A surprising chart was posted by Razib Khan. In the General Social Survey, the higher Americans score on a vocabulary test, the more likely they are to drink alcohol:

Of course we know that correlation is not causality, so one should not immediately infer that reading drives one to drink, or that drinking improves memory (perhaps because, as the old joke argues, alcohol kills weaker brain cells, increasing the average quality of the brain).

It does, however, raise a serious question:  Is it smart to drink?

Epidemiology Recommends Moderate Drinking

Most people have read of the studies that show that moderate drinkers – who drink, say, a glass of wine or two with dinner – tend to have the best health, while teetotalers and alcoholics have the worst.

A recent prospective cohort study confirms this pattern and shows it to be surprisingly strong.

The study followed 1,824 adults, initially between ages 55 and 65, for 20 years.  Their conclusion: “even after adjusting for all covariates, abstainers and heavy drinkers continued to show increased mortality risks of 51 and 45%, respectively, compared to moderate drinkers.” [1]

This is a pretty large effect. Without their adjustments, heavy drinkers had a 70% higher mortality rate, abstainers 23% higher. Still large, although not so bad for abstainers. If the choice is alcoholism or abstention, go with abstention.

What About the Biology?

Epidemiological studies often mislead due to confounding factors.  It would be nice to learn from biology that alcohol is safe.

A primary safety concern with alcohol is its effect on the liver. Alcohol consumption can produce fatty liver disease and, eventually, a scarred and damaged liver (cirrhosis).

Interestingly, in animal studies the harmful effects of alcohol on the liver occur only when it is combined with polyunsaturated fats:

• Researchers induced liver disease by feeding mice a combination of alcohol and omega-3-rich fish oil.  They then stopped the alcohol and split the mice into two groups, one fed fish oil plus glucose, the other palm oil plus glucose. (Palm oil consists predominantly of saturated fat, and is less than 10% polyunsaturated.) Livers of the fish oil group failed to recover, but the palm oil group “showed near normalization.” The researchers hailed saturated fat as “a novel treatment for liver disease.” [2]
• Mice fed 27.5% of calories as alcohol developed severe liver disease and metabolic syndrome when given a corn oil diet, but no disease at all when given a cocoa butter diet. (Corn oil is 55% polyunsaturated, cocoa butter is predominantly saturated fat and is less than 3% polyunsaturated.) The first line of this paper begins, “The protective effect of dietary saturated fatty acids against the development of alcoholic liver disease has long been known.” [3]
• Scientists induced liver disease in mice by feeding alcohol plus corn oil.  They then substituted a saturated-fat rich mix based on beef tallow and coconut oil for 20%, 45%, and 67% of the corn oil. The more saturated fat, the healthier the liver. [4]

This makes biological sense. Alcohol is metabolized in the liver just like fructose, a toxic sugar. Polyunsaturated fats are chemically fragile and quick to react with sugars; saturated fat, which lacks fragile carbon double bonds, does not.

It seems that if you keep your liver clear of polyunsaturated fats, the alcohol will be disposed of safely.

What Does This Mean on the Perfect Health Diet?

Our diet is very low in polyunsaturated fats:  We eat as few omega-6 fats as possible, and purposely include only 1 lb of oily marine fish per week in order to get long omega-3 fats.

Thus, two dinners per week may have omega-3 fats, other meals will be largely polyunsaturated fat free.

Mice on a saturated fat (cocoa butter) diet can get 27.5% of calories as alcohol with no liver damage. In humans, that would correspond to a daily 350 ml (12 fluid ounce) bottle of 80-proof gin, rum, or vodka, or a liter (36 fluid ounces, 1.3 bottles) of red wine.

We don’t recommend such alcohol intakes! That said, it does seem to confirm that there is little risk in moderate alcohol consumption, if the rest of the diet is sound.

For Perfect Health Dieters, perhaps on salmon days alcohol should be limited to a single glass of wine. In general, however, moderate drinking should hold no concern.

Oh, and for you alcoholics, a little friendly advice: If you value your liver, remove polyunsaturated fats from your diet. The safest foods? Red meats and seafood; starches (rice, sweet potatoes, potatoes); vegetables; butter/cream and coconut oil.

References

[1] Holahan CJ et al. Late-Life Alcohol Consumption and 20-Year Mortality. Alcohol Clin Exp Res. 2010 Aug 24. [Epub ahead of print] http://pmid.us/20735372. Full text: http://onlinelibrary.wiley.com/doi/10.1111/j.1530-0277.2010.01286.x/pdf. (Hat tip:  Robin Hanson, http://www.overcomingbias.com/2010/09/alcohol-is-healthy.html)

[2] Nanji AA et al. Dietary saturated fatty acids: a novel treatment for alcoholic liver disease. Gastroenterology. 1995 Aug;109(2):547-54. http://pmid.us/7615205.

[3] You M et al. Role of adiponectin in the protective action of dietary saturated fat against alcoholic fatty liver in mice. Hepatology. 2005 Sep;42(3):568-77. http://pmid.us/16108051.

[4] Ronis MJ et al. Dietary saturated fat reduces alcoholic hepatotoxicity in rats by altering fatty acid metabolism and membrane composition. J Nutr. 2004 Apr;134(4):904-12. http://pmid.us/15051845.