Health benefits and concerns
Anxiety
People with high levels of anxiety appear to be more susceptible to the actions of caffeine. All sources of caffeine should be avoided, including
caffeine-containing tea.
Chamomile tea is an old folk remedy for anxiety,
particularly when it causes insomnia. Often 1 cup of tea
is taken three or more times per day.
Age-related cognitive
decline
Caffeine may improve cognitive performance. Higher
levels of coffee consumption were associated with
improved cognitive performance in elderly British people in a preliminary study. Older people
appeared to be more susceptible to the performance-improving effects of caffeine than were
younger people. Similar but weaker associations were found for tea consumption. These
associations have not yet been studied in clinical trials.
Atherosclerosis
Quercetin, a
flavonoid found in black and green tea protects LDL
(“bad”) cholesterol against oxidation. Oxidation of LDL is thought to cause or
accelerate atherosclerosis. Several studies have found that eating foods high in quercetin
lowers the risk of heart disease, and much
of the research documenting the health benefits of green tea is based on the amount of green
tea typically drunk in Asian countries—about three cups per day (providing
240–320mg of polyphenols).
Cancer prevention
Several animal and test tube studies have demonstrated an anticancer effect of polyphenols
from green tea. In one of these studies, a polyphenol called catechin from green tea
effectively inhibited metastasis (uncontrolled spread) of melanoma (skin cancer) cells. The
polyphenols in green tea have also been associated with reduced risk of several types of
cancer in humans.
Canker sores
Because of its soothing effect on mucous membranes (including the lining of the mouth) and
healing properties, chamomile can be tried for canker
sores and other mouth irritations. A strong tea made from chamomile tincture can be swished in
the mouth three to four times per day.
Chronic venous
insufficiency
Proanthocyanidins (OPCs), a group of flavonoids found in both
green and black tea, have been shown to strengthen capillaries.
Diarrhea
Chamomile may reduce intestinal cramping and ease the
irritation and inflammation associated with diarrhea. Chamomile is typically drunk as a tea;
many doctors recommend dissolving 2–3 grams of powdered chamomile or adding 3–5mL
of a chamomile liquid extract to hot water and drinking it three or more times per day,
between meals. Two to three teaspoons of the dried flowers can be steeped in a cup of hot
water, covered, for 10 to 15 minutes as well.
Female
infertility
Caffeine is found in black and green tea. While not
every study finds that caffeine reduces female fertility, many doctors recommend that women
trying to get pregnant avoid caffeine.
In one study, consumption of 3 cups of decaffeinated coffee per day was associated with an
increased risk of miscarriage. In another study, caffeine consumption compounded the negative
effects of alcohol consumption on female fertility. Some researchers suspect that the tannic
acid found in any kind of coffee and black tea may
contribute to infertility.
Fibrocystic breast
disease
Long-term, complete avoidance of caffeine reduces
symptoms of what is commonly called fibrocystic disease. The decrease in breast tenderness can
take six months or more to occur after caffeine is eliminated. Breast lumpiness has been
reported to not respond well to avoidance of caffeine, but the pain decreases significantly in
some women.
Gastritis
Caffeine found in black and green tea, increases stomach
acid. Avoiding these substances should therefore aid in the healing of gastritis.
Gastroesophageal reflux disease
(GERD)
Acidic beverages, such as tea, have been linked to increased heartburn pain and may
contribute to symptoms in people with GERD.
High cholesterol
Green tea has been shown to lower total cholesterol
levels and to improve the cholesterol profile (decreasing LDL cholesterol and increasing HDL
cholesterol). However, not all trials have found that green tea intake lowers lipid
levels.
High
triglycerides
In a study of heavy caffeine users (people who were
consuming an average of 560mg of caffeine per day from coffee and tea), changing to
decaffeinated coffee and eliminating all other caffeinated products for two weeks resulted in
a statistically significant 25% reduction in triglyceride levels.
Although green tea contains a small amount of caffeine, intake of 3 cups or less of green
tea daily has been shown not to affect blood triglyceride levels. Intake of four or more cups
per day has been correlated with lower triglyceride levels. Overall, the evidence is unclear
on how much of an effect high levels of intake of green tea has on triglyceride levels. It is
likely that other constituents in green tea compensate for the presence of caffeine in the
beverage.
Hives
Green tea contains polyphenols with significant antihistamine effects. However, human
trials have not studied the effect of green tea or its constituents for the treatment or
prevention of hives. Doctors sometimes recommend 3 cups of green tea per day to prevent
hives.
Hypertension
Right after consuming caffeine from coffee or tea, blood
pressure increases briefly. While the effects of long-term avoidance of caffeine on blood
pressure remain unclear, a few reports have even claimed that long-term coffee drinkers tend
to have lower blood pressure than do those who avoid coffee. Despite the lack of
clarity in published research, many doctors tell people with high blood pressure to avoid
consumption of caffeine.
Hibiscus tea (made from Hibiscus sabdariffa) has been reported to reduce blood
pressure in people with hypertension. Boil two tablespoons of tea in 1 cup of water for 20 to
30 minutes and consume daily for at least two weeks.
Hypoglycemia
Even modest amounts of caffeine may increase symptoms of
hypoglycemia. For this reason, people with low blood sugar should avoid caffeinated beverages,
including tea.
Immune function
While green tea has stimulated production of immune
cells and has shown anti-bacterial properties in some studies, more research is needed to
evaluate the effectiveness of green tea in protecting against infection.
Indigestion
Chamomile (Matricaria recutita) has been
used traditionally to relieve inflamed or irritated mucous membranes of the digestive tract.
Since heartburn sometimes involves reflux of stomach acid into the esophagus, the
anti-inflammatory properties of chamomile are also useful. In addition, chamomile appears to
promote normal digestion. However, modern studies are lacking to prove chamomile beneficial
for people with heartburn or indigestion. Roman chamomile (Anthemis nobilis) has not
been studied for indigestion, though it has traditionally been used similarly to German
chamomile.
Insomnia
Chamomile tea is an old folk remedy for anxiety,
particularly when it causes insomnia. Often 1 cup of tea is taken three or more times per
day.
Iron-deficiency
anemia
Black tea contains tannins that strongly inhibit the absorption of non-heme iron (e.g.,
iron from non-animal sources). This iron-blocking effect is so strong that drinking black tea
can help treat hemochromatosis, a disease of iron overload.
Irritable bowel
syndrome
Chamomile essential oils have eased intestinal cramping
and irritation in laboratory experiments on animals. Herbalists sometimes recommend chamomile
to relieve alternating bouts of diarrhea and constipation, though research has yet to investigate these
effects. Chamomile is typically taken three times per day, between meals, in a tea form by
dissolving 2–3 grams of powdered chamomile or by adding 3–5mL of herbal extract
tincture to hot water.
Kidney stones
Increasing dietary oxalate can lead to an increase in urinary oxalate excretion. Increased
urinary oxalate increases the risk of stone formation. As a result, most doctors agree that
kidney stone formers should reduce their intake of
oxalate from food as a way to reduce urinary oxalate. Many foods contain oxalate; however,
only a few—including tea—appear to significantly increase urinary oxalate
levels.
Drinking caffeine-containing beverages increases urinary
calcium levels. Long-term caffeine consumers are reported to
have an increased risk of osteoporosis, suggesting
that the increase in urinary calcium caused by caffeine consumption may be significant.
However, tea consists mostly of water, and increasing water consumption is known to reduce the
risk of forming a kidney stone. While many doctors are concerned about the possible negative
effects of caffeine consumption in people with a history of kidney stones, preliminary studies
in both men and women have found that tea consumption is actually associated with a
reduced risk of forming a kidney stone. These reports suggest that the helpful effect of
consuming more water by drinking tea may compensate for the theoretically harmful effect that
caffeine has in elevating urinary calcium. Therefore, the bulk of current research suggests
that it is not important for kidney stone formers to avoid tea.
Osteoporosis
Like salt, caffeine increases urinary loss of calcium.
Caffeine intake has been linked to increased risk of hip fractures, and to a lower bone mass
in women who consumed inadequate calcium. Many doctors
recommend decreasing caffeinated coffee, black tea, and caffeine-containing soft drinks as a way to improve bone mass.
Curiously, while caffeine-containing tea consumption has been linked to osteoporosis in
some studies, others have reported that tea drinkers have a lower risk of osteoporosis than do
people who do not drink tea. Possibly, other constituents of tea, such as flavonoids, might override the calcium-depleting effect of
caffeine in tea.
Peptic ulcers
Tea drinking can aggravate or interfere with the healing of peptic ulcers in some
people.
Chamomile has a soothing effect on inflamed and
irritated mucous membranes. It is also high in the
flavonoid apigenin. Apigenin inhibits growth of Helicobacter pylori—the
organism that causes peptic ulcers—in test
tubes. Many doctors recommend drinking 2 to 3 cups of strong chamomile tea each day. The tea
can be made by combining 3–5mL of chamomile tincture with hot water or by steeping
2–3 teaspoons of chamomile flowers in the water, covered, for 10 to 15 minutes.
Chamomile is also available in capsules; two can be taken three times per day.
Premenstrual syndrome (PMS)
In a study of Chinese women, increasing tea consumption was associated with increasing
prevalence of PMS. Among a group of college students in the United States, consumption of caffeine-containing beverages was associated with increases in
both the prevalence and severity of PMS. The more caffeine women consumed, the more likely
they were to suffer from PMS. A preliminary study showed that women with heavy caffeine
consumption were more likely to have shorter menstrual periods and shorter cycle length
compared with women who did not consume caffeine. Therefore, many doctors recommend that women
with PMS avoid caffeine-containing beverages, including tea.
Tooth decay (dental caries)
Compounds present in both green tea and black tea have
been shown to inhibit the growth and activity of bacteria associated with tooth decay. Animals
given tea compounds in their drinking water develop fewer dental caries than those drinking
plain water. Human volunteers rinsing with an alcohol extract of tea leaves before bed each
night for four days had significantly less plaque formation, but similar amounts of
plaque-causing bacteria compared with those with no treatment. Tea drinking has not yet been
tested as a tooth decay preventative in humans.
Ulcerative
colitis
German doctors practicing herbal medicine have recommended
chamomile for people with colitis. A cup of strong chamomile tea drunk three times per day
is standard, along with chamomile tea enemas.
Weight loss and
obesity
Green tea extract rich in polyphenols (epigallocatechin gallate, or EGCG) may support a
weight-loss program by increasing energy expenditure. However, clinical trials on weight loss
in humans are needed to confirm these preliminary observations. No studies have tested the
effect in humans on energy expenditure of drinking brewed tea.
