Science News

Dietary Flavonoids May Lower Parkinson’s Risk, Especially in Men

Men who consume high amounts of flavonoids — plant pigments abundant in foods such as berries, tea and apples — may lower their risk of Parkinson’s disease (PD), according to a new study published in the April 10 issue of Neurology. Researchers led by Xiang Gao, M.D., Ph.D., at Harvard Medical School analyzed the diets and medical histories of 80,336 female registered nurses and 49,281 male health professionals enrolled in two long-term studies, the Nurses’ Health Study and the Health Professionals Follow-up Study, which began in 1976 and 1986 respectively.

Every four years, participants completed questionnaires about their lifestyles, including diet and health status. Based on these responses, Dr. Gao and colleagues calculated the total flavonoid intake and specific flavonoid intake for each individual. Then, they examined medical histories to determine which participants developed Parkinson’s.


  • 805 participants (438 men and 367 women) developed PD during 20–22 years of follow-up.
  • Men who consumed the highest levels of total flavonoids (80th percentile and above) had a 40 percent lower PD risk than those who consumed the
    least (20th percentile and below).
  • Researchers found no significant relationship between total flavonoid consumption and PD risk in women.
  • Men who ate five or more servings of apples per week showed a 46 percent reduced risk of PD compared with those who ate less than one apple a month. No similar effect was observed for women.
  • Men and women who had a high intake of a specific class of flavonoids known as anthocyanins, abundant in berries, lowered PD risk by about 24 percent.

What Does It Mean?
This study suggests that a person’s diet, specifically their flavonoid intake, may influence PD risk. In particular, high consumption of berries, which are rich in anthocyanins, appears to slightly lower PD risk for both men and women.

Men who ate high amounts of apples, or of total flavonoids showed a reduced risk of PD, but no such relationships were observed for women. One possible reason is that men’s and women’s bodies break down flavonoids differently.

Although a diet rich in fruits and vegetables is advisable from a general health standpoint, confirmation from additional studies is needed to determine whether berries and apples can indeed lower PD risk.

Bicycling Ability May be Unaffected by Freezing of Gait in Parkinson’s

People with Parkinson’s disease (PD) who have trouble walking due to freezing of their gait — the sudden inability to move while walking — may retain the ability to ride a bicycle. The new research, published in the September 20 online edition of the Journal of Neurology, Neurosurgery, and Psychiatry, could provide a realistic exercise option for people who find it difficult to perform other activities. Freezing of the gait often impacts ability to perform activities of daily living. In this study, researchers from Radboud University Nijmegen Medical Center in the Netherlands led by Bastiaan R. Bloem, M.D., Ph.D., interviewed 45 people with Parkinson’s who were consecutively seen in their outpatient clinic to discover whether they demonstrated freezing of gait and whether they retained the ability to bicycle.


  • Of the 45 people, 25 had regular freezing of gait.
  • Of these 25 people, 19 were still cycling. Of these 19, 14 reported no difficulties on the bicycle and only one reported freezing while bicycling.
  • Those who had difficulty cycling reported problems with uneven pedal pressure, balancing issues, mounting/dismounting and fitness.
  • Of the 20 people with no freezing of gait, 18 were still cycling. None had freezing instances on the bicycle.

What Does It Mean?
This study reinforces the idea that when freezing affects gait, it does not impact all forms of movement equally. It demonstrates that many people with PD may retain the ability to cycle despite freezing of gait. It does not clarify why bicycling and walking impact people with Parkinson’s differently, or how balance or other problems affect a person’s ability to bicycle.

There are no treatments for freezing for people who experience it in spite of treatment with levodopa. Therefore, it is encouraging that in some cases, bicycling may be an alternative means of exercise and transportation. The authors recommend that people with PD who want to cycle outdoors do so only if they can safely mount and dismount; otherwise, it is recommended to use controlled conditions such as stationary bicycles. People with PD should check with their doctors before beginning this or any other exercise program.

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*The two science stories in this issue of News & Review are abbreviated.  See full stories.