When talking about health benefits, we must differentiate between teas made from the Camellia sinensis plant and those made from other botanicals. Technically, only beverages derived from the Camellia sinensis plant should be called tea and the others should be referred to as herbal tea, herbal infusions, or tisanes. In this section, we will focus on the potential health benefits of true tea, from the plant Camellia sinensis. (Please note: the information below is for educational purposes only and has not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease.)
The five main types of tea are black, green, oolong, white, and pu-erh. Differences do occur in varietals, but ultimately all tea is made from the same botanical with the same components and, thus, potential health benefits.
There are five significant components found in all tea from the plant Camellia sinensis:
- Essential Oils: the source of tea’s delicious flavor and aroma
- Polyphenols: antioxidants that provide the tea’s brisk flavor and many of its potential health benefits
- Phytonutrients: small amounts of vitamins, minerals, and amino acids including L-theanine (a very rare molecule that has been found in only three sources including camellia sinensis!)
- Enzymes: Macromolecular biological catalysts, which accelerate chemical reactions in the body
- Methylxanthines: which are a family of alkaloids that include caffeine
Each of these components work differently in the human body and a full description is best left to a medical journal. However, recent research exploring the potential health attributes of tea is leading many scientists to agree that tea of all types may contribute positively to a healthy lifestyle.
Potential Health Benefits Research of All True Tea
The information below is a summary of the research on the potential health benefits of all tea compiled on the TeaUSA and UK Tea Council website. Please keep in mind that at Arbor Teas we are conservative in the health findings we discuss. We only relay information from peer-reviewed articles and scholarly sources.
Recent findings include:
- Cardiovascular Health: The antioxidant properties of tea flavonoids may play a role in reducing the risk of cardiovascular disease by decreasing lipid oxidation, reducing the instances of heart attacks and stroke, and may beneficially impact blood vessel function, an important indicator of cardiovascular health.
- Cancer Risk Reduction: Tea flavonoids may lower the risk of certain cancers by inhibiting the oxidative changes in DNA from free radicals and some carcinogens. Tea may also promote programmed cell death, or apoptosis, and inhibit the rate of cell division, thereby decreasing the growth of abnormal cells.
- Immune Function: Recent research indicates that tea contains a component that may help the body ward off infection and disease.
- Oral Health: The flavonoids in tea may inhibit plaque formation, while the fluoride in tea may support healthy tooth enamel. Obesity and Body Composition: Several studies suggest drinking calorie-free tea may help with weight management. Preliminary research suggests that tea flavonoids help elevate metabolic rate, increase fat oxidation and improve insulin activity. Tea catechins can also provide modest shifts in metabolism that may improve weight loss and maintenance Researchers concluded that daily consumption of 690 mg of catechins, the equivalent of five cups of strong green tea, might be useful in preventing and improving obesity. All tea contains catechins. Because different types of tea undergo different production methods, individual types have higher amounts of, or differently composed catechins than others.
- Stress Reduction: Tea is a natural source of polyphenols, which are a class of antioxidant that help your body maintain homeostasis. These polyphenols also help lower the amount of cortisol in the body after a stressful event. Research suggests that with enough polyphenols circulating in your body, the negative effects of excessive cortisol can be counteracted. Tea is also a source of L-theanine, an amino acid that also helps your body fight off stress. Theanine relies on its natural psychoactive abilities to not only decrease mental and physical stress, but also improve various cognitive abilities. Additionally, it's believed to strengthen the immune system.
For further reading and more detailed information (including copies of the original research papers), we strongly recommend visiting TeaUSA.com and www.tea.co.uk.
Tea and Bioavailability
Did you know that up to 80% of the catechins in tea are not absorbed (or bioavailable) by the body? Most are lost in your intestine. However, researchers found that adding citrus to your tea may improve your body’s ability to absorb these beneficial catechins by increasing the acidity in your small intestine. In particular, a 50-50 tea/citrus mix had the greatest catechin-preserving effect, with lemon juice performing best, followed by orange, lime and lastly grapefruit juice. So brew your tea and flavor it with freshly-squeezed lemon, orange, lime, or grapefruit juice.
Which Tea is the Healthiest?
Some research has shown that the manufacturing process affects the level of antioxidants in the final dry tea leaf. According to the study "Beneficial Effects of Green Tea - A Review" in the Journal of the American College of Nutrition, when dry tea leaves are compared, unoxidized green tea retains more antioxidants than black, oolong, or pu-erh. In this study, the catechin (or antioxidant) that is more abundant in green tea than in the black, oolong and pu-erh is EGCG (epigallocatechin-3-gallate). So if you are searching for a tea with a potentially higher antioxidant count, based on this research, we recommend choosing a green tea.
To our knowledge, there is no peer-reviewed literature that compares the EGCG levels of different green teas, so we can’t point to any one of them and say, "This tea has the highest EGCG count." There are also many other factors that can affect the final antioxidant count in your cup: varietal, age of leaf, growing location, method of manufacture, production techniques, and steeping time.
However, matcha green tea drinkers may ingest a higher level of antioxidants because of how it is consumed. Matcha green tea is consumed by whisking the entire tea leaf (in powder form) in water and drinking. Unlike most tea, in which the tea leaf is steeped and removed before consuming the beverage, matcha drinkers consume ALL of the components in the leaf rather than only those extracted from the tea leaf into the brew.
Our bottom-line advice is that all types of tea (green, black, oolong, pu erh and white) have been shown to have potential health benefits, so instead of searching for the most potent leaf, choose a tea that you enjoy drinking and rest easy.
Within tea research, the most research that has been conducted has revolved around green tea in particular. Much of this research has been commissioned by Japan and China, major producers of green tea, in an effort to increase exports. While potential health benefits of green tea have been studied more often, this does not mean that other types of tea are not beneficial. Below are highlights from some of the significant studies and research that have been done on the potential health benefits of green tea.
Green Tea and Cancer Research:
- A recent study from the biology department of East Carolina University published in Cancer Genomics Proteomics supports prior findings that the antioxidants in green tea may help protect against breast cancer. In the study, researchers found that treatment involving green tea extract decreased the development of the MCF-7 human breast cancer cells, which lead to a further decrease in cancerous tumor cells in the breast. The researchers concluded that green tea may be a strong tumor constrictor, hence, people with a family history of breast cancer may benefit from drinking green tea.
- According to research done at the Chung Shan Medical University in Taiwan, it is suggested that smokers who drink at least one cup of green tea daily have one-thirteenth the likelihood of getting lung cancer. Nonsmokers were similarly benefited by drinking green tea, showing an 80% lower risk of lung cancer.
- Researchers at the University of Fernando Pessoa in Portugal concluded a study indicating that green tea may be an effective anticancer agent for renal cell carcinoma (or RCC), the most common type of kidney cancer in adults. The team found, "green tea extract strongly inhibited the growth of both RCC cell lines in a concentration-dependent manner," stated an abstract of the findings. "This is the first report showing that green tea is likely to be an effective anticancer agent for renal cell carcinoma."
- According to a Japanese study published in the online version of the American Journal of Epidemiology, drinking five or more cups of green tea a day could halve the risks of developing advanced prostate cancer. A research team from Japan's health ministry surveyed 49,920 men aged 40-69 across the nation in 1990 and 1993 and followed up on their health until 2004, the National Cancer Center said. During this time, 404 men were newly diagnosed with prostate cancer, of whom 114 had advanced cases, 271 were localized, and 19 were of an undetermined stage. An analysis found the risks of having advanced prostate cancer was 50 percent lower for men who drink five or more cups of green tea a day compared with those who have less than one cup, the study said.
Green Tea and Weight Loss Research:
- Researchers at Penn State’s College of Agricultural Sciences found that the combination of green tea extract and exercise contributed to significant weight loss in mice. This study, led by Joshua Lambert, associate professor of food science at Penn State, looked at mice in three control groups for sixteen weeks: One group was fed a high-fat diet, and was given decaffeinated green tea extract and regular, voluntary, exercise. Another was fed a high-fat diet and given regular, voluntary exercise, but no green tea extract. And a third was given a high-fat diet and green tea extract, but no exercise. The mice that fared the best in the study were given the combination of green tea extract and regular voluntary exercise. After sixteen weeks, these mice had an average body mass reduction of 27.1%, and an average abdominal fat reduction of 36.6%. Joshua Lambert pointed out that it was the combination of voluntary exercise and green tea extract that likely had the greatest effect. As he told Penn State News, “Green tea seems to modulate genes related to energy metabolism.” This is not the first study to indicate green tea’s effect on metabolism. An earlier study indicated that green tea extract improved endurance and energy metabolism in mice during exercise.
- A Dutch study published in Physiology and Behavior offers compelling evidence that green tea may help trim your waistline and keep it off. Food energy that isn't used up metabolically is stored in the body as fat. This study explored how the combination of caffeine and catechins in green tea likely play a dual role in weight management, synergistically increasing energy expenditure (via caffeine) while aiding in overall body fat regulation (via green tea catechins).
- According to a study published in the Journal of Nutrition, a team of researchers from American and Japanese institutions found that consuming the catechin in green tea "enhances exercise-induced changes in abdominal fat loss.” The tried to determine whether green tea catechins would have an influence on body composition and fat distribution in overweight and obese adults who were on an exercise program to lose weight. Kevin Maki, PhD, president of Provident Clinical Research & Consulting, indicates that the group of 107 participants who completed the study were roughly half men and half women, with an average age of 48 years. Their average body mass index (a measure of weight divided by height) was 32.2 (25-29.9 is considered overweight). Researchers divided participants into two groups and gave one of them regular doses of green tea catechins over a 12-week period. During that time, the participants also were put on a regular exercise regime. While both groups lost weight and body fat, "Subjects in the catechin group [lost] more abdominal fat, suggesting the catechins may have promoted preferential loss of abdominal fat."
It’s important to note that in many of these weight loss studies the scientists are studying mice, not people, and that they’re giving the mice green tea extract, a concentrated form of green tea.
To get the most out of green tea, we suggest ingesting it the old fashioned way – brewing up a pot or whisking up a cup of matcha. In fact, scientists at the Mayo Clinic agree that the best way to get the benefits from food is to choose whole foods over supplements. How much green tea should you drink? The NIH says a common “dose” of green tea is 2-3 cups a day, what is typically consumed in Asian countries on a daily basis.
Green Tea and Memory Research:
Researchers in Basel, Switzerland have found that at least one form of tea – green tea – can be an effective memory enhancer as well. During the study, researchers gave 12 healthy individuals a milk whey-based soft drink with 27.5 grams of green tea extract, or a “placebo,” the milk whey-based soft drink on its own. Then, they monitored the participants’ brain activity using magnetic resonance imaging (MRI). Study participants who received the green tea concoction were found to have increased activity from the superior parietal lobule to the middle frontal gyrus. Researchers report this is “positively correlated with improvement in task performance.” This occurred, the researchers say, due to temporary changes in the “plasticity of parieto-frontal brain connections.” In other words, green tea helped fuel the brain’s synaptic connectivity, at least in the short term, leading to improved performance in “working memory tasks,” explains Science Daily.
Green Tea and Helping Potency of Antibiotics:
As published on Science Daily, a group of Egyptian scientists speaking at a meeting of the Society of General Microbiology indicate that green tea can play an important role in fighting back illness-causing "superbugs." The pharmacy researchers have shown that drinking green tea helps the action of important antibiotics in their fight against antibiotic-resistant superbugs, making them up to three times more effective. Green tea is a very common beverage in Egypt, and it is quite likely that patients will drink green tea while taking antibiotics. The researchers wanted to find out if green tea would interfere with the action of the antibiotics, have no effect, or increase the medicine's' effects. "We tested green tea in combination with antibiotics against 28 disease causing microorganisms belonging to two different classes," says Dr. Mervat Kassem from the Faculty of Pharmacy at Alexandria University in Egypt. "In every single case green tea enhanced the bacteria-killing activity of the antibiotics. For example the killing effect of chloramphenicol was 99.99% better when taken with green tea than when taken on its own in some circumstances." The results surprised the researchers, showing that in almost every case and for all types of antibiotics tested, drinking green tea at the same time as taking the medicines seemed to reduce the bacteria's drug resistance, even in superbug strains, and increase the action of the antibiotics. In some cases, even a low concentration of green tea was effective.
Green Tea and Skin Research:
A study from the Mohave Skin and Cancer clinic corroborates past evidence that the use of green tea in skin treatments (sometimes called "cosmeceuticals") may be a great way to limit the signs of aging skin. While all teas contain a fair amount of antioxidants, researchers consistently agree that green tea has the highest concentrations. The principle benefit of antioxidants is that they remove free radicals and inhibit inflammation. Free radicals are agents in the body that start harmful reactions that damage your cells. The more antioxidants active in the body, the less damage is caused by free radicals. According to the study, the strong combination of green tea's antioxidant and anti-inflammatory factors may help keep your skin looking younger as you age. Skin ages through two major mechanisms: collagen breakdown due to free radicals and harmful UV light exposure. Lab results have shown that the polyphenols in green tea have the ability to decrease collagen breakdown by eliminating the free radicals that are responsible. Researchers also suggest that the anti-inflammatory effect associated with polyphenols can reduce damage caused by UV radiation, such as intense sunlight.
Green Tea and Cholesterol Research:
According to a Saudi Arabian study published in the Journal of Physiological Biochemistry, green tea (and black tea, for that matter) may help lower cholesterol and improve your heart health. As you may know, HDL is the “good” cholesterol, which helps maintain LDH levels and protects against heart attack and stroke. LDL is the “bad” cholesterol which may clog arteries if there's too much of it circulating in the blood. In the study, rats that ingested green tea supplements demonstrated lower triglyceride and LDL levels, but higher HDL levels.
Green Tea and Diabetes Research:
A French study, published in the Journal of the American College of Nutrition, indicates that green tea may aid in the battle against diabetes. Diabetes and other insulin related disorders such as hyperglycemia result from insulin resistance in the body. In other words, the body simply doesn’t recognize high levels of insulin. The study suggests that green tea extract has the ability to combat such insulin resistance, and may very well help those with diabetes regulate their insulin levels.
In addition to all the potential health benefits listed in the All True Tea section, researchers have focused on black tea specifically for the following:
Antioxidants found in red wine and tea may help regulate blood sugar in diabetics, U.S. food scientists say. Researchers from the University of Massachusetts Amherst suggest red wine and tea may help type 2 diabetics by inhibiting the action of alpha-glucosidase, which slows down the absorption of glucose from the small intestine. "Levels of blood sugar, or blood glucose, rise sharply in patients with type 2 diabetes immediately following a meal," Shetty says in a statement. "Red wine and tea contain natural antioxidants that may slow the passage of glucose through the small intestine and eventually into the bloodstream and prevent this spike, which is an important step in managing this disease." The study, published in the Journal of Food Biochemistry, finds red wine was able to inhibit the enzyme by nearly 100 percent and white wine hovered around 20 percent. The team also tested four kinds of tea -- black, oolong, white and green -- and find extracts of black tea had the highest effect on inhibiting the activity of alpha-glucosidase, followed by white tea and oolong tea.
In addition to all the potential health benefits listed in the All True Tea section, researchers have focused on oolong tea specifically for the following:
Oolong tea shares many of the health benefits that other teas have, but one of our oolong offerings gets a special spotlight. GABA tea is an oolong tea that has an abundance of GABA (gamma-Aminobutyric acid), an amino acid that functions as a neurotransmitter in the brain. Like other GABA supplements, GABA tea is often consumed to help relax the mind and body during times of stress.
GABA tea is relatively new to the tea world. It was developed in the 1990s by Dr. Tsushima Tojiro, a scientist at Japan’s National Tea Experiment Station. Dr. Tojiro found that tea leaves that are deprived of oxygen during the oxidation process respond by producing an abundance of GABA, a naturally occurring substance in all teas.
This is not the first time that teas have been “exploited” to increase certain properties. For example, the Japanese tea Gyokuro is covered during the final weeks of the growing process in order to stress the tea and cause it to send more nutrients into the leaves. This is responsible for Gyokuro’s deep green color and elevated levels of chlorophyll and L-theanine, an amino acid that increases the production of serotonin, dopamine, and GABA in the brain. GABA tea is an excellent afternoon tea, especially during times of high stress. Because it’s caffeinated, GABA tea is not going to make you sleepy the way a caffeine-free Chamomile infusion might. Instead, its effect is of a calm alertness. For this reason, it’s a great tea to brew up when you’re faced with high-stress work situations when the only way out of a project (or a day at the office) is through it.
In addition to all the potential health benefits listed in the All True Tea section, researchers have focused on pu-erh tea specifically for the following:
Pu erh, the fermented and oxidized variety of tea that often comes in pressed cakes or pressings, has been known for its beneficial effect on cholesterol. A study in Experimental Gerontology done with rats showed results that pu-erh tea could be used to reduce the risk of cardiovascular diseases, of which high cholesterol can be a factor in.
In addition to all the potential health benefits listed in the All True Tea section, researchers have focused on white tea specifically for the following:
White Tea and Skin Research:
Researchers are finding that white tea, the most minimally processed form of Camellia sinensis, prevents wrinkles and when applied topically, can protect the skin from sun damage. In 2009, researchers at Kingston University studied 21 plant and herb extracts, looking specifically for those that would benefit the skin. The researchers were surprised to find that white tea extract came out on top every time. The study found that white tea benefits the skin by preventing the enzymatic activity involved in the breakdown of collagen and elastin, the proteins responsible for tissue repair and elasticity in the body. Most surprising, researchers said, was that these benefits were found by using a very small amount of white tea extract – “far less than you would find in a drink,” Professor Declan Naughton, who was involved in the study, said. Further research conducted at the University Hospitals of Cleveland found that white tea extract applied directly to the skin boosted the immune function of skin cells and protected the skin from sun damage. Ingredients in green tea, meanwhile, were found to decrease the “direct effects” of sunburn.
Unfortunately, white tea hasn’t been studied enough for us to know whether regularly drinking white tea has any protective effect against sun damage. But if you want to take advantage of white tea’s topical benefits, you can experiment by using white tea as a daily toner, applying cooled white tea to your skin with a cotton ball, or by spritzing the cooled tea directly onto your skin.
White Tea and Fat Metabolism Research:
Growing concern over obesity-related diseases prompted a team of German researchers to investigate the effects of white tea extract on the human body. They conducted in vitro studies to explore the cellular and molecular mechanisms underlying fat metabolism, more specifically the effect of white tea extract on cultured human subcutaneous preadipocytes and adiopocytes (fat cells). The study, published in Nutrition & Metabolism, found that white tea extract effectively inhibits adipogenesis (the production of fat) and stimulates lipolysis activity (the destruction of fats). According to the abstract, this means white tea extract “can be utilized to modulate different levels of the adipocyte life cycle.”