Black tea is a popular and healthy drink. However, those who are sensitive to caffeine or tannins might experience symptoms like heartburn after drinking too much of it.
What is black tea?
Black tea is a herbal tea of Chinese origin, produced from the leaves of the Camellia sinensis plant.
Unlike green tea, which is not oxidized, and oolong tea, which is only partially oxidized, black tea is completely oxidized, giving it its characteristic strong flavor.
When the tea leaves are harvested, they are withered, macerated, fermented, dried, sorted, and packaged. Oxidation occurs during the fermentation step, by the action of the enzyme polyphenol oxidase on polyphenols, leading to the formation of compounds called theaflavins.
These theaflavins are orange to red and thus responsible for the brisk taste and brightness of brewed black tea.
Theaflavins further react with other compounds forming thearubigins, responsible for transforming tea leaves to a dark brown color. Thearubigins also form flavor compounds by reacting with amino acids and sugars, thus they are responsible for the color and strength of black tea.
Examples of black tea types include Assam, Ceylon, Darjeeling, and Kenyan.
Health benefits of black tea
Black tea drinking is increasing yearly because the awareness of its numerous health benefits is also on the increase. It is rich in polyphenols such as catechins, theaflavins, and thearubigins, which are bioactive compounds that positively affect human health.
These are the most important health benefits of black tea:
Heart health benefits
Flavonoids are a group of polyphenols in black tea that show antioxidant activities that benefits the heart. Regular drinking of black tea is said to reduce blood pressure, cholesterol, and triglyceride levels, all of which are risk factors for heart diseases.
Blood sugar reduction benefits
Black tea is recommended for diabetics because it is an unsweetened beverage, whose consumption does not cause spikes in blood sugar levels. It may also prevent diabetes.
Also, black tea contains epigallocatechin gallate (EGCG) which improves insulin resistance. Research studies have reported that drinking black tea lowers blood sugar levels and improves sugar metabolism in the body.
Brain function benefits
Black tea contains caffeine (8 ounces of black tea contains about 14-61mg of caffeine) a well-established neurostimulator, that blocks the inhibitory neurotransmitter adenosine, and increases the concentration of neurotransmitters like dopamine and norepinephrine.
This action improves various aspects of brain function such as mood, memory retention, reaction time, and vigilance.
Black tea also protects against the age-related decline in brain organization.
Is black tea acidic or alkaline?
Black tea has a pH range of 4.99 – 5.55 which puts it in the slightly acidic range.
However, it is far from being very acidic, actually, this study recommends drinking black tea instead of other more acidic beverages, to protect tooth enamel.
In terms of digestion, a pH around 5 is unlikely to cause any stomach problems. (Stomach acids have a much lower pH, from 1.5 to 3.5 .)
Can black tea cause acid reflux?
Black tea is a potential acid reflux trigger, for two main reasons: tannins and caffeine.
Even though black tea contains less caffeine than coffee, it might still trigger symptoms for those, who are sensitive to caffeine, especially after drinking multiple cups.
The tannin concentration of black tea is the highest of all tea types because of its heavy processing and complete oxidation process.
Tannins have been reported to cause relaxation of the smooth muscles of the lower esophageal sphincter causing stomach acids to flow backward into the esophagus and cause heartburn.
Caffeine intake has reportedly triggered and worsened heartburn in people suffering from acid reflux or GERD.
Furthermore, caffeine also causes relaxation of the lower esophageal sphincter, preventing it from closing properly after food passes into the stomach. As such stomach acids flow back into the esophagus causing heartburn.
Is black tea good for the digestive system?
Black tea might be beneficial for the digestive health of those who are not sensitive to caffeine or tannins.
Improved gut microbiota
Black tea contains a large number of flavonoids (10 – 25% dry weight) which confer some kind of prebiotic effect on the microorganisms in the colon. A good bacteria flora in the gut:
- boosts general immunity
- protects the gut from colonization by pathogenic bacteria
- enhances proper digestion of food and absorption of nutrients by protecting the epithelial cells
Polyphenols in black tea suppress both the digestion and absorption of lipids, which reduces overall calorie intake. They increase lipolysis (fat breakdown) and decrease the multiplication of fat cells thus decreasing the accumulation of lipids.
This makes black tea suitable for weight loss and weight management for obese people and those who generally want to keep a healthy weight.
Black tea polyphenols inhibit the breakdown of disaccharides to monosaccharides by the enzyme, α-glucosidase in the small intestines preventing the absorption of glucose. They can also inhibit glucose transporters as well as the activities of enzymes like α-amylase in the saliva, and glucosidase.
All of these reduce glucose absorption which can be beneficial for diabetics and those who want to control their blood sugar levels.
Side effects of (too much) black tea
There is no standard amount of black tea, approved by any food authority for drinking, however, people are advised to stay within four to five cups a day. Drinking too much black tea has some harmful effects.
General side effects
The general side effects of drinking too much black tea are associated with its caffeine content. Some of these effects include:
- sleeping disorders
- increased urination
- nausea, vomiting
Drinking excess black tea can cause the development of psychological dependence which can lead to more drinking of tea and worsen side effects.
Drinking too much black tea causes pressure to build up inside the eyes which could damage optic nerves and impair vision. The increase in pressure of the eye can occur within 30 minutes but lasts for a minimum of 90 minutes.
Iron malabsorption issues
Excess intake of black tea polyphenols could negatively impact iron uptake in the diet especially in vulnerable groups – like children, pregnant women, and the elderly -, who already have low iron stores.
Some research studies reported that tea drinking limited only the absorption of non-haem iron and not the overall iron status of healthy individuals. Thus, it is recommended to avoid tea drinking during meals for vulnerable groups at risk of iron deficiency.
Black tea is one of the most popular teas consumed in the world today, loaded with various health benefits. However, consumption should be done moderately because excessive consumption can cause unwanted side effects.
Those who are very sensitive to caffeine might get heartburn upon moderate consumption of black tea. Switching to green or oolong teas (both contain some caffeine, albeit less than black tea), or rooibos tea, which contains no caffeine might prevent symptoms.