Coffee Drinking in Your Genes? Genetic Variants in Two Genes Linked With Caffeine Intake

Two genes in which variation affects intake of caffeine, the most widely consumed stimulant in the world, have been discovered. A team of investigators from the National Cancer Institute, Harvard School of Public Health, Brigham and Women's Hospital, and the University of North Carolina at Chapel Hill examined genetic variation across the entire genome of more than 47,000 individuals from the U.S., as described in the open-access journal PLoS Genetics.

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The genes identified were CYP1A2, which has previously been implicated in the metabolism of caffeine, and AHR, involved in the regulation of CYP1A2. Individuals with the highest-consumption genotype for either gene consumed ~40 mg more caffeine than those with the lowest-consumption genotype, equivalent to the amount of 1/3 cup of caffeinated coffee, or 1 can of cola.

Caffeine is implicated in numerous physiological and medical conditions; it affects sleep patterns, energy levels, mood, and mental and physical performance. The identification of genes that have an impact on daily consumption offers opportunities to better understand these conditions. Further exploration of the identified genetic variants may provide insight into the speed of caffeine metabolism, how long caffeine circulates in the blood, or how strong the physiological effects of consuming a given amount of caffeine are.

Apart from smoking, genetic determinants of lifestyle behaviors have generally not been consistently described. This study is among the first to examine the entire genome for a relationship between genetics and caffeine intake, a lifestyle behavior relevant to over 90% of U.S. adults. The study's success also suggests that additional genetic determinants of dietary and lifestyle behaviors may be identified in the future using a similar genome-based research strategy.

Organic Food in Pregnancy

Who eats organic food when they are pregnant? Is it just certain groups? What kind of organic foods are most popular? A recent study from the Norwegian Institute of Public Health provides some answers. The study includes nearly 65,000 women in the Norwegian Mother and Child Cohort Study.

"We know little about the consumption of organic food during pregnancy, and the goal of this study was to find out what is consumed and the characteristics of women who choose organic food," said PhD student Hanne Torjusen.

Questions were asked about six different food groups: milk and dairy products, bread and cereals, eggs, vegetables, fruit and meat. The results show that organic food is widely used among pregnant women in Norway across different groups.

One in ten consume organic food

Almost one in ten pregnant women consumes organic food regularly, and organic eggs and vegetables were most often selected. Compared to those who did not consume organic food, the women who did had the following characteristics:

• They were either in the group with more than 4 years of higher education, or in the group with under 12 years of education in total
• Most were either under 25 or over 40 years old
• There were many with low family incomes (below 300,000 Norwegian kroner per year)
• Many were students or had a partner who was a student
• They had normal or low weight (body mass index)
• They exercised frequently -- at least 3 times a week
• Overall, there were very few who were vegetarians (0.2 %), and a minority drank alcohol (11.6 %) or smoked (8.4 %) during pregnancy. However, the use of organic food is more widespread in these three groups.

"We see that although there are several elements that are consistent with health recommendations, organic food consumption in pregnancy is not unambiguously associated with what is perceived as a healthy lifestyle. It is also not uniquely associated with the group that traditionally is most healthy -- those with the highest education and income. This shows that it is important to take into account other factors besides education and income in the further research of possible health effects of organic foods in the diet," said Hanne Torjusen.

About MoBa

The study is based on a large number of women participating in the Norwegian Mother and Child Cohort Study (MoBa) from the Norwegian Institute of Public Health. MoBa is a unique follow-up study of 108,000 pregnancies among women recruited in the years 1999-2008.

This study includes 63,561 women who responded to two different questionnaires in MoBa during the years 2002-2007. The first questionnaire, containing questions on general health, was answered in week 15 of pregnancy. The second questionnaire about diet was answered during week 17-22 of pregnancy.