Frequent drinking of fruit and vegetable juices substantially decreases the risk of Alzheimer's disease, reported Dr. Qi Dai of Vanderbilt University, Nashville, Tenn., and associates.
Results of several studies have suggested that the antioxidants and polyphenols in dietary fruits and vegetables may reduce the risk of Alzheimer's disease (AD) or delay its onset. Dr. Dai and associates hypothesized that intake of fruit and vegetable juices also might be protective. They tested their hypothesis using data from 1,836 subjects involved in the Kame Project, a large, population-based prospective study of Japanese Americans living in King County, Wash.
The subjects, aged 65 years or older at baseline (mean age 72 years), completed food frequency questionnaires and underwent periodic cognitive assessments. Over a mean of 6 years of follow-up, 81 incident cases of AD were diagnosed.
The risk of developing AD declined with increasing consumption of fruit and vegetable juices. Subjects who drank juice three times a week or more had a hazard ratio of 0.24, compared with those who drank juice less often than once a week. This protective effect was seen in subjects with all different levels of education, physical activity, and fat intake (Am. J. Med. 2006;119:751–9).
As in previous studies, the antioxidant vitamins in dietary fruits and vegetables were found to be protective, but those in vitamin supplements were not.
Although tea was the beverage most often consumed, and tea is a rich source of some polyphenols, there was no relation between tea drinking and AD risk in this study. This finding agrees with those of two previous studies of tea drinking and AD. Wine is another potent source of antioxidants, and there was a small but statistically insignificant inverse association between wine or sake drinking and AD. The lack of statistical significance may be due to the small number of subjects (6%) who drank these beverages at least once per week, the researchers noted.
The protective effect of fruit and vegetable juices is being attributed to their antioxidant properties, but it is also possible that other characteristics such as anti-inflammatory properties are at work. Moreover, in addition to possessing antioxidant vitamins and polyphenols, juices may contain other components such as folate and minerals, which contribute to the protective effect, they added.