Dr Kevin McCarroll
A look at how alcohol affects our health
One could be forgiven for not knowing what constitutes a healthy level of alcohol consumption given the disparity in national guidelines worldwide.
The recently updated recommendation by the British Department of Health earlier this year raised some eyebrows by redefining low risk consumption for males at 14 units per week. Not only is this a 33% reduction by comparison with the previous guidelines, the advised level for females remained unchanged setting a new ‘gender equality’ for healthy alcohol intake. These guidelines equate to an upper limit (for low risk intake) of about six pints of average strength beer or 1.5 bottles of wine per week.
So how did these changes come about? The new thresholds came after a review of the up-to-date evidence established since the last recommendations made over 20 years ago in 1995. In particular, more light has been shed on the association between alcohol consumption and cancer risk (which appears to happen at lower levels of intake than previously thought).
Carcinogen
Alcohol is classified as Group I carcinogen and is causally implicated in at least eight cancers (including throat, gullet, breast, colon, stomach and pancreas) in a dose dependent fashion. Put simply, the more you drink the greater the risk and indeed based on observational studies this risk is apparent even at intakes of less than 10.5 units per week. What becomes an acceptable risk as applied to alcohol intake or indeed other matters becomes somewhat arbitrary and will also depend on other factors specific to the individual. For example, other lifestyle factors like smoking when combined with alcohol produce a multiplicative negative effect.
In formulating the British guidelines, ‘low-risk’ drinking was defined as that which gives a less than a 1% chance of dying from an alcohol-related condition. To put this in perspective, the lifetime chance of dying in a car accident is about 1/400 or a fraction of this, whist the lifetime risk of mortality from cancer is about 25%. Higher levels of alcohol consumption (35 units or more a week) or associated with a 1.5 times greater likelihood of colorectal and breast cancer and 2-3 times increased risk of head and neck cancer. Whilst this may seem alarming the absolute risk of developing certain cancers like that of the head and neck in the first instance is relatively low meaning that any negative effect of slight alcohol excess is small.
In reality, long term health risks arise from regularly drinking alcohol over prolonged periods of time, typically over 10 to 20 years or more. Importantly, the risk of getting some alcohol related cancers may diminish gradually after cutting back or stopping higher levels of drinking. Whilst some level of alcohol intake has been associated with positive cardiovascular outcomes in numerous studies, the British review only identified a potential benefit in women aged 55 or over.
Standard drinks
An important contributory factor to health risk is the pattern of alcohol drinking. In general, it is best to spread weekly consumption over several days. The HSE guidelines define binge drinking as taking six or more standard drinks (equating to about three pints of beer) in a short space of time and advise not taking alcohol for at least two days of the week.
Despite the controversy regarding guidelines, numerous large observational studies have consistently shown increased risk of cancer and other negative health outcomes with alcohol consumption at levels lower than previously believed. It is crucially important, however to point out that intake marginally above even current Irish recommendations is still associated with a relatively small increase to health risk. In addition, there are many confounding factors in population studies and in practice at an individual level, genetic and other lifestyle determinants substantially modify this risk.
In this regard, guidelines apply to a typical person and cannot be used in a ‘one size fits all’ approach. Indeed, applying equal cut-offs for males and females is in part aimed at creating a more simple and clearer public health message.
In summary, the current Irish guidelines still indicate for most a ‘low risk’ level of alcohol consumption. The overall risk attributable to alcohol intake depends not just on the quantity consumed but the pattern and duration of drinking. In addition, other lifestyle and biological factors modify this risk. In those with lower body mass index, liver disease, cognitive impairment, depression or mental health problems alcohol intake should be reduced or sometimes avoided. In addition, alcohol should be restricted or avoided when taken in conjunction with certain medications like hypnotics. As always, make sure to keep a check on your alcohol intake and try and cut back where necessary!
* Dr Kevin McCarroll is a consultant physician in geriatric medicine in St James’ Hospital, Dublin.