Effect of daily ingestion of walnuts for 2 years on age-related cognitive decline and macular degeneration in healthy elderly subjects: A randomized, single blind, dual center, controlled trial. The WAHA Study

Study description:
This study is investigating the effects of walnuts in preventing or slowing age related cognitive declaine and age related macular degeneration in the health elderly. The study will be conducted at two locations: Loma Linda University in California and Clinic Hospital in Barcelona, Spain. It is a single blind, randomized, controlled intervention trial. 350 healthy elderly (ages 65-75) participants will be recruited in each of the sites for a total of 700 participants. A dual center trial increases the validity of the study and it makes the study feasible given the large number of participants required.

Participants will be randomly assigned to one of each group: the Walnut group (habitual diet with 1.0, 1.5 or 2.0 oz/d walnut supplementation) or the Control group (habitual diet only). The intervetion will be for 2 years. At baseline and yearly, cardiometabolic risk factors, red blood cell membrane fatty acids, urinary polyphenols and biomarkers of inflammation and oxidation willl be measured at both sites. Eye exam and ambulatory blood pressure will be measured at these same time points but only at the Barcelona site. Cognitive function test, magnetic resonanace imaging (on a subset of participants) will be measured at baseline and year 2 end at both sites, while in addition, carotid intima-media thickness and dual x-ray absorptiometry will be measured only at the Barcelona site during these two time points. Because the trial is free living and utilizes realistic intakes of whole food, it will help in providing recommendations to consumers.

Increased lifespan in developed countries has resulted in a greatly increased frequency of disesases related to aging, such as cardiovascular diseases and neurogenerative disorders. The latter being Alzheimer's disease, the most common type of dementia , and age-related macular degeneration, the leading cause of visual loss and blindness in the Western World. Inflammation and oxidative stress are believed to play a major role in the pathogenesis of all age-related diseases. As a result these are ideal targets for nutritional intervention with antioxidant-rich foods, for which walnuts are particulary well suited.

Long Chain n-3 polyunsaturated fatty acids are considered important during early development of the brain and for preventing or slowing age-related congnitive delicne and age-related macular degeneration. Epidemiological studies suggest that nutrients such as n-3 PUFAs, antioxidants and B-vitamins may protect against cognitive decline. Walnuts are rich source of the n-3 PUFA, alpha-linolenic acid, antioxidants, polyphenols and other bioactive compounds. Small human studies have shown beneficial effects of polyphenol rich foods on cognition and macula. Walnuts have shown to improve memory and motor functions in animal models. Given the outcomes of these studies, a systematic investigation of the role of walnuts in prevention or slowing age related cognitive decline and age related macular degeneration in the healthy elderly is warranted.



Study funded by the California Walnut Commission