The Effects of Walnuts on Antioxidant Capacity and Nutritional Status in Humans

Tufts University

Status

Completed

Conditions

Healthy

Treatments

Behavioral: Walnut consumption

Study type

Interventional

Funder types

Other

Identifiers

NCT00626691

PV2707

Details and patient eligibility

About

The goal of this study is to find out if the daily consumption of English walnuts (Juglans regia L.) for 6 wk, at a dose readily incorporated into the diet (0.75 or 1.50 oz), will have a positive effect on antioxidant capacity and nutrient status in a population of healthy adults, aged 50-70 y.

Full description

Epidemiological studies conducted in large populations have consistently shown that increased consumption of plant-based, antioxidant-rich foods, i.e., fruits, vegetables, grains, and nuts, reduces the risk for several chronic diseases. Among the various plants consumed worldwide, English walnuts (Juglans regia L.) have been reported to have the highest antioxidant activity, second only to rosehips (Rosa canina L.). There are a number of different compounds present in walnuts that are known to exhibit antioxidant activity, including vitamin E (as γ-tocopherol), melatonin, and several non-flavonoid polyphenols (e.g., ellagic acid monomers and polymeric ellagitannins). In vitro and ex vivo, studies have demonstrated the ability of walnuts and walnut extracts to increase the resistance of low density lipoprotein (LDL) to oxidation. Walnuts and/or their constituents have also been shown to decrease levels of oxidative stress in diabetic mice and increase serum antioxidant capacity in rats2. In humans, in vivo antioxidant capacity changes after consuming walnuts have only been measured in subjects with Type 2 diabetes. The antioxidant capacity of the lipophilic compartments, as well as the cooperative/synergistic interactions between the water- and fat-soluble antioxidants present in plasma after walnut consumption have not been measured. Indeed, there have been no studies conducted to date of the effect of walnut consumption on the total antioxidant capacity of healthy men and women. The goal of our proposed study is to determine if consuming walnuts in amounts readily incorporated into the diet can affect the antioxidant capacity of older adults.

Enrollment

24 patients

Sex

All

Ages

50+ years old

Volunteers

Accepts Healthy Volunteers

Inclusion criteria

Generally healthy men and postmenopausal women age 50 or over
BMI 18.5-35 kg/m2

Exclusion criteria

Cigarette smoking and/or nicotine replacement use
History or known allergy to nuts of any kind
Regular consumption of ≥ 5 oz nuts/week for 6 weeks prior to study admission
Individuals taking estrogen
Use of cholesterol-lowering medications
Gastrointestinal disease
Kidney disease
Endocrine disease: including diabetes, untreated thyroid disease
Rheumatoid arthritis
Active treatment for any type of cancer, except basal cell carcinoma, within 1 year prior to study admission
Systolic blood pressure > 150 mmHg and/or diastolic blood pressure > 95 mmHg
Regular use of oral steroids
Regular daily intake of ≥ 2 alcoholic drinks
Illicit drug use
No fish oil supplements (including cod liver oil) for 6 weeks prior to study admission
No high dose (≥ 3X RDA) supplements of vitamins C, E, selenium, or beta-carotene for one month prior to study admission
No dietary supplements containing phenolic compounds, i.e., herbal preparations, or berry containing preparations (such as cranberry capsules) for one month prior to study admission
No regular consumption of pomegranate juice (≥ 180 mL or 6 oz/d, ≥ 3 times/wk) for one month prior to study admission