Caffeine: The Genetics Behind Your Love/Hate Relationship — Part 2

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 Sources

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.

 

Check back soon for the next article in the series!

 

Caffeine: The Genetics Behind Your Love/Hate Relationship — Part 1

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 1: Caffeine’s Unpleasant Side

Caffeine is prized the world over for its ability to increase alertness and reduce fatigue. On the other hand, it has also been known to produce side effects of increased heart rate, jitters, anxiety, and insomnia. The major method by which caffeine produces its effects is by influencing the adenosine signaling pathway. Understanding this pathway is essential for understanding the side effects that can result from excessive caffeine consumption and the role genes play in side effects such as insomnia and anxiety.

Adenosine: Your Battery Meter

Adenosine is used as an indicator of current energy stores, and when energy stores are depleted it signals to slow everything down so that energy stores can be replenished. Adenosine is made when you burn ATP, the body's main energy currency. High levels of adenosine indicate that ATP is being burned faster than it is being made, sending a signal that an ongoing activity must be slowed. Adenosine acts as a sort of battery manager, as your cell phone's battery is depleted, background apps are shut off in order to conserve battery power for only essential operations. High levels of adenosine are why you feel fatigue after an intense workout and they are also why you feel tired or sleepy as your bedtime nears.

While very high levels of adenosine produce potent feelings of fatigue, a baseline or basal level of adenosine in your cells allows for wakefulness. When adenosine levels drop below this baseline, you experience feelings of alertness. Just as high levels of adenosine signal a lack of fuel, low levels of adenosine signal an abundance of fuel. Fuel demanding to be used! This is how caffeine works its magic.

Caffeine Hacks Your Battery Meter

Caffeine, and the byproducts of its metabolism, bind to adenosine receptors, block adenosine from binding, and in so doing, trick the cell into thinking that adenosine levels are low. This is the signal that there is fuel to burn, so energy and activity are increased. There are several different adenosine receptors, but caffeine and its metabolites target two in particular — the A1 and A2A receptors. These receptors are just the first step in a long signaling chain, so their triggering produces a series of effects.

Caffeine-Induced Insomnia

Genetic variants in the adenosine A1 and A2A receptors have also been associated with poor sleep in response to caffeine. Poor sleep can mean either a reduction in sleep quality, lots of tossing and turning, or reduction in sleep duration due to trouble staying asleep. The disruption of sleep produced by caffeine is not related to a person's ability to metabolize caffeine; instead, it is a function of the brain's initiation and control of sleep. In studies of individuals with nearly identical caffeine metabolism, and identical amounts of caffeine in their blood, people with caffeine-sensitive adenosine receptors suffered from worse sleep.

Caffeine-Induced Anxiety

One of the downstream effects of caffeine binding involves the neurotransmitter dopamine and may play a role in producing feelings of anxiety. While dopamine has often been described as "the pleasure chemical,” the neurotransmitter is involved in both reward-seeking behaviors and pain-avoidance behaviors. Reward-seeking behaviors are encouraged by triggering feelings of pleasure when a task is accomplished or an item is obtained. On the other hand, pain-avoidance behavior can be promoted by triggering feelings of fear and anxiety.

For example, when a child commits to a lengthy search for the cookie jar and they find it, they enjoy pleasure sensations along with their cookie. Tenacity and commitment are encouraged. On the other hand, if a child were to accidentally come into contact with a hot stove during their cookie search, feelings of pain and fear would wash over them. By promoting anxiety when near the stove, the child would be protected from further injury.

Genetic variants in both the adenosine A2A receptor [ADORA2A] and the dopamine D2 receptor [DRD2] have been associated with feelings of anxiety and stress in response to caffeine.

 

Check back soon for the next article in the series!

 

Lactose Intolerance

 

 

Whipped cream, milk, and ice cream: delicious dairy products that up to 65% of the world’s population cannot easily digest. Is your body sensitive to lactose? Learn about the science and genetics behind lactose intolerance and check your genes for this common trait!

A (brief) summary of lactose intolerance

The sugar found in dairy products like milk is called lactose. In order for it to be used as an energy source, it must be broken down into two simple sugars: glucose and galactose. The enzyme that accomplishes this is called lactase. Without the production of lactase in the small intestines, an individual cannot digest lactose and it passes undigested to the large intestines (or colon). Here an individual's bacterial colonies, or gut microbiota, make use of the energy source, but their metabolism of lactose produces gas and other byproducts. The diminished ability to produce lactase and the symptoms of bloating, abdominal cramps, nausea, and diarrhea are referred to as lactose intolerance.

The influence of genes

DNA contains regions that code for enzymes, as well as regions that regulate genes. The lactase enzyme is produced from the LCT gene and has at least one regulator — MCM6. The MCM6 gene that is upstream from, or ahead of, the LCT gene plays a role in regulating the gene. Several genetic variants (or SNPs) in the MCM6 gene have been linked to lactose intolerance.

Check your genetic variants for the “Lactose Intolerance

 

Global genetic varaiations

Interestingly, the SNPs related to lactose intolerance vary widely by ethnicity.

 

In people of European descent, two genetic variants in the MCM6 gene that have been linked to lactose intolerance. [R1]

In people of African descent, research has identified three different SNPs in the MCM6 gene. [R1R2]

In people of Asian descent, studies have identified three additional SNPs in the MCM6 gene. [R1R3]

 

These variations suggest that the mutations developed separately, but for similar reasons — a process called convergent evolution. In other words, the ability to digest milk was incredibly valuable for populations that relied on domesticated animals for food. In times of famine and reduced food availability, those in pastoralist communities who could digest milk were more likely to survive and produce offspring. These strong evolutionary pressures existed primarily in the pastoralist populations in Africa and Europe.

For more, watch this video: “Got Lactase? The Co-Evolution of Genes and Culture”

 

Two types of lactose intolerance - Genetic vs acquired

While pastoralist populations developed the ability to digest lactose throughout the lifespan, all infants have the ability to digest the lactose in human breastmilk.

Primary lactose intolerance is the most common type, and is determined by genes. Normally, an infant’s body produces a substantial amount of lactase to break down all the milk being consumed. As other food begins replacing milk in a child’s diet, the production of lactase decreases. This sharp decrease results in too little lactase for the amount of dairy consumed by a typical adult.

Secondary lactose intolerance on the other hand occurs when the body decreases lactase production following an injury, illness, or surgery related to the small intestine.

Fight Photoaging with Vitamins E & K

The sun is out! Protect your skin from photoaging with the right vitamins and minerals.

Up to 90% of the visible signs of aging — and most types of skin cancer — are caused by the sun’s UV rays. Long-term sun exposure can cause premature aging of the skin, including wrinkles, pigmentation, and sunspots. This is known as photoaging, and the rate at which it happens is influenced by our genes.

How does photoaging happen?

Photoaging is the premature aging of the skin due to repeated exposure to UV radiation. UV radiation causes DNA damage and oxidative stress, a situation in which the production of harmful free radicals overwhelms the body’s ability to neutralize them using antioxidants. In order for the body to protect itself from oxidative stress, the skin produces several enzymes built with antioxidants including vitamin E, vitamin K, vitamin C, vitamin A, iron, and selenium.

While modest UV exposure can prompt the body to increase epidermal thickness, which helps to protect from further UV damage, prolonged exposure overwhelms the skin’s antioxidant defense system. This damage of overexposure, referred to as photoaging, manifests as facial pigmented spots and wrinkles. It is the result of both diminished collagen production (needed to increase epidermal thickness) and diminished antioxidant activity.

Check your Skin Care Reports for the Photoaging, Facial Pigmented Spots, and Skin Antioxidant Deficiency traits.

 

The Importance of Antioxidants

Our bodies produce a number of antioxidative and detoxifying enzymes, such as superoxide dismutases (SODs), to fight free radicals and prevent damage to our skin. However, in order to work properly, SODs require certain minerals, such as copper and zinc, to act as cofactors. To achieve maximum protective capacity, it is important to ensure adequate daily intake of these minerals. This daily need may be higher if you have certain genetic variants that are associated with copper or zinc deficiency.

Check your Nutrition Reports for these traits!

Additionally, genetic variations in the NRF2, SOD2, and CAT genes have been associated with reduced antioxidant activity in cells throughout the body and an increased risk of damage to lipids and proteins in the skin. It is even more harmful for individuals with these genetic variants to have reduced dietary intake of antioxidants — i.e. to not get the recommended FIVE daily servings of vegetables and fruits.

Do you need to keep a close eye on your vegetable intake? Check your risk of “Skin Antioxidant Deficiency.”

 

Vitamins E and K Fight Photoaging

Vitamin E is a fat-soluble antioxidant which absorbs UV rays from the sun to protect your skin, thus preventing wrinkles, dark spots, and certain types of skin cancer. It is an essential ingredient in the sebum, the oil secreted by the skin for protection and hydration. Vitamin E’s anti-inflammatory and hydrating properties keep the skin looking youthful. In order to maximize its benefits as an antioxidant, make sure to get enough vitamin C and B3 as well because their presence enhances vitamin E’s activity.

Vitamin E: How Much and From Where? Check this handy guide.

While vitamin E prevents photoaging by acting as an antioxidant, vitamin K works to treat other skin troubles to keep the skin healthy and youthful, minimizing the effects of photoaging. Its main functions as a vitamin are blood clotting to heal wounds and strengthening capillaries to heal bruises. Vitamin K additionally helps treat spider veins, stretch marks, and dark spots, while increasing circulation to reduce undereye darkness and puffiness. Vitamin K: How Much and From Where? Check this handy guide.

Fun fact: A recent study found that the MC1R gene, which is responsible for pale skin and red hair, is also linked to increased photoaging.

This gene codes for a protein that plays a role in normal pigmentation. It is found on the surface of melanocytes, which are cells responsible for the production of melanin — the pigment giving skin, hair, and eyes their colour. There are 2 types of melanin produced: eumelanin and pheomelanin. People with more eumelanin tend to have brown or black hair and skin that tans easily. On the other hand, people with more pheomelanin production tend to have blonde or red hair, freckles, and less protection from UV rays and photoaging. One gene responsible for the synthesis of pheomelanin is the ASIP gene. Having variants of this gene could lead to an increased risk of facial pigmented spots with sun exposure, as it would lead to the clumping of melanin to form areas of hyperpigmentation. [NIH]
If you are worried about photoaging, protect yourself! By having a diet with sufficient vitamins, minerals, and antioxidants for your genetic makeup, you can reduce your the risk of photoaging and have plenty of fun outside this summer. ??

The Mediterranean Diet – Is this the one?!

Eating healthy doesn’t have to mean being restrictive, but rather being mindful of which foods work best for your body. To assess whether a certain dietary plan is best for you, it’s important to look at genetic predispositions you may have for a variety of influential traits, from nutrition to personality!

The Mediterranean diet consists mainly of plant-based foods such as fruits and vegetables, nuts and whole grains. It incorporates healthy fats, such as the monounsaturated fats [MUFAs] found in olive oil or avocados, and emphasizes fish while limiting red meat.

How could my genes affect the outcome of this diet?

Genetic variations in the ADIPOQ gene have been found to be associated with an increased advantage of following the Mediterranean diet, as a way to facilitate fat loss and improve metabolic health. Other genes contributing to the effectiveness of this diet include PPARG and LPL. Do you have any of these genes? All three of these genes are related to fat storage and are produced by your fat [adipose] cells. Imagine your fat storage apparatus as the organizational system in an airport. Molecules of fat would be the suitcases to be stored within the airplanes, or cells. PPARG is responsible for directing which line and to which gate the suitcases need to go through in order to reach the right plane. When suitcases are being checked in, adiponectin would in charge of determining how much space is available to accommodate them. Finally, the enzyme LPL is the labourer who does the hard work, loading each suitcase onto the planes, like molecules of fat entering the cells.

Variants of the mentioned genes could result in an LPL that doesn’t work as hard, for example, or PPARG that has trouble signalling efficiently. Due to these variations in how each person’s body deals with fat, the Mediterranean diet, rich in healthy fats, can be more beneficial for some than others.

Your Basic Wellness Package includes a report on the effectiveness of the Mediterranean diet for your health and wellness. However, having a genetic predisposition for this trait may not necessarily mean it is practical or even maximally effective for you. This is due to the fact that a combination of different traits affect how you lose weight, which nutrients your body needs most, and even how easily you embrace a specific lifestyle change. Delve a little deeper and find out!

What other traits should I look at?

For example, if your Vitamin Reports show a predisposition for Iron Deficiency and Vitamin C Deficiency, you may need to supplement your diet with foods rich in iron and vitamin C, such as oranges, strawberries, spinach, and poultry. Due to these predispositions, relying solely on the Mediterranean Diet — which is not particularly rich in these vitamins — would not be enough to cover all your body’s nutritional needs.

Example 2: If you are elevated for Sweet Tooth and Carb Overconsumption, you may find it more difficult to reduce your sugar intake and moderate your carbohydrate consumption. Thus embracing the Mediterranean diet, with its focus on carbs from vegetable, fruits, and whole grains and minimization of sweets, could be more challenging for you than the average person.. If you know whether you have predispositions for these traits, you can be aware of what makes a certain diet challenging for you to follow, and focus on making the necessary  adjustments.

Example 3: If someone has a predisposition for Satiety Impairment and Fat Taste Perception, the increased protein and healthy fats of the Mediterranean diet would help contribute to satiety and make the diet easier to follow.

 

Learn more and read a sample report here 

It’s All About Vitamin D!

Several studies have examined the relationship between vitamin D and mood disorders such as depression and seasonal affective disorder [SAD].

(Check your genes for SAD or Seasonality!)

One study found that depression was greater, as assessed by the Hospital and Anxiety Depression Scale (HADS), in people with deficient levels of vitamin D compared to people with normal levels. It was also found that just 1 hour of light therapy a day during winter months significantly decreased symptoms of depression in people with SAD, as compared to the control group. No wonder we tend to feel better when it's sunny! Interestingly, in addition to mood, another study found a link between vitamin D deficiency and worse cognitive performance in older adults.

Vitamin D production is initiated by sun exposure and is impacted by age, location (latitude), time of year, as well as the amount of melanin our bodies have, corresponding to skin pigmentation or colour.
If your Vitamin D Deficiency trait is at all elevated, check your Skin Care Report for traits such as Sensitivity to Sun, Facial Pigmented Spots, Poor Tanning Ability, etc. You may have genetic predispositions that increase the risk of sensitivities due to UV rays of the sun, making it a wiser choice to incorporate foods rich in vitamin D into your diet and to avoid prolonged exposure to the sun!

If you have a poor tanning ability for example, your skin may have lower levels of melanin, a natural pigment produced by the body. Melanin reacts with UV rays to produce a darker skin tone as a way of adaptation (tanning), and so in some ways it provides the skin with protection and tolerance to the sun. Having less melanin (and so lighter skin) means the skin can be more prone to sensitivity, sun burn, and skin disease.

Variants of genes such as PDE3B, CYP2R1, and NADSYN1 contribute to the Vitamin D Deficiency trait. Check your Vitamin Reports Package to see if you have any of these genes!

Always remember, having a genetic predisposition doesn’t necessarily mean the genes are active and the trait is expressed, so consult a healthcare professional before making major changes to your lifestyle. They can order blood tests to verify nutrient deficiencies and determine if supplementation is necessary.

CRISPR, Patents, and Nobel Prizes

A CRACK IN CREATION is not The Double Helix. They are both stories of revolutionary biological advances, told by one of the discoverers, but The Double Helix feels like a novel. And, like a historical novel, it was eventually understood to be “based on real events” but not always reliable history.

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