1. The Facts About Caffeine
Research & Recommendations

2. Objectives Common Sources Physiological Effects Caffeine… Bottom Line
& Mental & Physical Performance
& Cardiovascular Disease
& Diabetes
& Cancer
& Osteoporosis
& Women’s Health
Bottom Line
Caffeine is one of the most studied ingredients in the food supply, yet controversy & misperceptions regarding this food still exist.
I’m going to give a brief overview of common sources of caffeine & its physiological effects on the body. I will then highlight some of the existing science between caffeine and common medical conditions.

3. Drug effects on spiders
1995 NASA research group --
Drug effects on spiders
In 1995, a NASA research group studied the effect of different drugs on European garden spiders.
All drugs reduced web regularity, except for small doses of LSD, which resulted in more ordered webs.
Caffeine, obviously, resulted in the most disordered web.

4. Common Sources
What is caffeine? A naturally occurring substance found in leaves, seeds,
and/or fruits of at least 63 plant species
Item (12 oz)
Caffeine (mg)
Coffee, brewed
128
Coffee, instant
113
Espresso (1 oz) 40
Tea, brewed 60
Tea, iced 38
Item (12 oz)
Caffeine (mg)
Soda 40
Energy Drink
116
Hot cocoa/chocolate milk 8
Milk chocolate
(1.5 oz) 9
Dark chocolate (1.5 oz) 30
Caffeine is a naturally occuring substance found in the leaves, seeds and/or fruits of at least 63 plant species.
These are the most common sources of caffeine. I made the chart according to what is, today, a “normal” servings size. 12 oz. is the size of our smallest coffee cup in the cafeteria, the smallest size at Starbucks, a Hershey’s chocolate bar, or a can of soda.
Caffeine is also added to many over-the-counter pain relievers in amounts of mg because it increases the absorption rate of medications.
For our purposes today, when I say “in moderation,” I mean 300mg/day, which would be about 2 “small” cups of coffee. The average caffeine intake for adults is mg/day and is provided mostly by coffee. For children and young adults, caffeine consumption derives mostly from soda.
fun fact: caffeine is added to many OTC pain relievers, ranging from mg – it increases the rate at which medication is absorbed into the body

5. Physiological Effects
Stimulant
Metabolized quickly
Caffeine sensitivity varies greatly from person-to-person
Are children more sensitive?
Withdrawal symptoms: headache, insomnia, anxiety
Hydrating
Caffeine is a mild central nervous system stimulate. It is rapidly absorbed in the bloodstream and passes the blood-brain barrier to elicit physiological changes. Caffeine sensitivity varies from person-to-person and depend on factors such as frequency & amount of regular intake, the body’s rate of metabolism, body weight and physical health. Even small amounts of caffeine can keep some people awake at night, while others can consume caffeine late in the evening without experiencing that effect.
There is no evidence that caffeine is associated with hyperactive behavior in children. However, caffeinated drinks shouldn’t replace healthier drinks in a child’s diet like milk or water.
It is excreted through the urine. The time this takes can vary from person-to-person, but the average half-life (or time it takes for half of the caffeine to be excreted) is 5 hours.
Caffeine is not “clinically” considered addictive, although you may hear people say they are “addicted.” When caffeine intake is stopped abruptly, a person may experience headaches, insomnia or anxiety. Although, again, these are not clinically called “withdrawal” symptoms. [Per DSM-IV, APA’s Diagnostic & Statistical Manual].
Caffeinated beverages consumed in moderation can contribute to total daily water intake. Caffeine has a diuretic effect, but it is offset by the fluid of the beverage.
Fun fact: DSM-IV DOES cite evidence for caffeine intoxication in sensitive individuals who consume 250mg. These people may experience excitement, restlessness, nervousness, insomnia, diuresis & GI disturbances such as nausea & vomiting.
fun fact: caffeine intoxication may occur with consumption of more than 250 mg in sensitive individuals – excitement, restlessness, nervousness, insomnia, diuresis, GI disturbances

6. Mental & Physical Performance
Caffeine has been linked to:
Increased alertness, concentration, & mental acuity
Even in well-rested individuals
Enhanced mood
Improved athletic performance and endurance
Lowers threshold for “runner’s high”
Will not affect sleep if consumed more than 8 hrs before
Tolerance
Caffeine has been linked to increased alertness, concentration, mental acuity and improved mood (which is why I think most of us drink coffee in the morning, especially after a late night). I thought it was interesting to read that even well-rested people benefit from these effects.
As little as 32mg/day has been shown to increase memory and the ability to reason. Low levels can also enhance feelings of vigor, efficiency, energy and clear-headedness.
Caffeine can improve athletic performance and endurance, especially during the latter parts of sporting events. According to current research, caffeine may lower the threshold for “runner’s high,” which is a chemical hormone release that is caused by exercise. [beta-endorphins, cortisol]
We touched briefly on this, but if caffeine is consumed more that 8 hours before going to bed, it should not affect a person’s sleep.
Regular consumption can result in tolerance to its effects, so all these mental and physical benefits may not last forever if we have prolonged, continuous consumption.
Fun fact: Caffeine may make us feel better and more alert in the morning simply because it relieves us from withdrawal symptoms we are experiencing overnight.
[fun fact: caffeine does not reduce the effects of alcohol although many people still believe a cup of coffee will help a person “sober up”]
fun fact: it may be that caffeine’s “morning-pick-me-up” is simply relief of overnight withdrawal symptoms

7. Cardiovascular Disease
More than 100 studies: no relationship between caffeine and hypertension, arrhythmia, or coronary heart disease
Immediately following consumption, short-lasting rise in blood pressure
Honolulu Heart Study – association between moderate coffee consumption and stroke in high-risk men
Coffee or caffeine?
Hyperlipidemia and unfiltered coffee
More than 100 studies have looked at the possible relationship between caffeine consumption and blood pressure, cardiac arrhythmia or coronary artery disease. Caffeine may cause a temporary, and small, rise in blood pressure, especially in people who don’t consume caffeine regularly. This rise is less than what is normally experienced when climbing a single flight of stairs.
Caffeine does not cause chronic hypertension, but it is recommended that people who already have high blood pressure to consult with their doctor, just to be safe.
No studies have shown a causal affect on cardiac arrhythmia.
One study did show an association between moderate coffee consumption and stroke in high-risk men with existing hypertension and previous history of stroke. However, more research is needed to figure out if this was caused by caffeine or another element found in coffee. Again, it is always safe for someone who has survived a stroke to seek the advice of their doctor.
There are studies that have shown an increase in blood lipids associated with unfiltered coffee, which is becoming more popular in the US. Examples of unfiltered coffee are those made with a French press or percolator and espresso, which is used in lattes/cappuccinos.
fun fact: the rise in blood pressure experienced after coffee consumption is no greater than that experienced when climbing a flight of stairs

8. Cancer Sparse research Caffeine or coffee?
Caffeine has not been shown to be carcinogenic [WHO]
Colorectal cancer & coffee
A protective effect?
Most research done on the links between cancer and caffeine has been conducted on coffee and tea, which makes it hard to isolate an effect specifically of caffeine. That being said, a lot of the research in this area has shown positive effects.
According to the World Health Organization, there is no evidence that caffeine causes cancer in animals or humans. Other studies have had similar results at caffeine levels below 500mg/day.
Caffeine may have a shown a reduced risk of colorectal cancer with coffee consumption and have even gone so far as to say there may be a protective effect against colorectal, liver, and colon cancers.

9. Osteoporosis Coffee & other caffeinated beverages may displace milk
Caffeine itself is not associated with change in bone density
Adequate calcium is the most important factor in bone health
Caffeine intake ~750mg+/day has been shown to increase urinary excretion of Ca and Mg
Caffeine itself is not associated with changes in bone density. The trouble occurs when coffee and other caffeinated drinks displace calcium & vitamin D containing milk. Inadequate calcium is a risk factor for osteoporosis.
Higher caffeine intakes of ~750mg/day or higher has been shown to increase excretion of calcium and magnesium in the urine. However, the amount of calcium lost from consuming one 12-oz cup of coffee per day can be offset by adding three tablespoons of milk to the coffee.
[Moderate amounts of caffeine don’t have significant effects on bone density or on calcium balance in individuals consuming at least 800 mg calcium per day [Nawrot, et al., 2003]]
fun fact: calcium lost from consuming one 12-oz cup of coffee per day can be offset by adding just 3 tablespoons of milk

10. Women’s Health
Moderate consumption of caffeine is safe for women who are pregnant, nursing, or post-menopause
Not associated with fertility, birth defects, premature birth, miscarriage, or low birth weight
Pregnancy & aging may affect sensitivity to and metabolism of caffeine
Talk to your MD
This is one area with a lot of confusion & fear surrounding caffeine, which is not unsurprising given the nature of reproductive health.
Experts and government agencies, like the FDA, have agreed that caffeine is safe to consume in moderation by pregnant, lactating and post-menopausal women. Consumption of 300mg or less is not related to fertility, birth defects, premature birth, miscarriage or low-birth weight.
Some studies have found a link between caffeine and miscarriage, but study limitations and confounding factors can’t be ruled out as causing the results. As always, it is best to talk to your doctor with concerns & it certainly can’t hurt to limit caffeine intake.
When caffeine is consumed in moderation, the amount passed through breast milk is small and should not have an effect on the baby. However, consuming larger amounts of caffeine may cause some nursing infants to become irritable or it can affect their sleeping patterns.
Lastly, pregnancy & aging can both affect caffeine sensitivity. It is never wrong to talk to your doctor.

11. Bottom Line
Moderate amounts of caffeine – about 300mg/day – are safe for most adults
More sensitive individuals may feel effects at smaller doses.
Watch caffeine intake if you:
Are prone to stress, anxiety or sleep problems
Have acid reflux or stomach ulcers (coffee)
Have high BP that doesn’t respond to medication or diet
Have chronic headaches
Researchers continue to study caffeine
In a nutshell, these are the recommendations for caffeine consumption:
Moderate amounts of caffeine, about 300mg/day, are safe for most adults. More sensitive people may feel physiological effects or “withdrawal” symptoms at lower levels.
You might want to limit your caffeine intake if you are prone to stress, anxiety or sleep problems, as it can exacerbate these effects.
- Have acid reflux or stomach ulcers. We didn’t touch on this, but there are mixed results as to whether caffeine causes GERD or heartburn. Some studies show that it is the caffeine that has the effects, it is more likely that it is the actual coffee that has the effect. More research is needed in this area.
- Have high blood pressure that doesn’t respond to medication or diet. This might be an area your doctor can advise you in.
- Have chronic headaches. Headaches can occur with caffeine consumption in sensitive individuals and it can occur with “withdrawal” from caffeine.
As I mentioned earlier, this is a huge area of study in the food industry and caffeine will continue to be the subject of research on these topics and beyond.
Any questions?

12. References
International Food Information Council Foundation (2011, September 16). All about caffeine: Clarifying the controversies surrounding caffeine and health. Food insight: Your nutrition and food safety resource. Retrieved October 3, 2012, from pdf
International Food Information Council Foundation (2008, March). Caffeine & health: Clarifying the controversies. Food insight: Your nutrition and food safety resource. Retrieved October 3, 2012, from
International Food Information Council Foundation (2007, August 1). Fact Sheet: Caffeine and Health. Food insight: Your nutrition and food safety resource. Retrieved October 3, 2012, from nd_Health
U.S. National Library of Medicine, National Institutes of Health (2011, May 5). Caffeine in the diet. In Medline Plus Medical Encyclopedia. Retrieved October 3, 2012, from