Is There Really No Safe Amount of Alcohol?

I’m enjoying a refreshing shandy (a mix of beer and diet lemonade) as I write this, but maybe I should switch to something stronger. Like cocaine.

That’s what you might think after reading some of the recent headlines about nutrition and health. They say things come in threes and this has certainly been the case here:

1.  Alcohol ranks as the most harmful drug in NZ,  surpassing even the likes of methamphetamine, synthetic cannabinoids, and tobacco, and leaving cocaine far behind according to a study in the Journal of Psychopharmacology
2. The Heart Foundation of New Zealand (NZ) says there is ‘no safe level’ of alcohol consumption;
3. The WHO might classify aspartame, a common artificial sweetener, as a potential carcinogen.

What can we make of all of this? Rather than delving into each claim extensively, let's instead offer some food for thought when interpreting such findings.

The expert panel

Let’s start with the claim that alcohol is the most harmful drug in NZ. This was not based on a rigorous systematic review of the literature, but instead on the ranking and weighting of the harms of alcohol from a panel of experts.

 The strength of this approach is that it encompassed a diverse range of expertise, from fields such as emergency medicine, law enforcement, addiction treatment, Māori health and advocacy, Pacific health, toxicology, criminology, youth justice, harm reduction, pharmacology, clinical psychology, peer support, drug markets, and drug policy. This collaborative effort provided a broad perspective on the overall harm caused by drugs.

Falling prey to cognitive and social biases

But with expert panels subjectivity can affect the objectivity and consistency of the decision-making process. Even the authors of the study acknowledge that the expert panel is more likely to prioritise the harms associated with more common drugs or those with higher visibility. This means that they could fall prey to:

• Cognitive biases such as availability and confirmation bias.
• Group decision making is also subject to social biases.

And as for the quality of evidence — expert opinion ranked low, along with personal anecdotes.

The Heart Foundation’s advice that the only safe amount of alcohol is none at all, is interesting. We don’t want to downplay the harms of alcohol, both to oneself and to others. It’s a notable contributor to mortality. And yes, some people would be better off not drinking at all.

But is a blanket ‘no alcohol’ rule helpful?

Or should we focus more on the factors that lead to harmful drinking?

There’s little recognition that most New Zealanders drink moderate amounts of alcohol and are not considered hazardous drinkers.

Alcohol consumption may facilitate social interaction, create a sense of relaxation, and contribute to enjoyment for individuals. Sharing a drink with friends or family members can be a cultural or social tradition that enhances connections and contributes to well-being.

However, it is essential that public health authorities and policymakers consider whether the risks outweigh these less tangible benefits.

While moderate drinking is linked to higher risk of many diseases like mouth cancer, liver disease, and breast cancer, it is not linked to coronary heart disease, also known as ischaemic heart disease (IHD), and may even lower the risk slightly. And what do most people die of in NZ—IHD. A woman with breast cancer is more likely to die of heart disease.

What's considered moderate alcohol consumption?

There's this interesting study suggesting that the threshold for the lowest all-cause mortality is around 100 grams of alcohol per week. Now, that's slightly lower than what many international guidelines recommend.

In New Zealand, a standard drink contains about 10 grams of alcohol.

The New Zealand Ministry of Health currently suggest that women should stick to no more than 10 standard drinks per week (equivalent to 100 grams of alcohol), while men should keep it at no more than 15 (exceeding 100 grams). They also say you should take a break from drinking at least 2 days a week.

Here's where things get interesting—sometimes we underestimate our alcohol intake without even realising it. For example, 100 milliliters of wine contains 10 grams of alcohol. When you pour your next glass of wine, it's worth taking a moment to consider just how generous you're being.

Other examples of 10-gram portions include: a 330-milliliter beer with a 4% alcohol content, and half a 335-milliliter bottle of ready-to-drink spirits with an 8% alcohol content. And when it comes to cocktails, it's important to be cautious because some recipes can pack up to 6 standard drinks.

Effect of potential confounders

As a last word here on alcohol — one big challenge in researching the link between alcohol and health lies in the reliance on observational studies, which are prone to confounding.

Confounding is a situation where a third factor, related to both the exposure (alcohol) and the outcome of interest (i.e., cancer, heart disease), distorts the causal relation between them.

For example, some studies have found that drinking alcohol increases risk of various types of cancer, such as oral cavity, pharynx, esophagus, larynx, breast , and colorectal cancer. However, this association might be confounded by other factors that are related to both alcohol consumption and cancer risk, such as tobacco use, diet, obesity, genetic factors and hormonal factors. Tobacco use can enhance the effects of alcohol on the risk of cancers of the upper digestive and respiratory tracts. Similarly obesity can increase the risk of cancers of the breast, colon, rectum and liver.

Researchers try to account for known confounders and use methods such as statistical adjustment or stratification to separate or control for the effects of potential confounders in the analysis, but this is never perfect.

And so, we can never be entirely certain that the increased risks of diseases and mortality associated with alcohol consumption, as observed in some studies, are not influenced by other differences between individuals who consume low to moderate amounts of alcohol and those who indulge more heavily.

We also worry about the confounding factors we can’t measure.

Bottomline

These are the kind of factors we need to think about carefully when interpreting research findings.  As we navigate the vast and often confusing world of research, it becomes clear that we need to delve a little deeper (meaning go read the papers!) with a critical eye.

For now, I’m happy with my one shandy, but I will keep an eye on my relationship with alcohol — a regular honest check-in is probably a good idea.

Next Week

We move on to the WHO's position on aspartame - a harmless sugar substitute or a hidden cancer risk?