardiac care is not clear. Similar data on males are not available. From a negative standpoint, moderate intake is associated with an increased risk of cancer (12) and premature mortality (13). Thus the relative disease risk requires assessment in each subject. Moreover, the use of alcohol for cardio protective purposes has been discouraged as a general public health measure since alcohol abuse appears to correlate with average alcohol consumption in populations (14).

Why is alcohol cardio protective? Most experts agree that increased HDL-C is a major determinant of the cardio protective effect of alcohol. Many estimates place its contribution as 50% of the total cardio protective effect. Other estimates run as high as 90%. The question is in what way is HDL cardio protective. The simplest explanation is that the increased HDL provides an additional number of carriers for the transport of cholesterol from peripheral tissue including the arterial wall to the liver where the cholesterol is recycled or converted to more benign products such as bile acids. This pathway of reverse cholesterol transport is a widely used model of cardio protection by HDL. Elevated HDL, however, is not always cardio protective. 

The Honolulu heart study, which was done among 3,500 men of Japanese ancestry, showed that high plasma HDL, per se, is less important to cardio protection than the mechanisms that raise HDL. Some mechanisms that raise HDL are cardio protective although CETP (cholesterol ester transfer protein) mutations is clearly not one of them. Increased cardiovascular disease in men with the CETP mutations was observed in those with HDL of 41 to 60 but not for those with HDL greater than 60. Thus, within that group, HDL was cardio protective.(15)

It is clear that heavy alcohol intake is associated with increased risk of death from several causes and is a major public health concern. However, mild to moderate alcohol consumption is associated with reduced rates of coronary disease compared with abstainers.(16) Studies suggest a j-shaped relation between the level of alcohol consumption and total mortality such that a protective effect is apparent at low levels of consumption, namely one to two drinks a day, while there is substantial hazard among heavy consumers (17) In large part, this dose dependent balance reflects summation of three effects: 

The mechanisms in the cardio protective effect of moderate alcohol use are several. Alcohol intake increases total HDL as well as HDL2 and HDL3 cholesterol ( 19). Alcohol consumption also has potentially beneficial effects on fibrinolytic function (20) and on platelet aggregation (21). There has been no randomized trial of alcohol use for primary or secondary prevention.

How to best advise patients concerning the potential use of alcohol for protection of their heart is a complex process because of this agent’s potential for abuse. Abstinence is advised for patients who are pregnant, or who have liver disorders, pancreatic disease, congestive heart failure, idiopathic, cardiomyopathy or degenerative neurological conditions. On the other hand, the recommendation to drink moderately, one drink per day for women and two drinks per day for men, may be safe when made on a case-by-case basis in the absence of a history of abuse or medical contraindication.

Evidence indicating benefits for white wine, red wine, beer and liquor suggest that alcohol content rather than type is the more important predictor of cardiovascular risk reduction.(22)

In Summary, health decisions are based on risk: benefit analyses, the validity of which depends on the quality of information available. The decision to consume alcohol, is associated with risks and benefits that vary according to family history, and environment such as diet, exercise and stress. Alcohol associated problems include addiction, liver disease, pancreatitis, cancer risk, hypertension, cardiomyopathy, stroke and hypertriglyceridemia. Yet adults have traditionally used alcohol as a way to relax in a social setting. The risk for Coronary Heart Disease, is reduced in populations that regularly consume moderate amounts of alcohol. Individuals with hypertriglyceridemia and a family history of pancreatitis might consider the benefits of alcohol consumption not worth the health risk. But, someone with a family history of CHD a low HDL-C and no family history of addictive disease might find the risks quite acceptable. An understanding of the metabolic effects of alcohol and a careful study of personal and family histories should permit physicians and their patients to make informed decisions about the risks and benefits of alcohol consumption.

Footnotes:

9)  Pownall,H.J.;Alcohol and Coronary Heart Disease;2000:pp1-8
10) Friedman,GD,NEJM1993;329:1882-1883
11) Fuchs,CS;Alcohol Consumption and MortalityNEJM1995;332:1245-1250
12) Boffetta P;Epidemiology1990;1:342-348
13) Zureik M;AlcoholClin Exp Res1996;20:428-433
14) Criquiu MHLancet 1994;344:1719-1723
15) Criqui MH,Am.J.of Epid. 1987;126:620-637
16) Moore RD;Medicine1986;65:242-267
17) Gaziano JM;1995;Newsletter4:1-5
18) Maclure,M;Epidem.Review1993;15:1-24
19) Langer RD;Circ.1992;85:910-915
20) RidkerPMJAMA1994;272:929-933
21) Deykin D;NEJM1982;306:852-854
22) Stampfer MJ;NEJM1988;319:267-273

Dr. Perlow is a cardiologist who retired from private practice in Lynn, Massachusetts in November 1999, and has been Associate Clinical Professor of Cardiology at Tufts University School of Medicine since 1972.

Article source: http://www.highlandridgehospital.com/