One alcoholic drink is about 15 g of alcohol, such as in one pint of beer, a glass of wine or a measure of spirits.
The researchers used data from questionnaires regularly completed by female nurses taking part in the US Nurses' Health Study, which started in 1976. The questionnaires include questions about food and drink and the answers were sufficiently detailed and frequent to enable Sun and colleagues to assess alcohol consumption of the nurses during middle age (at average age 58 years).
These records also included health status data and allowed the researchers to look for diseases into old age. The researchers used an expression "successful aging" to describe those nurses who lived to the age of 70 and over, were free of 11 major chronic diseases (such as diabetes, cancer, heart disease), and had no signs of cognitive impairment, physical impairment, or mental health limitations. 10.7% (1,491) of the eligible participants attained successful aging.
The researchers excluded heavy drinkers (women who drank 45 g of alcohol a day or more; less than 2% of the participants) from their analysis.
The results showed that:
- After adjusting for the effect of potential health influences, such as smoking, light-to-moderate alcohol consumption in midlife was linked to a modestly increased odds of successful aging.
- Compared to non-drinkers, the odds ratios (and 95% confidence intervals) were 1.11 (09.6-1.29) for those who drank 5.0 g or less per day, 1.19 (1.01-1.40) for those who drank between 5.1 and 15.0 g per day, 1.28 (1.03-1.58) for 1.5-30.0 g per day, and 1.24 (0.87-1.76) for 30.1-45.0 g per day.
- Spreading out drinking over the week rather than consuming at one or two sittings also appeared to give better odds of successful aging.
- For example, compared with non-drinkers, the odds ratio (and 95% confidence intervals) of successful aging was 1.29 (1.01 -1.64) for those drinking on 3 or 4 days of the week, and an even more favourable 1.47 (1.14-1.90) for those who spread their drinking over 5 to 7 days per week. For those drinking on 1 or 2 days per week the odds ratio was only 1.10 (0.94-1.30).
"... 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."
They noted that the 2010 US Department of Agriculture guidelines say moderate alcohol consumption of up to one drink per day for women and two for men may give health benefits to some people.
These findings seem to support these guidelines and appear to give new evidence to support the idea that regular, light-to-moderate consumption of alcohol, up to just less than two drinks per day, may be linked to a modest increase in overall health among American women who survive to older ages.
However, we should note that this study does not prove cause and effect: it does not show that it is drinking the alcohol that leads to the benefits, only that there is a link. The researchers did not examine what might be causing this link and therefore do not rule out the possibility that it is simply a coincidental feature of the lifestyle of women who do other things to stay healthy, although they did rule out smoking status as a possible reason.