Study confirms narcolepsy as an autoimmune disease

A new study that offers some of the most compelling evidence to date for the idea of "mimicry," where the immune system attacks a body protein because of its similarity to a pathogen protein, confirms that narcolepsy is an autoimmune disease.
Reporting in the latest online issue of Science Translational Medicine, researchers at Stanford University School of Medicine in California show how in genetically susceptible individuals, narcolepsy can be triggered because part of a wakefulness protein, called hypocretin, is very similar to part of a protein from the pandemic 2009 H1N1 "swine flu" virus.
Narcolepsy is a chronic disorder where the brain cannot control sleep-wake cycles, leading to sudden bouts of sleep, often accompanied by cataplexy, an abrupt loss of voluntary muscle tone that can cause collapse.
The National Institutes of Health estimates that narcolepsy affects around 1 in 3,000 Americans. Currently, there is no cure.

Immune system attacks brain cells that make the 'wakefulness' protein

In 2009, Emmanuel Mignot, professor of psychiatry and behavioral sciences at Stanford, who has been working on narcolepsy for over 20 years, led a study that gave the first genetic clue that narcolepsy is an autoimmune disorder where the body's immune system attacks brain cells that make the "wakefulness" protein hypocretin.
Prof. Mignot, who is co-senior author of the new paper, says:

"The relationship between H1N1 infection, vaccination and narcolepsy gave us some very interesting insight into possible causes of the condition. In particular, it strongly suggested to us that T cells of the immune system primed to attack H1N1 can occasionally also cross-react with hypocretin and somehow cause the destruction of hypocretin-producing neurons."

The latest work suggests new ways to interrupt the process before all the hypocretin-producing cells are lost and produce the dramatic symptoms of narcolepsy.
It also opens the prospect of a blood test to diagnose the disease, and it offers new insights into a link between a pandemic H1N1 vaccine used in Europe in 2009 and a spike in narcolepsy cases in Scandinavia the year after.
The team says their work will also give new ideas to researchers investigating other types of autoimmune disorders, particularly those involving the brain.
Co-senior author Elizabeth Mellins, an immunology researcher and professor of pediatrics at Stanford, adds: "By giving us a new way to think about how neurons in these patients die, it also suggests new therapeutic approaches that we would not have considered if we hadn't learned that this is an autoimmune disease."

Focus on T cells because of link to HLA signature

Previous studies have established that the vast majority of people with narcolepsy have a variant of the human leukocyte antigen (HLA) gene that is found in only a quarter of the general population.
For their work, Prof. Mignot and colleagues decided to focus on the T cells of the immune system because of their association with the HLA signature found in nearly all narcolepsy patients.
HLA is a molecule that sits on the surface of cells that present antigens and bits of proteins they gather from their environment. T cells come along and scan these proteins, and if any of these is "foreign," they start to divide and go around the body looking for it so as to destroy it.
However, if there is a case of mistaken identity on the part of the T cells, then things can go drastically awry. Prof. Mellins explains how they started to suspect this was the case in narcolepsy:

"When we saw that the portion of the hypocretin that seemed to be recognized by the immune system in narcolepsy patients was similar to a part of the pandemic 2009 H1N1 influenza hemagglutinin molecule, we were very hopeful that we were on the right track."

They found that a short, 13-amino-acid section of the H1N1 hemagglutinin protein was very similar to two equally short pieces of the hypocretin protein.
The resemblance was close enough so that the T cells of people who suffer from narcolepsy reacted strongly to the hypocretin protein segments.
The researchers tested this by presenting the small piece of the H1N1 protein to cultured T cells from narcolepsy patients, and saw how this increased the proportion of hypocretin-reactive cells.

Other pathogens may cause similar confusion in immune system

The team was also surprised to find hypocretin cross-reactive T cells in blood taken from narcolepsy patients before H1N1 began circulating in humans in 2009.
Prof. Mignot says this suggests other viruses or pathogens may sometimes cause a similar confusion in the immune system, adding that:

"Indeed, there is a growing appreciation that cross-reactivity of immune T cell recognition may not be as uncommon as once thought. Although this cross-reactivity may make the immune system more adaptable to new infections, it may also increase the chance of mistakes that could result in autoimmune diseases."

In another study published earlier this year, researchers at the UCLA Center for Sleep Research offer another clue to the cause of narcolepsy in humans. They suggest an excess of histamine brain cells may reduce hypocretin cells.

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HIV cure may lie in radioimmunotherapy

A new study suggests targeting HIV with radioimmunotherapy could eradicate HIV from infected cells. If given in conjunction with highly active antiretroviral therapy, it may form the basis of a cure.
Although highly active antiretroviral therapy (HAART) kills human immunodeficiency virus (HIV) in the bloodstream, it does not completely eliminate it from the body because the virus can linger in infected cells and replicate.
Researchers from the Albert Einstein College of Medicine of Yeshiva University in New York presented their findings at the 99th Scientific Assembly and Annual Meeting of the Radiological Society of North America (RSNA) in Chicago, IL, this week.
Study leader Ekaterina Dadachova, professor of radiology and of microbiology & immunology, says although there has been enormous progress in HIV treatments that slow progression to AIDS, the search for a permanent cure continues. She explains:

"To combat HIV, we need a method that will completely eliminate all HIV-infected cells without damaging non-infected cells."

In radioimmunotherapy (RIT), which has been used for a while to treat cancer, antibodies charged with radioactive isotopes target and destroy cancer cells.
The antibody selects the particular type of cancer cell and the attached radioisotope delivers a lethal dose of radiation that kills the target cell, while leaving untargeted (healthy) cells unharmed.

HIV infection reduced to undetectable levels

In previous work, Prof. Dadachova had already managed to use the approach in the lab to target and destroy human immune cells infected with HIV.
At the meeting, she and her colleagues presented the results of a study in which they used the approach to treat blood samples from people infected with HIV.
The blood samples came from 15 HIV patients receiving HAART treatment at the AIDS Center at Montefiore, the University Hospital for Einstein College and academic medical center.
The results showed that RIT targeted and killed HAART-treated lymphocytes - types of white blood cells - and in most samples, reduced HIV infection to undetectable levels.
The team then went on to see if RIT could reach HIV-infected cells in the brain and central nervous system.
This would be a big step because current antiretrovirals do not cross the blood-brain barrier very well, which is why so many HIV patients treated with HAART often have severe mental impairment.
For this test, they used a lab model of the blood-brain barrier made with human cells and discovered that the same radioisotope-charged antibodies used in earlier experiments could destroy HIV-infected cells in the brain without damaging the barrier.
Prof. Dadachova says:

"We found that radioimmunotherapy could kill HIV-infected cells both in blood samples that received antiretroviral treatment and within the central nervous system, demonstrating RIT offers real potential for being developed into an HIV cure."

In another study published recently in the Journal of Infectious Diseases, researchers from Lund University in Sweden describe how they found that an aggressive new HIV strain leads to AIDS more quickly than other current strains.

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Oxytocin activates 'social' brain regions in children with autism

Researchers from Yale University have found that while engaging with social information, children with autism spectrum disorders experienced enhanced brain activity after a single dose of the hormone oxytocin was administered through a nasal spray.
Results of their findings are published in the journal Proceedings of the National Academy of Sciences.
Oxytocin is a naturally occurring hormone in the human body that has been implicated in social bonding. In fact, other research recently found that oxytocin stimulates the reward center in the brain, increasing partner attractiveness and strengthening monogamy.
According to the researchers from Yale, theirs is the first study to analyze how oxytocin affects brain function in children with autism spectrum disorders (ASDs).

Researchers delivered oxytocin to children and adolescents with ASDs via a nasal spray, which resulted in enhanced brain activity toward social cues.

Led by study author Ilanit Gordon, the team conducted a double-blind, placebo-controlled experiment involving 17 children and adolescents with ASDs who were between the ages of 8 and 16.5.
After the participants were given either the oxytocin spray or a placebo, the researchers measured brain activity via functional magnetic resonance imaging (MRI) while the children and adolescents judged both socially and non-socially meaningful pictures.
The "social" pictures were images of eyes, whereas the "non-social" pictures were images of vehicles.
Because autism is a result of a neurological disorder that affects normal brain function, individuals with ASD have difficulty with communication and social interaction skills.
How the brains of these individuals react to socially meaningful images is therefore helpful for treatments that "target the core social dysfunction in ASD," the researchers note.

Oxytocin 'assists social attunement'

The team found that, compared with the placebo group, the participants who received a single nasal dose of oxytocin experienced enhanced activity in the brain.
Ilanit Gordon explains further:

"We found that brain centers associated with reward and emotion recognition responded more during social tasks when children received oxytocin instead of the placebo. Oxytocin temporarily normalized brain regions responsible for the social deficits seen in children with autism."

She adds that the oxytocin assisted social attunement - a process whereby brain regions involved with social behavior and cognition are activated more for social stimuli and less for non-social stimuli.
The researchers say that the neural attunement they observed "might facilitate social learning, thus bringing about long-term change in neural systems and subsequent behavioral improvements."
"Our results are particularly important considering the urgent need for treatments to target social dysfunction in autism spectrum disorders," Gordon concludes.

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Low vitamin D levels may damage the brain

Vitamin D plays an important role in maintaining bone health, but a new study led by University of Kentucky researchers claims that deficiency of this vitamin may cause damage to the brain and other organs.
The results, published in Free Radical Biology and Medicine, showed that when middle-aged rats were fed a diet low in vitamin D for several months, they developed free radical damage to the brain. They also performed less well in cognitive functioning tests for learning and memory.
The researchers say that several brain proteins were found to have significantly higher levels and that this contributes to significant nitrosative stress in the brain, possibly leading to cognitive decline.
The researchers claim that vitamin D deficiency is increasing in the US and its effects on an aging brain should not be underestimated.
Prof. Allan Butterfield, lead author of the paper, explains:

"Given that vitamin D deficiency is especially widespread among the elderly, we investigated how, during aging from middle-age to old-age, low vitamin D affected the oxidative status of the brain.
Adequate vitamin D serum levels are necessary to prevent free radical damage in brain and subsequent deleterious consequences."

Catch some rays

Often called the "sunshine vitamin," dietary sources of vitamin D are limited, and the study notes that when times are hard, individual food intake is not always the most nutritious.
The result of this is low levels of the vitamin, particularly among the elderly population. Coupled with the widespread use of sunscreens and popularity of wearing of long-sleeved clothing in the sunshine, levels of vitamin D are declining.
Low levels of vitamin D have previously been linked to Alzheimer's disease, the development of certain cancers and heart disease.
Prof. Butterfield recommends that everyone should allow themselves at least 10-15 minutes' exposure to sunshine every day to ensure that vitamin D levels are adequate.
He also suggests that vulnerable people should contact their physicians to have their levels tested. If they are low, individuals should consider taking supplements and eating more foods containing the vitamin, including oily fish, eggs and fortified milk.
Medical News Today recently reported that dancers from Birmingham's Royal Ballet in the UK have benefitted from vitamin D supplements, citing a report that showed greater improvements in muscle strength and fewer injuries for dancers taking them.
However, researchers from Johns Hopkins caution that too much can do more harm than good. Levels over 21 nanograms per milliliter increased levels of c-reactive protein, which is associated with hardening of blood vessels and an increased risk of cardiovascular problems.

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Menstrual cramps relieved by erectile dysfunction drug

For many women, monthly menstrual cramps can stop them in their tracks, causing nausea, vomiting, diarrhea and dizziness. But according to researchers from Penn State College of Medicines, a common drug used to treat erectile dysfunction in men could provide some relief.
In a recent study published in the journal Human Reproduction, the researchers, led by Dr. Richard Legro, studied the effects of sildenafil citrate - commercially known as Viagra - on women with primary dysmenorrhea (PD).
According to the team, PD is the most common reason for pelvic pain in women. Although it is painful and disruptive, it is not due to other diseases.
Anti-inflammatory drugs - including ibuprofen - are the most widely used treatment for pain relief of menstrual cramps, but the researchers say it does not work for all women, and is associated with ulcers and kidney damage when used repeatedly.
Erectile dysfunction drugs have previously shown an improvement in pelvic pain when taken orally, the researchers note, but this can often result in headaches, which they say makes it largely unsuitable for chronic use.
As a result, the researchers from this latest study assessed the results of using sildenafil citrate vaginally, which they say had not yet been tried to alleviate PD.

Larger studies needed to confirm results

Little blue pill: women who took a drug that is used to treat erectile dysfunction in men experienced relief from their menstrual pain.

To conduct their research, the investigators randomized 25 women between the ages of 18 and 35 to use either sildenafil or a placebo drug.
Working with researchers at Nova Gradiska General Hospital in Croatia, the team from Penn State collected data on how the participants rated their pain during a 4-hour period.
After 2 hours, the researchers observed that uterine artery pulsatility index was "significantly lower" in the group taking sildenafil citrate, compared with those in the placebo group.
More importantly, the patients in the sildenafil group experienced alleviated menstrual pain, and there were no reported side effects.
Although the researchers thought the drug would soothe pain by increasing blood flow, they observed that both sildenafil and the placebo increased uterine blood flow, so they say they do not yet understand why the drug alleviates pain.
Dr. Legro, who is also professor of obstetrics and gynecology and public health sciences at Penn State, says:



"If future studies confirm these findings, sildenafil may become a treatment option for patients with PD. Since PD is a condition that most women suffer from and seek treatment for at some points in their lives, the quest for new medication is justified."

The study was funded by the National Institutes of Health, but the authors note that they did not meet their sample size due to loss of funding.
As a result, they say larger, multi-center studies must be completed in order to confirm the findings of their study.

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Long-term antacid use linked to vitamin B12 deficiency

Antacids are commonly used to neutralize the acid in the stomach, helping many individuals who have acid reflux. But a new study suggests that using this medication consistently for 2 years or more is linked to a deficiency of vitamin B12, which can have adverse effects for the nervous system.
The research, published in JAMA, is among the first to show associations between long-term exposure to antacids and vitamin B12 deficiency in a large population-based study.
The investigators say that antacids, including proton pump inhibitors (PPIs) and histamine 2 receptor antagonists (H2RAs), are some of the most commonly used pharmaceuticals in the US.
However, because they suppress the creation of gastric acid, the team says antacids may lead to malabsorption of vitamin B12. This vitamin helps to keep the nervous system - consisting of the brain, nerves and spinal cord - healthy.
"Vitamin B12 deficiency is relatively common," say the researchers, "especially among older adults; it has potentially serious medical complications if undiagnosed."
They continue:

"Left untreated, vitamin B12 deficiency can lead to dementia, neurologic damage, anemia and other complications, which may be irreversible."

To conduct their study, the researchers, led by Jameson R. Lam of Kaiser Permanente in California, looked at the link between using antacids and vitamin B12 deficiency within the Northern California population of Kaiser Permanente patients.

Stronger association in women and younger age groups

The study found a link between 2 years' use of antacids or more and a deficiency of vitamin B12.

With a study population consisting of 25,956 vitamin B12-deficient patients and 184,199 control patients without the deficiency, the researchers compared their use of acid inhibitors by using electronic pharmacy, laboratory and diagnostic databases.
They found that among the patients who were newly diagnosed with a vitamin B12 deficiency, 12% were given a 2-year or more supply of PPIs, compared with 7.2% of patients who were exposed to PPIs in the control group.
Similarly, 4.2% of the vitamin-deficient patients had a 2-year or more supply of H2RAs, versus 3.2% in the control group.
The researchers say that receiving a 2 or more years' supply of either of these medications was associated with a greater risk for becoming vitamin B12 deficient. They add that doses over 1.5 PPI pills per day were more strongly linked to the deficiency than doses under 0.75 pills per day.
Though they say cannot completely rule out confounding factors as they relate to their findings, they do note that using antacids "identifies a population at higher risk of B12 deficiency."
The magnitude of the association was stronger in women and younger age groups, they add, noting that the association decreased after patients stopped using the antacids.
The authors conclude:

"These findings do not recommend against acid suppression for persons with clear indications for treatment, but clinicians should exercise appropriate vigilance when prescribing these medications and use the lowest possible effective dose."

Vitamins have been a hot topic of late. A recent study cast doubts over vitamin D supplementation, while another suggested that low vitamin B9 in males' diets could cause birth defects in offspring.

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Multivitamins 'waste of money,' say medical experts

"Enough is enough: stop wasting money on vitamin and mineral supplements," say medical experts in an editorial of a leading journal that has just published three new studies examining whether routine use of vitamin and mineral supplements brings health benefits.
Writing in Annals of Internal Medicine, the editorial authors conclude that most supplements do not prevent chronic disease or death, some may even be harmful in well-nourished adults, and there is a large body of evidence to support this.
Their routine use is not justified and they should be avoided, they urge, noting that:
"This message is especially true for the general population with no clear evidence of micronutrient deficiencies, who represent most supplement users in the United States and in other countries." Editorial co-author Dr. Edgar Miller, professor of medicine and epidemiology at Johns Hopkins Bloomberg School of Public Health in Baltimore, MD, told CBS News that people would be better off spending money on healthy foods, such as "fruits, vegetables, nuts, beans, low-fat dairy," and getting exercise.

US consumers spend over $28 billion a year on supplements

In the editorial, Dr. Miller and colleagues say despite "sobering evidence" of no health benefit and even of possible harm, US adults are spending more and more on multivitamins.
They note how use of multivitamins increased among US adults from 30% between 1988 and 1994 to 39% between 2003 and 2006, while overall use of dietary supplements grew from 42% to 53% over the same period.
There have been some dips - for instance, studies have linked certain supplements to negative outcomes - but overall the supplements industry has kept growing. In the US, it reached $28 billion a year in 2010. Trends in the UK and other European countries are similar, notes the editorial.
One point that stands out in the editorial is that consumers seem to react differently to evidence of negative results versus null results.
While overall use of supplements has gone up, use of certain individual supplements has gone down, for example beta-carotene and vitamin E. This decline followed reports of studies that showed these could be harmful.
On the other hand, evidence that daily supplements have null effects - that is, they make no difference to health - appear to have no effect on consumers and overall sales have kept growing.

Three studies suggest no benefit to supplements

In one of the studies published in the same issue as the editorial, Dr. Francine Grodstein, of Harvard School of Public Health, and colleagues examined data from the The Physicians' Health Study II, to look at the effect of long-term use of multivitamins on cognitive health.
The participants were nearly 6,000 male doctors aged 65 and over, who were randomized to take either a daily multivitamin pill or placebo pill for 12 years.
Tests of memory and cognitive function showed no difference between the two groups, and the researchers conclude:

"In male physicians aged 65 years or older, long-term use of a daily multivitamin did not provide cognitive benefits."

In another study, researchers reviewed evidence on the use of vitamin and mineral supplements to prevent heart disease and cancer, in order to update the guidelines for the US Preventive Services Task Force - an expert panel that advises the US government.
Their review found "limited evidence" to justify regular supplementation with vitamins and minerals for the prevention of cancer and cardiovascular disease (CVD).
They also note that beta-carotene appears to increase risk of lung cancer in smokers. And in the third study, researchers looked at the role of multivitamins and minerals in preventing a further heart attack, in more than 1,700 patients recruited at least 6 weeks after a heart attack (myocardial infarction).
Having a heart attack raises a person's risk of a further attack, stroke or death.
The patients were randomly assigned to receive either a daily high dose of multivitamins and minerals, or placebo pills for 5 years.
The study results showed no differences between the two groups in rates of chest pain, another attack, need for hospitalization, stroke or early death. However, the authors note that these results should be treated with caution since not all participants took the pills as they should.

Strong reaction from the supplement industry

The Council for Responsibile Nutrition (CRN), a group that represents the supplement industry, has voiced strong objections to the editorial.
They argue that while it is all very well to say instead of taking supplements people should concentrate on eating a healthy diet and exercising, this "fantasy" vision fails to recognize "real life."
Steve Mister, CRN's President and CEO, says:

"The editorial demonstrates a close-minded, one-sided approach that attempts to dismiss even the proven benefits of vitamins and minerals. It's a shame for consumers that the authors refuse to recognize the real-life need for vitamin and mineral supplementation, living in a fairy-tale world that makes the inaccurate assumption that we're all eating healthy diets and getting everything we need from food alone."

He says while not suggesting supplements are a panacea, he hopes the authors agree they have their place, especially as government studies show consumers are repeatedly failing to eat a healthy diet.

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What are the health benefits of green tea?

Green tea, native to China and India, has been consumed and hailed for its health benefits for centuries globally, but has only recently gained popularity in the US.
Tea is considered the most consumed beverage in the world behind water, however 78% of the tea consumed worldwide is black and only about 20% is green.¹
All types of tea except herbal tea are brewed from the dried leaves of the Camellia sinensis bush. The level of oxidation of the leaves determines the type of tea.
Green tea is made from un-oxidized leaves and is the least processed type of tea and therefore contains the most antioxidants and beneficial polyphenols.
Green tea was used in traditional Chinese and Indian medicine to control bleeding and heal wounds, aid digestion, improve heart and mental health and regulate body temperature.⁴ Recent studies have shown green tea can potentially have positive effects on everything from weight loss to liver disorders to type 2 diabetes.
This Medical News Today information article on green tea provides a nutritional breakdown and an in-depth look at its possible health benefits, the different forms of green tea, and some precautions when consuming green tea.

Nutritional breakdown of green tea

Unsweetened brewed green tea is a zero calorie beverage. The caffeine contained in a cup of tea can vary according to length of infusing time and the amount of tea infused.

Green tea is becoming increasingly popular in the US

In general, green tea contains a relatively small amount of caffeine (approximately 20-45 milligrams per 8 oz cup), compared with black tea which contains about 50 milligrams and coffee with 95 milligrams per cup.²
Green tea is considered one of the world's healthiest drinks and contains the highest amount of antioxidants of any tea. The natural chemicals called polyphenols in tea are what are thought to provide its anti-inflammatory and anti-carcinogenic effects.
Epigallocatechin-3-gallate (EGCG) is the most studied and bioactive polyphenol in tea and has been shown to be the most effective at eliminating free radicals.^{1, 4}
Green tea is approximately 20% to 45% polyphenols by weight, of which 60% to 80% are catechins such as EGCG.¹

Possible health benefits of green tea

Below are the potential health benefits associated with green tea:
Cancer:
According to the National Cancer Institute, the polyphenols in tea have been shown to decrease tumor growth in laboratory and animal studies and may protect against damage caused by ultraviolet UVB radiation.
In countries where green tea consumption is high cancer rates tend to be lower, but it is impossible to know for sure whether it is the green tea that prevents cancer in these specific populations or other lifestyle factors.⁴
One large-scale clinical study compared green tea drinkers with non-drinkers and found that those who drank the most tea were less likely to develop pancreatic cancer, particularly women, who were 50% less likely to develop the disease.
Studies have also shown the positive impacts of green tea on breast, bladder, ovarian, colorectal, esophageal, lung, prostate, skin and stomach cancer.
Researchers believe that it is the high level of polyphenols in tea that help kill cancerous cells and stop them from growing, however the exact mechanisms by which tea interacts with cancerous cells is unknown.
Other studies have shown a lack of preventative effects of tea on cancer. The amount of tea required for cancer-preventive effects has also varied widely in studies - from 2- 10 cups per day.¹
In 2005, the FDA stated that "there is no credible evidence to support qualified health claims for green tea consumption and a reduced risk of gastric, lung, colon/rectal, esophageal, pancreatic, ovarian, and combined cancers."¹
Heart Disease:
A 2006 study published in the Journal of the American Medical Association concluded that green tea consumption is associated with reduced mortality due to all causes, including cardiovascular disease.
The study followed over 40,000 Japanese participants between the ages of 40 and 79 for 11 years, starting in 1994.
The participants who drank at least 5 cups of green tea per day had a significantly lower risk of dying (especially from cardiovascular disease) than those who drank less than one cup of tea per day.
Another study found that consuming 10 cups of green tea per day can lower total cholesterol, however, consuming 4 cups or less had no effect on cholesterol levels.¹
Type 2 Diabetes:
Studies concerning the relationship between green tea and diabetes have been inconsistent. Some have shown a lower risk of developing type 2 diabetes for green tea drinkers than for those who consumed no tea, while other studies have found no association between tea consumption and diabetes at all.¹
Weight Loss:
Green tea may promote a small, non-significant weight loss in overweight and obese adults; however, since the weight lost in the studies were so minimal, it is unlikely that green tea is clinically important for weight loss.
Other studies have found that green tea is helpful in preventing dental cavities, stress, chronic fatigue, treating skin conditions and improving arthritis by reducing inflammation.

Recent developments on the benefits of green tea from MNT news
Green tea or coffee may reduce stroke risk. Drinking green tea or coffee on a regular basis is associated with a reduced risk of stroke, according to a study published in the journal Stroke: Journal of the American Heart Association.⁵
Green tea may help fight prostate cancer. British researchers have scientifically proven that broccoli, turmeric, green tea and pomegranate help fight the most common cancer in men in the United States and the United Kingdom - prostate cancer.⁶

Forms of green tea

Green tea is available bottled and sweetened with sugar or an artificial sweetener, in single tea bags, loose-leaf, and in instant-powder. Green tea supplements are sold in capsule form or liquid extracts.
According to 2010 research presented at the American Chemical Society, bottled teas are not equivalent to brewed teas as some 16-oz bottled teas can contain fewer polyphenols than one cup of brewed tea.¹
Green tea extract ointments have been approved by the FDA to topically treat genital warts.

Precautions and risks

There are little to no known side effects or contraindications to drinking green tea for adults. Those with severe caffeine sensitivities could experience insomnia, anxiety, irritability, nausea or upset stomach.³
Those taking anticoagulant drugs such as Coumadin/warfarin should drink green tea with caution due to its vitamin K content.³
If taken with stimulant drugs, green tea could possibly increase blood pressure and heart rate.³
Green tea supplements however, contain high levels of active substances that can trigger side effects and interact with other herbs, supplements, or medications.⁴ Green tea supplements are unregulated by the FDA and may also contain other substances unsafe for health or with unproven health benefits. Always check with a physician before starting any herb or supplement regimen.
In particular, pregnant or breastfeeding women, those with heart problems or high blood pressure, kidney or liver problems, stomach ulcers, or anxiety disorders should not take green tea supplements or extracts.⁴

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