Caffeine can send the heart racing, but for some people it may help prevent abnormal heartbeats, according to Australian researchers report which found coffee and tea are safe and may sometimes reduce the frequency of abnormal heart rhythms (arrhythmias).
To see how caffeine affects patients with the common heart rhythm disorder known as atrial fibrillation, Kistler and colleagues looked at eight previously published studies.
The report published (April 16) in the journal JACC: Clinical Electrophysiology suggest that up to 300 milligrams of caffeine a day may be safe for patients with abnormal heartbeats.
In addition, the researchers found that caffeine had no effect on abnormal heartbeats in the lower chambers of the heart, called ventricular arrhythmias.
“Although coffee increases your heart rate, it does not make it abnormal,” explained senior researcher Dr. Peter Kistler, director of electrophysiology at Alfred Hospital and Baker Heart and Diabetes Institute in Melbourne.
“We found that there is no detrimental effects of coffee on heart rhythm and, in fact, coffee at up to three cups per day may be protective,” he added.
Some people, however, may notice palpitations after drinking coffee, and those folks should avoid caffeine, Kistler added.
“We have completed the largest review of the medical literature to date to determine the relationship between coffee and arrhythmias, or abnormal heartbeats,” he said.
Kistler’s group found that, among more than 228,000 patients, drinking coffee cut the frequency of episodes of atrial fibrillation by 6 percent. A further analysis of nearly 116,000 patients found a 13 percent risk reduction.
One cup of coffee contains about 95 milligrams of caffeine and acts as a stimulant to the central nervous system. Caffeine also blocks adenosine, a chemical that can trigger atrial fibrillation, Kistler explained.
As many as six cups of coffee a day, about 500 milligrams of caffeine, did not increase the severity or rate of ventricular arrhythmias, the study authors said.
Moreover, one study of 103 heart attack patients who got about 353 milligrams of caffeine a day found improved heart rate and no significant arrhythmias, according to the new report.
Two studies, however, found an increase in the risk for ventricular arrhythmias among patients who drank as much as nine or 10 cups of coffee a day.
But Kistler’s team did find that patients with heart conditions should avoid caffeinated energy drinks. These drinks can each contain 160 to 500 milligrams of concentrated caffeine.
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Vitamin D deficiency linked higher diabetes risk
KATHMANDU — People with vitamin D deficiency might have a greater risk of developing diabetes, researchers at the University of California San Diego School of Medicine and Seoul National University said in a new study report.
For the study published in PLOS One, researchers studied 903 healthy adults without pre-diabetes or diabetes during clinic visits from 1997 to 1999, and followed up with them for 10 years, to study their levels of 25-hydroxyvitamin and their medical condition.
Among the study participants, who had a mean age of 74, researchers found 47 new cases of diabetes and 337 new cases of pre-diabetes.
“Further research is needed on whether high 25-hydroxyvitamin D levels might prevent type 2 diabetes or the transition from pre-diabetes to diabetes,” study co-author Dr. Cedric F Garland, adjunct professor in the UC San Diego School of Medicine Department of Family Medicine and Public Health, said in a press release.
“But this paper and past research indicate there is a strong association,” he said.
The 25-hydroxyvitamin D, which is known as the ‘sunshine’ vitamin because it’s produced in your skin in response to sunlight, also can be received through certain foods and supplements. The vitamin helps in growth and development of bones and teeth, and resistance against certain diseases.
The minimum healthy level of 25-hydroxyvitamin D in blood plasma was listed as 30 nanograms per milliliter, which is 10 ng/ml above the level recommended in 2010 by the Institute of Medicine, now part of The National Academies.
“We found that participants with blood levels of 25-hydroxyvitamin D that were above 30 ng/ml had one-third of the risk of diabetes and those with levels above 50 ng/ml had one-fifth of the risk of developing diabetes,” first author Dr. Sue K. Park, of the Department of Preventive Medicine at Seoul National University College of Medicine in South Korea, said.
Those below 30 ng/ml were considered vitamin D deficient and up to five times at greater risk for developing diabetes than those above 50 ng/ml.
To reach the D levels of 30 ng/ml, Garland said it would require dietary supplements of 3,000 to 5,000 international units per day, but less with moderate daily sun exposure.
The recommended average daily amount of vitamin D is 400 IU for children up to 1 year, 600 IU for ages 1 to 70 years and 800 IU for persons over 70, according to the National Institutes of Health.
Good food sources for vitamin D include egg yolk, shrimp,salmon, sardines, fortified milk, cereal, yogurt and orange juice.
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