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food for thought

There’s no specific diet for Parkinson’s disease. A healthy and balanced diet that includes vegetables and fruits, whole grains, healthy protein foods and unsaturated fats is recommended to promote overall health and well-being.

According to new research, however, eating flavonoid-rich foods should be added to that dietary advice. Doing so, the findings suggest, can improve the chance that people with Parkinson’s will live longer.

About Parkinson’s disease

Parkinson’s disease is a progressive neurological disorder characterized by slowness of movement, rigid muscles, tremour, impaired posture and lack of balance and co-ordination. It’s caused by a loss of nerve cells that produce dopamine, a neurotransmitter (brain chemical) that controls body movements.

While most cases are diagnosed after age 60, at least 10 per cent of people with Parkinson’s disease develop symptoms before 50. Besides older age, risk factors include family history, sex (men are more likely to develop Parkinson’s than are women) and exposure to environmental toxins such as herbicides and pesticides.

According to Parkinson Canada, Parkinson’s disease is the world’s fastest-growing neurological disease with Canada having some of the highest rates. It’s estimated to affect one in 500 Canadians, with 25 more diagnosed every day.

The latest research

The study, published March 8 in the journal Neurology, examined the relationship between the habitual consumption of flavonoids and flavonoid-rich foods and risk of death among 1,251 people, average age 72, with Parkinson’s disease.

Flavonoids are a family of over 5,000 bioactive compounds that occur naturally in fruits, vegetables, soybeans, tea, wine and chocolate. They’re categorized into six subclasses, namely anthocyanins, flavan-3-ols, flavonols, flavanones, flavones and isoflavones.

The researchers assessed participants’ diets before their Parkinson’s diagnosis and for 33 years after. Intake of flavonoids and flavonoid-rich foods, including apples, berries, oranges, orange juice, tea and red wine, was measured every four years.

By the end of the study, 944 participants had died. Of those, one-half died from Parkinson’s, 112 died from cardiovascular disease and 69 died from cancer.

Participants who had the highest total flavonoid intake before diagnosis had a 70 per cent greater chance of survival compared to those who consumed the least.

Researchers also looked at flavonoid subclasses. The highest intakes of anthocyanins (found in berries, red grapes, red wine), flavones (celery, parsley, thyme, peppermint) and flavan-3-ols (apples, pears, dark chocolate, green tea, black tea) were tied to a significantly lower death rate compared to the lowest intakes.

When top food contributors of flavonoids were examined, berries and red wine were found to be especially protective. For each, consuming at least three servings a week (versus fewer than one a month) was linked to a significantly lower mortality risk.

The researchers accounted for other risk factors such as age, smoking, body mass index, physical activity, hypertension, Type 2 diabetes and alcohol intake to arrive at their findings.

Protective effects of flavonoids

Flavonoids can cross the blood-brain-barrier and protect brain cells from free radical damage and inflammation. Anthocyanins and flavan-3-ols are also thought to improve blood flow to brain tissue.

Flavonoids have also been associated with protection against major chronic diseases such as hypertension, heart disease, stroke and certain cancers.

Strengths, limitations

A notable strength of this study is that it captured people’s habitual flavonoid intake by measuring it repeatedly over 30 years.

The researchers also assessed flavonoid intake before and after diagnosis of Parkinson’s, allowing them to see that flavonoid intake didn’t change after diagnosis. Associations between survival rate and flavonoid intake pre- and post-diagnosis were similar.

Limitations include the study’s observational design, which can’t prove that people with Parkinson’s who eat a diet high in flavonoids will have a lower mortality risk. Instead, the study found associations.

Still, the new findings are in line with previous studies that have tied a higher flavonoid intake to a lower risk of developing Parkinson’s disease and to a lower mortality risk in other populations.

They also add to growing evidence that diet may be an effective tool to delay the onset of Parkinson’s disease and its progression.

Higher adherence to the MIND diet (Mediterranean-DASH Intervention for Neurodegenerative Delay), for example, known for its brain healthy foods, has been associated with a later age of onset of Parkinson’s disease, as well as a slower rate of progression of parkinsonism. (Parkinsonism describes the signs and symptoms found in Parkinson’s disease; Parkinson’s is the most common form, but other conditions can also have these symptoms.)

Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan. Follow her on Twitter @LeslieBeckRD

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