Studies of the amyotrophic lateral sclerosis parkinsonism dementia complex of Guam direct suspicion to a heat-labile component of vegetables found in greatest concentration in seeds. We therefore surveyed patients with Parkinson's disease (PD) regarding early adult consumption of fruits and vegetables usually eaten raw, with seeds that are swallowed or scraped with the teeth. We administered a pretested questionnaire by telephone to 81 nondemented patients with PD and to a same-sex married sibling without PD. The patients and their siblings were asked whether they or their spouse (as an internal standard) had been more likely to eat each of 17 food items between marrying and age 40 years. No item was associated with the presence of PD. Unexpectedly associated with the absence of PD were preference for nuts (odds ratio, 0.39), salad oil or dressing (pressed from seeds) (odds ratio, 0.30), and plums (odds ratio, 0.24). These three items have higher vitamin E content than the other 14 items in our questionnaire. Our data are consistent with the hypothesis that vitamin E, as an antioxidant, may have prophylactic value against PD.