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

 

Dry Onion Skin Has A Use

The brown skin and external layers of the onions are rich in fiber and flavonoids. Photo: SINC.

More than 500,000 tonnes of onion waste are thrown away in the European Union each year. However, scientists say this could have a use as food ingredients. The brown skin and external layers are rich in fibre and flavonoids, while the discarded bulbs contain sulphurous compounds and fructans. All of these substances are beneficial to health.

Production of onion waste has risen over recent years in line with the growing demand for these bulbs. More than 500,000 tonnes of waste are generated in the European Union each year, above all in Spain, Holland and the United Kingdom, where it has become an environmental problem. The waste includes the dry brown skin, the outer layers, roots and stalks, as well as onions that are not big enough to be of commercial use, or onions that are damaged.

“One solution could be to use onion waste as a natural source of ingredients with high functional value, because this vegetable is rich in compounds that provide benefits for human health”, Vanesa Benítez, a researcher at the Department of Agricultural Chemistry at the Autonomous University of Madrid (Spain), tells SINC.

Benítez’s research group worked with scientists from Cranfield University (United Kingdom) to carry out laboratory experiments to identify the substances and possible uses of each part of the onion. The results have been published in the journal Plant Foods for Human Nutrition.

According to the study, the brown skin could be used as a functional ingredient high in dietary fibre (principally the non-soluble type) and phenolic compounds, such as quercetin and other flavonoids (plant metabolites with medicinal properties). The two outer fleshy layers of the onion also contain fibre and flavonoids.

“Eating fibre reduces the risk of suffering from cardiovascular disease, gastrointestinal complaints, colon cancer, type-2 diabetes and obesity”, the researcher points out.

Phenolic compounds, meanwhile, help to prevent coronary disease and have anti-carcinogenic properties. The high levels of these compounds in the dry skin and the outer layers of the bulbs also give them high antioxidant capacity.

Meanwhile, the researchers suggest using the internal parts and whole onions that are thrown away as a source of fructans and sulphurous compounds. Fructans are prebiotics, in other words they have beneficial health effects as they selectively stimulate the growth and activity of bacteria in the colon.

Sulphurous compounds reduce the accumulation of platelets, improving blood flow and cardiovascular health in general. They also have a positive effect on antioxidant and anti-inflammatory systems in mammals.

“The results show that it would be useful to separate the different parts of onions produced during the industrial process”, explains Benítez. “This would enable them to be used as a source of functional compounds to be added to other foodstuffs”.

 

Reference

Benítez V, Mollá E, Martín-Cabrejas MA, Aguilera Y, López-Andréu FJ, Cools K, Terry LA, Esteban RM. Characterization of industrial onion wastes (Allium cepa L.): dietary fibre and bioactive compounds. Plant Foods Hum Nutr 2011; 66 (1): 48-57.