Giving up alcohol for a month really does have a dramatic effect on health, lowering blood pressure, cholesterol, and diabetes risk. The first ever extensive study of the health benefits of abstemious periods like “Dry January” also discovered that alcohol is linked to cancer-related proteins in the blood, and taking time off from drinking can drastically reduce their levels. The finding could help explain why alcohol is linked to at least seven types of cancer.
The study involved 141 moderate-to-heavy drinkers, who on average drank more than double the UK recommended limit, consuming around 30 units a week – about 3 bottles of wine, or more than 14 pints of beer. Of these people, 94 completely gave up drinking for a month, while the remainder continued to drink as usual. A team at the Royal Free Hospital in London then analysed blood samples taken at the start and end of the month from each of the participants.
While the people who continued drinking showed no particular changes over the course of the month, big improvements were seen in the abstainers, confirming those reported in an earlier, smaller study of 14 żěè¶ĚĘÓƵ staff in 2013.
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Widespread benefits
Most striking was the non-drinkers’ drop in insulin resistance. When insulin becomes less effective at making the body remove sugar from the bloodstream, a person risks developing type 2 diabetes. But after a month of abstaining from alcohol, participants saw their insulin resistance decrease by an average of 26 per cent.
“Our data suggest that alcohol use above recommended guidance markedly increases the risk of type 2 diabetes,” says Gautam Mehta, of University College London.
As well as improvements in liver health, the abstainers also saw an average 13 per cent decline in cholesterol levels, a 6 per cent drop in blood pressure, and a 1.5 per cent decline in weight. “Over one month, that’s as much as you could hope to lose if you were dieting,” says Mehta.
Surprisingly, the team also found a dramatic drop in the levels of two growth factors linked to cancer. One, vascular endothelial growth factor, helps tumours spread and grow by building networks of supporting blood vessels. After a month of not drinking, blood levels of this growth factor fell by 41 per cent.
Epidermal growth factor is known to promote the growth and spread of cancers by encouraging cells to multiply and proliferate. But after a month without alcohol, the levels of this factor fell by an average of 74 per cent.
“The reductions were very striking,” says Mehta. “They fell in almost every abstaining participant,” he says.
Cancer progression
The findings suggest that alcohol might play a role in pushing small tumours to progress into more serious cancer, says Mehta. In mouse studies, these two growth factors have been implicated in the link between alcohol and gastrointestinal and female breast cancers in particular.
“They are only correlations at this stage, but deserve further investigation,” says of the MRC Laboratory of Molecular Biology in Cambridge, UK. “The evidence is overwhelming that drinking leads to cancer,” he says. “The question is by what mechanism.”
Although the study included a comparison group that continued to drink, it’s difficult to do alcohol experiments where the participants don’t know if they are in the control group or not. In theory, the people in the non-alcohol group may have unknowingly felt encouraged by their own abstinence to pursue other healthy lifestyle changes during the study. However, Mehta says that the team did not see any changes in the participants’ reported lifestyles, diets and exercise regimes during the study.
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Despite the observed benefits of a month’s abstinence, Mehta warns that people shouldn’t assume that their body and liver are fully “detoxed” and ready for further bouts of excessive drinking after doing Dry January. The findings are very positive, but we don’t know how long they last, he says.
However, the act of abstaining for a period seems to also have a beneficial effect on a person’s drinking habits. When the team contacted their abstainers around 7 months later, they found that, on average, they were now drinking 20 per cent less alcohol than they used to.
“It shows if you have a month off, it can reset your relationship with alcohol long term,” says of the University of Southampton, UK.
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Read more: The weekly alcohol limit still carries a risk of early death
