Fitness Facts: What you should know about caffeine

By Connie Colbert
GCU Director of Health Services

Should you have another cup of coffee?

Here are some facts regarding caffeine that may help you make your decision.

What is caffeine?

Caffeine is a plant product found in coffee beans, tea, energy drinks, soft drinks, cocoa and chocolate. It also can be found in some prescription and nonprescription drugs, including cold and allergy medications and pain relievers.

Often, caffeine is a hidden ingredient. Make sure you check labels of food, drinks and medications.

Caffeine is a natural stimulant. It works by stimulating the brain and central nervous system, helping you stay alert and prevent the onset of tiredness.

How does caffeine work?

Caffeine acts as a stimulant by exerting an effect on the central nervous system. The effects of caffeine on the body may begin as early as 15 minutes after ingesting and last up to six hours.

Is caffeine safe?

Caffeine is recognized as an addictive substance by the World Health Organization (WHO).  

Up to 400 milligrams (mg) of caffeine a day appears to be safe for most healthy adults. That is roughly the amount of caffeine in four cups of brewed coffee, 10 cans of cola or two energy drinks. Keep in mind that the actual caffeine content in beverages varies widely, especially among energy drinks.

What are the health benefits of caffeine?

Caffeine can improve memory, decrease fatigue and improve mental functioning.

Caffeine can help improve energy levels, mood and various brain functions.

Caffeine may reduce the risk of developing certain neurological disorders such as Parkinson's disease, Alzheimer’s and liver and colorectal cancer. Coffee is rich in antioxidants, which can promote overall health.

What are the negative side effects of caffeine?

Caffeine may increase blood pressure, body temperature, blood flow to the skin and extremities, blood sugar levels, stomach acid secretion and production of urine (it acts as a diuretic).

People may experience dizziness, hypoglycemia, fruit-like breath odor, troubled breathing, muscle tremors, nausea, diarrhea, increased urine, ketones in urine, drowsiness, thirst, anxiety, confusion, irritability, insomnia, changes in appetite, dry mouth, blurred vision, jitters and cold sweats.

Too much caffeine may lead to sleep deprivation and a tendency to disregard the normal warning signals that the body is tired and needs rest.

Caffeine does not replenish energy or prevent emotional fatigue; food and sleep are the only remedies for these. When normal sleeping patterns are continually disrupted, mood depression may occur. Too much caffeine may also lead to anxiety-related feelings, such as excessive nervousness, sweating and tremors.

If you want to avoid some of the unintended side effects of caffeinated beverages (e.g., jitters or sleeplessness), switching to decaffeinated drinks may help.

You may want to cut back if you are drinking more than four cups of caffeinated coffee a day (or the equivalent in energy drinks, tea or other caffeinated beverages) and you have side effects such as:

Are there long-term health risks of consuming caffeine?

While consuming moderate amounts of caffeine does not seem to have long-term detrimental effects, consuming large amounts of caffeine (1,000 mg or about 10 eight-ounce cups of coffee a day) on a regular basis may be linked to fertility issues, increased episodes of heartburn and changes in bowel habits.

People who take medications for depression, anxiety or insomnia, high blood pressure, other heart problems, chronic stomach upset or kidney disease should limit caffeine until discussing the matter with a health care provider.

Can you get withdrawal symptoms when you stop drinking caffeine?

People who stop drinking caffeinated drinks may notice several side effects, especially if they are used to consuming large amounts of caffeine. Some symptoms of caffeine withdrawal include headaches, irritability, nervousness, nausea, constipation and muscular tension.

These symptoms usually appear about 12-24 hours after someone has stopped consuming caffeine and usually last about one week. It is recommended that you gradually decrease your caffeine intake to avoid withdrawal symptoms. 

Is caffeine OK during pregnancy?

Some studies show an association between high doses of caffeine and an increased rate of miscarriages and premature or low birth weights. In extremely high doses, caffeine can affect fetal breathing and heart rate. Limiting caffeine use to less than 200 mg or one eight-ounce cup of coffee daily is recommended during pregnancy.

If you are pregnant or planning to become pregnant, please discuss caffeine intake with your clinician.