Alcohol Causes Liver Damage But May Be Beneficial To The Cardiovascular System: A Short Discussion On The Relative Risk And Benefits Of Alcohol Consumption
S Dindyal. Alcohol Causes Liver Damage But May Be Beneficial To The Cardiovascular System: A Short Discussion On The Relative Risk And Benefits Of Alcohol Consumption. The Internet Journal of Cardiovascular Research. 2004 Volume 2 Number 1.
Alcohol is a widely used drug, tolerated physiologically and socially, with a place in religion and in everyday social transactions, but also a drug that contributes extensively to illness and to mortality. However, an abundance of recent literature has suggested that alcohol may have a protective effect in man, especially with hepatic regeneration and cardioprotection.
Effects of alcohol on the liver
Hepatic changes resulting from the regular alcohol ingestion are many and include benign fat infiltration, alcoholic hepatitis, an increased prevalence of concomitant infection with hepatitis C virus, cirrhosis and hepatocellular carcinoma. Only approximately 10% of chronic alcoholics develop liver disease (1,2,3,4,5,6,7,8).
Progression to cirrhosis is correlated with severity of fatty liver and particularly with the presence of alcoholic hepatitis. Mortality from cirrhosis is strongly correlated with alcohol consumption. Becker
However, the graphical display of this study has been repeated by a number of other studies, so is widely accepted by many. The interpretation of the “J-shaped curve” (16,24), which some say is “U-shaped” (17, 18,20), relating alcohol intake to mortality, is that the lowest point on the curve (light/moderate drinking) represents optimum exposure to alcohol and the increased risk in non-drinkers reflects the consequence of sub-optimal exposure. Reduction in alcohol intake or giving up drinking is associated with higher rates of cardiovascular and non-cardiovascular disease (16).
Current hypothesis on mechanisms of alcoholic liver disease relate largely to the effects of ethanol metabolism generating acetaldehyde and free radicals, which bind to proteins thus altering function and also initiating an immune response (7,8). Oxygen derived free radicals can also damage hepatocytes directly, by initiating peroxidation of membrane lipids, and indirectly by stimulating transcription of pro-inflammatory cytokines. One might expect that these postulated mechanisms would increase in intensity with increasing alcohol doses. Day (8) feels the threshold effect reflects that, below a certain level of intake, the body's intrinsic defences can cope with the insult. Above this threshold, the balance between disease mechanisms and these defence systems favour the development of tissue damage.
A number of studies conducted on rats have revealed a positive role for alcohol with respects to hepatic regeneration. Zhang
In agreement, Gong
On the other hand, Minuk
Effects of alcohol on the cardiovascular system
Pathological textbooks agree, as do many studies including Kajander
Moderate alcohol regularly with food (not in binges) may be the key to the “French paradox”. The French have a lipid profile similar to their neighbours, and eat more dietary fat, but their death rate from coronary heart disease is a third that of their neighbours. Alcohol inhibits platelet aggregation: one of the reasons why it's one of the best cardioprotective agents known, nevertheless this benefit accrues only to patients with low-density lipoprotein levels >5.25mmol/l, which is deemed cardiogenic.
Another important consideration is that the non-drinker group included more people with a lower vegetable intake and a larger percentage were obese due to being educated less about healthy lifestyles. Clearly, drinking or not drinking alcohol was not the only way these groups differed from each other, so alcohol may not be the sole agent for the difference in mortality between groups. Researchers have also noted that participants in studies that are heavy drinkers are often older, smoke more, and are more likely to suffer from hypertension (13).
In agreement with Thun
They also found women had a reduced risk of a major coronary event in the 24 hours after consuming 1-2 alcoholic drinks compared with regular drinkers who consumed no alcohol in the period, in agreement with Garg
On the other hand Friedman and Klatsky (14), noted that regular consumption of alcohol at high levels is undesirable and they argued that low-moderate drinking might reduce or increase the risk of disease depending on individual characteristics. This belief was based on the fact that drinkers and non-drinkers may not arise from the same population, and that a great deal of alcohol consumption remains underreported by participants during experimental studies.
Most research focuses on how much alcohol is considered protective, and how much is harmful. However, another important question is whether some types of alcohol provide more benefit than others.
Recently there has been an abundance of literature on the subject of antioxidants present in red wine, which might be more protective than alcohol itself in preventing heart disease.
Flavanoids (including phenolic acids and polyphenols), present in red wine (and in fruit and vegetables), act as antioxidants to prevent the oxidation of low-density lipoprotein, which normally facilitates fatty plaque formation in arteries (13, 22).
This effect has been demonstrated by a Brazilian team (13), who conducted a study in which rabbits were given red wine, red wine without alcohol, or no wine at all. After three months the rabbit's aorta was examined for fatty plaques. Rabbits given no wine at all displayed 60% stenosis; this declined to 50% in rabbits fed non-alcoholic red wine and was 40% in the rabbits given red wine.
Not all researchers share this view, including Rimm
Bearing in mind that alcohol consumption is inversely related to heart disease, Hemstrom (29) conducted a large-scale study in 14 EU countries and Norway. He discovered that the alleged cardioprotective effect of alcohol is absent at the population level, so great caution should be taken concerning alcohol policies for cardioprotective purposes.
Outside the alcohol industry, there are no voices calling for an increase in consumption. Nonetheless, embedded in the advice that we can derive from the limited reduction in risk of some diseases (but not all) and in overall mortality in some groups is the concept of drinking alcohol is good for us, rather than drinking more than one or two drinks a day is bad. If you are not a drinker, don't start to prevent or treat heart disease, as alcohol is not a medication. However, one must note from the well-known Framingham study (31), that even moderate drinking, which seems to be cardioprotective, causes a number of deaths from cirrhosis, cancers of the mouth, throat and liver and especially due to trauma.
For those at high risk of cardiovascular disease, is alcohol the preventative therapy of choice, or would an appropriate regime of exercise and diet be at least as efficacious in lowering mortality? On balance, alcohol consumption exceeding this modest allowance is probably responsible for more harm than good. The adverse physical and social effects of alcohol should prevent consumption being recommended as a health measure.
Plato, quoting from the inscription in the temple at Delphi, suggested “nothing in excess is good for you”, this is obviously a good starting point for health advice with respects to alcohol consumption, even 2400 years later.