Caffeine Consumption in Adults

Caffeine is a naturally occurring drug found in more than 60 plant species. It stimulates the central nervous system and may temporarily increase alertness and relieve fatigue. Caffeine is found in a range of popular foods and beverages including coffee, tea, chocolate, cola flavoured soft drinks and energy drinks. Some medicines also contain caffeine.

Caffeine is the most commonly consumed psychoactive (affecting the mind or mood) drug globally. When consumed in moderation caffeine does not appear to have adverse health affects but excessive consumption poses health risks.

Australian statistics are limited, but as a guide, adults in Canada obtain some 60% of their caffeine from coffee, 30% from tea and the remaining 10% from a combination of chocolate, cola beverages and medications.

Humans have no nutritional requirement for caffeine and their health will not suffer if they do not consume any caffeine. However, caffeine can be consumed safely by humans, provided it is consumed in moderation. Research shows that most adults can consume up to 400mg of caffeine per day, without negatively affecting their health in terms of:

In Australia, it is recommended that individuals consume no more than 600mg of caffeine per day in order to avoid health risks. However, recommendations regarding how much caffeine an individual should consume vary from country to country. For example, in the United States health authorities recommend adults consume no more than 250mg of caffeine per day, while in Canada up to 400mg per day is considered safe for adults.

Some adults may be more sensitive to the effects of caffeine and need to consume less caffeine or avoid caffeine intake altogether in order to protect their health and wellbeing, including:

Pregnant women;Breastfeeding women;Individuals with peptic ulcers;Individuals taking medications which interact with caffeine;Individuals with cardiovascular disorders or risk factors such as high blood pressure. This is because caffeine increases cardiac risk factors including blood pressure and homocysteine (an amino acid found in blood, high concentrations of which are associated with cardiovascular disorders); andChildren.

Caffeine is a stimulant which can temporarily increase alertness and improve mood. However, when consumed in excess it may have negative health affects. You can use this tool to calculate your daily caffeine intake.

Caffeine overdose is rare and occurs in adults following consumption of >5-10mg of caffeine (equivalent to drinking about 80 cups of strong coffee in a row). However, symptoms of toxicity (poisoning) may occur with lower doses and include:

In severe cases caffeine overdose may lead side effects including:

Delirium;Seizures; and/orDeath resulting from seizure related breathing problems causing asphyxia (lack of oxygen).

Physical

Short term effects

Excessive caffeine consumption is associated with numerous short term physical health effects including:

Temporary changes to the heart - including increased heart rate, heart arrhythmia (abnormal heart rhythm) andincreased blood pressure. It should be noted that these temporary changes have not been shown to increase the risk of long term cardiac disorders such as coronary heart disease and irregular heartbeat (atrial fibrillation);Headaches;Excessive urination due to the diuretic effect of caffeine. It causes the kidneys to produce more urine and may in turn lead to dehydration, and increase the loss of dietary minerals including calcium, as these minerals are excreted from the body in urine;Nausea and vomiting;Increased secretion of gastric acids;Muscle tremors (involuntary muscle movements); andInsomnia (inability to sleep).

The exact amount of caffeine required to produce these effects varies from person to person, as individual bodies tolerate caffeine differently and some are more sensitive to its effects. Some individuals require only a small amount of caffeine (e.g. a cup of coffee) to produce these effects. Others, and particularly those who consume caffeine regularly, are less sensitive to its effects.

Appetite suppression

Caffeine is an appetite suppressant and individuals who consume excessive amounts of caffeine may eat less. Caffeine containing beverages may also replace more healthy alternatives including milk, water and juice.

Bone mineral density in women

Caffeine is a diuretic which increases urinary output and the excretion of calcium and other minerals, which may affect bone mineral density. However, the association between bone mineral loss and caffeine consumption remain inconclusive. Some studies have found associations between caffeine consumption and bone mineral loss, while others have not.

Other studies have found that the association between caffeine and bone mineral density depends on a woman's overall calcium intake. For example, one early study found that post-menopausal women with low calcium and high caffeine consumption had significantly reduced bone mineral density, but women who consumed the recommended daily intake of calcium (800mg) did not have reduced bone mineral density if they consumed a lot of caffeine. However, other studies indicate that excessive caffeine consumption may also negatively affect bone mineral density in women who consume adequate amounts of calcium.

A woman's history of oral contraceptive use and genetic factors may also influence the associations between caffeine intake and bone mineral density. One study showed that oral contraceptive use significantly reduced the amount of calcium lost through urination following caffeine consumption. The results of the study suggest that oral contraceptive use may protect against reduced bone mineral density arising from high caffeine consumption.

Another study reported that all post-menopausal women with caffeine consumption >300mg per day had significantly greater bone mineral loss compared to those consuming ?300mg per day. However genetic factors, specifically genetic differences in the way in which the body processes vitamin D, influenced the severity of bone mineral loss.

Psychological

The effects of excessive caffeine consumption may mimic those of psychological disorders including anxiety, sleep and eating disorders. Doctors are therefore likely to ask an individual about their caffeine intake, if they present with an anxiety or sleep disorder.

Anxiety disorders

Excessive caffeine intake is associated with increased anxiety and increased caffeine intake may worsen existing anxiety disorders.

Sleep disorders

Caffeine is a stimulant and its sleep disturbing effects are well documented. It reduces both slow wave sleep (in the early part of the sleep cycle) and rapid eye movement sleep (deep sleep in the later part of the cycle). Caffeine consumption increases periods of wakefulness, the time it takes an individual to fall asleep and difficulty individuals have falling asleep.

More information on Sleep

Eating disorders

While research evidence is limited, some doctors report that individuals with eating disorders may consume excessive caffeine in the belief that it will stimulate their metabolism and/or suppress their appetite and assist weight loss.

Sexual

There is also some evidence that caffeine consumption affects aspects of sexual and reproductive health for both men and women.

In vitro fertilisation outcomes

Caffeine consumption has been shown to reduce the likelihood of successful outcomes following assisted reproductive treatments, including in vitro fertilisation.

Pregnancy outcomes

Excessive caffeine intake may also negatively affect foetal development and pregnancy outcomes.

More information on Caffeine in Pregnancy.

Outcomes for breastfed infants

Excessive caffeine consumption during breastfeeding may have negative affects for the baby being breastfed.

More information on caffeine and breastfeeding

Cardiovascular disease

Initial evidence from research studies suggested that excessive caffeine intake may adversely affect the cardiovascular system and increase an individual's risk of cardiovascular disorders. However, later studies suggest that there is no association between excessive caffeine consumption and cardiovascular disorders. The American Heart Foundation has concluded that there is currently insufficient evidence to determine whether or not excessive caffeine consumption increases the risk of coronary heart disease.

There have been very rare cases of death associated with very high caffeine intake by individuals with existing heart disorders, but most individuals can tolerate moderate amounts of caffeine. Evidence demonstrates no association between caffeine consumption and an increased risk of atrial fibrillation, and most studies have not found an increased risk of coronary heart disease. However, caffeine consumption is associated with increased blood pressure and homocysteine, which are risk factors for cardiovascular disease. Because of these effects it is recommended that individuals with cardiac disorders or risk factors for developing cardiac disorders limit their caffeine intake.

Gastro-oesophageal reflux disease

Caffeine affects the gastrointestinal system and numerous studies of the associations between caffeine consumption and gastro-oesophageal reflux disease (GORD) have been conducted. However, results are conflicting and there is currently insufficient evidence to determine whether or not caffeine intake influences an individual's risk of developing this disease.

Infertility

Research investigating the effects of caffeine consumption on fertility is limited. Current evidence is inconsistent, meaning that some studies indicate caffeine consumption reduces fertility, while others do not. As such there is insufficient evidence to suggest an association between caffeine consumption and reduced fertility. However, there is some evidence that combined smoking and caffeine consumption negatively affects sperm health.

Fibrocystic breast disease

While early uncontrolled studies linked caffeine consumption to fibrocystic breast disease (a condition characterised by non-cancerous lumps in the breasts), later studies indicate caffeine does not play a causative role in the development of this common disease.

Migraine headaches

Caffeine may be used to relieve migraine headaches.

Fatigue and drowsiness

Consuming caffeine can provide short term relief from fatigue and drowsiness. It may also increase alertness and improve an individual's mood. However, it is important to note that individuals who consume large amounts of caffeine to relieve short-term fatigue (e.g. to allow them to stay up studying late at night) may feel tired and lethargic the following day.

Type 2 diabetes mellitus

Of 17 studies conducted, 14 showed that caffeine consumption lowers the risk of type 2 diabetes mellitus amongst both men and women, obese and non-obese individuals. Many of the studies, which have been conducted amongst a range of ethnic groups, have found a dose-response relationship, meaning that the more caffeine and individual consumed, the less likely they were to develop diabetes. In addition, caffeine intake has been shown to reduce insulin sensitivity in the short term. However, this is not an indicator to start consuming greater quantities of caffeine.

Stroke

Data from the Nurses Health Study suggest that caffeine consumption reduces the risk of stroke in women.

Parkinson's disease

Men who regularly consume caffeine have a lower risk of developing Parkinson's disease.

Moderate caffeine consumption reduces the risk of Parkinson's disease in women who do not use hormone replacement therapy, but increases the risk in those who take post-menopausal hormones. Women with high caffeine intake who use hormones are almost 4 times more likely to develop Parkinson's disease.

Reducing caffeine consumption

Individuals who consume too much caffeine (>600mg daily) should attempt to reduce their caffeine intake. The best approach is to reduce caffeine intake gradually, for example by replacing one caffeinated drink with one non-caffeinated drink each day. This will reduce the likelihood of withdrawal symptoms, which may occur if caffeine is eliminated completely from the diet.

Individuals who have heart problems, take medications that interact with caffeine or women who may become pregnant should also consider reducing their caffeine intake, even if they consume

For more information on caffeine, including consumption by adults, children and pregnant women, as well as some useful tools, see Caffeine.For more information on nutrition, including information on?types and composition of food, nutrition and people, conditions related to nutrition, and diets and recipes, as well as some useful videos and tools, see Nutrition.?National Institutes of Health. Caffeine in the diet. 2009. [cited 2010, June 23]. Available from: http://www.nlm.nih.gov/medlineplus/ency/article/002445.htmWinston AP, Hardwick E, Jaberi N, Neuropsychiatric effects of caffeine. Advances Psychiatric Treat. 2005; 11: 432-9.National Institutes of Health. Caffeine. 2010. [cited 2010, June 23]. Available from: http://www.nlm.nih.gov/medlineplus/caffeine.htmlAustralian Drug Foundation. Caffeine- fact sheet. 2003. [cited 2010, July 2]. Available from: http://www.druginfo.adf.org.au/druginfo/fact_sheets/caffeine/caffeine.htmlHealth Canada. Caffeine. 2010. [cited 2010, June 23]. Available from: http://www.hc-sc.gc.ca/hl-vs/iyh-vsv/food-aliment/caffeine-eng.phpNawrot P, Jordan S, Eastwood J, Rostein J, Hugenholt A, Feeley M. Effects of caffeine on human health. Food Addit Contam. 2003; 20(1): 1-30.Katan MB, Schouten E, Caffeine and arrhythmia. Am J Clin Nutr. 2005; 81(3): 539-40.NSW Health. Caffeine- fact sheet. 2007. [cited 2010, June 29]. Available from: http://www.health.nsw.gov.au/factsheets/drugandalcohol/caffeine.htmlListon J. Breastfeeding and the use of recreational drugs: alcohol, caffeine, nicotine and marijuana. Breastfeeding Review. 1998: 6(2): 27-30.National Drug and Alcohol Research Centre- University of New South Wales. Caffeine- fact sheet. 2001. [cited 2010, June 30]. Available from: http://ndarc.med.unsw.edu.au/NDARCWeb.nsf/resources/NDARCFact_Drugs6/$file/caffeine+fact+sheet.pdfNational Health and Medical Research Council. Dietary Guidelines for Australian Adults. 2003. [cited 2010, June 23]. Available from: http://www.nhmrc.gov.au/publications/synopses/dietsyn.htmHigdon JV, Frei B, Coffee and health: a review of recent human research. Crit Rev Food Sci Nutr. 2006; 46(2): 101-23.American Heart Association. Recommendations- Caffeine. 2010. [cited 2010, June 23]. Available from: http://www.americanheart.org/presenter.jhtml?identifier=4445Ilich JZ, Brownhill RA, Tamborini L, Crncevic-Orlic Z. To drink or not to drink: how are alcohol, caffeine and past smoking related to bone mineral density in elderly women. Am J Nutr. 2002; 21(6): 536-44.Harris SS, Dawson-Hughes B, Caffeine and bone loss in healthy postmenopausal women. Am J Clin Nutr. 1994; 60: 573-8.Rapuri PB, Gallagher JC, Kinyamu HK, Ryschon KL, Caffeine intake increases the rate of bone loss in elderly women and interacts with vitamin D receptor genotypes. Am J Clin Nutr. 2001; 74(5): 694-700.Ribeiro-Alves MA, Trugo C, Donangelo CM, Use of oral contraceptives blunts the calciuric effects of caffeine in young adult women. J Nutr. 2003; 133: 393-98.Royal College of Obstetricians and Gynaecologists. Fertility: assessment and treatment for people with fertility problems. 2004. [cited 2010, June 29]. Available from: http://www.rcog.org.uk/womens-health/clinical-guidance/fertility-assessment-and-treatment-people-fertility-problems.Lohsiriwat S, Puengna N, Leelakusolvong S. Effect of caffeine on lower esophageal sphincter pressure in Thai healthy volunteers. Dis Esophagus. 2006; 19: 183-88.Ashton CH. Caffeine and health. BMJ. 1987; 297: 1293.van Dam RM. Coffee consumption and risk of type 2 diabetes, cardiovascular diseases and cancer. Appl Physiol Nutr Metab. 2008; 33(6): 1269-83.Lopez-Garcia E, Rodriguez-Artalejo F, Rexrode KM, Logroscino G, Hu FB, van Dam RM. Caffeine consumption and risk of stroke in women. Circulation. 2009; 119: 1116-23.Ascherio A, Chen H, Schwarzschild MA, Zhang SM, Colditz GA, Speizer FE. Caffeine, postmenopausal estrogen and risk of Parkinson's disease. Neurology. 2003; 60(5): 790-5.

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Caffeine Consumption in Children and Teens

Caffeine is a naturally occurring drug which stimulates the central nervous system and may increase an individual's alertness and concentration. It is the only psychoactive drug (drug which affects the mind or mood) that is legally available to children and adolescents. While caffeine is generally considered safe for consumption in moderation by adults and children, concerns have been raised about the health effects of children consuming large quantities of caffeine.

A United States study reported that 57% of children 9 years and under consumed caffeine. In the US, 31% of 12-17 year olds report regularly consuming energy drinks. An Australian survey found that 27% of 8-12 year old boys consumed energy drinks in the two weeks prior to the survey.

Canadian statistics indicate that children obtain their caffeine mostly from cola beverages (55%) and tea (30%). Chocolate also contributes a considerable proportion of the caffeine consumed by children (14%). Other sources, including medicines contribute only around 1% of children's caffeine intake. A US based survey of children 9 years and under reported similar results. US children obtained 52% of their caffeine from carbonated beverages, 28% from tea, 2% from coffee and 18% from chocolate.

The 2007 Australian Child Nutrition Survey estimated the daily caffeine intake of Australian children for the first time. That survey reported increasing caffeine consumption with increasing age. Children aged 2-3 years consumed 3.4mg of caffeine daily and 4-8 year olds consumed 8.1mg of caffeine. Caffeine intake increased to 19.2mg in the 9-13 year age group and 41.7mg amongst 14-16 year olds. On average, boys consumed slightly more caffeine than girls.

Maximum daily caffeine intake

It is recommended that children and adolescents consume no more than 2.5mg of caffeine per kg of body weight per day.

Safe consumption of energy drinks

A recent trend which has created considerable concern amongst health professionals is the regular consumption of caffeinated energy drinks by children. Most energy drinks contain approximately 80mg of caffeine per 250ml can or about the same amount as a cup of coffee. However, some energy drinks contain as much as 300mg of caffeine. In Australia, legal loop-holes mean that energy drinks sold as "dietary supplements" can contain more than the 80mg of caffeine usually prescribed as the maximum caffeine quantity.

There are conflicting opinions about how much energy drinks can be safely consumed by a child. Some experts believe that only excessive consumption of caffeinated energy drinks poses a health risk, while others believe that even moderate consumption may be dangerous at a young age and that addiction or dependency is likely in children who regularly consume energy drinks. In some European countries(including Denmark, Norway, Sweden, Germany and Turkey) have banned entirely or placed restrictions on the sale of caffeine-containing energy drinks to children (under 15 years of age) due to concerns about the safety of children consuming the large amounts of caffeine these drinks contain. Australia has recently banned five brands of energy drink with a very high caffeine content (>320mg per litre). In the absence of research demonstrating the safety of caffeinated energy drinks in childhood, some experts recommend a cautious approach and that children should not consume these products at all.

Caffeine is a stimulant which can temporarily increase alertness and improve mood. However, when consumed in excess it may have negative health affects. You can use this tool to calculate your daily caffeine intake.

Few studies have been conducted to investigate the effects of caffeine consumption in children over one year of age and there are no long term studies of the health effects of caffeine consumption in those agedsimilar effectsas caffeine consumption in adults. Then again, children are smaller than adults and will be more sensitive to the effects of an equal amount of caffeine because of their lower body weight.

Behavioural effects

Behaviour may be affected, particularly in children, as caffeine is a stimulant. Some teachers have noted that children who consume energy drinks are impulsive and disruptive in the classroom. Caffeine intake may also result in temporary side effects including irritability, restlessness, difficulty concentrating and sleepiness, particularly in the afternoon. This may in turn affect school performance.

Sleep disturbances

School children who consume >50mg of caffeine per day experience more wakefulness than those who consume ?10mg per day.

Bed wetting

Children who consume caffeine may suffer from bed wetting. Guidelines recommend that children who wet the bed avoid caffeine.

Appetite suppression

Caffeine is an appetite suppressant and individuals who consume excessive amounts of caffeine may eat less. Caffeine containing beverages may also replace more healthy alternatives including milk, water and juice. This is a particular concern for children, whose nutrition may be affected even from consuming caffeine in moderation. Consumption of caffeine in the form of energy drinks may also lead to dehydration during sports and dental problems if the drinks also contain large quantities of sugar.

Food preference, diabetes and obesity

Caffeine affects parts of the brain which make an individual feel rewarded and/or addicted. It is therefore believed that caffeine consumption may influence the food preference of young people who regularly consume sugary caffeinated drinks. For example, young people who regularly consume caffeinated soft drinks may develop a preference for sugary drinks because they feel rewarded when they drink sugary caffeinated drinks. This has potential implications for a child's nutritional status as energy drinks are high in calories and sugar (a 250ml can may contain up to 9 teaspoons of sugar). Regular or over-consumption may increase the risk of nutritional disorders such as obesity and diabetes. In addition, sugary caffeinated drinks which typically have no nutritional value (do not contain vitamins and other healthy micronutrients) may affect a child's nutritional status if they are consumed as substitutes for nutritional beverages such as milk, water and juice.

Increased hyperactivity

Caffeine consumption in children with attention deficit hyperactivity disorder (ADHD) has been reported to increase hyperactive behaviour. However, a study of caffeine therapy in children with ADHD reported the opposite. Caffeine therapy reduced aggression, impulsivity and parent and teacher perceptions of the severity of symptoms of ADHD in children. (Please note this was conducted under medical supervision.)

Apnoea (breathing difficulty) of prematurity

Caffeine is one of the drugs most commonly used for treating newborn babies in the intensive care unit. It has been used as a respiratory stimulant in this setting for more than 30 years. Caffeine therapy increases survival rates and improves neurological outcomes in premature infants. A large randomised controlled trial of infants born premature and weighing 500-1,250 grams at birth, reported that those treated with caffeine therapy were 23% more likely to survive without neurodevelopment disability after 18-21 months, compared to infants who did not receive caffeine therapy. Caffeine treated babies were 42% less likely to develop cerebral palsy and 19% less likely to experience a developmental delay. Caffeine therapy also reduced the length of time for which the preterm infants needed machine-assisted breathing.

The effects of caffeine vary from person to person and are affected by size, weight and previous intake of caffeine. Caffeine overdose may occur in children following consumption of relatively small amounts of caffeine. While overdose in adults occurs following consumption of 5-10g of caffeine, children may experience the toxic effects of caffeine overdose following consumption of 1g of caffeine. Children who drink around seven cups of strong coffee (or 12 cans of energy drink) may experience caffeine overdose, which results in a range of symptoms and can be fatal.

Symptoms of caffeine overdose include:

In order to reduce caffeine intake in children, replace their coffees and other caffeinated beverages with calcium rich beverages such as coffee flavoured milk and decaffeinated cappuccino or cafe latte.

For more information on caffeine, including consumption by adults, children and pregnant women, as well as some useful tools, see Caffeine.For more information on nutrition, including information on?types and composition of food, nutrition and people, conditions related to nutrition, and diets and recipes, as well as some useful videos and tools, see Nutrition.?Oddy WH, O'Sullivan TA. Energy drinks for children and adolescents- erring on the side of caution may reduce long term health risks. BMJ. 2010; 340: 64.Ahuja JKC, Perloff BP, Caffeine and Theobromine Intakes of Children: Results from CFII 1994-96, 1998. Fam Economics Nutr Rev. 2001; 13(2): 47-51.O'Dea J & Rawstorne P. Consumption of dietary supplements and energy drinks by schoolchildren. Med J Aust. 2000 Oct 2; 173(7): 389.Health Canada. Caffeine. 2010. [cited 2010, June 23]. Available from: http://www.hc-sc.gc.ca/hl-vs/iyh-vsv/food-aliment/caffeine-eng.phpDepartment of Health and Ageing. 2007 Australian National Nutrition and Physical Activity Survey- Main Findings. 2008. [cited 2010, July 2]. Available from: http://www.health.gov.au/internet/main/publishing.nsf/Content/phd-nutrition-childrens-survey-keyfindingsNawrot P, Jordan S, Eastwood J, Rostein J, Hugenholt A, Feeley M. Effects of caffeine on human health. Food Addit Contam. 2003; 20(1): 1-30.Smith PF, Smith A, Miners J, McNeil J, Proudfoot A, Report from the Expert working Group on The Safety Aspects of Dietary Caffeine. Australia New Zealand Food Authority. 2000. Available from: http://www.foodstandards.gov.au/consumerinformation/adviceforpregnantwomen/caffeine/safetyaspectsofdieta890.cfmBritish Columbia Community Nutrition Council- School Food Advisory Committee. Caffeine and the student body. 2007. [cited 2010, July 2]. Available from: http://www.bced.gov.bc.ca/health/caffeine.pdfNational Institutes of Health. Caffeine in the diet. 2009. [cited 2010, June 23]. Available from: http://www.nlm.nih.gov/medlineplus/ency/article/002445.htmAustralian Drug Foundation. Caffeine facts. 2011. [cited 2010, July 2]. Available from: http://www.druginfo.adf.org.au/drug-facts/caffeineLogan R. Hey ‘cool kid', where's your drink bottle? Sports Nutr. 2006. [cited 2010, July 3]. Available from: http://www.ausport.gov.au/__data/assets/pdf_file/0010/144937/hey_cool_kid.pdfLeon MR, Effects of caffeine on cognitive psychomotor and affective performance of children with Attention-deficit/hyperactivity disorder. J Att Disorders. 2000; 4(1): 27-47.Schmidt B, Roberts RS, Davis P, Doyle LW, Barrington KJ, Ohlsson A, et al. Long term effects of caffeine therapy for apnoea of prematurity. NEMJ. 2007; 357(19): 1892-93.Seifert SM, Schaechter JL, Hershorin ER, et al. Health effects of energy drinks on children, adolescents and young adults. Pediatrics. 2011; 127: 511-29. [Full Text]

Vande Walle J, Rittig S, Bauer S, et al. Practical consensus guidelines for the management of enuresis. Eur J Pediatr. 2012. [online Ahead of print] [Abstract]

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Caffeine Consumption While Breastfeeding

Caffeine is a naturally occurring substance which stimulates the central nervous system. In doing so, it may temporarily increase alertness and relieve fatigue. While it is not nutritionally required by humans, most adults can safely consume moderate amounts of caffeine. Breastfeeding women can also safely consume caffeine, but they should consume less caffeine than non-breastfeeding women, to protect their health and the health of their breastfed baby.

Many women feel excessively tired and stressed in the breastfeeding period, as at this time they are also adapting to the lifestyle changes associated with having a newborn baby. Some women may use caffeine to increase alertness and relieve fatigue, without considering that caffeine is a drug which may adversely affect their baby's health. It is important to remember that caffeine is transferred to a baby through the mother's breastmilk, and excessive consumption by the mother may have adverse health effects for the baby.

Caffeine consumed by a breastfeeding woman is transferred to her breastmilk as quickly as 15 minutes after consumption. Breastmilk concentrations are highest approximately one hour after caffeine consumption, although caffeine may remain present in breastmilk for up to 14.5 hours. However, the concentration of caffeine in breastmilk does vary between individuals, due to differences in the ways individuals metabolise?caffeine.

Evidence suggests that babies breastfed by women who consume large quantities of caffeine (> 750 mg per day or 6–8 cups of coffee) are exposed to 0.6–0.8 mg of caffeine in breastmilk per day. While this is only a fraction of the caffeine to which the mother is exposed, babies, particularly in the first month of life, metabolise caffeine much more slowly than adults.

In neonates (babies less than four weeks old) caffeine has a 97.5-hour half life. This means that it takes the neonate's body 97.5 hours to reduce the quantity of caffeine by half. So, if a baby was exposed to 0.8mg of caffeine at a given point in time, 0.4mg of caffeine would remain in its system after 97.5 hours (about 4 days), and 0.2mg would remain in its system 195 hours later (approximately 8 days), if the baby was not exposed to any further caffeine. Each further 0.8mg of caffeine the baby was exposed to would also take 197 hours to reduce to 0.2mg of caffeine, and so caffeine could quickly accumulate in the system of a young baby.

The time a baby takes to metabolise caffeine does reduce as they age. While caffeine has a half-life of 97.5 hours in neonates, the half life in newborns (4 weeks-6 months) is 80 hours and this reduces to 2.5 hours by the time the baby is six months old.

It is interesting to note that the increased metabolism time for caffeine in newborns may relate in part to the effects of breastfeeding. Some components of breastmilk are thought to inhibit the function of cytochrome P450, the cytochrome which metabolises caffeine.

It is recommended that lactating women restrict their caffeine intake to less than 300mg per day. However, it is important to note that smoking appears to increase the health risks of caffeine consumption in breastfeeding women. Therefore smoking women who breastfeed may need to further restrict their caffeine intake. A doctor or other health professional can provide advice about reducing caffeine intake and quitting smoking if you have difficulty.

Caffeine is a stimulant which can temporarily increase alertness and improve mood. However, when consumed in excess it may have negative health affects. You can use this tool to calculate your daily caffeine intake.

For lactating women, evidence suggests that excessive caffeine consumption is associated with:

Reduced breastmilk production, which may mean that the woman cannot produce as much milk as her baby wants to consume;Recurrent mastitis (inflammation of the breasts).

While research evidence is lacking, health professionals who work closely with breastfeeding women believe that infants breastfed by women who are heavy caffeine consumers are more likely to experience the following health problems:

Agitation;Being unsettled;Sleep difficulties;Being jittery;Being colicky (having upset stomachs); and/orConstipation.

Nutritional deficiencies, particularly iron deficiency

Excessive caffeine consumption by a breastfeeding woman changes the composition of her breastmilk. In particular, research has shown that the breastmilk of heavy coffee consumers contains approximately one-third less iron than the breastmilk of women who do not consume caffeine. Women who consume caffeine and their babies have also been shown to have reduced levels of haemoglobin (the component of blood responsible for oxygen transport) and haematocrit (red blood cell) levels, both of which are affected by iron concentrations. Iron deficiency can lead to conditions such as anaemia.

Dental health

One study which compared the teeth of baby rats breastfed by mother rats who were and were not given caffeine supplements, reported a higher rate of dental cavities in babies fed by the rats on caffeine supplements. However, studies have not been conducted to investigate the effects of caffeine use in breastfeeding and the dental health of human babies.

Reducing caffeine consumption

Breastfeeding women should consume no more than 300mg (about three cups of brewed coffee) each day.Women who consume more caffeine than this may find it difficult to reduce their intake and should reduce their caffeine intake gradually to avoid withdrawal symptoms. For example they might replace one caffeinated beverage with a non-caffeinated beverage each day, until their caffeine consumption is below the recommended level.

For more information on caffeine, including consumption by adults, children and pregnant women, as well as some useful tools, see Caffeine. For more information on breastfeeding, including what to eat while breastfeeding and contraception after childbirth, see Breastfeeding.Nawrot P, Jordan S, Eastwood J, Rostein J, Hugenholt A, Feeley M. Effects of caffeine on human health. Food Addit Contam. 2003; 20(1): 1-30.Liston J. Breastfeeding and the use of recreational drugs: alcohol, caffeine, nicotine and marijuana. Breastfeeding Review. 1998: 6(2): 27-30.Berlin CM, Denson HM, Daniel CH, Ward RM. Disposition of dietary caffeine in milk, saliva and plasma of lactating women. Pediatrics. 1984; 73(1): 59-63.NSW Health. Caffeine- factsheet. 2007. [cited 2010, June 29]. Available from: http://www.health.nsw.gov.au/factsheets/drugandalcohol/caffeine.htmlNational Institutes of Health. Breastfeeding- self care. 2009. [cited 2010, July 3]. Avialable from: http://www.nlm.nih.gov/medlineplus/ency/article/002454.htmNakamoto T, Cheuk SL, Yoshino S, Falster AU, Simmons WB. Cariogenic effect of caffeine intake during lactation on first molars of newborn rats. Arch Oral Biol. 1993; 38(10): 919-22.American Heart Association. Recommendations- Caffeine. 2010. [cited 2010, June 23]. Available from: http://www.americanheart.org/presenter.jhtml?identifier=4445

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Caffeine

Caffeine is a natural substance found in more than 60 plant species. These include tea leaves, coffee beans, guarana and cocoa seeds. Caffeine can also be produced synthetically and added to certain foods, beverages and medications.

Caffeine is one of a group of drugs called methylxanthines, which have several effects on the body:

Caffeine is the most commonly consumed psychoactive (affecting the mind or moods) drug globally and the consumption of natural caffeine has a long history. Coffee has been consumed in Arabia since the 13th century and tea has been consumed in China for several thousand years.

Caffeine is found in many foods, beverages and medications. Naturally occurring caffeine is found in coffee, tea, cocoa and chocolate.Some nuts also contain caffeine, for example kola nuts which are consumed as a nut but also used to make tea in parts of West Africa. Caffeine is also present in many soft drinks, particularly cola flavoured drinks and energy drinks. A typical cola drink will contain about one third to one quarter the amount of caffeine found in an equal volume of coffee.

Synthetically produced caffeine is a component of many common medications, including cold and flu, appetite suppressing and pain relieving (analgesic) medications.

However, it is important to note that not all the caffeine contained in a product is necessarily detailed in the ingredient list. If caffeine occurs naturally in an ingredient of the product (e.g. guarana) the ingredient may be listed but not the caffeine it contains. Only if synthetically produced caffeine is added will it appear on the ingredients list as caffeine. In addition, caffeine can be removed from foods in which it is naturally found through a process known as decaffeination, for example with decaffeinated coffee and tea.

Globally, the average caffeine intake per person is 70mg per day (approximately equivalent to the amount of caffeine contained in one cup of instant coffee). However, individuals in developed countries consume more caffeine. In the United States, individuals consume on average 200mg (1-1.5 cups of coffee brewed from coffee beans) of caffeine per day.

In Australia, research conducted in the 1980s indicated that average per capita caffeine consumption is 240mg per day (about two cups of coffee bean coffee per day). This equates to 2.8 kg of coffee and 5.8 kg of chocolate per person per year.

The amount of caffeine which can be safely consumed varies between individuals. In Australia, health authorities recommend that adults consume no more than 600mg of caffeine per day. However, individuals who are sensitive to the effects of caffeine consumption, particularly pregnant and lactating women and children, should consume less caffeine.

Caffeine is a stimulant which can temporarily increase alertness and improve mood. However, when consumed in excess it may have negative health affects. You can use this tool to calculate your daily caffeine intake.

When a human consumes caffeine, the substance is absorbed, distributed and excreted in the urine very quickly. It does not accumulate in the bloodstream or body tissues. Following absorption, caffeine is directed to the brain where it stimulates the nervous system. It also stimulates the heart and increases smooth muscle relaxation. As smooth muscles regulate the flow of blood through the body, this can affect an individual's blood flow.

Caffeine is metabolised by the liver and is typically excreted in urine within several hours of consumption. While it remains in the body caffeine increases the release of free fatty acids stored in fatty tissues. It also affects the kidneys, which causes increased urination which may in turn cause an individual to become dehydrated.

Caffeine is an addictive substance. Following regular consumption of as little as 350mg of caffeine per day (within the recommended safe limits, equivalent to roughly three cups of coffee bean coffee) an individual may become dependent on caffeine. Caffeine addiction can be physical or psychological and varies in severity. Some addicted individuals will be mildly dependent on caffeine while others will compulsively consume caffeine.

Individuals who are addicted to caffeine may experience withdrawal symptoms if they stop consuming caffeine. Individuals who consume large amounts of caffeine and wish to reduce their consumption, should therefore reduce caffeine consumption gradually, for example by substituting one caffeinated drink per day with a non-caffeinated beverage.

Caffeine withdrawal may result in side effects in caffeine dependent individuals. Symptoms usually begin 12-24 hours following the last dose of caffeine and persist for 24-48 hours. However, heavy caffeine consumers may experience withdrawal symptoms earlier (within six hours of the last dose) and the symptoms may last for a longer period of time.

Symptoms of caffeine withdrawal include:

For more information on caffeine, including consumption by adults, children and pregnant women, as well as some useful tools, see Caffeine. For more information on nutrition, including information on?types and composition of food, nutrition and people, conditions related to nutrition, and diets and recipes, as well as some useful videos and tools, see Nutrition.?National Institutes of Health. Caffeine in the diet. 2009. [cited 2010, June 23]. Available from: http://www.nlm.nih.gov/medlineplus/ency/article/002445.htmWinston AP, Hardwick E, Jaberi N, Neuropsychiatric effects of caffeine. Advances Psychiatric Treat. 2005; 11: 432-9.National Institutes of Health. Caffeine. 2010. [cited 2010, June 23]. Available from: http://www.nlm.nih.gov/medlineplus/caffeine.htmlAustralian Drug Foundation. Caffeine- fact sheet. 2003. [cited 2010, July 2]. Available from: http://www.druginfo.adf.org.au/druginfo/fact_sheets/caffeine/caffeine.htmlNational Health and Medical Research Council. Dietary Guidelines for Australian Adults. 2003. [cited 2010, June 23]. Available from: http://www.nhmrc.gov.au/publications/synopses/dietsyn.htmHealth Canada. Caffeine. 2010. [cited 2010, June 23]. Available from: http://www.hc-sc.gc.ca/hl-vs/iyh-vsv/food-aliment/caffeine-eng.phpNational Drug and Alcohol Research Centre- University of New South Wales. Caffeine- fact sheet. 2001. [cited 2010, June 30]. Available from: http://ndarc.med.unsw.edu.au/NDARCWeb.nsf/resources/NDARCFact_Drugs6/$file/caffeine+fact+sheet.pdfNSW Health. Caffeine- fact sheet. 2007. [cited 2010, June 29]. Available from: http://www.health.nsw.gov.au/factsheets/drugandalcohol/caffeine.htmlAmerican Heart Association. Recommendations- Caffeine. 2010. [cited 2010, June 23]. Available from: http://www.americanheart.org/presenter.jhtml?identifier=4445

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Caffeine Consumption During Pregnancy

Caffeine is a naturally occurring substance which stimulates the central nervous system and can temporarily relieve tiredness and increase alertness. While humans have no nutritional requirement for caffeine (caffeine is not an essential part of the human diet), most adults can safely consume moderate amounts of caffeine. Pregnant women can also safely consume caffeine, however they should consume less caffeine than non-pregnant women, to protect the health of their developing foetus.

Caffeine is passed onto the foetus via the placenta (the membrane that nourishes the foetus during pregnancy). A foetus is therefore exposed to caffeine when it is consumed by a pregnant woman. However, cytochrome P450 1A2, which breaks down caffeine in children and adults, is absent in the foetus. As a result, a foetus cannot metabolise caffeine, and caffeine entering the foetus's system is not cleared out.

It is recommended that pregnant women restrict their caffeine intake to 200 mg per day to reduce the risk of adverse affects to the pregnancy and the foetus. A doctor or other health professional can provide advice about reducing caffeine intake if you have difficulty.

Caffeine is a stimulant which can temporarily increase alertness and improve mood. However, when consumed in excess it may have negative health affects. You can use this tool to calculate your daily caffeine intake.

Consuming excessive caffeine during pregnancy is associated with a range of adverse health outcomes for the woman and her foetus.

Pregnancy outcomes

Excessive caffeine consumption (> 300 mg per day) during pregnancy has been associated with bearing a low birth weight infant (an infant which weighs less than 2.5 kg at birth) and miscarriage. However, not all studies have shown a relationship between caffeine intake and pregnancy outcomes. This may be because studies have relied on women's reports of how much coffee and tea they drink to measure caffeine intake. This may not be a reliable measure, as women may not remember exactly how much coffee and tea they drink, or they may also consume caffeine in other products, such as chocolate and medication which they do not report to researchers.

Restricted foetal growth and low birth weight

A study involving over 7,000 Dutch women found that high caffeine consumption was associated with bearing a small for gestational age child (a child which is smaller than expected for the length of the pregnancy, taking into consideration that a baby born premature is smaller than a baby born at full term) and impaired foetal growth. Another study of British women reported an increased risk of foetal growth restriction with caffeine intake ? 100 mg per day, which is less than the recommended safe levels. Women with daily caffeine consumption of 100–199 mg had a 1.2 times increased risk of foetal growth restriction while those who consumed 200–299 mg had a 1.5 times increased risk of foetal growth restriction.

Miscarriage

The link between caffeine intake and miscarriage were examined in a recent Swedish study. Non-smoking women who consumed more than 300 mg of caffeine per day were more likely to experience a miscarriage between 6–12 weeks gestation than those who consumed less caffeine. The risk of miscarriage increased relative to the amount of caffeine consumed. Non-smoking women consuming 300–499 mg were 1.4 times more likely to miscarry and those consuming ? 500 mg were 2.2 times more likely to miscarry.

Outcomes for infants born to women who consume caffeine during pregnancy

Sudden infant death syndrome

A New Zealand study reported that the babies of women who consumed greater than 400 mg of caffeine per day during pregnancy were 1.65 times more likely to die of sudden infant death syndrome than the babies of women who consumed less caffeine.

More information on SIDS.

Sleep apnoea

The New Zealand study also found that infants born to women who consumed high quantities of caffeine whilst pregnant were more likely to experience sleep apnoea (difficulty breathing during sleep).

Pregnant women who consume more than 200mg of caffeine daily (about two cups of brewed coffee) should reduce their caffeine consumption whilst pregnant. Health professionals advise individuals to reduce their caffeine consumption gradually, for example by replacing one caffeinated drink with a non-caffeinated alternative each day, in order to avoid withdrawal symptoms.

For more information on caffeine, including consumption by adults, children and pregnant women, as well as some useful tools, see Caffeine.
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For more information about pregnancy, including preconception advice, stages of pregnancy, investigations, complications, living with pregnancy and birth, see Pregnancy.

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