Energy-boosting and Mind-sharpening Caffeine


A lot of wage earners like to have a cup of coffee or milk tea in the morning to start a working day. Besides of coffee, caffeine is also present in tea and tea-based beverages, energy drinks, Cola soft drinks, chocolate and other related products. We take caffeinated beverages to cope with daily activities, but somehow caffeine gives us energy. What is the exact material? How much caffeine is safe to consume on a daily basis?


Sources of caffeine

Caffeine is a purine alkaloid naturally existing in plants such as cacao tree, coffee tree and tea tree, and acts as a natural pesticide for plants. That is why the plant-derived caffeine is found in chocolate, coffee, tea and their products. Moreover, food industry also uses caffeine as a food additive in sparkling drinks, energy drinks and chewing gums. It is as well used in medical treatments.


Metabolism of caffeine in the body

After caffeine is ingested through our diet, the time from metabolism to excretion varies from individual to individual depending on age, body weight, liver conditions, pregnancy and use of medication. For an average healthy adult, it takes around 4 hours to excrete 50% of the ingested caffeine from the body. Caffeine consumption in children and adults over a short period of time is associated with anxiety and sleep disorder; whereas, the long-term effects of caffeine is based on daily intake amount, and high ingestion may lead to cardiovascular problems and affect fetal development in pregnant women.


Caffeine contents in bubble milk tea

Many hand-shaken beverage shops have been set up in Macao in recent years. Their beverage products become an afternoon treat loved by many adults and children. Yet, some consumers may have difficulty on sleeping at night after drinking these tea-based beverages. The Municipal Affairs Bureau and Macao Consumer Council jointly conducted a survey on commercially available beverages1. In the 12 random samples of bubble milk tea (including bubble milk tea with brown sugar syrup, bubble milk tea prepared with fresh milk and bubble milk tea prepared with green tea), the caffeine contents ranged from 76.2 mg to 207.0 mg per cup. In Issue No. 266 of ‘Consumer Report’, it reveals that a can of energy drink (473 mL) has 160.3 mg of caffeine, which means we take more caffeine from a cup of bubble milk tea than from a can of energy drink. Thus, we need to pay attention how much and at what time of the day we drink hand-shaken beverages so as not to let it affect sleep quality.


Consumption of caffeinated beverages and foods in moderate amounts is unlikely to pose serious health impacts, but pregnant women, breastfeeding women and children should avoid excessive. As recommended by the European Food Safety Authority (EFSA)2, pregnant and lactating women should limit their caffeine consumption up to 200 mg per day.


Furthermore, we should heed that the caffeine containing in coffee and milk tea varies depending on the ingredients and preparation methods. Still, the caffeine content in these beverages is typically high, meanwhile the sugar content in caffeinate dinks should not be overlooked. Excessive sugar consumption over long periods of time can increase the risk of obesity and cavities. Consumers should drink more water and refrain from taking too much caffeinated beverages.



1. “Consumer Report”, Issue no. 314: “Choose hand-shaken beverages with care and pay attention to calorie intake” (Chinese and Portuguese Version Only).

2. Scientific Opinion on the safety of caffeine. EFSA Journal 2015; 13(5):4102.