How much alcohol is a healthy dose for women?

A study just published in PloS Medicine (Public Library of Science) offers more evidence that alcohol consumed in moderation can promote overall health and successful aging for women. The data presented also helps to firm up guidelines for determining amounts that are beneficial and harmful. The authors state:

"Observational studies have documented inverse associations between moderate alcohol consumption and risk of premature death. It is largely unknown whether moderate alcohol intake is also associated with overall health and well-being among populations who have survived to older age. In this study, we prospectively examined alcohol use assessed at midlife in relation to successful ageing in a cohort of US women."

They defined “successful ageing” as being free of 11 major chronic diseases and having no major cognitive impairment, physical impairment, or mental health limitations, and applied this to the 13,894 Nurses' Health Study participants who survived to age 70 or older for whom they had comprehensive and continuously updated health data. This was correlated with habits of alcohol consumption. Their data paints an interesting picture:

"...light-to-moderate alcohol consumption at midlife was associated with modestly increased odds of successful ageing. The odds ratios were 1.0 (referent) for nondrinkers, 1.11 for ≤5.0 g/d, 1.19 for 5.1–15.0 g/d, 1.28 for 15.1–30.0 g/d, and 1.24 for 30.1–45.0 g/d. Meanwhile, independent of total alcohol intake, participants who drank alcohol at regular patterns throughout the week, rather than on a single occasion, had somewhat better odds of successful ageing; for example, the odds ratios were 1.29 and 1.47 for those drinking 3–4 days and 5–7 days per week in comparison with nondrinkers, respectively, whereas the odds ratio was 1.10 for those drinking only 1–2 days per week."

In other words, consuming 30 to 45 grams of alcohol per day conferred a 24% increase in the odds for successful aging. Moreover, drinking 5-7 days per week increased the odds of a good outcome by 47%. The authors conclude:

"These data suggest that regular, moderate consumption of alcohol at midlife may be related to a modest increase in overall health status among women who survive to older ages."

So how much is 30 to 45 grams of alcohol? A 'standard drink' = 10 grams of pure alcohol. A 750 ml (regular size) bottle of red wine with a typical 14% alcohol volume equals approximately 8.3 standard drinks (82.8 grams of pure alcohol). A 30 ml (one ounce) shot of 80 proof (40% alcohol volume) is 9.4 grams of pure alcohol (just shy of one standard drink). An ounce of stronger spirits like 94 proof gin or vodka is 11.12 grams of pure alcohol.