Are you a slow or fast metabolizer of caffeine & how does this affect your health?

Arden Arcade area Sacramento nutritionist, A.J.D took a DNA test at Family Tree DNA early in March, 2010 to find out the answers to two questions. Why does even a half cup of coffee cause a panic reaction or fast heartbeat or a piece of dark chocolate keep her up all night? And how would caffeine in the long term affect her general health?

Years ago, at the age of 23, even taking a pain medication for a toothache that contained caffeine kept her up all night with a fast heartbeat. One cup of coffee gave her tremors, and three cups of coffee in 1980 sent her to a hospital emergency room in the middle of the night with a fast heartbeat.

Her blood glucose went up to 140 early in the morning after consuming a pumpkin pie with three cups of coffee between the morning and evening. Did the coffee or the sugar wash out the little magnesium in her body? Or was it the sugar and raisins in the pumpkin pie?

She found out she was a fast caffeine metabolizer. Yet, she continues to get the shakes whenever she eats too much chocolate or drinks too much tea, yes, even decaf tea, that contains only around 9 percent of caffeine. She switched to ginger tea.

For some people, "food hits them like a bomb." All of a sudden, they start to shake and feel anxious, as if too much insulin and adrenalin is pouring into their blood as soon as they eat something that is not mainly protein. Their blood glucose levels may plummet to 60 after eating a tablespoon of honey, for example, as is what happened to Darcy, who has metabolic syndrome and gains weight primarily in the abdomen.

She no longer eats foods containing sugar, but will eat fresh fruit. A.J.D decided to take a caffeine metabolism test. She sent in a sample of DNA from a swab of her inner cheeks to Family Tree DNA. A few weeks later, she got the results. She's a fast caffeine metabolizer. Her body is supposed to metabolize caffeine quickly.

Yet she still reacts to caffeine with extreme sensitivity, as if her body can't get rid of it. She thinks, "maybe my body gets rid of it so fast that the caffeine hits so quickly, it's like a jolt where everything inside seems to speed up almost immediately." She gets the same reaction from dental anesthetics, even the type with no vaso-constrictors.

Some people have a liver that gets rid of caffeine quickly. They are called fast caffeine metabolizers. Other people have a liver that gets rid of caffeine slowly. These people are called slow caffeine metabolizers. But how does the rate at which your body gets rid of caffeine affect your general health?

First, you should know that the DNA test is a factoid test. It's for speculation or entertainment at cocktail parties. A factoid could resemble a fact, but is not necessarily a fact because it has not been proven. But genetic factoid tests are available currently at Family Tree DNA and other genetic testing companies to see how fast your body metabolizes a particular food or beverage.

The Caffeine Metabolism Factoid test is based on one study noted at the Family Tree DNA site. Basically the conclusion of the study revealed that the intake of coffee was associated with an increased risk of nonfatal MI (non-fatal heart attack) only among individuals with slow caffeine metabolism, suggesting that caffeine plays a role in this association.

A.J.D. took two of the factoid tests, one testing specific genes as related to caffeine metabolism, and another test, related to avoidance of errors. She was surprised at the results that she's a fast caffeine metabolizer.

Regarding the idea of tailoring your foods to your genes, you should know that when ordering or viewing your individual "Factoids", you acknowledge your understanding that these tests are based on studies - some of which may be controversial - and results are not intended to diagnose disease or medical conditions, therefore not serving the purpose of medical advice.

They are offered exclusively for curiosity purposes, for example, to see how your result compare with what the scientific papers say. Other genetic and environmental variables may also impact these same physiological characteristics. They are merely a conversational piece, or a "cocktail party" test.

Even if these tests are theoretical, at best, if you have the gene to metabolize caffeine slowly, that means the caffeine stays in your body longer. Why would you want to stress out your body with caffeine if your genes, organs, cells, and blood all have problems getting rid of caffeine?

Here's what the study pointed to, when it comes to tailoring your food and beverages to your genetic expression. And all you really can surmise is what the study points to.

According to the results of a case-control study reported in the March 8, 2006 issue of JAMA, coffee is the most widely consumed stimulant in the world, and caffeine consumption has been associated with increased risk for non-fatal myocardial infarction.

Caffeine is primarily metabolized by the cytochrome P450 1A2 in the liver, accounting for 95% of metabolism. Carriers of the gene variant *1F allele are slow caffeine metabolizers, whereas individuals homozygous for the *1A/*1A genotype are rapid caffeine metabolizers.

When A.J.D. read the results online at the Family Tree DNA browser, she first looked at the "results column" which offers the 3 possible results from the test, and the arrow labeled "your results" pointed to the one that has been verified for her.

The disclaimer on the site note that the results are not intended to diagnose disease or medical conditions, and do not serve the purpose of medical advice. They are offered exclusively for curiosity purposes, for example to see how your result compared with what the scientific papers say.

Other Variables May Impact The Same Physiological Characteristics

That explains why A.J.D. continues to feel anxious when consuming any food or beverage containing caffeine. Other genetic and environmental variables may also impact these same physiological characteristics. They are merely a conversational piece.

What Did the Actual Caffeine Study Reveal?

The association between coffee intake and risk of myocardial infarction (MI) remains controversial. According to the March 8, 2006 study, "Coffee, CYP1A2 genotype, and risk of myocardial infarction," AMA. 2006 Mar 8;295(10):1135-41, by authors, Cornelis MC, El-Sohemy A, Kabagambe EK, Campos H. Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada. Read the study and/or abstract at: JAMA. 2006 Aug 16;296(7):764-5; author reply 765-6.

The researchers used coffee in their study because coffee is a major source of caffeine, which is metabolized by the polymorphic cytochrome P450 1A2 (CYP1A2) enzyme. Individuals who are homozygous for the CYP1A2*1A allele are "rapid" caffeine metabolizers, whereas carriers of the variant CYP1A2*1F are "slow" caffeine metabolizers.

The purpose of the study was to find out whether CYP1A2 genotype modifies the association between coffee consumption and risk of acute nonfatal MI. DESIGN, SETTING, AND PARTICIPANTS: Cases (n = 2014) with a first acute nonfatal MI (nonfatal heart attack) and population-based controls (n = 2014) living in Costa Rica between 1994 and 2004, matched for age, sex, and area of residence, were genotyped by restriction fragment-length polymorphism polymerase chain reaction. A food frequency questionnaire was used to assess the intake of caffeinated coffee.

Researchers studied risk. That means they studied the risk of caffeine on the heart. They wanted to know whether people that are slow metabolizers of caffeine are more likely to suffer non-fatal heat attacks. The researchers compared specific genes of fast and slow metabolizers of caffeine. What the scientists studied was the relative risk of nonfatal MI (nonfatal heart attack) associated with coffee intake, calculated using unconditional logistic regression.

What they found as the results of the study, were that fifty-five percent of cases (n = 1114) and 54% of controls (n = 1082) were carriers of the slow *1F allele. So you have a majority of cases carrying the gene for slow metabolism of caffeine.

For carriers of the slow *1F allele, the multivariate-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of nonfatal MI associated with consuming less than 1, 1, 2 to 3, and 4 or more cups of coffee per day were 1.00 (reference), 0.99 (0.69-1.44), 1.36 (1.01-1.83), and 1.64 (1.14-2.34), respectively.

Corresponding ORs (95% CIs) for individuals with the rapid *1A/*1A genotype were 1.00, 0.75 (0.51-1.12), 0.78 (0.56-1.09), and 0.99 (0.66-1.48) (P = .04 for gene x coffee interaction). For individuals younger than the median age of 59 years, the ORs (95% CIs) associated with consuming less than 1, 1, 2 to 3, or 4 or more cups of coffee per day were 1.00, 1.24 (0.71-2.18), 1.67 (1.08-2.60), and 2.33 (1.39-3.89), respectively, among carriers of the *1F allele.

The corresponding ORs (95% CIs) for those with the *1A/*1A genotype were 1.00, 0.48 (0.26-0.87), 0.57 (0.35-0.95), and 0.83 (0.46-1.51). Basically the conclusion of the study revealed that the intake of coffee was associated with an increased risk of nonfatal MI (non-fatal heart attack) only among individuals with slow caffeine metabolism, suggesting that caffeine plays a role in this association.

So did the study suggest that caffeine plays a role in the association between having the gene for metabolizing caffeine slowly and non-fatal heart attack? If you are a fast metabolizer of caffeine and still have problems with it, maybe there are other factors involved besides the genes studied, whether in your organs, or environmental.

You react to foods and your environment at the cellular, chemical, molecular and even sub-atomical levels in addition to whether you have specific genes that metabolize foods, chemicals, or medicines at different rates. Ask yourself whether if you metabolize a specific food quickly, do you also metabolize your medicines or anesthetics fast as well?

Has anyone studied your genes on how you react to medicines so you can tailor your anesthetics or treatments to your individual genetic responses? Without doing your entire genome, how can you really know how your genes respond? Are the tests still in their infancy? Or can you learn to tailor foods to your body with some of these factoid tests based on medical studies?

This goes in the face of the latest studies, still controversial telling people to drink coffee to help protect against heart arryhthmias. Maybe with so many other factors involved, you should just gulp down coffee just because you hear it's safe on the news.

How do you know whether it's safe for you as an individual? That's why you need to apply your own body's response to foods or beverages rather than look at what studies show. There could be a lot more factors that determine what caffeine will do to you.

A.J.D.'s results of the Caffeine Metabolism Test looked like the following: