Eating flavonoids protects men against Parkinson’s disease

Men who eat flavonoid-rich foods such as berries, tea, apples and red wine significantly reduce their risk of developing Parkinson’s disease, according to new research by Harvard University and the University of East Anglia (UEA).

Published April 4 in the journal Neurology®, the findings add to the growing body of evidence that regular consumption of some flavonoids can have a marked effect on human health. Recent studies have shown that these compounds can offer protection against a wide range of diseases including heart disease, hypertension, some cancers and dementia.

This latest study is the first study in humans to show that flavonoids can protect neurons against diseases of the brain such as Parkinson’s.

Around 130,000 men and women took part in the research. More than 800 had developed Parkinson’s disease within 20 years of follow-up. After a detailed analysis of their diets and adjusting for age and lifestyle, male participants who ate the most flavonoids were shown to be 40 per cent less likely to develop the disease than those who ate the least. No similar link was found for total flavonoid intake in women.

The research was led by Dr Xiang Gao of Harvard School of Public Health in collaboration with Prof Aedin Cassidy of the Department of Nutrition, Norwich Medical School at UEA.

“These exciting findings provide further confirmation that regular consumption of flavonoids can have potential health benefits,” said Prof Cassidy.

“This is the first study in humans to look at the associations between the range of flavonoids in the diet and the risk of developing Parkinson’s disease and our findings suggest that a sub-class of flavonoids called anthocyanins may have neuroprotective effects.”

Prof Gao said: “Interestingly, anthocyanins and berry fruits, which are rich in anthocyanins, seem to be associated with a lower risk of Parkinson’s disease in pooled analyses. Participants who consumed one or more portions of berry fruits each week were around 25 per cent less likely to develop Parkinson’s disease, relative to those who did not eat berry fruits. Given the other potential health effects of berry fruits, such as lowering risk of hypertension as reported in our previous studies, it is good to regularly add these fruits to your diet.”

Flavonoids are a group of naturally occurring, bioactive compunds found in many plant-based foods and drinks. In this study the main protective effect was from higher intake of anthocyanins, which are present in berries and other fruits and vegetables including aubergines, blackcurrants and blackberries. Those who consumed the most anthocyanins had a 24 per cent reduction in risk of developing Parkinson’s disease and strawberries and blueberries were the top two sources in the US diet.

The findings must now be confirmed by other large epidemiological studies and clinical trials.

Parkinson’s disease is a progresssive neurological condition affecting one in 500 people, which equates to 127,000 people in the UK. There are few effective drug therapies available.

Dr Kieran Breen, director of research at Parkinson’s UK said: “This study raises lots of interesting questions about how diet may influence our risk of Parkinson’s and we welcome any new research that could potentially lead to prevention.

“While these new results look interesting there are still a lot of questions to answer and much more research to do before we really know how important diet might be for people with Parkinson’s.”

 

Reference

Gao X, Cassidy A, Schwarzschild MA, Rimm EB, Ascherio A. Habitual intake of dietary flavonoids and risk of Parkinson disease. Neurology, 2012 DOI: 10.1212/WNL.0b013e31824f7fc4

 

Researchers Demonstrate Green Tea Compound Is Effective In Treating Genetic Disorder And Two Types Of Tumors

A compound found in green tea shows great promise for the development of drugs to treat two types of tumors and a deadly congenital disease.  The discovery is the result of research led by Principal Investigator, Dr. Thomas Smith at The Donald Danforth Plant Science Center and his colleagues at The Children’s Hospital of Philadelphia. Their findings are published in the recent article, “Green Tea Polyphenols Control Dysregulated Glutamate Dehydrogenase In Transgenic Mice By Hijacking The ADP Activation Site” in The Journal of Biological Chemistry.

Shown here is a ribbon diagram of glutamate dehydrogenase with each of the identical subunits represented in different colors. The orange spheres represent the substrate and the yellow spheres denote the location of the green tea compounds bound to the enzyme. The background is of a tea plantation in India.

Glutamate dehydrogenase (GDH) is found in all living organisms and is responsible for the digestion of amino acids. In animals, GDH is controlled by a complex network of metabolites. For decades it was not clear why animals required such regulation but other kingdoms did not.  This was partially answered by the Stanley group’s finding that a deadly congenital disease, hyperinsulinism/hyperammonemia (HHS), is caused by the loss of some of this regulation. In this disorder, patients (typically children) respond to the consumption of protein by over secreting insulin, becoming severely hypoglycemic, often leading to death.

Using atomic structures to understand the differences between animals and plants, Dr. Smith and his colleagues discovered that two compounds found naturally in green tea are able to compensate for this genetic disorder by turning off GDH in isolated and when the green tea compounds were administered orally. The Smith lab also used X-ray crystallography to determine the atomic structure of these green tea compounds bound to the enzyme. With this atomic information, they hope to be able to modify these natural compounds to design and develop better drugs.

Interestingly, two other research groups have validated and extended these findings to demonstrate that blocking GDH with green tea is very effective at killing two different kinds of tumors; glioblastomas, an aggressive type of brain tumor, and tuberous sclerosis complex disorder, a genetic disease that causes non-malignant tumors to grow on a number of organs.

Shown here is a surface representation of glutamate dehydrogenase (GDH) with each of the six identical subunits represented by different colors. Also shown is the location of ECG, a major compound found in green tea. From this structure, it appears that ECG inhibits GDH by binding to the back of the active site and forcing it open. This effectively shuts the enzyme down. Our other studies have shown that these green tea compounds are effective at shutting down the enzyme in tissue and in whole animals. This not only treats a deadly congenital disorder but is also useful in treating at least two types of tumors.

“While these compounds from green tea are extremely safe and consumed by millions every day, they have a number of properties that make them difficult to use as actual drugs. Nevertheless, our ongoing collaboration with the Stanley lab shows that there are natural compounds from plants that can control this deadly disorder and, with the atomic structure in hand, can be used as a starting point for further drug design.”

 

About The Donald Danforth Plant Science Center

Founded in 1998, the Donald Danforth Plant Science Center is a notforprofit research institute with a mission to improve the human condition through plant science. Research at the Danforth Center will feed the hungry and improve human health, preserve and renew the environment, and enhance the St. Louis region and Missouri as a world center for plant science. The Center’s work is funded through competitive grants and contract revenue from many sources, including the National Institutes of Health, U.S. Department of Energy, National Science Foundation, U.S. Department of Agriculture, U.S. Agency for International Development, the Bill & Melinda Gates and Howard G. Buffett Foundations.

 

Mechanism Discovered For Health Benefit Of Green Tea, New Approach To Autoimmune Disease

CORVALLIS, Ore. – One of the beneficial compounds found in green tea has a powerful ability to increase the number of “regulatory T cells” that play a key role in immune function and suppression of autoimmune disease, according to new research in the Linus Pauling Institute at Oregon State University.

This may be one of the underlying mechanisms for the health benefits of green tea, which has attracted wide interest for its ability to help control inflammation, improve immune function and prevent cancer.

Pharmaceutical drugs are available that perform similar roles and have been the subject of much research, scientists say, but they have problems with toxicity. A natural food product might provide a long-term, sustainable way to accomplish this same goal without toxicity, researchers said.

“This appears to be a natural, plant-derived compound that can affect the number of regulatory T cells, and in the process improve immune function,” said Emily Ho, an LPI principal investigator and associate professor in the OSU Department of Nutrition and Exercise Sciences.

“When fully understood, this could provide an easy and safe way to help control autoimmune problems and address various diseases,” Ho said.

The findings have been published in Immunology Letters, a professional journal.

There are many types of cells that have different roles in the immune system, which is a delicate balancing act of attacking unwanted invaders without damaging normal cells. In autoimmune diseases, which can range from simple allergies to juvenile diabetes or even terminal conditions such as Lou Gehrig’s disease, this process goes awry and the body mistakenly attacks itself.

Some cells exist primarily to help control that problem and dampen or “turn off” the immune system, including regulatory T cells. The number and proper function of those regulatory T cells, in turn, is regulated by other biological processes such as transcription factors and DNA methylation.

In this study, OSU scientists did experiments with a compound in green tea, a polyphenol called EGCG, which is believed to be responsible for much of its health benefits and has both anti-inflammatory and anti-cancer characteristics. They found it could cause a higher production of regulatory T cells. Its effects were not as potent as some of those produced by prescription drugs, but it also had few concerns about long-term use or toxicity.

“EGCG may have health benefits through an epigenetic mechanism, meaning we aren’t changing the underlying DNA codes, but just influencing what gets expressed, what cells get turned on,” Ho said. “And we may be able to do this with a simple, whole-food approach.”

Laboratory studies done with mice, Ho said, showed that treatment with EGCG significantly increased the numbers and frequencies of regulatory T cells found in spleen and lymph notes, and in the process helped to control the immune response.

“Epigenetic regulation can be potentially exploited in generating suppressive regulatory T cells for therapeutic purposes, and is of significant clinical importance for the suppression of autoimmune diseases,” the researchers said in their study.