This seems to follow the same course as alcohol consumption. Only those with the proper genetic marker benefit. But your doctor will unlikely ever do gene testing prior to telling you coffee is bad for you because it raises your blood pressure. I most assuredly will not get gene testing to see if I'm in the right category.
Four key studies that link coffee to heart attacks and hypertension
Is drinking coffee good for you? Some research indicates that that simple question cannot be answered without knowing something about your DNA.
Maybe
the clearest evidence that genetics determines caffeine metabolism
arises from a study of twins, published in 2002, that indicates that the
speed with which a person processes caffeine is largely heritable.
At
the same time, other studies have identified a single nugget of our DNA
that seems to determine whether we process caffeine quickly or slowly.
That, in turn, appears to have a large effect on whether coffee is good
for your health.
For those who process caffeine slowly, this line
of research indicates, drinking coffee raises the risks of heart
attacks and high blood pressure. For those who process it quickly,
drinking coffee seems to be safe - it may even protect against a heart
attack or high blood pressure.
While researchers caution that
more work needs to be done, they suggest that giving the public a
general guideline regarding coffee doesn’t make sense. People are too
different.
Here are some of the highlights in this line of research.
For the key studies in favor of coffee, try this.
“The
interindividual differences in the 3-demethylation of caffeine alias
CYP1A2 is determined by both genetic and environmental factors.”
Pharmacogenetics, August 2002.
http://www.ncbi.nlm.nih.gov/pubmed/12172216
Finding:
Forty-nine identical twins and 34 fraternal twins were given 200
milligrams of caffeine; six hours later, a urine sample was taken. Those
sample were then analyzed to see how quickly each person had broken
down, or metabolized, the caffeine. In identical twins, the rates of
metabolism were about twice as correlated as they were in fraternal
twins. The scientists concluded that genetics largely determines the
rate at which a person processes caffeine.
“CYP1A2 phenotype and genotype in a population from the Carboniferous Region of Coahuila, Mexico.”
Toxicology Letters, April 2005
http://www.ncbi.nlm.nih.gov/pubmed/15763632
Finding:
Scientists in Mexico gave 46 volunteers a cup of instant coffee
containing 140 milligrams of caffeine. Eight hours later, urine samples
were collected. Those subjects who had one variant of the CYP1A2 gene
processed caffeine more than twice as quickly as those who had the
other, researchers found. Other similar efforts in China and Germany
found a link between the gene and caffeine metabolism, predominantly in
smokers.
“Coffee, CYP1A2 Genotype, and Risk of Myocardial Infarction”
JAMA, March 2006
http://www.ncbi.nlm.nih.gov/pubmed/16522833
Finding: Researchers
compared about 2,000 people in Costa Rica who had a heart attack with
2,000 others who had not, examining both how much coffee they drank, as
well as their DNA. In those subjects with the genetic marker indicating
slow caffeine metabolism, the chance of heart attack appeared to rise
with each cup of coffee. By contrast, those subjects with the genetic
marker for rapid caffeine metabolism had a lower chance of heart attack
with each cup.
The authors
concluded: “Intake of coffee was associated with an increased risk of
nonfatal [heart attack] only among individuals with slow caffeine
metabolism, suggesting that caffeine plays a role in this association.”
“CYP1A2 genotype modifies the association between coffee intake and the risk of hypertension”
Journal of Hypertension, August 2009.
http://www.ncbi.nlm.nih.gov/pubmed/19451835
Finding: Researchers
looked at the genetics, blood pressure and coffee habits of 553 young
Italian over more than eight years. As with heart attacks (see above),
the effects of coffee diverged depending on a person’s genetics.
For
those with the gene for slow caffeine metabolism, the risks of high
blood pressure rose dramatically with coffee intake. For those with the
gene for rapid caffeine metabolism, the risk of high blood pressure
dropped with coffee intake.
The authors concluded: People with
the slower caffeine metabolism “are at increased risk and should thus
abstain from coffee.” On the other hand, people with the genetics for
the rapid caffeine metabolism “can safely drink coffee.”
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