For thousands of years, the people of China, Japan, India, and Thailand have consumed green tea and used it medicinally to treat everything from headaches to heart diseases. Over the past few decades, however, research in both Asia and the West have taken place providing scientific evidence of green tea’s numerous health benefits. As a whole, studies indicate that regular consumption of green tea may slow or prevent conditions including high cholesterol, heart disease, arthritis, impaired immune disease and liver disease. In yet another recent study on the beverage’s healthful properties, published in the academic journal Phytomedicine, researchers have found evidence that enzymes in the drink may help in fighting Alzheimer’s and other forms of dementia.
Researchers at the Newcastle University have also found that the Chinese brew may also play a vital role in guarding against cancer. The Newcastle team focused on whether or not once the tea was in the digestive system if the protective properties were still as effective. “What was really exciting was that we found when green tea is digested, the resulting chemicals are actually more effective against key triggers of Alzheimer’s,” said Ed Okello, from the university’s School of Agriculture, Food and Rural Development. “The digested compounds also had anti-cancer properties, significantly slowing down the growth of tumour cells which we were using in our experiments,” Okello said.
Previous studies have shown that polyphenols, present in black and green tea, bind with the toxic compounds and protect brain cells. When ingested, the polyphenols are broken down to produce a mix of compounds and it was these the team tested in their research. According to Okello, there are many factors that together have an influence on diseases such as cancer and dementia – a good diet, plenty of exercise and a healthy lifestyle are all important. “But I think it’s fair to say that at least one cup of green tea a day may be good for you and I would certainly recommend it,” he added.
Regularly drinking green tea could protect the brain against developing Alzheimer’s and other forms of dementia. The study, published in the academic journal Phytomedicine, also suggests this ancient Chinese remedy could play a vital role in protecting the body against cancer. Led by Dr Ed Okello, the Newcastle team wanted to know if the protective properties of green tea – which have previously been shown to be present in the undigested, freshly brewed form of the drink – were still active once the tea had been digested. Digestion is a vital process which provides our bodies with the nutrients we need to survive. But, says Dr Okello, it also means that just because the food we put into our mouths is generally accepted to contain health-boosting properties, we can’t assume these compounds will ever be absorbed by the body.
“What was really exciting about this study was that we found when green tea is digested by enzymes in the gut, the resulting chemicals are actually more effective against key triggers of Alzheimer’s development than the undigested form of the tea,” explains Dr Okello, based in the School of Agriculture, Food and Rural Development at Newcastle University and executive director of the university’s Medicinal Plant Research Group. “In addition to this, we also found the digested compounds had anti-cancer properties, significantly slowing down the growth of the tumour cells which we were using in our experiments.”
As part of the research, the Newcastle team worked in collaboration with Dr Gordon McDougall of the Plant Products and Food Quality Group at the Scottish Crop Research Institute in Dundee, who developed technology which simulates the human digestive system. It is this which made it possible for the team to analyse the protective properties of the products of digestion. Two compounds are known to play a significant role in the development of Alzheimer’s disease – hydrogen peroxide and a protein known as beta-amyloid. Previous studies have shown that compounds known as polyphenols, present in black and green tea, possess neuroprotective properties, binding with the toxic compounds and protecting the brain cells.
When ingested, the polyphenols are broken down to produce a mix of compounds and it was these the Newcastle team tested in their latest research. “It’s one of the reasons why we have to be so careful when we make claims about the health benefits of various foods and supplements,” explains Dr Okello. “There are certain chemicals we know to be beneficial and we can identify foods which are rich in them but what happens during the digestion process is crucial to whether these foods are actually doing us any good.” Carrying out the experiments in the lab using a tumour cell model, they exposed the cells to varying concentrations of the different toxins and the digested green tea compounds.
Dr Okello explained: “The digested chemicals protected the cells, preventing the toxins from destroying the cells. “We also saw them affecting the cancer cells, significantly slowing down their growth. Green tea has been used in Traditional Chinese medicine for centuries and what we have here provides the scientific evidence why it may be effective against some of the key diseases we face today.”
The next step is to discover whether the beneficial compounds are produced during digestion after healthy human volunteers consume tea polyphenols. The team has already received funding from the Biotechnology and Biological Sciences Research Council (BBSRC) to take this forward. Dr Okello adds: “There are obviously many factors which together have an influence on diseases such as cancer and dementia – a good diet, plenty of exercise and a healthy lifestyle are all important. “But I think it’s fair to say that at least one cup of green tea every day may be good for you and I would certainly recommend it.”
(Source: Newcastle University: Phytomedicine)
Bouhlal and co workers reported that salt had an impact on intake but fat did not. They found that in general food intake increased with salt level, noting that compared with the 'normal' salt levels, a suppression of salt induced a 25 per cent decrease in green bean intake, whereas an addition of salt induced a 15 per cent increase in pasta intake. Contrarily to initial beliefs, the researchers observed no increase in food intake with increasing added sugar level. They said the findings indicate that two to three year old children's food intake may not be affected by its added sugar content.
The study data also showed that preschool children with a higher BMI score consumed more pasta when fat level was higher. The authors said this finding may confirm previous results which highlight fatter children prefer high-fat foods. The researcher said their results imply that fat and sugar addition could be avoided in foods for children without having an impact on palatability, allowing the energy density of children's diet to be limited.
“Furthermore, these findings suggest that there is no need to add salt to pasta which is consumed anyway. On the contrary, salt suppression in vegetables, whose intake is to be promoted, should be considered cautiously,” they said.
Source: British Journal of Nutrition
Published online ahead of print, doi: 10.1017/S0007114510003752
“The impact of salt, fat and sugar levels on toddler food intake”
Authors: S. Bouhlal, S. Issanchou, S. Nicklaus
Fish oil, when combined with epigallocatechin‑3‑gallate (EGCG—a polyphenol and antioxidant found in green tea), may affect chemical processes in the brain associated with Alzheimer's disease, according to a study published in Neuroscience Letters. This study, which used an animal (mouse) model of Alzheimer's disease, builds on previous research linking the disease to peptides (amino acid chains) called beta‑amyloids and laboratory studies suggesting that EGCG decreases memory problems and beta‑amyloid deposits in mice.
Researchers from the University of South Florida divided Alzheimer's disease‑model mice into five feeding groups. During a period of 6 months, each group was fed one of five diets: fish oil only; high‑dose EGCG; low‑dose EGCG; low‑dose EGCG and fish oil; or a regular diet (control). The researchers observed that low‑dose EGCG alone did not reduce the Alzheimer's disease-related chemical processes in the brain. However, the mice fed the combination of fish oil and EGCG had a significant reduction in amyloid deposits that have been linked with Alzheimer's disease.
Upon examination of blood and brain tissues of the mice, the researchers found high levels of EGCG in the mice that were fed the combination of fish oil and low‑dose EGCG compared with those fed low‑dose EGCG alone. A possible explanation, according to the researchers, is that fish oil enhances the bioavailability of EGCG—that is, the degree to which EGCG was absorbed into the body and made available to the brain. This effect, in turn, may contribute to the increased effectiveness of this combination. Further research is necessary, however, to determine if the combination of fish oil and EGCG affects memory or cognition, and whether it might have potential as an option for people at risk of developing Alzheimer's disease.
Giunta B, Hou H, Zhu Y, et al. Fish oil enhances anti‑amyloidogenic properties of green tea EGCG in Tg2576 mice. Neuroscience Letters. 2010;471(3):134–138.
“Fruit and vegetables are all good, but the data significantly show that green leafy vegetables are particularly interesting, so further investigation is warranted,” Carter said. “Green leafy vegetables contain antioxidants, magnesium and omega 3 fatty acids — all of which have been shown to have health benefits”, she added.
Each of the studies that Carter and her colleagues analyzed followed a group of adults over periods of 4-and-a-half to 23 years, recording how many servings of fruits and vegetables each participant ate on a daily basis then examining who was diagnosed with type 2 diabetes.
The researchers found no significant difference in diabetes risk with higher intake of vegetables in general, fruits in general, or combinations of vegetables and fruits.
Green leafy vegetables stood out, however, with an increase of 1.15 servings a day producing a 14 percent decrease in an individual's risk of developing diabetes. Type 2 diabetes is caused by the body's inability to adequately use insulin, a hormone produced by the pancreas, to regulate levels of glucose produced from food. Uncontrolled, the sugar levels rise and can damage the eyes, kidneys, nerves, heart and major arteries.
An estimated 180 million people worldwide have diabetes. The costs of caring for those with the disease are soaring in wealthy nations and becoming an increasing burden in developing countries too. Although there is no cure for diabetes, people with the condition can minimize their chances of getting sicker by being more active and losing weight.