Caffeine: The Genetics Behind Your Love/Hate Relationship
This four-part series takes a deep-dive into the genetics behind caffeine consumption, taste, metabolism, and side effects.
Part 2: Caffeine’s Tasty Side
Some like it black, while others need a little cream and sugar. These coffee preferences may be the result of genetics. In fact, numerous genetic variants have been linked to taste perception. In some individuals, the taste receptors for bitter-tasting compounds, like caffeine, are less sensitive than the general population.
Bitter Taste Perception
As a survival mechanism, humans developed an adaptation to taste toxic compounds as bitter. Plants produce many toxic bitter-tasting compounds, developed as pesticides, to disincentivize consumption. In response, herbivores developed more potent liver enzymes to neutralize these toxins, while omnivores (like humans) developed enhanced detection and screening mechanisms. It is estimated that 75% of humans have a relatively robust detection system, but some individuals have a diminished ability to sense bitter compounds. These individuals are less sensitive to the bitter taste of caffeine.
The type 2 taste receptors, or TAS2Rs, are responsible for tasting bitter compounds and one member in particular is responsible for tasting caffeine — Taste 2 Receptor Member 46 (TAS2R46). Genetic variants of this gene have been linked to reduced taste sensitivity. Since taste is one of the key drivers of food preferences and dietary habits, genetic variants that make individuals less sensitive to caffeine could drive dietary behavior. Individuals who are less sensitive to the bitter taste of caffeine may need less cream and sugar to mask the bitterness in their morning cup of joe. However, they may also be more likely to consume greater quantities — putting them at greater risk of sleep disturbances or anxiety if this trait is paired with other genetic variants.
Caffeine comes in two varieties — natural and synthetic.
The primary sources of natural caffeine are coffee, tea, and dark chocolate. These are derived from coffee beans, tea leaves, and cocoa beans.
The synthetic version of caffeine is produced in the lab with petroleum-based chemicals. It is often referred to as "anhydrous caffeine" on food labels and it is the version most often found in soft drinks and energy drinks.
Frequent consumers of natural caffeine sources, like coffee and tea, are noted to have better health than regular consumers of synthetic caffeine sources, like sodas (diet or regular) and energy drinks. It is unclear if this is a response to the type of caffeine or if it is a result of the phytonutrients (healthy plant compounds) that accompany natural sources of caffeine, but this distinction is important to note. Therefore, it is advisable to choose natural sources of caffeine. Caffeine content can vary dramatically by coffee bean or tea leaf variety, as well as by preparation method, so it is wise to check the caffeine content of a beverage before you drink it.
Daily Recommended Intake
According to the USDA's Dietary Guidelines, moderate coffee consumption can be part of a healthy diet. Moderate coffee consumption means 3-5 cups per day, providing approximately 200-400 mg of caffeine. For reference, one cup (8 oz) of brewed coffee contains 95 mg on average. A Starbucks Grande [16 oz] is a two-cup serving that provides 310 mg of caffeine. An identical serving of black tea will provide about 35 mg of caffeine, while green tea will give you 25 mg.
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