The Health Effects of Caffeine

by Health Canada

Caffeine in its natural and added forms is found in a growing list of products including coffee, tea, cola beverages, new "energy" drinks, chocolate and even some medicines. The increasing presence of caffeine in our lives raises the question of how much is too much for the average consumer.

Health Canada's recommendations on caffeine intake for women of child-bearing age and children were lowered in 2003 based on new research. For the rest of the general population of healthy adults, the long-standing advice still applies of no more than 400 - 450 mg of caffeine per day, the equivalent of about three 8-oz (237 ml) cups of brewed coffee.

Caffeine is a natural ingredient found in the leaves, seeds or fruit of a number of plants, including coffee, tea, cocoa, kola, guarana and yerba maté. It is also manufactured and used as a food additive in some carbonated drinks, and as an ingredient in certain drug products, such as cold and headache remedies.

Canadian adults get an estimated 60% of their caffeine from coffee and about 30% from tea. The remaining 10% comes from cola beverages, chocolate products and medicines.

For children aged one to five, about 55% comes from cola drinks, about 30% from tea, and about 14% from chocolate. The rest comes from other sources, including medicines.

It is difficult to link precise intake levels of caffeine to specific health effects because tolerance to caffeine differs widely from person to person. For healthy adults, a small amount of caffeine may have positive effects, such as increased alertness or ability to concentrate. However, some people are more sensitive to caffeine. For them, a small amount could cause insomnia, headaches, irritability and nervousness.

There have been many studies over the years dealing with caffeine and human health. These studies have looked at the potential adverse effects of caffeine in such areas as:

• general toxicity (e.g., muscle tremors, nausea, irritability)
• cardiovascular effects (e.g., heart rate, cholesterol, blood pressure)
• effects on calcium balance and bone health (e.g., bone density, risk of fractures)
• behavioural effects in both adults and children (e.g., anxiety, mood changes, attentiveness)
• potential links to cancer
• effects on reproduction (e.g., male and female fertility, birth weight)

Health Canada scientists recently reviewed these studies and found that:

• The general population of healthy adults is not at risk for potential adverse effects from caffeine if they limit their caffeine intake to 400-450 mg per day.
• People who get an adequate daily amount of calcium have greater protection against the possible adverse effects of caffeine on bone health. For most people, choosing foods according to Canada's Food Guide to Healthy Eating can provide the calcium needed for good health.
• Compared to the general adult population, children are at increased risk for possible behavioural effects from caffeine.
• Women of childbearing age are at increased risk of possible reproductive effects.

These conclusions prompted Health Canada to establish new recommendations on maximum daily caffeine intakes for the groups that may be at higher risk.

Health Canada's New Recommendations

For children age 12 and under, Health Canada recommends a maximum daily caffeine intake of no more than 2.5 milligrams per kilogram of body weight. Based on average body weights of children, this means a daily caffeine intake of no more than:

• 45 mg for children aged 4 - 6
• 62.5 mg for children aged 7 - 9
• 85 mg for children aged 10 - 12

Those recommended maximums are equivalent to about one to two 12-oz (355 ml) cans of cola a day.

For women of childbearing age, the new recommendation is a maximum daily caffeine intake of no more than 300 mg, or a little over two 8-oz (237 ml) cups of coffee.

For the rest of the general population of healthy adults, Health Canada advises a daily intake of no more than 400-450 mg.

About the Author

www.hc-sc.gc.ca
Health Canada is the Federal department responsible for helping Canadians maintain and improve their health, while respecting individual choices and circumstances.