Caffeine, a xanthine alkaloid, appears in some of our favourite foods and beverages in various forms including coffee, tea (green, black and white), cola, ‘energy’ drinks, cocoa, chocolate, guarana and mate. It is also added to some pharmaceutical drugs and is available in popular over the counter stimulants.
Physiologically, caffeine has a stimulant effect on the body. It increases nerve cell activity in the brain and triggers the pituitary gland to release more adrenaline (also known as epinephrine, the ‘fight or flight’ hormone). Some of the effects include an initial sense of alertness, increased cardiac activity (heart beats faster) and a release of glycogen (stored sugar) giving us an energy boost. The first cup or two of caffeine may have what is perceived as being a positive effect on wellbeing, helping us think more clearly and act faster, those these benefits are reversed with increased intake. If you are already stressed, the added adrenaline will potentiate this state – increasing your chance of panic attacks, palpitations, insomnia, sweating etc.
However – as we are all individuals this can have different effects on us depending on how long it takes to metabolise caffeine, such as age, various medications and health of the liver. For example the half life (how long it takes the body to clear half of the caffeine from the body) in a healthy adult is about 3-4 hours, in a woman taking the oral contraceptive pill that increases to 5-10 hours, while in a pregnant woman it is up to 11 hours. The half life for a baby in utero or a newborn is even higher, so that even on one decent cup of caffeine a day via the mother’s milk the neonate may not have got rid of yesterdays intake fully before today’s hit.
Much of the conjecture as to whether caffeine may be harmful or beneficial comes down to genotype, how your individual blueprint dictates your metabolism of certain drugs. In science speak, it is all to do with your variant of the cytochrome P450 enzymes. Current wisdom deems that it is your variation of this enzyme that effects how you utilise caffeine (CYP1A21A allele are "rapid" caffeine metabolisers, whereas carriers of the variant CYP1A21F are "slow" caffeine metaboliers). For example see this study on caffeine metabolism and heart attack risk.
Interestingly, as caffeine is metabolised in the liver by the cytochrome P450 (enzyme) pathway – so do a number of herbs and drugs. The reason St John’s wort (and other herbs) is contraindicated with a number of pharmaceuticals (including the contraceptive pill, antivirals, anti-rejection drugs and some chemotherapy agents) is due to competing with this same metabolic pathway. Considering the popularity of coffee etc and quantity consumed – should there be a warning label slapped on your latte or cola drink?
Want to know more? Here's a good reference on the chemistry, metabolism and addictiveness of caffeine
Because there are so many variables in the way that caffeine is broken down in the body it could explain why it affects individuals so differently, though tolerance and addiction are also key players in the caffeine picture. This delicious alkaloid has a similar effect on dopamine, one of our ‘happy hormones’, as cocaine and heroin. It also interferes with another chemical, adenosine, which may cause insomnia. With less sleep we wake up ‘needing’ our caffeine hit to get going in the morning – and so the cycle continues.
When we abstain from our daily caffeine hits, the tiredness that many people experience is actually how you felt before – only the drug was masking it. So stopping caffeine doesn’t actually make you any tireder – rather it gets you in touch with where your body is really at. Increasing the amount of water you drink and taking a good multivitamin with at least 50 mg of B6, plus a few early nights should help remedy this.
There has been a flurry of negative studies about caffeine published recently, what is most significant is they overturn previous studies (or assumptions) as to benign or even beneficial effects of caffeine. These include an increase in first trimester miscarriage at even half (200 mg) the presumed ‘safe’ dose and a harmful rise in blood glucose levels in people with diabetes.
While most obstetricians have assured women for years that a caffeine intake equivalent of 3 standard cups of coffee a day in pregnancy will not harm the foetus, (keep in mind it was only a generation or ago that smoking in pregnancy wasn’t considered harmful) a study published this year in The American Journal of Obstetrics and Gynaecology has overturned this assumption. In a well-designed study a mere 200mg (just over one decent café cup of coffee) a day was shown to double the chance of miscarriage in the first trimester. This was shown to be even more detrimental in women who had previously had a miscarriage.
Previous studies have also shown a connection between delayed conception (ie: taking longer to get pregnant) and caffeine intake in women. Paradoxically, it may have a positive effect on sperm motility (though I have not cited the study this claim is based on).
The second negative study regarding caffeine to hit the news already this year is in connection with Type 2 diabetes. While previous investigations have suggested that caffeine may be beneficial for those with diabetes, a pilot study in this month’s issue of Diabetes Care, tracks the effects of pure caffeine (versus tea or coffee drinking) on blood sugar levels. On average blood glucose levels rose by 8% after caffeine though after an evening meal this could peak to 26%. While it had a very small sample size, considering that we already know that caffeine triggers the liver to release glycogen, there is compelling evidence that avoiding caffeine of all kinds could help diabetics achieve better control.
Other than ‘helping’ us think and act initially quicker, caffeine appears to assist bronchodilatation – meaning if you are an asthmatic at the beginning of an attack without your inhaler, a strong cup of coffee immediately may bring some relief. There are some studies that coffee drinking may also be protective against Parkinson’s disease.
Don’t forget that all forms of caffeine (even so-called ‘decaf’) can negatively impact on your absorption or utilisation of a variety of nutrients – especially calcium, protein, iron and water soluble vitamins (eg B and C) so keep caffeine consumption away for meal times and supplement taking.
Updates: Here are some other articles on interest on the topic.
Red bull - heart attack in a can?
Coffee psychosis
Showing posts with label miscarriage. Show all posts
Showing posts with label miscarriage. Show all posts
Monday, February 04, 2008
Tuesday, January 22, 2008
Caffeine and miscarriage
A study released this week has confirmed that caffeine intake in the first trimester of pregnancy increases the chance of early miscarriage. Most naturopaths advise women planning to become pregnant to stop drinking caffeine related drinks, especially coffee, and to resist drinking it again til after they have ceased breastfeeding. Yet conventional medicine has continued to declare that up to 300 mg of caffeine a day in pregnancy does no harm. While American literature equates this to 4 cups of coffee a day, it would be closer to 2 decent cups from a Melbourne barista.
But now a study published in the American Journal of Obstetrics and Gynaecology has found more than 200mg of caffeine a day doubled the risk compared to abstainers. That means just half the presumed ‘safe’ intake of caffeine doubles the chance of a miscarriage in the first 12 weeks of pregnancy.
Link to BBC report
Coffee 'raises miscarriage risk'
Pregnant women should consider avoiding caffeine, say researchers who found even moderate consumption in early pregnancy raises the miscarriage risk.
Currently, the Food Standards Agency sets an upper limit during pregnancy of 300mg - or four cups of coffee a day.
But an American Journal of Obstetrics and Gynaecology study found more than 200mg of caffeine a day doubled the risk compared to abstainers.
Experts said they would review the data to see if advice needed changing.
Pat O'Brien, consultant obstetrician and spokesman for the Royal College of Obstetricians and Gynaecologists, said based on the findings he would now be advising women in their first 12 weeks of pregnancy to abstain from caffeine altogether.
"The first 12 weeks is a very vulnerable time for the baby. It's when most miscarriages occur," he explained.
He said most women in early pregnancy went off the taste of caffeinated drinks anyway and so should not find abstaining from them too difficult.
But he said it was unclear whether pregnant women needed to avoid caffeine in later pregnancy.
Miscarriage risk
An estimated one in five pregnancies in the UK will end in miscarriage, affecting around 250,000 women in the UK every year.
There are a number of well-established risk factors, such as increased maternal age, a previous history of miscarriage, and infertility.
But the causes of the majority of miscarriages are not fully understood.
Caffeine has been mooted as a risk factor before, but studies have yielded conflicting results.
For the latest research, Dr De-Kun Li and colleagues at the Kaiser Permanente Division of Research, studied 1,063 women who had become pregnant in the last month or two.
300 mg of caffeine is roughly equivalent to:
Four average cups or three average mugs of instant coffee
Three average cups of brewed coffee
Six average cups of tea
Eight cans of regular cola drinks
Four cans of so-called "energy" drinks
400g (eight standard 50g bars) of normal chocolate
Caffeine content in a cup of tea or coffee varies by different brands and brewing methods
Source: Food Standards Agency
They asked the women to provide a detailed diary about their caffeine intake up to their 20th week of pregnancy.
When they compared this information with how many of the women had miscarried by 20 weeks gestation, 172 of the women in total, they found a link.
Compared with non-users, women who consumed up to 200mg of caffeine a day had an increased risk of miscarriage - 15% versus 12%.
For women who drank more than 200mg, the risk increased to 25%.
Abstinence
The increased risk appeared to be related to the caffeine itself, rather than other coffee ingredients because other caffeinated beverages such as tea and hot chocolate showed a similar trend to coffee.
Caffeine is able to cross the placenta to the foetus, but it is not clear what affect this has on the growing baby.
Dr Li said: "The main message for pregnant women from these findings is that they probably should consider stopping caffeine consumption during pregnancy."
Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/2/hi/health/7195500.stm
Published: 2008/01/21 05:06:05 GMT
But now a study published in the American Journal of Obstetrics and Gynaecology has found more than 200mg of caffeine a day doubled the risk compared to abstainers. That means just half the presumed ‘safe’ intake of caffeine doubles the chance of a miscarriage in the first 12 weeks of pregnancy.
Link to BBC report
Coffee 'raises miscarriage risk'
Pregnant women should consider avoiding caffeine, say researchers who found even moderate consumption in early pregnancy raises the miscarriage risk.
Currently, the Food Standards Agency sets an upper limit during pregnancy of 300mg - or four cups of coffee a day.
But an American Journal of Obstetrics and Gynaecology study found more than 200mg of caffeine a day doubled the risk compared to abstainers.
Experts said they would review the data to see if advice needed changing.
Women probably should consider stopping caffeine consumption during pregnancy. Study author Dr Li
Pat O'Brien, consultant obstetrician and spokesman for the Royal College of Obstetricians and Gynaecologists, said based on the findings he would now be advising women in their first 12 weeks of pregnancy to abstain from caffeine altogether.
"The first 12 weeks is a very vulnerable time for the baby. It's when most miscarriages occur," he explained.
He said most women in early pregnancy went off the taste of caffeinated drinks anyway and so should not find abstaining from them too difficult.
But he said it was unclear whether pregnant women needed to avoid caffeine in later pregnancy.
Miscarriage risk
An estimated one in five pregnancies in the UK will end in miscarriage, affecting around 250,000 women in the UK every year.
There are a number of well-established risk factors, such as increased maternal age, a previous history of miscarriage, and infertility.
But the causes of the majority of miscarriages are not fully understood.
Caffeine has been mooted as a risk factor before, but studies have yielded conflicting results.
For the latest research, Dr De-Kun Li and colleagues at the Kaiser Permanente Division of Research, studied 1,063 women who had become pregnant in the last month or two.
300 mg of caffeine is roughly equivalent to:
Four average cups or three average mugs of instant coffee
Three average cups of brewed coffee
Six average cups of tea
Eight cans of regular cola drinks
Four cans of so-called "energy" drinks
400g (eight standard 50g bars) of normal chocolate
Caffeine content in a cup of tea or coffee varies by different brands and brewing methods
Source: Food Standards Agency
They asked the women to provide a detailed diary about their caffeine intake up to their 20th week of pregnancy.
When they compared this information with how many of the women had miscarried by 20 weeks gestation, 172 of the women in total, they found a link.
Compared with non-users, women who consumed up to 200mg of caffeine a day had an increased risk of miscarriage - 15% versus 12%.
For women who drank more than 200mg, the risk increased to 25%.
Abstinence
The increased risk appeared to be related to the caffeine itself, rather than other coffee ingredients because other caffeinated beverages such as tea and hot chocolate showed a similar trend to coffee.
Caffeine is able to cross the placenta to the foetus, but it is not clear what affect this has on the growing baby.
Dr Li said: "The main message for pregnant women from these findings is that they probably should consider stopping caffeine consumption during pregnancy."
Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/2/hi/health/7195500.stm
Published: 2008/01/21 05:06:05 GMT
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