Is Caffeine a Friend or Foe?

Laura Williamson wrote . . . . . . . . .

Caffeine jump-starts your day and puts a bounce in your step. It can help you focus, improve your mood and maybe even help you live longer.

But how much is too much?

Caffeine, a natural stimulant, can be found in a variety of foods, such as coffee beans, tea leaves, cacao beans, guarana berries and yerba maté leaves. It also can be synthetically created and added to beverages such as soda and energy drinks. Research shows that about 90% of U.S. adults consume some form of caffeine every day.

One of the most popular ways people consume it is through coffee. Because of that, most caffeine research centers around this drink, said Dr. Greg Marcus, associate chief of cardiology for research and a professor of medicine at the University of California, San Francisco.

“The literature on the whole shows that coffee consumption is generally not a detriment to health,” he said. “But I am very reluctant to recommend anyone begin drinking coffee if they aren’t otherwise doing so, or to increase consumption for any health benefit.”

Studies have found caffeine can do both good and harm. People who regularly drink coffee may be less likely to develop chronic illnesses, such as cardiovascular disease, diabetes, Parkinson’s disease and some cancers. A few studies suggest they are less likely to die from heart disease and other illnesses.

According to the Food and Drug Administration, as much as 400 milligrams of caffeine a day – equal to four or five cups of coffee – is considered safe for healthy adults. An 8-ounce cup of green or black tea has 30-50 mg of caffeine. Energy drinks may contain 40-250 mg for every 8 ounces, and a 12-ounce can of caffeinated soda contains 30-40 mg.

In moderate doses – up to two 8-ounce cups of coffee – caffeine can make people less tired and more alert. Some studies suggest it can reduce appetite and lower the risk for depression. But high doses – 12 cups or more – can make people feel anxious, raise blood pressure and lead to heart palpitations and trouble sleeping. For people who consume caffeine regularly, stopping consumption abruptly can lead to symptoms of withdrawal, such as headaches, fatigue and depressed mood.

Determining how much is too much can be tough. A moderate amount of caffeine for one person may feel like a high dose for someone else. That’s because some people metabolize caffeine faster than others, Marcus said. Factors such as how much someone weighs and what medications they take also can play a role. The bottom line is, caffeine affects everyone differently.

“The compound is complex, and we need to recognize that not only might there be benefits and harms, but this may vary from one person to another,” Marcus said.

He and his colleagues recently completed one of the few randomized studies on caffeine consumption, which he presented at the American Heart Association’s Scientific Sessions last year. The researchers asked participants to drink – or refrain from drinking – coffee for no more than two consecutive days each for two weeks.

The findings, which are considered preliminary until the full results are published in a peer-reviewed journal, showed that people were more physically active and slept less on days they drank coffee than on days they went without. They also had more irregular heartbeats from the lower chambers of the heart but fewer episodes of abnormally rapid heartbeats from the upper chambers.

Marcus said one limitation of the study was that people were starting and stopping caffeine consumption, which could be causing an exaggerated reaction in people who were used to drinking it every day. “The effects of caffeine are attenuated when you drink it regularly,” he said. “The body adapts to that caffeine level. And more regular consumption of caffeine can speed up the metabolism.”

People who metabolized caffeine faster had fewer problems sleeping than those whose bodies broke it down more slowly, he said.

In his cardiology practice, Marcus tells patients who are having trouble sleeping or experiencing abnormal heart rhythms to see what role caffeine might be playing. “I generally advise that it is reasonable for patients bothered by trouble sleeping or with palpitations to experiment with their caffeine consumption. Take some time off of caffeine to see if it makes a difference.” But he does not give a blanket recommendation to avoid caffeine.

Marcus doesn’t distinguish between the caffeine that people get from coffee versus hot or iced tea. “There may be health differences between the two, but they haven’t been studied yet,” he said.

He is less flexible about the consumption of energy drinks, which typically have a higher concentration of caffeine, as well as added sweeteners or carbohydrates and no evidence they provide any health benefits. Research has found energy drinks can cause abnormal electrical activity in the heart and higher blood pressure that persists for several hours.

“In general, I would caution against the use of energy drinks,” Marcus said.

There are other ways to stay alert.

“The best strategies and overall most healthy strategies to boost alertness are long-term healthy habits,” such as getting a good night’s sleep and exercising regularly, Marcus said. He recommends people who have trouble staying awake consult a physician to see if they have sleep apnea or another sleep disorder.

Source: American Heart Association

 

 

 

 

High Caffeine Consumption May be Associated with Increased Risk of Glaucoma

Consuming large amounts of daily caffeine may increase the risk of glaucoma more than three-fold for those with a genetic predisposition to higher eye pressure according to an international, multi-center study. The research led by the Icahn School of Medicine at Mount Sinai is the first to demonstrate a dietary – genetic interaction in glaucoma. The study results published in the journal Ophthalmology may suggest patients with a strong family history of glaucoma should cut down on caffeine intake.

The study is important because glaucoma is the leading cause of blindness in the United States. It looks at the impact of caffeine intake on glaucoma, and intraocular pressure (IOP) which is pressure inside the eye. Elevated IOP is an integral risk factor for glaucoma, although other factors do contribute to this condition. With glaucoma, patients typically experience few or no symptoms until the disease progresses and they have vision loss.

“We previously published work suggesting that high caffeine intake increased the risk of the high-tension open angle glaucoma among people with a family history of disease. In this study we show that an adverse relation between high caffeine intake and glaucoma was evident only among those with the highest genetic risk score for elevated eye pressure,” says lead/corresponding author Louis R. Pasquale, MD, FARVO, Deputy Chair for Ophthalmology Research for the Mount Sinai Health System.

A team of researchers used the UK Biobank, a large-scale population-based biomedical database supported by various health and governmental agencies. They analyzed records of more than 120,000 participants between 2006 and 2010. Participants were between 39 and 73 years old and provided their health records along with DNA samples, collected to generate data. They answered repeated dietary questionnaires focusing on how many caffeinated beverages they drink daily, how much caffeine-containing food they eat, the specific types, and portion size. They also answered questions about their vision, including specifics on if they have glaucoma or a family history of glaucoma. Three years into the study later they had their IOP checked and eye measurements.

Researchers first looked at the relationship looked between caffeine intake, IOP and self-reported glaucoma by running multivariable analyses. Then they assessed if accounting for genetic data modified these relationships. They assigned each subject an IOP genetic risk score and performed interaction analyses.

The investigators found high caffeine intake was not associated with increased risk for higher IOP or glaucoma overall; however, among participants with the strongest genetic predisposition to elevated IOP – in the top 25 percentile – greater caffeine consumption was associated with higher IOP and higher glaucoma prevalence. More specifically, those who consumed the highest amount of daily caffeine– more than 480 milligrams which is roughly four cups of coffee – had a 0.35 mmHg higher IOP. Additionally, those in the highest genetic risk score category who consumed more than 321 milligrams of daily caffeine – roughly three cups of coffee – had a 3.9-fold higher glaucoma prevalence when compared to those who drink no or minimal caffeine and in lowest genetic risk score group.

“Glaucoma patients often ask if they can help to protect their sight through lifestyle changes, however this has been a relatively understudied area until now. This study suggested that those with the highest genetic risk for glaucoma may benefit from moderating their caffeine intake. It should be noted that the link between caffeine and glaucoma risk was only seen with a large amount of caffeine and in those with the highest genetic risk,” says co-author Anthony Khawaja, MD, PhD, Associate Professor of Ophthalmology University College London (UCL) Institute of Ophthalmology and ophthalmic surgeon at Moorfields Eye Hospital. “The UK Biobank study is helping us to learn more than ever before about how our genes affect our glaucoma risk and the role that our behaviors and environment could play. We look forward to continuing to expand our knowledge in this area.”

Source: Icahn School of Medicine at Mount Sinai

European Food Safety Authority Concludes 400 mg/day of Caffeine Is Safe

Single doses of caffeine up to 200mg and daily intakes of up to 400mg do not raise safety concerns for adults in Europe. These are two of the provisional findings of EFSA’s Scientific Opinion on the safety of caffeine from all sources. EFSA is now seeking comments and feedback on the draft document through a public consultation which is open until 15 March 2015.

EFSA is also planning to hold a stakeholder meeting in the first week of March 2015 to explain and discuss the draft opinion with interested parties. Details of the meeting will be announced shortly on EFSA’s website.

Other key provisional conclusions include:

  • Single doses of caffeine up to 200mg do not raise safety concerns for adults (18-65 years) also when consumed less than two hours before intense exercise.
  • It is unlikely that caffeine interacts adversely with other constituents of “energy drinks” – such as taurine and D-glucurono-γ-lactone – or alcohol.
  • For pregnant women, caffeine intakes of up to 200mg a day do not raise safety concerns for the foetus.
  • For children (3-10 years) and adolescents (10-18 years), daily intakes of 3mg per kg of body weight are considered safe.
  • Single doses of 100mg may increase sleep latency (the amount of time it takes to fall asleep) and shorten sleeping time in some adults.

Source: EFSA


Today’s Comic

Coffee and Tea during Pregnancy Affect Fetal Growth

Drinking just two cups of coffee a day is associated with the risk of low birth weight. Researchers at Sahlgrenska Academy have conducted a study on 59,000 women in collaboration with the Norwegian Institute of Public Health.

Expectant mothers who consume caffeine, usually by drinking coffee, are more likely to have babies with lower birth weight than anticipated, given their gestational age. Researchers at Sahlgrenska Academy conducted a study on 59,000 pregnant Norwegian women in collaboration with the Norwegian Institute of Public Health.

“The correlation between intake of caffeine and fetal growth was established even among women who followed the official recommendation that they limit caffeine consumption to 200 milligrams a day (two cups of coffee),” researcher Verena Sengpiel says.

Elevated risk of mobidity

The medical term used in this connection is “small for gestational age” (SGA), which is associated with an elevated risk of morbidity and death.

The new results are consistent with previous international studies but are based on a considerably larger cohort. The participants were healthy and had uncomplicated pregnancies until delivery, while the results were adjusted for age, smoking, body mass index, nicotine consumption, alcohol use and other variables that affect fetal growth.

Additional research needed

“We need to stress that our study did not examine whether caffeine is the specific mechanism substance by whichresponsible for the fetus is being at greater risk of low birth weight,” Ms. Sengpiel says. “Nor did we look at whether these babies actually had special health problems during the neonatal period. Additional research is needed before we can say for sure what our finding actually means for pregnant women and their babies.”

No correlation with premature birth

The other purpose of the study, which is being published in BMC Medicine, was to determine whether women who consumed caffeine during pregnancy were more likely to give birth prematurely. Such a correlation could not be established.

The research team is hoping to conduct more in-depth studies about the cause-effect relationship between caffeine use and SGA, as well as any correlation between SGA and neonatal morbidity and death.

Source: University of Gothenbury