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Transcript
Caffeine:
A positive addition to a
healthy lifestyle?
Ross Grant PhD
Australasian Research Institute
“ Coffee-drinking is used for social
engagement, leisure, enhancement of work
performance and well-being.”
“Unlike other [functional foods]….the wide
use of coffee-drinking impacts a broad
demographic (from children to elderly),
with a wide spectrum of health benefits.
Dorea J.G. etal. Br J Nutr (2005), 93:773-782
“Tea acts as a stimulant and, to a certain extent, produces
intoxication. The action of coffee and many other popular
drinks is similar. The first effect is exhilarating. The nerves
of the stomach are excited; these convey irritation to the
brain, and this in turn is aroused to impart increased action
to the heart and short-lived energy to the entire system.
Fatigue is forgotten; the strength seems to be increased.
The intellect is aroused, the imagination becomes more
vivid.
“Because of these results, many suppose that their tea or
coffee is doing them great good. But this is a mistake. Tea
and coffee do not nourish the system.
“The continued use of these nerve irritants is followed by
headache, wakefulness, palpitation of the heart,
indigestion, trembling, and many other evils; for they wear
away the life forces. Tired nerves need rest and quiet
instead of stimulation”. Ministry of Healing p326
Caffeine Use
by Age and Sex
Australia & New Zealand SDA 2001
Never
Tried
Past use
Current use
50%
40%
30%
20%
10%
0%
11-18 years
19-29 years
30+ years
The issue:
In recent times the ingestion of tea and
coffee has become a topic of debate within
the Adventist community.
The issue:
Is the introduction of caffeine into the SDA diet a
beneficial adjunct to an already well-balanced lifestyle?
Background: origins and sources
of caffeine
Molecular structure of caffeine identified by
German chemist Runge in 1918
Background: origins and sources
of caffeine
Coffee drinking in the middle east is
traceable to the 15th century
Sufi monks drank coffee to stay awake
during prayers (Yemen, Arabia)
By 1510 coffee was
widely used in all levels
of Arab society from
Cairo to Mecca
Background: origins and sources
of caffeine
Tea was consumed in China from at least the 6th
century AD
Olmec’s (ancient American civilization)
may have used cacao pods for making
chocolate drinks from 400BC
Carbonated beverages containing caffeine were
introduced by Coco-Cola in 1866 in Atlanta
Georgia, USA.
Common dietary sources of caffeine
Food/Beverage
Caffeine content
Instant coffee (1 tsp)
60-80 mg/250 mL
Percolated coffee
60-120 mg/250 mL
Instant decaffeinated
2 mg/250 mL cup
Tea
10-50 mg/250 mL
Tea decaffeinated
1 mg/250 mL cup
Coca-Cola
36-50 mg/375 mL
Milk Chocolate
20 mg/100g* bar
Energy Drinks (R.Bull)
80 mg/250mL can
Table 1: Caffeine content of selected foods (source: ANZFA caffeine report, 2001 and Choice Magazine
online (Sept, 2001)). *An average sized Mars bar weighs 80g
Common dietary sources of caffeine
Guarana
• Guarana is a woody climbing
plant that is native to the Amazon
basin
• Guarana seeds contain more
than 4% caffeine by weight, in
comparison with coffee beans
which may contain up to 2.2% by
weight depending on the variety
Absorption of Caffeine into the body
Caffeine is metabolized in the liver by CYP1A2
and is converted into the three products
paraxanthine, theobromine and theophylline
each of these have physiological effects on the
body.
Peak caffeine blood levels reached in 30-40
minutes
typical half-life of between 4-6 hours
Once caffeine is absorbed, it is able to enter all
body tissues and easily crosses the blood-brain,
placental and blood-testicular barriers
Action of Caffeine on the body
PHARMACOLOGICAL REVIEWS Vol. 51, No. 1. 1999
Action of Caffeine on the body
Principle action of caffeine is thought to be
through blocking adenosine receptors on
nerve tissue.
Caffeine
Serotonin
Function of Adenosine receptors
Adenosine levels are raised whenever there is an
increase in the amount of energy (ATP) consumption
compared to energy (ATP) synthesis.
Activation of adenosine receptors in various tissues
allow the body to modulate cellular activity in
response to decreasing energy (ATP) levels.
Distribution of Adenosine receptors
in the body
Brain
Lung
Muscle
Liver
Lymphocytes
Heart
Stomach
Pancreas
Fat tissue
www.survivaltechnology.com/.../ human-body.jpg
Action of Caffeine on the body
Receptor HEART
subtype
Heart rhythm
A1
Decrease heart rate
& force of atrial
contraction
& responsiveness
to adrenaline
A2A
Regulates blood
vessel tonedilation of the
coronary arteries
supplying blood to
heart and muscle
CNS
Wakefulnessdecrease in
electrical
excitability and
inhibition of
excitatory amino
acid (EAA) release
Anti-inflammatory
– increases
cerebral blood
flow
KIDNEY OTHER
Antidiuresis
Anti-lipolytic
insulin enhancer
Anti hypertensive
Wound healing
Hair growth
Wound healing
Anti – aggregation
of platelets
Increases gastric
mucosal blood
flow (ethanol)
Action of Caffeine on the body
The widespread prevalence of caffeinesensitive (adenosine) receptors in the
body suggests the likelihood of multiorgan involvement following caffeine
consumption.
Immediate effects of Caffeine
Positive:
Caffeine can increase serotonin and dopamine
release in the brain; somewhat mimicking the
effect caused by antidepressants. (Casas, 2004)
Elevated Mood; including increased;
Feeling of wellbeing
Alertness
Energy
Sociability
Immediate effects of Caffeine
Positive:
Studies indicate that:
Caffeine decreases reaction times and improves
vigilance, sustained attention and selective
attention (Smith, 2004).
Tasks requiring speed are more sensitive to
caffeine’s benefits than tasks involving intellectual
power (Snel, 2004).
NOTE: Caffeine seems to have either no effect or a
negative effect on memory (Smith, 2004).
Immediate effects of Caffeine
Negative:
Studies indicate that:
Higher doses of caffeine produce:
Anxiety
Jitteriness
Upset stomach
(Juliano and Griffiths, 2004)
Immediate effects of Caffeine
Negative:
Studies indicate that:
caffeine can exaggerate the body’s response to
stress by increasing heart rate and blood pressure
(Lane et al., 2002)
It is possible that caffeine alone may induce an
adrenocortical stress response during rest and in
the absence of explicit stressful challenge
(al'Absi and Lovallo, 2004)
Longer-term effects of Caffeine
Negative: cardiovascular
James (2004) suggests that population
studies of BP indicate that caffeine use
could account for:
14% of premature deaths due to coronary heart
disease, and
20% due to stroke.
Longer-term effects of Caffeine
Negative: cardiovascular
A prospective study of 1971 middle-aged men,
showed that heavy coffee consumption (814 mL or
more/day), increased the risk of acute myocardial
infarction or coronary death by up to 75%
compared to non- coffee drinkers (Happonen et
al., 2004).
Caffeine has been shown to, dose dependently,
increase serum homocysteine levels (Verhof et al.,
2002, Panagiotakos et al., 2004)
Increased serum cholesterol and urinary excretion
of 8-hydroxy-2-deoxguanosine in rats (Sakamoto
et al., 2005)
Longer-term effects of Caffeine
Negative: osteoporosis
Basic science experiments show that
caffeine increases calcium excretion in the
urine
In a prospective study of ~ 35 000 women
followed for 6.5 years a weak association of
highest caffeine intake (>6 cups daily) was
observed with osteoporosis
(Hansen et al., 2000).
Longer-term effects of Caffeine
Negative: Urinary
A high caffeine intake (>400 mg/d) was associated
with urinary urge incontinence in a study of
almost 260 women (overall risk, 2.4%; 95% CI,
1.1-6.5),
Note: This is similar to the likelihood of urinary
stress incontinence of a vaginal delivery compared
with caesarean delivery (2.4%; 95% CI, 1.7-3.2)
(Arya et al., 2000; Rortveit et al., 2003; HolroydLeduc and Straus, 2004).
Longer-term effects of Caffeine
Negative: Brain
Headache
Caffeine is considered a modest risk factor in
chronic daily headache, (Gadoth and HeringHanit, 2005).
Caffeine withdrawal headache, (beginning 1 to 2
days following cessation of regular caffeine use),
can last up to a week (van Dusseldorp and Katan,
1990).
Caffeine may disrupt sleep or aggravate mood,
both of which may exacerbate headache (van
Dusseldorp and Katan, 1990).
Longer-term effects of Caffeine
Negative: Behavioural
Dependence
Caffeine exhibits physical dependence in up to 30%
of consumers (Griffiths and Chausmer, 2000)
Some caffeine users may also demonstrate clinical
dependence (Strain et al., 1994).
Withdrawal symptoms (start 12-24hr–last 2-9 days)
Headache, fatigue, depressed mood, irritability,
nausea, vomiting muscle pain/stiffness
Longer-term effects of Caffeine
Negative: Behavioural
Sleep
Sleep is one of the physiological functions most
sensitive to the effect of caffeine in humans
200mg caffeine will:
Prolong sleep latency
Increase initial light sleep
Decrease later deep sleep
Increase shifts between sleep stages
Decrease in subjective sleep quality
Increased time taken to reach REM sleep
Longer-term effects of Caffeine
Negative: Brain
Can precipitate the onset and/or exacerbation
symptoms of anxiety disorders, including panic
disorder and obsessive-compulsive disorder,
(Smith, 2004).
Caffeine can interfere with the action of
medication used to treat anxiety disorders and
depression (Greden et al., 1981; Jefferson, 1988).
Long term caffeine use affects serotonin
metabolism in the brain of rats: implications for
depression (Haider etal 1998, Haleem etal 1995)
Longer-term effects of Caffeine
Negative: pregnancy/foetus
Caffeine is cleared at a slower rate from the
pregnant woman and foetus (t1/2 18hrs)
Caffeine readily crosses the placenta into the
foetus
Metabolising enzymes not present in foetus or
placenta (Grosso and Bracken, 2005).
Foetus therefore exposed to caffeine and its
metabolites for a prolonged periods of intrauterine life.
Longer-term effects of Caffeine
Negative: pregnancy/foetus
Conflicting reports - foetal development
Increased caffeine use may cause spontaneous
abortion
A decrease in intervillous placental blood flow has
been documented after maternal ingestion of just
200 mg of caffeine (Kirkinen et al., 1983).
May effect foetal oxygenation and nutrition
(Ghidini, 1996)
After reviewing several animal studies, Nakamoto
(2004) suggests that caffeine may affect
neurodevelopment; further human studies required
Longer-term effects of Caffeine
Negative: Child
Insufficient research precludes a definite conclusion
as to whether caffeine consumption during pregnancy
leads to mood disorders in children.
However, cortisol, which is increased by caffeine, may
influence the foetal hypothalamic-pituitary-adrenal axis
which controls the stress response
Prenatal stress has been linked to interference in neuron
development in the serotonergic system in late gestation
(Linnet et al., 2003; Lovallo et al., 2005).
Longer-term effects of Caffeine
Negative: Adolescence
Significantly higher anxiety scores were observed
in caffeine dependent 13-17 year-olds (13.7 ± 7.7)
compared with the non-dependent group (7.5 ±
5.9) (Bernstein et al., 2002).
It would be useful to study more about how much
caffeine children consume, and how this may
affect them as adolescents are currently exposed to
the opportunity to consume large amounts of
caffeine due to the introduction of energy drinks,
and frequenting of coffee lounges.
Longer-term effects of Caffeine
Positive:
Diabetes
Coffee drinkers in the highest category
(≥6 or ≥7 cups/day) showed a relative risk of 0.65.
(4-6 cups/day) had a relative risk of 0.72 compared
with the lowest category (0 or ≥2 cups/day).
Two reasons were suggested for the apparent protective
effect of caffeine against diabetes: 1. Coffee
contributes antioxidants to the diet (Pulido et al., 2003;
Svilaas et al., 2004). 2. Caffeine ingestion can acutely
reduce glucose storage (Greer et al., 2001).
However, authors don’t recommend increasing coffee
consumption as other health effects should first be
considered (van Dam and Hu, 2005).
Longer-term effects of Caffeine
Positive:
Gallstones
Leitzmann et al., ( 1999) reported that 4 cups of
coffee per day showed a relative risk of gallstone
formation of 0.55,
This indicates a 45% reduction in the risk of forming
gallstones in moderately heavy coffee drinkers.
Colon Cancer
Case-control studies seem to indicate a lower risk
of colon cancer associated with coffee drinking,
but cohort study results are less clear (Tavani and
La Vecchia, 2004).
Longer-term effects of Caffeine
Positive:
Parkinson’s disease
A 5-fold lower risk of developing PD was
observed in those who drank over 4 medium cups
of coffee per day.
This protection was not seen in decaffeinated coffee
(Xu et al., 2005).
Animal experiments also show that caffeine directly
protects against the death of neurons in Parkinson’s
disease (Xu et al., 2005).
CONCLUSIONS
Almost 2000 research papers have been
published that included caffeine as a research
variable in the title in the last 10 years
Almost universal use of caffeine throughout the
world have made well controlled studies
difficult
CONCLUSIONS
Caffeine is a drug that blocks activation of a specific
nerve receptor system
Benefits observed include reduced risk of Parkinson’s
disease, type 2 diabetes, colon cancer and gallstones
These are offset by negative biological effects;
physical dependence, exacerbation of anxiety
increased blood pressure & cardiac fatality risk
osteoporosis, urge incontinence,
potential harm to the foetus.
The collection of negative effects impact on
the quality of life in the community.
CONCLUSIONS
A lifestyle with moderate energy intake,
exercise and a diet high in fruit and
vegetables would not appear to benefit from
the inclusion of caffeine;
but would rather result in the addition of
unnecessary negative physiological
stressors.
“Tea acts as a stimulant and, to a certain extent, produces
intoxication. The action of coffee and many other popular
drinks is similar. The first effect is exhilarating. The nerves
of the stomach are excited; these convey irritation to the
brain, and this in turn is aroused to impart increased action
to the heart and short-lived energy to the entire system.
Fatigue is forgotten; the strength seems to be increased.
The intellect is aroused, the imagination becomes more
vivid.
“Because of these results, many suppose that their tea or
coffee is doing them great good. But this is a mistake. Tea
and coffee do not nourish the system.
“The continued use of these nerve irritants is followed by
headache, wakefulness, palpitation of the heart,
indigestion, trembling, and many other evils; for they wear
away the life forces. Tired nerves need rest and quiet
instead of stimulation”. Ministry of Healing p326