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jeudi, 20 septembre 2012

ALCOHOL, WINE... AND HEALTH PART III

IS THERE A SAFE (MINIMUM RISK) CONSUMPTION OF ALCOHOL ?


Claude Gilois

RECOMMENDATIONS OF THE PUBLIC HEALTH INSITUTES ON ALCOHOL CONSUMPTION

Recommendations on drinking levels considered safe or “minimum risk”  depending on your view point  exist in many countries globally.  Official  guidelines  on  alcohol  consumption  are  usually  produced  by  a  government  department, public  health  bodies,  medical  associations  or  non-governmental  organisations  such  as  the World  Health Organisation (WHO). They  do  not  apply  to  those  under  the legal drinking age or to pregnant women.  

 

There is no consensus internationally on what constitute a single standard drink size. Official “drinks” or “units” generally contain between 8 and 14 grams of pure ethanol. For the purpose of this study we will define a unit as the consumption of 10 cl of wine ( 10 g of alcohol) at 12.5 0 which is equivalent to 25 cl of beer   at 5 0 or  3 cl of whisky at 40 0,  or a glass of Pastis at 45 0 diluted in 3 volumes of water.

 

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Over twenty years ago,  World Health Organisation established the guidelines on alcohol consumption to 21 units for men and 14 units maximum for women per week (women, as we have seen in the previous article  have a weaker expression, of one the enzymes that detoxify alcohol[i]). At that time A large number of prospective studies had already observed an inverse relationship between a moderate intake of alcohol and coronary heart disease morbidity and mortality. The WHO set its recommendation so on the basis on  the publication of the largest study ever undertaken on alcohol consumption by the American Cancer Institute[ii] which followed 276,000 people over 12 years The results are  summarised graphically by  Professor Serge Renault [iii]

AlcoholConsumption.JPG

 

The J curves indicate that the effect observed depends on the dose. For a daily consumption of up to 36 grams (3.6 units of alcohol), the mortality, all causes included was inferior or equal to that of the non-drinkers. 3.6 grams of alcohol by our definition of a unit is half a bottle a day. This study was corroborated by that of Gronbaek et al en 1995 (iv) (also a large study) which concluded that the drinker’s mortality was significantly lower than of those who did not drink. However no consensus emerged and there were studies on smaller cohorts that indicated that there were no protection (v). Could the difference be explained by the size of the cohort or could  it be the type   of alcohol consumed that was the explanation between the differences obtained by the various studies ?

ARE ALL ALCOHOLIC BERERAGES THE SAME FOR THE HUMAN BODY?

In 1994 Sir Richard Doll et al.(vi), also in Great Britain, in their study on British physicians, reported that a moderate intake of alcohol (21 units/week) reduced by more than 20 % the mortality from all causes, in addition to the usual protective effect on cardio-vascular mortality. In USA, a prospective study on 22 701 men, also physicians, reported that the consumption of 2 to 6 drinks of alcohol per week lowered mortality from all causes by 21 to 28 % (vii). As physician tend to be wine drinkers this arose the suspicion that wine may have a better protective effect than any other alcoholic drinks. 

The first study to suggest this  was that of  Klatsky et al in 1992 [viii)] based  on 128 900 subjects followed for seven years which shows that wine offered a protection of some 30-40%  superior than that of spirit drinks.This was confirmed by the study of of Gronbaek mentionned above. In this study, for 3 to 5 drinks per day cardiovascular mortality was reduced by 47 % in the wine drinkers, but the other causes were also 50 % lower. An important issue was that the other causes were not reduced in the drinkers of beer and spirits.

Finally  prospective studies carried out  in France (ix) on 35 000 middle-aged men, concluded that only wine at moderate intake, was associated with a protective effect on all-cause mortality. In addition to the well known effect on cardiovascular diseases, a very moderate intake of wine, protected also from cancer and other causes. The superiority of wine over any other type of alcoholic drinks seems to emerge. It is worth pointing out that these studies have the same methodological weaknesses that most of the epidemiological studies have as the index that expresses the strength of the relationship  is very unlikely to be above 3 which is considered the minimum to be sure that a cause-effect relationship does exist. This is why more scientists prefer to express their results in terms of percentages as it as a greater impact on readers.  But,   after all, it is hardly surprising that wine should be superior to any other drinks as wine  contains high level of anti-oxdants, polyphenols and especially phenolic acids and perhaps more importantly flavonoids (x), that possess highly anti-oxydative properties, in particular a substance known as resveratrol appear to play a critical role.This substance is a good candidate to explain the French paradox which is the expression used to coin the observation that the region of the south west of France, which has a high consumption of saturated fat, has a much lower incidence of heart diseases compared to northern Europe countries(xi) (xii). The role of antioxydants is to mop up free radicals. Free radicals are harmful substances that can originate endogenously (inside the body) from normal metabolic reactions or exogenously (outside the body) as components of tobacco smoke, air pollutants and indirectly through the metabolism of certain solvent drugs, pesticide as well as through exposure to radiation. There is some evidence that free radicals contribute to the etiology (origin) of many chronic health problems such as emphysema, cardiovascular and inflammatory diseases, cataracts and cancer. 

CONCLUSION:

There has been no major studies since the American Cancer Institute to challenge the conclusion of their publication. Other studies have confirmed the finding of the American Institute. All studies that cast doubts on the finding of these researches   were done on smaller samples of population, hence they carry probably  less validity. There is a number of publications that point towards wine as the best alcoholic beverage  to confer some protection when consumed in moderation. On the basis of these findings the WHO recommendation of 21 units a week  for a man and 14 for a woman are still the best available advice to-day. Beyond this, the risk increases with  the quantity consummed as indicated on the graph above.

Why, then, are the Public Health Institutes from several countries advising a marked reduction in the consumption or even a total abstinence of alcohol on the basis of health. This is what we will try to answer in the last article of the series.

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(i)  Frezza, M.; Di Padova, C.; Pozzato, G.; Terpin, M.; Baroana, E.; & Lieber. C.S. High blood alcohol levels in women: The role of decreased gastric alcohol dehydrogenase activity and first-pass metabolism. The New England Journal of Medicine 322(2): 95-99, 1990

(ii) Bofeta P ET Garfinkel L. Alcohol drinking and mortality among men enrolled in an American Cancer Society prospective study. 1990. Epidemiol. 1.342-348.

(iii) Renaud Serge Pr. Le régime crétois.2004. Edition Odile Jacob. ISBN :2-7381-1471-7

(iv) ]Gronbaek M, Deis A, Sorensen TIA, Becker U, Schnohr P, Jensen G. Mortality associated with moderate intakes of wine, beer, or spirits. Br Med J 1995;310:1165-1169.  

(v) LEINO EV, ROMELSJO A, SHOEMAKER C, AGER CR, ALLEBECK P, FERRER HP, FILLMORE KM,

GOLDING JM, GRAVES KL, KNIEP S. (1998) Alcohol consumption and mortality. II. Studies of male populations. Addiction 93:205-218. 

(vi) DOLL R, PETO R, HALL E, WHEATLEY K, GRAY R (1994) Mortality in relation to consumption of  alcohol: 13 years’ observations on male British doctors. BMJ 309:911-918.  

[vii] CAMARGO CA JR, HENNEKENS CH, GAZIANO JM, GLYNN RJ, MANSON JE, STAMPFER MJ. (1997) Prospective study of moderate alcohol consumption and mortality in US male physicians. Arch Intern Med 157:79-85.  

(vii) Klatsky A.L., Armstrong  MA et Friedman DG., Alcohols and mortality. Ann. Inter. Med.117,1992, p 646-654. 

[ix)   SERGE RENAUD , DOMINIQUE LANZMANN-PETITHORY , RENÉ GUEGUEN  and PASCALE CONARD.  Alcohol and Mortality from All Causes. Biol Res 37: 183-187, 2004.

(x) COOK NC, SAMMAN S. Flavonoids - Chemistry, metabolism, cardioprotective effects, and dietary sources. J Nutr Biochem 1996;66-76S).

(XI) REANUD, DE LONGERIL ' Wine, alochol,  platelets, and the French paradox for coronary heart diseases. Lancet, vol 339, No 8808, p1523-6. vol 341. no 8852, 1993 p 1103-4.

(xi) RENAUD, MICHEL DE LONGERIL 'Wine, alcohol, platelets and the French paradox for coronary heart diseases'. Lancet. Vol 339. No 8808.

(xii) E.N. FRANKEL, A.L. WATERHOUSE & J.E. KINSELLA, 'Inhibition of human LDH oxidation by reseratrol'. Lancet, vol 341, no 8852, 1993, p 1103-4.

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