Walnuts And Heathy Aging Study

Study Description

Walnuts are a rich source of long chain n-3 fatty acids (n-3 PUFA), a-linolenic acid (ALA), antioxidants, polyphenols and other bioactive compounds. n-3 PUFAs are considered important during early development of brain and for preventing or slowing age related cognitive decline (ARCD) and age-related macular degeneration (AMD). Epidemiological studies suggest that nutrients such as n-3 PUFA, antioxidants and B-vitamins may protect against ARCD. Small human studies have shown beneficial effects of polyphenol rich foods on cognition and macula health. Walnuts have shown to improve memory and motor functions in animal models as well.

Objectives

This study is a dual center (Loma Linda University site and Clinic Hospital in Barcelona Site), single blind, randomized, controlled intervention trial. The primary objective is to determine the effect of consuming 30 to 45 g (approximately 1 to 1.5 ounces) a day of walnuts for 2 years on age-related cognitive decline and macular degeneration in healthy elderly subjects under free living conditions. The study hypothesis is that for healthy, cognitively normal adults aged 65-75 years, daily ingestion of walnuts will slow the rate of cognitive decline and delay onset and progression of macular degeneration.

Methods

350 healthy participants, ages 65-75 years, will be recruited in 2012 and 2013 in each of the sites for a total of 700 participants. Following baseline data collection, participants will be randomly assigned to either: the walnut group (habitual diet with 1 or 1.5 oz/d walnut supplement based on energy consumption) or the control group (habitual diet only). The intervention will be conducted for 2 years. At baseline and yearly, cardiometabolic risk factors, red blood cell membrane fatty acids, urinary polyphenols and biomarkers of inflammation and oxidation will be measured. Cognitive function tests and optical coherence tomography (eye tests) will be administered at baseline and year 2 end. A dual center trial increases external validity of the study and it makes the study feasible given the large number of participants required. Because the trial utilizes realistic intakes of a whole food, it will help in providing recommendations to consumers. Our proposed study will provide powerful and important data on the effect of a highly bioactive whole food in preventing or slowing ARCD and AMD.

Expected Results

Based on the different nutrient and non-nutrient components of walnuts, particularly ALA and antioxidants, we anticipate that their daily consumption for 2 years will reduce the decline in cognitive function and delay the onset and/or progression of AMD compared to the control diet. We also anticipate that the walnut diet will have beneficial effects on other markers of cardiometabolic risk and bone health.

This study is funded by the California Walnut Commission