Tea, Coffee and Health Aspects

Tea and Coffee are the most popular and highly consumed beverages (drinks) all over the world. And with no doubt, the majority consumes these beverages on a daily basis. I am a tea lover and suppose the majority of the readers are either tea or coffee enthusiasts. The main reason behind this popularity of these beverages is their unique flavour and the stimulating effect they have on our brain. However, are we aware of the health aspects that are induced by the consumption of these beverages? Do we know about the nutritional values that these beverages have?

In this article, we shall look at the purpose that these beverages serve us, concerning our health, other than just presenting the flavour and stimulating effect.



            Tea, an aromatic beverage (drink) produced by steeping in freshly boiled water the young leaves and leaf buds of the tea plant, Camellia sinensis [1]. After water, it is the most popular drink and consumed by two-thirds of the world’s population. A tea infusion is best made by pouring water just brought to the boil over dry tea in a warm teapot and steeping it from three to five minutes. The liquor is separated from the spent leaves and may be flavoured with milk, sugar, or lemon. Moreover, it is also preferred as a social drink in many communities, and it is the aesthetic way of welcoming guests and showing honour [1].

Tea, Coffee and Health Aspects

Image: Tea  [A]

Types of Tea

Based on processing, tea can be divided into different types such as black (fermented), green (non-fermented), and oolong/pouchong (semi-fermented). These major tea types differ in how tea is being harvested and processed, which also determines the chemical composition of tea [2].

During tea manufacture, the leaf undergoes some or all of the stages of withering, rolling, fermentation, and drying. The process has a twofold purpose:

1)         To dry the leaf

2)         To allow the chemical constituents of the leaf to produce the quality peculiar to each type of tea.

Only black tea goes through all stages of the manufacturing process. Green tea and Oolong tea acquire their qualities through variation in the crucial fermentation stage [1]. It should be perceived that the term herbal tea refers to the drinks not made from Camellia Sinensis, the infusion of fruit, leaves, or other parts of plants [3].

Based on preparation, tea can also be classified into masala chai, tandoor tea, Pu’erh tea, cold brew tea, etc. Based on the packaging, tea can be further divided into tea bags, loose tea, compressed tea, instant tea, and canned tea.

Chemical Composition of Tea

The chemical constituents are responsible for the colour, flavour, strength and stimulating properties of the tea. The best-known constituent of tea is Caffeine, which gives the beverage its stimulating character. Tea is also composed of flavonoids, naturally occurring compounds that are believed to have antioxidant properties [4].

However, the most important chemicals in tea are the tannins, or polyphenols, which are colourless, bitter-tasting substances that give the drink its astringency. The enzyme polyphenol oxidase acts upon polyphenol, to acquire reddish colour and form the flavouring compounds of the beverage. Certain volatile oils contribute to the aroma of tea and also contribute to beverage quality [1]. Though the exact chemical composition of tea varies with its types, processing and harvesting methods.

Health Benefits of Tea

The health benefits of tea slightly vary with the types of tea being consumed, as the chemical composition varies with the processing, some tea might have a higher degree of benefits than others. Overall, the health benefit of tea remains the same, some with fewer and some with higher benefits, depending on the exact chemical composition of the final beverage that’s being consumed.

Improve Cardiovascular Health

Green tea contains catechins that affect lipid metabolism by different pathways and prevent the appearance of atherosclerotic plaque. Moreover, catechins also decrease the absorption of triglycerides and cholesterols [2].

Human population studies and clinical studies suggest that consumption of black tea has reduced the risk of heart disease and stroke. This reduction associated with black tea consumption may be due to improvement in some risk factors for cardiovascular disease, including cholesterol levels, blood vessel function and reduction in oxidative damage [4].

Cancer Risk Reduction

Several studies have suggested that catechins and theaflavins present in tea may reduce the risk of various types of cancers in humans [2]. Researchers suggest that the flavonoids present in tea may assist in human cancer risk reduction, by combating free radical damage, inhibiting uncontrolled cell growth and by promoting apoptosis (programmed cell death) [4].

Different clinical and epidemiological studies have found that tea consumption aids in the reduction of digestive cancers, skin cancers, oral cancers, lung cancer and ovarian cancer [4]. The consumption of green tea was associated with a reduced risk of developed breast cancer in a case-control study with breast cancer confirmed patients [2].

Supports Immune System

 A subsequent human clinical trial suggests that tea consumption provides a stronger immune system with natural resistance to microbial infection. Recently researchers have identified a substance in tea, named L-theanine, which primes the immune system in fighting infection, bacteria, viruses and fungi [4]. The melanin-like pigment from black tea has immunostimulant activity [5].

Diabetes Prevention and Control

Various studies have shown that tea consumption may affect glucose metabolism and insulin signaling. And many researchers concluded that regular consumption of black tea extract (BTE) had anti-oxidative and anti-inflammatory effects in patients with Type II diabetes mellitus [2].

Some studies suggest that the catechins in green tea may help to keep blood sugar in check, reducing the risk of developing Type II diabetes [8]. Many cohort studies have shown that people who consumed tea regularly had a lower risk of diabetes compared to those who didn’t consume tea [2].

Better Oral Health

The flavonoids in the tea assists in the inhibition of plaque-formation, caused by oral bacteria. The Fluoride in tea may support healthy tooth enamel [4]. More recent studies have pointed out that the polyphenols content of tea also affects plaque formation [5].

Reduce Obesity

Preliminary research suggests that drinking tea may have effects on body weight, fat accumulation and insulin activity [4]. The consumption of green tea or its catechins helps in a significant reduction of body mass index (BMI), body weight and body fat by increasing postprandial thermogenesis and fat oxidation. Besides, it was also found to reduce blood cholesterol, triglyceride, glucose and insulin levels [7].

Osteoporosis and Arthritis Risk Reduction

            The researchers have concluded that the flavonoids in tea might influence bone mass and tea consumption aids in the reduced risk of osteoporosis. It was also found that habitual tea consumption had a significant beneficial effect on Bone Mineral Density (BMD)  [4]. In a study in Britain, it was found that those who drank tea had greater BMD compared to those who did not consume tea [2].

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Neurological Effects

            Tea contains many bioactive components such as polyphenols, theanine, caffeine, and theaflavins [13]. Many case-control and cohort studies have shown that consumption of tea regularly has reduced the risk of Parkinson’s disease [2]. Tea polyphenols can lower the morbidity of Parkinson’s Disease and Alzheimer’s Disease by reducing the oxidative stress and regulating signaling pathways and metal chelation. Theanine, present in tea, can inhibit the glutamate receptors and regulate the extracellular concentration of glutamine, presenting neuroprotective effects [9].

Negative Aspects

            As they say, too much of anything will lead to negative effects. Just like almost everything in this world, along with the positive aspect, these beverages also have some negative aspects to health as well. Thus, the consumer should also be aware of the negative aspects of drinking too much tea.

Reduce Iron Absorption

            Iron is an important nutrient for the human body, it is involved in many cellular functions and metabolism. It is also used in the formation of the haemoglobin and helps in the transport of oxygen to the cells  [6].

            Research suggests that tea tannins are more likely to hinder the absorption of iron, especially from plant sources rather than from animal-based foods, so strict vegan should pay close attention to the amount of tea consumed  [10].

Increased Anxiety, Stress, and Restlessness

            Overconsumption of caffeine, naturally present in tea, may lead to feelings of anxiety, stress and restlessness. Research suggests that caffeine doses under 200 mg per day are unlikely to cause significant anxiety in most people. However, some people are more sensitive to these effects and may require to limit their consumption of tea/caffeine [10].

Poor Sleep or Insomnia

            Excessive intake of caffeine may interrupt the normal sleep cycle of a person, as caffeine inhibits melatonin production (a hormone that signals the brain to sleep). Inadequate sleep is linked to a variety of mental issues, including fatigue, impaired memory, and reduced attention span. Moreover, chronic sleep deprivation is associated with an increased risk of obesity and poor blood sugar control  [10].

Constipation, Dehydration and Bloating

            Theophylline, a chemical in the tea, can lead to a dehydrating effect during digestion, causing constipation [12]. Excess caffeine consumption also reduces the absorption abilities of tubules, which might lead to dehydration. This dehydration may further lead to unwanted water retention and thus, result in bloating [11].


            The caffeine in tea could cause heartburn or exacerbate pre-existing acid reflux due to its ability to relax the lower esophageal sphincter and increase acid production in the stomach [10].

Pregnancy Complications

            Overexposure to caffeine from tea during pregnancy may contribute to complications, such as miscarriage or low infant birth weight  [10].  Pregnant women should prefer to limit their tea consumption or even avoid it at least during their pregnancy phase.

Caffeine Dependency

            Caffeine is a habit-forming stimulant, and regular intake from tea or any other source of caffeine could lead to its dependence. And withdrawal symptoms may include fatigue, irritability and headaches [10]. Hence, the number of cups consumed and the amount of beverage taken should be considered.



            Coffee is a beverage consisting of an infusion of the roasted ground or crushed coffee beans of a certain tropical shrub and has a stimulating effect on the human body. The word ‘coffee’ comes from the Arabic word ‘qahwah’ which refers to a type of wine [19]. It is also one of the most famous beverages and more than 400 billion cups of coffee are consumed each year. Before people learned how to brew coffee, east African tribes mixed coffee berries with animal fat and consumed it as food [19]. And now, there are so many different ways of brewing coffee, each with its unique style and flavour. Moreover, it is also preferred as a social drink in many communities.


Image: Coffee  [B]

Types of Coffee

            Based on processing, coffee can be distinguished into three types, such as washed coffee, natural/ dry-processed coffee, honey/pulped natural coffee. There are 30 different types of coffee based on their flavours, aroma, and additives, for instance, Arabica, Robusta, Black, Latte, Cappuccino, Americano, Espresso, Doppio and many others.

Chemical Composition of Coffee

            Coffee is composed of caffeine, chlorogenic acid, trigonelline, polyphenol, quinic acid, caffeic acid, diterpene, kahweol, theophylline, ferulic acid, and many other phenolic compounds. Moreover, coffee contains several beneficial nutrients, including riboflavin, niacin, magnesium, potassium, and various phenolic compounds, or antioxidants [13].

            The exact amount of caffeine present in coffee varies depending on the type of processing, and the value can range from 0 to over 500mg per cup. However, coffee is a huge dietary source of caffeine.

Health Benefits of Coffee

            The health benefits of coffee may slightly vary with the types of coffee being consumed, as the caffeine content and chemical composition varies with its types of processing and brewing. Even though, the overall health benefit of coffee remains the same, some with fewer and some with higher benefits, depending on the exact chemical composition of the final beverage that’s being consumed.

Type II Diabetes Risk Reduction

            Research showed that people who consumed coffee every day had a lower risk of type II diabetes [13]. Although ingestion of caffeine can increase blood sugar in the short-term, long-term studies have shown that habitual coffee drinkers have a lower risk of developing type II diabetes compared with non-drinkers. And different meta-analysis and cohort studies have suggested that coffee reduces the risk of type II diabetes by 7%  [14] [3].

Metabolic Syndrome Risk Reduction

            The polyphenols and minerals such as magnesium in coffee may improve the effectiveness of insulin and glucose metabolism in the body [14]. Several studies show that caffeine can boost your metabolic rate by 3-11% [3].

Improve Mood and Reduce Depression

            Caffeine may affect mental states such as increasing alertness and attention, reducing anxiety, and improving mood. However, in some cases of sensitive individuals, higher amounts of caffeine may increase anxiety, restlessness and insomnia, and suddenly stopping caffeine intake may lead to headache, fatigue and anxiety [14].

            A study suggested that people who consumed coffee have a lower chance of having depression and cognitive conditions such as Alzheimer’s [13].

Improve Liver Health

            Italian researchers found that coffee consumption lowers the risk of liver cancer by around 40%. Also, a meta-analysis from 2011 concluded that consuming any type of coffee reduced the risk of nonalcoholic fatty liver disease and cirrhosis [13].

Obesity and Body Fat Reduction

            Caffeine breaks down fats, making free fatty acids available as fuel. Studies indicate that caffeine can specifically increase fat burning by as much as 10% in obese individual and 29% in lean people [15].

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Protects from Alzheimer’s disease, Parkinson’s disease and Dementia

            Several studies show that coffee drinkers have up to a 65% lower risk of Alzheimer’s disease, which is a leading cause of dementia worldwide [15]. Studies including cohort and case-control studies have found that intake of coffee reduces the risk of Parkinson’s disease by 25% [14].

Prevent from Certain Types of Cancer

            Coffee may affect cancer development, polyphenols inhibit cancer cell growth, caffeine may interfere with the growth and spread of cancer cells. Coffee has also been associated with decreased estrogen level, a hormone linked to several types of cancer [14]. Studies show that coffee drinkers have up to a 40% lower risk of liver cancer. Similarly, studies have also suggested that coffee intake reduces the risk of colorectal cancer [15].

Rich in Antioxidants and Essential Nutrients

            Coffee is a rich source of phenolics, also packed with a high amount of antioxidants and vitamins. Studies show that many people get more antioxidants from coffee than from fruits and vegetables combined [15]. Coffee is composed of many essential nutrients, for instance, vitamin B1 (thiamine), vitamin B2 (riboflavin), vitamin B3 (niacin), vitamin B5 (pantothenic acid), folate, manganese, potassium, magnesium, phosphorus, and many others [16].

Negative Aspects

            As discussed before, too much of anything will have a negative impact in the future, and overconsumption of coffee also has some negative aspects, which must be considered.


            Coffee inhibits the effect of adenosine, a hormone that makes you feel tired, and helps to increase the alertness. However, at higher doses, this inhibition may lead to anxiety and nervousness [16]. Several randomized studies show that coffee has anxiogenic (anxiety-causing) properties and that consumption increases measures of anxiety [18].


            Caffeine aids people to stay awake and be energetic. However, high caffeine intake appears to increase the amount of time it takes to fall asleep. It may also decrease total sleeping time, especially in some individuals and the elderly [16]. Though, a recent meta-analysis suggests that low to moderate coffee consumption has an insignificant association with insomnia [18].

Digestive Issues

            Coffee’s laxative effect has been attributed to the release of gastrin, a hormone the stomach produces that speeds up activity in the colon. Caffeine also stimulates bowel movements by increasing peristalsis, the contractions that move food through your digestive tract. However, high doses may lead to loose stools or even diarrhoea. Some studies have suggested that caffeinated beverages worsen gastroesophageal reflux disease (GERD) in some people [16].

Caffeine Dependency

            People who are used to higher doses of caffeine might develop caffeine dependence. In a study, the researchers demonstrated that stopping daily caffeine consumption reduces the brain’s electrical activity and increases blood flow velocity [18]. And going without caffeine for several hours may lead to psychological or physical withdrawal symptoms (headaches, exhaustion, brain fog, irritability) in those who consume large amounts daily [16].

High Blood Pressure

            Overall, caffeine doesn’t seem to increase the risk of heart disease or stroke in most people. However, several studies have shown that it may lead to short term high blood pressure, due to its stimulatory effect on the nervous system [16][18]. Therefore, people with hypertension should consider this point while consuming coffee.

Muscle Break Down and Bone Fracture

             High caffeine intake may lead to rhabdomyolysis or the breakdown of damaged muscle [16]. Studies also have shown that high caffeine intake increases the risk of bone fracture [17].

Increases Risk of Miscarriage

            In a dose-response systematic review of 60 studies, greater caffeine intake correlated with a greater risk of spontaneous abortion and stillbirth. The risk of low birth weight increases in a linear manner alongside greater caffeine intake [18]. Also, in a recent study, both men and women who consumed at least two caffeinated beverages a day during the weeks prior to conception slightly increased the risk of a miscarriage [17].

Worsen Fertility and Menopause Symptoms

            A study from The University of Nevada School of Medicine showed that caffeine can reduce a woman’s chances of becoming pregnant by about 27%. A study published in The Journal of The North American Menopause Society showed that menopausal women who consumed caffeine had a greater degree of vasomotor symptoms [17].

Final Thoughts

The main purpose of sharing this information was to make the readers aware of the health aspects of drinking these respective beverages along with their negative effects. Now, as we are aware of these facts, it would be amazing if every person fancies their beverage considering the health effects these beverages will have on their health in the future.

Each individual has their taste and habits, so their preferences will also be different. Also, the metabolism processes of each individual are unique depending on their genetics, lifestyle, gender, body fat percentage and many other aspects. So, there’s no ideal beverage which would be appropriate for every individual. Thus, what’s good for your body and what’s not, might be different for each individual.

Making a conscious effort to focus on your body and health is essential. Choosing the most appropriate beverage for your health requires knowledge and observance of how your body reacts to these beverages. All these pieces of information might help you, to be more mindful every time you choose to consume a beverage, concerning your health condition, and knowing its possible health advantages and disadvantages. Also, the number of cups consumed every day should be considered, as discussed before, too much of anything will ultimately have a negative effect.

I believe, from today every reader will make a deliberate choice of which and how much beverage they consume. And prefer something which would have a positive influence on their body and health, rather than just drinking these beverages based on their flavour and stimulating effect without considering their effect on the body.

Being healthy is one of the most amazing blessings of our life and the maintenance of this health depends on nearly every small habit that we prefer to do every single day, so let’s choose to be healthy and happy.


 [1].     https://www.britannica.com/topic/Tea-beverage

 [2].     https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4055352/

 [3].     https://en.wikipedia.org/wiki/Tea

 [4].     http://www.Teausa.com/14852/an-overview-of-research

 [5].     https://www.intechopen.com/books/Tea-chemistry-and-pharmacology/

 [6].     http://www.Teausa.org/14850/Tea-and-iron

 [7].     https://austinpublishinggroup.com/clinical-medicine/fulltext/

 [8].     https://www.eatright.org/Health/wellness/preventing-illness/the-Health-benefits

 [9].     https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6017384/

 [10].   https://www.Healthline.com/nutrition/side-effects-of-Tea#10

 [11].   https://food.ndtv.com/food-drinks/5-side-effects-of-Tea

 [12].   https://recipes.timesofindia.com/articles/Health/6

 [13].   https://www.medicalnewstoday.com/articles/270202

 [14].   https://www.hsph.harvard.edu/nutritionsource/food-features/Coffee/

 [15].   https://www.Healthline.com/nutrition/top-13-evidence-based-Health-benefits

 [16].   https://www.Healthline.com/nutrition/caffeine-side-effects#section1

 [17].   https://www.caffeineinformer.com/harmful-effects-of-caffeine

 [18].   https://www.nutritionadvance.com/Coffee-negative-effects/

 [19].   https://www.boredpanda.com/interesting-Coffee-facts/




Smriti Kumari YadavSmriti Kumari Yadav

About Post Author

Smriti Kumari Yadav

Smriti Kumari Yadav is an aspiring Dietitian, ambitious to serve people to lead a healthy life, moreover a Robust Nation and a Powerful World.
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