To those among us who wake up to drink coffee and to those who drink coffee to wake up: good morning, and let’s talk about … coffee and caffeine!

Coffee and tea, of course, are the most consumed, socially acceptable stimulants in the world.

Approximately 90 per cent of all adults in the world consume caffeine in their daily diet.

Coffee consumption is higher in men than women.

Coffee is preferred over tea in the developed countries, except England and Ireland, although tea consumption in the US is on the rise and varies greatly by type — 87 per cent prefer black tea as opposed to green tea and herbals.

Average US coffee consumption is about two cups per day; approximately 280 mg of caffeine.

Caffeinated soft drinks are another significant source of caffeine intake, where the range is 50 mg to 500 mg per drink [see table].

Coffee and tea contain several chemical components: caffeine, but also polyphenols and flavonoids which may confer both beneficial and adverse health effects.

What are coffee and caffeine effects?

• Alertness: caffeine consumption leads to increased alertness, energy, and concentration, particularly when subjects are fatigued or working at night.

In clinical trials, it was similarly effective to some pharmacologic cognitive enhancers.

• Headache: caffeine can alleviate or generate headache. When intermittently used, it is effective against tension-type and/or migraine headaches. However, habitual caffeine consumption could be associated with chronic migraine and withdrawal headaches.

• Parkinson and Alzheimer’s disease: coffee consumption was associated with a small protective effect against both conditions.

• Cardiac: multiple studies, including a very recent one, show that coffee protects against heart failure and myocardial infarction.

This effect is present with both regular and decaffeinated forms, suggesting that it is not related to caffeine content, but to other ingredients in coffee. And while coffee is a natural diuretic, the protection from heart failure is not merely due to that effect.

Through these diverse cardiac benefits, coffee has been repeatedly shown to decrease overall mortality. On the other hand, heavy and binged intake of caffeine, especially in energy drinks, may trigger dangerous coronary and arrhythmia events and should be avoided.

• Diabetes: caffeine consumption is associated with a reduced risk of diabetes via improved insulin impact (or sensitivity) and better control of blood sugar in diabetics.

• Liver disease: including cirrhosis and autoimmune hepatitis are reduced by coffee consumption.

• Cancer: while there is reason to postulate that coffee and tea may reduce the risk of cancer because of their antioxidant properties, there is a lack of consistent evidence for this finding across studies.

• Osteoporosis: high coffee intake may be associated with lower bone mineral density and increased fracture risk in women.

Tea consumption, on the other hand, was associated with higher bone density although this finding did not translate into a decrease in fracture risk.

It is postulated that higher flavonoids in tea, compared to coffee, may account for the preservation of bone minerals.

• Pregnancy: caffeine can have negative effects on pregnant women or on women who would like to become pregnant, including an increased risk for difficult conception and miscarriage.

In addition, caffeine is transmitted through the placenta to the foetus, and through breast milk to the baby.

• Abuse and dependency: although these terms are used frequently in the medical literature, conclusive clinical indicators of either condition have not been demonstrated with caffeine.

Nonetheless, caffeine withdrawal is a well-documented clinical problem. Also, heavy caffeine use can be associated with increased risk for other addictive behaviours, including tobacco and alcohol abuse.

A final word of caution: non-dairy creamers contain partially hydrogenated oils and, when used in large amounts, could be a significant dietary source of trans-fats.

Also, addition of a non-dairy creamer delayed appearance in blood of phenolic acid, an excellent antioxidant.

Added sugar may make a significant contribution to the dietary sugar load and thus negate some of the potential benefits of coffee. Milk may diminish the beneficial effect of tea on vessel dilation. Hence, with coffee and tea — and everything else probably — the dictum is “in moderation”.

• Joe Yammine is a cardiologist at Bermuda Hospitals Board. He trained at the State University of New York, Brown University and Brigham and Women’s Hospital. He holds five American Board certifications. He was in academic practice between 2007 and 2014, when he joined BHB. During his career in the US, he was awarded multiple teaching and patients’ care recognition awards. The information herein is not intended as medical advice nor as a substitute for professional medical opinion. Always seek the advice of your physician. You should never delay seeking medical advice, disregard medical advice or discontinue treatment because of any information in this article.