Caffeine: What women should know

Caffeine has some key effects on women. (Getty Images)
Caffeine has some key effects on women. (Getty Images)

Caffeine has been dubbed the world's most popular drug. Fortunately, it's very safe when consumed in moderation. A considerable amount of research has been conducted on the various effects of caffeine, the pick-me-up ingredient most commonly found in coffee, tea and soft drinks. Here's what women should know about the popular alertness booster.

Did you know that:

Caffeine might have more impact on women than on men.

That's because caffeine may accelerate bone loss and caffeinated beverages such as coffee and tea can inhibit iron absorption. "Thus, women, who have higher iron requirements and are at a higher risk of osteoporosis than men, might be more affected by caffeinated beverages," says Ong Chengsi, dietitian at the Department of Nutrition and Dietetics of KK Women's and Children's Hospital.

Caffeine is a stimulant, and large amounts may have adverse effects on pregnancy, including an increased risk of miscarriage or birth defects. "Pregnant women, breastfeeding women and women planning for pregnancy should limit caffeine to 300 mg a day, which is the equivalent of about two cups of coffee," says Ong.

Generally speaking, adults should limit their consumption to 400mg a day to avoid unwanted effects such as restlessness or increased anxiety.

Related article: How to Boost Your Metabolism

Caffeine content may vary widely from one cuppa to the next.

If you check the packaging of your favourite source of caffeine, chances are, you won't actually find the caffeine content per serving.

Not helping you to keep track, caffeine content can vary wildly from one cuppa to the next, depending on the beans, brewing time and method used. When researchers bought the same 16-oz coffee at the same Starbucks, six days in a row, they found out that the caffeine content varied from 259 mg to 564 mg.

What about your local kopi? "Local kopi uses Robusta coffee beans, which have twice as much caffeine as the Arabica beans typically used in popular coffee chains and in the studies," says Ong. In other words, don't underestimate your local kopi -- it can definitely be a potent brew.

Use the following table as a guide to evaluate your daily caffeine intake:


Serving size

Caffeine (mg)

Coffee, generic, brewed

8 oz (240 ml)

133 (range: 102-200)

Instant coffee, generic

8 oz (240 ml)

93 (range: 27-173)

Espresso, generic

1 oz (30 ml)

40 (range: 30-90)

Tea, brewed

8 oz (240 ml)

53 (range: 40-120)

Cola drinks

12 oz (1 can)


Red Bull

8.3 oz (250 ml)



1.5 oz (45 g) bar


Hot Cocoa

8 oz (240 ml)


Source: Centre for Science in the Public Interest

A few points worth mentioning:

  • In popular coffee chains, serving size can be quite generous. For instance, at Starbucks, the medium-sized "grande" (16 oz) represents two servings according to the chart above.

  • Tea roughly has half the caffeine content of coffee.

  • A can of Red Bull actually contains less caffeine than a coffee. Watch out for other brands, though.

  • Clear soft drinks such as 7-Up or Sprite are caffeine-free.

Related article: Soy vs. Dairy: Which Is Best for You?

Regular caffeine consumption can decrease the risk of some diseases

No one has ever suggested consuming caffeinated beverages to treat or prevent a specific disease. But while you're drinking your much-needed cuppa in the morning, know that research has shown potential health benefits to your addiction.

For starters, many studies have confirmed the high antioxidant value of caffeine. Antioxidants protect against free radicals, which are molecules responsible for aging and tissue damage.

According to Ong, there is some evidence that caffeine reduces the risk of Parkinson's disease and dementia. However, as far as type 2 diabetes, heart disease, cancer and stroke (in women) are concerned, the evidence for any risk reduction is "inconsistent".

At least, "reviews of current studies show no increased risk for breast and ovarian cancer," she adds.

Better to just keep enjoying your caffeinated drink in moderation for its effects on mental alertness and, of course... its taste.

This article was written by the Health Xchange editor, with expert input from the Dept of Nutrition and Dietetics at KK Women's and Children's Hospital.

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