Caffeine

Assessment and Plan: Caffeine

• Caffeine intake up to 300 mg per day is generally safe for healthy adults. Older patients or those with hypertension, cardiovascular disease, or cerebrovascular disease, avoid more than 1-2 cups of caffeinated beverages per day. Caffeine intake is generally recognized as safe by the FDA and AMA but can be dangerous with adverse effects such as high bp, stroke, and arrythmias reported. See adverse effects below. If more than 1-2 cups of caffeinated beverages are consumed per day, it is prudent to seek physician and/or pharmacist approval of caffeine consumption with any medications or supplements.

• The American Academy of Pediatrics recommends that adolescents consume no more than 100 mg of caffeine daily. Younger children should not drink caffeinated beverages on a regular basis.

• Caffeine causes insomnia and sleep disturbances. Caffeine has a variable duration of action across different individuals and may have a longer duration of action in patients which metabolize caffeine at a slower rate.

• Caffeine used by athletes without any medical problems may result in a small benefit in endurance sports when even a small time improvement can be important. The dose range of caffeine used in studies was 1.5 – 5 mg per kilogram and greater benefit was seen in especially colder compared to warmer surrounding temperatures.

• High dose caffeine contributed to improved muscle contraction velocity but may not be safe.

• Individuals with many years of previous daily caffeine intake of 198.7 mg per day were found to have less risk of Alzheimer’s dementia than those who had 73.9 mg of caffeine per day with multiple studies quoting coffee as beneficial and one study quoting 3 -5 cups per day of coffee  as beneficial.

• The research represented here shows that black tea improved focus of attention, improvement in visual tasks, and mental fatigue likely due to combined effects of both caffeine and L-theanine contained in the tea but not in either substance alone.

• Black, green, and oolong tea consumption was associated with a reduced risk of ischemic stroke and cardiovascular disease with the greatest benefit seen when drinking about 1-3 cups per day in the studies mentioned above.

• For benefits of caffeine benefits as found in the form of black tea or green tea please see those sections.

• Caffeine may improve lung function in adults but the doses used in the studies are fairly high amounts (equivalent to 3-4 cups of coffee) which may improve lung function for a duration of up to 2-4 hours after ingestion.

• There are mixed results in studies for the relationship of caffeine intake on pregnancy. According to the American College of Obstetricians and Gynecologists caffeine consumption of less than 200 mg/day during pregancy does not seem to be associated with miscarriage or preterm birth (34). Other sources have quoted that the higher the caffeine intake, the higher the risk for spontaneous abortion. Non-smoking pregnant women who drank coffee were found to have an increased risk of spontaneous abortion of 30%, 40%, and 120% at intakes of 100 to 299 mg/d, 300 to 499 mg/d, and 500 mg/d respectively (20). On the other hand, caffeine consumption of no more than 300 mg per day did not affect pregnancy duration and the condition of the newborn in another study but the impact of caffeine on the growth of the baby is not known. (21)

• Caffeine in the form of coffee consumed prior to meals may improve insulin sensitivity (allow insulin to become more effective at lowering of blood glucose levels) but more research is needed.

• Based on a large cohort study, caffeine should be further studied for prevention of basal cell skin cancers.

• Osteoporosis patients should limit caffeine intake.

• The subject of caffeine and fibrocystic breasts is controversial. Research supports both that caffeine may increase breast pain in this condition and possibly affect hormone levels leading to the condition. Other studies have shown that decreasing caffeine intake does not result in improvement. More research is needed on this subject.

• Caffeine Adverse Reactions and Interactions: Caffeine is classified as a methylxanthine and stimulant which may cause indigestion, palpitations (rapid heart beat), tremor, headache, and sleep difficulty. Caffeine should be avoided when taking the medications theophylline, aminophylline and pentoxyfylline which may potentiate (increase) the effects of these drugs. Caffeine may increase risk of premature death in patients with hypertension, cardiovascular disease, and stroke. Caffeine consumption increases calcium excretion in the urine and may increase the risk of kidney stones. Excessive caffeine in supplements may cause stroke. High caffeine intake may result in hypokalemia. Consumers should be aware that guarana has one of the highest concentrations of caffeine in any plant and intake of this herb supplement is not advised. The subject of caffeine and fibrocystic breasts is controversial. Research supports both that caffeine may increase breast pain in this condition and possibly affect hormone levels leading to the condition. Other studies have shown that decreasing caffeine intake does not result in improvement.