Why alcohol and coffee affect us more as we age

For most people in their 20s, a few glasses of wine or cups of coffee probably wouldn't be a big deal.

So why do alcohol and caffeine feel harder to tolerate as we age? Here's what the experts say…

"Drinking excessively, exceeding guidelines and binge drinking are not good at any age!" says dietitian and British Dietetic Association spokesperson, Clare Thornton-Wood, external.

"Alcohol and caffeine are metabolised in the liver," she explains. "As we age our liver becomes less efficient at this.

"Alcohol is metabolised at a slower rate, meaning it stays in the body longer with more chance of a hangover.

"It's the same for caffeine, it's not cleared from the bloodstream as quickly as we get older so its effects, such as being alert, will stick around for longer."

"Body composition changes as we age," adds Thornton-Wood. "We lose muscle and gain fat – muscle is about 75% water, external but fat can be as low as 10% water."

Less water in the body means alcohol is absorbed more quickly and increases the risk of dehydration – that can cause headaches.

And it means you're more likely to have a hangover from a smaller amount of alcohol when you're older.

Disturbed sleep is another unfortunate side-effect of ageing, external. Add alcohol and coffee, and it doesn't look good.

"REM (rapid eye movement) sleep decreases after drinking, external – we need adequate REM sleep for good mental health, concentration and memory," says Thornton-Wood.

"Caffeine blocks adenosine receptors, external which promote sleep, which then increases production of neurotransmitters that play a role in cognitive function. So, you feel more alert and your blood pressure and heart rate increase.

"In the right circumstances this can be very useful. But, too much and you can feel jittery, have trouble sleeping and feel anxious."

The half-life for caffeine clearance can range from 1.5-9.5 hours, helping explain why having coffee later in the day could lead to disturbed sleep.

Both drinks are diuretics, too, which means you might be woken up with a need to go to the toilet.

"If you are predisposed to acid reflux or you're older then it's more likely your stomach will be easily irritated when you drink alcohol," explains Thornton-Wood. Coffee has been shown to have a similar negative effect, external.

"As we age our muscles weaken, this includes the sphincter at the top of the stomach, which if not closed leads to acid flowing back up from the stomach into the oesophagus and causing heartburn." Alcohol, external also, unhelpfully, relaxes this muscle.

But it might not be just your age that's affecting your ability to enjoy these drinks.

The University of Bath looked at how drinking coffee following a night of bad sleep, external could disrupt blood sugar levels and impact metabolism. Age didn't seem to affect this, but a gene mutation did.

"[A mutation] could be why some people are able to have more than five cups without consequence whereas others can only manage one per day," explains lead researcher, Harry Smith.

Smith also identified biological sex, body composition, lifestyle choices (like smoking) and diet as other factors that can contribute to our ability to tolerate caffeine.

"There are also links with body weight – heavier people generally tolerate more caffeine," says Thornton-Wood.

If you're feeling stressed, coffee also might not be your best friend, says Thornton-Wood. "If you already suffer with anxiety then caffeine is likely to exacerbate this. In fact, there's a recognised caffeine-induced anxiety, external disorder." Alcohol can cause similar issues, external.

The NHS advises, external adults not to drink more than 14 alcohol units per week on a regular basis – that's about six pints of beer or 10 small glasses of wine – spread over at least three days.

"It's about moderation, know your limits, intersperse with water, have spritzers or lower alcoholic-content drinks," says Thornton-Wood.

The NHS advises, external that we also "drink caffeine in moderation".

Thorton-Wood recommends interspersing coffee "with water or decaf and leave longer spaces between cups. Consider the caffeine strength, too. There are differences between coffee chains and ground coffee is always higher in caffeine than instant."

If you are concerned about alcohol addiction, help and support is available.

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