The freshly brewed coffee to wake up the weary brain, the strong cup of tea to comfort the broken heart: but can tea and coffee have much longer-lasting effects on the heart and brain? Could they even prevent disease?

What the Media Says about caffeine 

According to the media, “three to five cups of coffee a day may prevent heart attacks”; “coffee could cure Alzheimer’s” and “two cups of coffee a day could help relieve shakes caused by Parkinson’s disease”. Given that tea is the second most widely consumed drink in the world after water, and coffee is the world’s second most traded commodity after oil, the public health implications could be huge if caffeine really is a medicine.

 

Can Coffee really help Parkinson's and Alzheimer's?

Some studies do indeed seem to show that coffee and tea offer some protection from Alzheimer’s and Parkinson’s disease, and this may be due to effects of caffeine on brain chemicals such as dopamine and adenosine, and, in the case of Alzheimer’s, caffeine seems to reduce the build-up of toxic proteins in the brain. Caffeine may also help the blood-brain barrier to remain intact, stopping harmful cells and chemicals from entering into the brain from the rest of the body. But why do some studies seem to show no association between caffeine intake and brain diseases? Why is the protection often lost once consumption exceeds three cups per day? Why do the effects sometimes appear gender-specific?

 

Caffeine and Heart Disease

Whether caffeine protects against heart disease also remains unknown: scientists have shown that coffee-drinking sometimes seems to reduce the risk of heart attacks, perhaps by reducing the stickiness of blood in arteries or by altering blood cholesterol or calcium levels. A potential role for caffeine in reducing rates of depression and diabetes has also been suggested, both known risk factors for heart disease. But for every study showing that caffeine helps the heart, other studies raise alarm about effects on blood pressure, heart rhythm and cholesterol. And it certainly is true that caffeine overdose is very dangerous, leading to insomnia, anxiety, hallucinations, seizures and even death.

 

So Will Coffee Help Us Stay Healthy?

The jury is still out. The media will no doubt continue to print conflicting headlines. Read each report with a pinch of salt (or a spoonful of sugar). In some studies, more than twelve cups of coffee are being drunk daily; there can be considerable variability in the strength and cup size, and the type of milk used; coffee drinking may be a marker of other lifestyle factors such as cigarette smoking; the study may be looking at effects of caffeine on animal models or human blood chemicals, but not yet be applicable to actual numbers of people affected by real symptoms of disease. Coffee and tea contain a vast array of compounds including potassium, niacin, magnesium and antioxidants. What role do these play, since decaffeinated coffee is also showing promise in disease prevention? So far, all we can conclude is that tea and coffee may confer some health benefits when consumed in moderation as part of a healthy lifestyle.

 

Helen Cowan studied human physiology at Oxford University from 1996-1999 then completed a PhD in cardiac pharmacology at Oxford in 2002. She is also a qualified nurse and has worked widely in cardiac surgery, neurosurgery, clinical trials and elderly care. She is a freelance writer and has published in the British Journal of Cardiac Nursing, worked as a columnist in the Nursing Times, and written for local and online publications. She is fascinated by the workings of the human body.

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