Food & recipes

Coffee Break: Should you love that latte?

Ditch your preconceptions! Coffee could actually be one of the best health-boosters around, says nutrition expert Dr Carina Norris

Ditch your preconceptions! Coffee could actually be one of the best health-boosters around, says nutrition expert Dr Carina Norris
Are you a latte lover, or is your drink of choice a virtuous green tea? Coffee has a rather mixed reputation. It’s the world’s most popular psychoactive drug, and one of the most studied food compounds there is, but coffee is still surrounded by myth, disinformation and misunderstanding. Some swear by its health benefits, others believe it’s a toxin. And it’s the first thing to go in many so-called detox diets. But gradually, the scientific consensus is shifting, as the evidence base for coffee as a ‘health food’ expands.

What’s in your cup?

Coffee has many active ingredients, but for health purposes we’re mainly interested in caffeine, plus the wide range of antioxidants.

Caffeine

Caffeine is a mild stimulant found naturally in coffee, tea and cocoa, as well as several over-the-counter and prescription drugs. Its effect hits us almost immediately, thanks to its rapid absorption. In a study involving 688 university students, subjects began feeling more alert after just 10 minutes, and caffeine levels in their blood peaked after 45 minutes. The way caffeine is metabolised means that levels drop away rapidly but it takes a long time to be completely cleared from the system; caffeine’s effects generally last for two to three hours, though this can extend to around five hours in people who are particularly sensitive to the compound. Indeed, recent research from Duke University Medical Centre in the USA found that levels of the stress hormone adrenaline, raised by caffeine, remained high at bedtime even when the last coffee cup was drained at lunchtime.

Antioxidants

It’s not just fruit and vegetables that provide those antioxidants that protect our body’s cells from damage – drinks such as coffee, tea and wine also make respectable contributions, with coffee having the highest antioxidant activity of commonly consumed drinks.

Coffee provides one of the richest sources of antioxidant polyphenols, which include chlorogenic acids, in the Western diet. Roasting produces melanoidin compounds, dramatically increasing coffee’s antioxidant activity.

Many of coffee’s health benefits have been tagged to its caffeine content, but antioxidants take the credit for some others. Regarding its lowering the ‘bad’ form of blood cholesterol, coffee’s antioxidants have greater effectiveness than cocoa, green, black or herbal tea.

Coffee drinking is linked with a lower risk of type 2 diabetes, but when a review of research revealed that four out of six studies showed a risk-lowering effect from drinking decaffeinated coffee, it became apparent that something else also played a role. One explanation is that substances produced during coffee roasting produce compounds that help regulate blood glucose levels.

Physical effects

So how does the black bean affect your body? Caffeine blocks the action of a sleep-promoting brain chemical called adenonsine, and this is what produces that wide-awake feeling. Recent research concluded that caffeine reduced the errors made by shift workers, and also reduced daytime sleepiness in jet lag. This led to the American Academy of Sleep Medicine suggesting caffeine for enhancing alertness during night work, and as a jet lag treatment.

Caffeine also boosts metabolism – your heart beats faster, blood flows quicker, glucose is released into your system and you get that energy buzz. It also increases the amount of fat burned during exercise by up to 40 per cent, according to research published in the Journal of Medicine & Science in Sports and Medicine.

Coffee cures

Coffee can have a positive benefit on your health in several ways:

Heart health

Once coffee was believed to be bad for the heart, but this was based on research involving coffee made by long boiling or percolating (which could slightly raise blood cholesterol), rather than the filtration methods we use today. Now we know that moderate coffee-drinking reduces your heart risk. A review from the International Journal of Cardiology, involving hundreds of thousands of people, concluded that those drinking moderate amounts of coffee (one to four cups daily) had a lower risk of heart disease and stroke than those drinking less than one cup.

Type 2 diabetes

It’s now widely accepted that coffee consumption reduces the risk of type 2 diabetes. One study, from the USA’s Harvard Medical School, following 126,000 people over 18 years, concluded that one to three cups of coffee daily can reduce diabetes risk by up to 10 per cent, and six or moreslashed it by up to 54 per cent. And a review in the Journal of the American Medical Association, found that six to seven cups a day reduced your risk by 35 per cent, while four to six cups reduced it by 28 per cent. As well as the antioxidant chlorogenic acid we’ve already mentioned, it’s suggested that caffeine’s metabolism-boosting effect, the stimulation of fat-burning and the mobilisation of glucose in muscles could play a role.

Brain ageing

It appears that coffee could also help you to stay sharp in old age. In a study of nearly 2,000 elderly people in America, women with higher lifetime and current caffeinated coffee intakes scored better in tests of brain function (although, interestingly, no effect was seen for the men).

Parkinson’s disease

Many studies have found a link between caffeine intake and a reduced risk of Parkinson’s and men appear to be betterprotected than women.

Liver cancer

Much research has shown caffeine to reduce liver cancer risk, and a review of the evidence suggests that an extra cup of coffee per day can decrease your risk by 23 per cent.

Caffeine sensitivity

Perhaps you’re one of those people who finds that a single espresso turns you into a twitchy wreck? People’s caffeine-sensitivity varies enormously due to genetics, sex, body weight, and health.

Is it addictive?

Although coffee is sometimes described as ‘addictive’, habit-forming would be more accurate. An addiction is “abuse of a psychoactive substance so that it interferes with health, economic and social functioning”, which clearly isn’t the case with coffee. Coffee’s detractors say that, like addictive drugs, more and more coffee is needed over time to get the same effect, but this isn’t strictly true. Although studies have shown that people develop a tolerance to coffee, so that drinking it doesn’t make them any more alert, it simply restores them to ‘normal’ levels; they don’t have to constantly increase their intake to get the same effect.

What about ‘coffee withdrawal’? If a heavy coffee drinker attempts to go ‘cold turkey’, they’ll probably suffer from jitters and headaches, but these can be reversed by simply having a cup of coffee or even tea. If you do want to cut down your intake, go slowly and you shouldn’t experience any problems.

Possible negatives

So what are the downsides to caffeine?

Blood pressure

Caffeine can temporarily increase blood pressure if you’re not used to it, but the effect is tiny – the main risks for raised blood pressure are obesity and salt intake.

Stomach problems

There is no convincing evidence that coffee causes stomach ulcers, and it may even reduce the risk of gallstones. It can be a heartburn trigger for some people, but most of us are able to drink it without experiencing any problems.

Anxiety

Studies finding coffee to cause anxiety have used doses much higher than a single serving. However, some people are very sensitive to caffeine’s anxious-making effects, and even a single cup makes them feel twitchy.

Bone-thinning

Some studies show caffeine to increase the amount of bone-building calcium lost from the body, but the effect is tiny – you could counteract it with a couple of extra tablespoons of milk in your coffee!

Sleep

Caffeine can keep you awake, especially if you’re not used to it. But you canget around this by not drinking caffeinated coffee after a certain time of day.

Dehydration

It’s commonly believed that coffee dehydrates you, but research shows that it isn’t actually a diuretic. Coffee simply ‘brings forward’ urine production. Over the course of the day, you’ll still lose the same amount of water.

Coffee in pregnancy

The official NHS advice is that you needn’t cut out coffee when you’re pregnant, but don’t have more than 200mg of caffeine a day, as more can lead to low birth-weight babies. This amount hasn’t been found to lead to any increase in the risk of premature births or miscarriages.

The bottom line?

A moderate amount of coffee – say, four cups daily – is perfectly safe for most people, and may even be good for you. Within this guideline, just experiment to find the level that works best for you – what’s moderate for one person could be too much for another.

And be sensible – try to avoid the unhealthy additives like cream, sugar and syrups. Not only do they all pile on the calories, sugar and non-dairy creamers inhibit the antioxidant effects of the coffee polyphenols – although adding milk is fine. Also, coffee can inhibit the absorbtion of certain nutrients, including iron, so try to drink it at least an hour away from your main meals.

Calculating caffeine

Mug of instant coffee 100mg

Mug of brewed coffee 140mg

Single espresso 75mg

Tea 50mg

(Bear in mind that although the smallest cappuccino in coffee shop chains generally contains a double-shot of espresso, larger sizes contain two, three or even four times this amount).

Article by

Carina Norris

Registered Nutritionist

Registered nutritionist Carina Norris is an author and health journalist. She was the nutritionist for Channel 4s Turn Back Your Body Clock, and her 12 books include You Are What...

Discover more

Article by

Carina Norris

Registered Nutritionist

Registered nutritionist Carina Norris is an author and health journalist. She was the nutritionist for Channel 4s Turn Back Your Body Clock, and her 12 books include You Are What...

Discover more