Good hydrations: Is there a safe level of alcohol?

Shared from the New Scientist

Good hydrations: Is there a safe level of alcohol?

For many of us it’s an essential social and creative lubricant – yet it’s undoubtedly a killer. Here’s how to get the good stuff while limiting the bad

glass of wine

Nick Purser/Getty

WE RAISE a glass to celebrate, sip wine to unwind, knock back a few beers while catching up with friends. Alcohol plays a central role in socialising in many cultures, especially at this time of year. In December, consumption is 41 per cent higher in the UK than during the other months.

Yet the warm glow of a holiday tipple may be tempered by a growing awareness of alcohol’s harms. Drinking can increase your risk of cancer, stroke and liver disease. It exacerbates the harms of smoking, can undermine your immune system, impair your judgement and make you more likely to have risky sex, injure yourself or hurt someone else. Each year, alcohol-related crime costs the UK a whopping £11 billion, and the country’s National Health Service spends £3.5 billion treating alcohol-related medical issues. That’s not to mention the £7.3 billion hangover in lost workdays.

So far, so clear. Booze is bad. But what about the steady trickle of findings that suggest, in moderate amounts, it may have some benefits? There is the seductive story of red wine staving off dementia, and the finding that regular drinking decreases your risk of heart disease and premature death. Do these stories stand up? In other words, can we really raise a glass to our health?

First, let’s face the facts. According to the World Health Organization, 3.3 million deaths worldwide are attributable to alcohol each year. The WHO classifies alcohol as a group 1 carcinogen, alongside asbestos and plutonium. That’s because regularly drinking three units a day – a premium pint of lager or large glass of wine – can cause seven types of cancer, including those of the mouth, breast and bowel, as well as increasing your risk of liver disease. Across the different types of cancer, that risk tends to rise with each additional daily drink.

A major part of the problem comes from a chemical called acetaldehyde, which is produced as our body breaks down alcohol. Acetaldehyde damages DNA and prevents our cells from repairing this damage, leading to cancer. And while our liver is a fairly hardy organ, its superb ability to replace damaged cells while healthy is limited by chronic alcohol consumption. Too much booze can also produce a build up of fatty acids in the liver, which eventually results in liver disease.

So how much is too much? Public health officials hedge by saying that there is no “safe” level of drinking, and some studies indicate even one drink a day can increase the risk of cancer. The UK government recently updated its guidance, recommending no more than 14 units a week – the equivalent of six pints of beer – spread evenly over three days or more. This was based on findings that showed the risk for injury and disease significantly increases above that level. Pregnant women are advised to avoid alcohol completely.

Weekly guidelines

It didn’t go down well. Even though alcohol consumption and binge drinking have been declining (see “Generation clean: why many young adults choose to stay sober”) in recent years (see “Down in one”), people were up in arms that their suggested weekly limits were being cut again. Over the past 40 years, the upper limit in UK guidelines has fallen sharply: in 1979, it was 56 units a week – about 24 pints or 23 glasses of wine. “These limits are about a vague national self-image of puritanism, not health,” declared Simon Jenkins in The Guardian.

Glass half-full

It didn’t help that in other countries the guidelines for low-risk drinking are, for the most part, more lenient than those of the UK. They are also very different, even down to what constitutes a unit of alcohol or “standard drink” (see “Weekly guidelines”). In Austria, one drink can have up to 20 grams of alcohol in it. In the UK, it’s just 8 grams. Guidelines also vary in whether they are daily or weekly limits. And some countries, like Canada, make allowances for an extra drink on special occasions. This lack of agreement merely shows how difficult it is to pinpoint a safe level.

What’s more, many countries have different guidelines for men and women. In the UK, the new limits apply to everyone. That’s because even if the route to harm is different, when you look at the health hazards for each sex the statistics start balancing out, says Petra Meier at the University of Sheffield, UK, one of the researchers whose work informed the new guidelines. Alcohol does affect men and women differently – women have a higher blood alcohol concentration than men after drinking the same amount, but metabolise it more quickly and may sober up sooner. Women are also at higher risk for some alcohol-related cancers. But men are more frequent binge drinkers and tend to engage in more risky behaviour when drinking. “Accounting for all the outcomes, it’s so similar that there isn’t a good base for saying men can drink more,” says Meier.

men and women in pub
The recommended UK alcohol consumption limit is now the same for men and women

Philip Jones Griffiths/Magnum Photos

One thing national guidelines can’t do is take into account how risk varies between individuals. Lots of things determine how bad alcohol is for each of us, from social circumstances to mental health issues. Even our genes may play a part: studies in mice show associations between particular genes and propensity to drink alcohol. “Knock out that gene in animals and they become heavy drinkers,” says Klaus Miczek at Tufts University in Medford, Massachusetts. In humans, several studies have shown that certain variations of genes – specifically those that drive cycles of sleep and wake – can cause a person to have a higher risk of alcoholism.

“There are other things that the guidelines can’t address – how drinking a certain amount of units affects someone’s family, or their risk of criminal activity, or their risk to other people,” says Meier. It would be difficult to come up with recommendations around those things that were applicable to everyone.”

Guidelines are designed to get people drinking less. And that can have tremendous benefits. In the Soviet Union in 1985, life expectancy at birth increased by two years in a single calendar year – largely because of a reduction in deaths from cardiovascular disease. This leap was attributed to a campaign by communist party leader Mikhail Gorbachev to lower alcohol consumption.

Pass the bottle

But when researchers compared intake and health with that of other countries, they were befuddled. At the time, the Soviet Union had high levels of heart disease and the highest consumption of alcohol in any OECD country. But France, the country with the second highest consumption, had surprisingly low levels of cardiovascular disease. The finding didn’t square with studies showing diminishing heart health with increasing alcohol consumption either. Researchers were bemused – they called it the “French paradox”.

Part of the reason for the disparity was how they looked at drinking, considering only the total consumed in a week, without looking at when people drank. The French were more likely to consume alcohol as wine with meals, whereas the Soviets drank more spirits and binged at the weekends. Then these differences were taken into account, it revealed that bingeing was significantly detrimental to cardiovascular health.

The French paradox also led people to look into whether drinking alcohol has any beneficial effects. There are now more than 100 studies that show a link between having just one or two drinks a day and a decreased risk of heart attack, stroke and sudden cardiac death. Some also suggest that small amounts of alcohol can decrease your risk of gallstones and type 2 diabetes. The key here is moderation. A meta-analysis of 15 studies that followed more than 300,000 people for 12 years found none of these benefits for those who consumed more than four drinks a day.

These potential benefits make sense biologically. Moderate drinking seems to boost the amount of high-density lipoproteins (HDL) in our blood. These cruise around getting rid of low-density lipoproteins, which tend to promote the formation of fatty deposits in our arteries, so high levels of HDL may reduce the risk of heart disease.

One study in monkeys supports this idea: six months of regular moderate intake of alcohol was associated with improved levels of HDL, and this wasn’t seen in animals given alcohol in binges or no alcohol at all. In humans, providing solid evidence of a link between regular drinking and heart health has been more difficult. To run a controlled trial you would have to ask people to drink a certain amount every day for many years, something that is impractical if not unethical. So instead, researchers look for trends in people’s drinking habits and health markers over time. Shue Huang at Pennsylvania State University and her colleagues recently analysed alcohol intake and cholesterol levels of more than 80,000 Chinese adults over six years. Those who drank moderately – one drink per day for women and two for men – maintained higher levels of HDL over time than those who abstained or drank more heavily.

Unfortunately, Huang’s study is subject to the same pitfalls as other observational studies. People who drink in moderation also tend to exercise regularly, have a healthy weight and get a decent amount of sleep, all reasons they may have better heart health. Additionally, many studies don’t differentiate between never-drinkers and those who have given up drinking. The health issues of people who have quit may undermine data on non-drinkers, and serve to exaggerate the benefits seen in others.

Another pitfall is that when people are reporting how much they drink, they underestimate both how much alcohol is in their beverages, and how many they have across a week. Self-reported consumption is well below the level calculated from alcohol sales data and may be off by as much as 40 per cent, according to the UK Department of Health. That amounts to one additional large glass of wine each day. This all make it very difficult to tease out which benefits are actually down to alcohol consumption.

Everything in moderation

When studies have tried to control variables including level of physical activity, number of friends and socio-economic status, they have reached different conclusions. After factoring in demographics, lifestyle, family background and health history, Michael French at the University of Miami, Florida, found that there were protective effects of moderate alcohol consumption, particularly among women. Yet he says there are many factors that are harder to take into account. “It could be that those who drink moderately live a moderate lifestyle,” he says. “Maybe they’re moderate in their work-family balance, for instance. Perhaps it’s that which helps their heart. If that’s the case, it is merely an indicator of living a balanced life.”

One consistent finding is that the benefit is more pronounced in older people, says Annie Britton, an epidemiologist at University College London. “They have a higher risk of heart disease so it may be that the alcohol has more to work with, which is why you see more of an effect.”

But there is no consensus that a certain amount of alcohol is good for your heart. “There are people who are passionate that there are health benefits, and there are others who are equally passionate that it is all down to errors in the data,” says Britton.

What about tales that red wine might prevent cognitive decline? It is packed with resveratrol, a chemical thought to protect against the effects of stress and a poor diet by activating a group of enzymes that affect gene expression. It has also been linked to a reduction in age-related conditions such as arthritis, macular degeneration and dementia, but many of these studies have been in animals.

Last year, though, Scott Turner at Georgetown University Medical Center in Washington DC put it to the test in humans. His team gave 119 people with mild to moderate symptoms of Alzheimer’s disease either a resveratrol pill or a placebo twice a day for a year. Over time, the placebo group’s Alzheimer’s symptoms worsened, and there were changes in their blood biomarkers. Those taking resveratrol had fewer symptoms and showed little or no change in the blood biomarkers. One small catch: to consume the same amount of resveratrol, you would have to glug about 1000 bottles of red wine a day.

The story is similarly underwhelming when it comes to claims that champagne may help stave off dementia. Spatial memory is one of the first things to be affected by Alzheimer’s disease, so it is no surprise that a study suggesting that this type of memory can be improved by phenolic acids in champagne made viral headlines. Unfortunately, that was only found that to be true in rats. Far more research has to be done before the same can be said for humans.

If it seems like none of the reported benefits stand up, there is at least evidence for one straightforward perk we have all heard: a small tipple makes it easier to solve problems that require creative solutions. Andrew Jarosz, now at Mississippi State University, Starkville, and his colleagues had 40 men do a battery of memory tests, then grouped them into pairs with roughly the same working memory capacity. They asked one of each pair to drink a vodka and cranberry, then had both try to solve a series of word problems. Those who drank were better at solving problems that required thinking outside of the box.

Running it off

The theory is that alcohol reduces your working memory capacity, in other words, your ability to focus on one thing while blocking out peripheral information. By lowering these walls, your mind can wander, making novel connections that would otherwise be overlooked.

The evidence may be thin that the odd drink can be a boon, but you might at least be able to counteract its damage. One way is exercise. A recent look at data from 36,370 men and women aged 40 years and over showed that in people who did little to no exercise, there was a direct relationship between alcohol intake and cancer risk. But in those who drank moderately and did at least 7.5 hours of activity a week – from walking or gardening to more rigorous exercise – the risk of death from cancer or heart disease was decreased (see “Running it off”).

runners drinking
Exercise seems to help you negate the effects of your beers

Chris Sembrot

A break from booze might also help. In work in press, Gautam Mehta and his colleagues at University College London studied 100 people who took part in “Dry January” – a campaign by UK charity Alcohol Concern that encourages people to give up alcohol for a month. Mehta’s team analysed the participants before and after their abstinence and found that it reduced their blood pressure, weight and markers of insulin resistance, a key factor in diabetes. When a small group of New Scientist employees teamed up with Rajiv Jalan at University College London Medical School to test a similar period of abstinence, they found hints that liver fat – which can prelude liver damage – might also fall when you stop drinking.

“Any time off alcohol can only be a good thing,” says Mehta. “But in terms of how much you need to completely reset the body, it’s impossible to say.”

While it’s clear that there’s no “safe” amount to drink, a small tipple could nevertheless get your creativity going and might – just might – benefit your heart in old age. If you don’t exceed recommended limits, avoid bingeing and try to exercise for at least an hour a day, you should keep your long-term hangover to a minimum. Cheers!


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