Benefits of Walnuts for Male Reproductive Health

Walnuts as a whole food contain polyunsaturated fatty acids, anti-oxidants, and other nutrients essential to sperm development and function. This randomized controlled trial sought to determine if a Western style diet supplemented with walnuts would improve sperm quality as a predictor of male fertility.

Study Overview

• Status: Completed
• Conditions: Nutrition Disorders; Infertility
• Intervention / Treatment: Other: Whole walnuts

Detailed Description

A vast research base on human sperm shows the following to be critical for normal sperm development and function: Polyunsaturated fatty acids provide fluidity to sperm membranes allowing sperm to swim, fuse with ova, and support key cellular functions. Antioxidants protect sperm from reactive oxygen species generated during normal physiologic processes or white blood cells that infiltrate into seminal fluid and injure membranes and fragment sperm DNA. Selenium is critical in the form of anti-oxidant selenoproteins protecting developing sperm in the testes and later selenium in the epididymis participates in cell shape for motility. Folate, in a recent study, was associated with decreased aneuploidy (abnormal number of chromosomes)in sperm. Deficiency in any of these factors - lipids, antioxidants, selenium, or folate could manifest as poor semen quality and sub-fertility.

Walnuts provide a rich dietary source of each of the critical factors discussed above. Walnuts contain beneficial lipids, antioxidants, selenium, and folate. Walnuts, as a natural whole food source, may be preferential to commercial supplements and, as a plant source of nutrients, leave a positive green footprint on the planet.

Hypothesis The investigators hypothesize that diets enriched in walnuts will improve semen quality. Semen quality is a predictive marker for male infertility and sub-fertility, thus, the overall goal is to determine if dietary intake of walnuts will benefit male reproductive health.

A randomized, controlled intervention will be used to study the effects of walnut supplementation on semen quality measures in young men (ages 21 to 35) eating Western diets. Participants will be enrolled from the West Los Angeles area (n=120). Men will be randomly assigned to consume 3 oz of walnuts per day as part of their usual diet or to continue their habitual diet but avoid nuts. Each will follow the assigned diet for three months to cover one complete cycle of spermatogenesis.

The specific aims of the study are to:

1. Establish at baseline: habitual diet; serum omega-3 to omega-6 ratio, serum selenium and folate; semen quality (sperm count, motility, morphology) and sperm DNA integrity (COMET assay); sperm aneuploidy; and semen anti-oxidant levels
2. Randomly assign men to habitual diet plus 3 oz walnuts per day or usual diet without nuts for three months monitored by six telephone 24 hour dietary recalls
3. Compare intervention and control groups at three months on blood and semen measures
4. Compare blood and semen measures within man between baseline and three months.

• Study Type: Interventional
• Enrollment (Actual): 120
• Phase: Phase 2

Contacts and Locations

Study Locations

• United States
  • California
    • Los Angeles, California, United States, 90095-6919
      • University of California, Los Angeles

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 19 years to 33 years (Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: Male

Description

Inclusion Criteria: Males

1. Age 21 to 35 years
2. Residence is in West Los Angeles for the next three months
3. Non-smoker
4. Free from chronic diseases requiring medications
5. Free from nut allergies or nut intolerance
6. Not taking anti-oxidant supplements

Exclusion Criteria:

1. Outside the age range of 21 to 35 years
2. Residence outside West Los Angeles area prohibiting two trips to the clinical research laboratory
3. Current smoker
4. Taking medications for chronic disease
5. Nut allergies or nut intolerance
6. Taking anti-oxidant supplements -

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
No Intervention: Usual Western style diet; Participants will consume their usual Western style diet avoiding tree nuts
Experimental: Whole walnuts; Participants will consume usual Western style diet adding 75 gm whole walnuts per day	Other: Whole walnuts; 75 gm whole walnuts per day will be consumed with usual Western style diet

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
change from baseline in semen quality at 12 weeks	semen quality is measured as sperm count, motility, vitality, morphology, DNA integrity	change from baseline at 12 weeks
change from baseline in serum fatty acids at 12 weeks		change from baseline at 12 weeks
change from baseline in serum selenium at 12 weeks		change from baseline at 12 weeks
change from baseline in serum folate at 12 weeks		change from baseline at 12 weeks
change from baseline in serum zinc at 12 weeks		change from baseline at 12 weeks

Secondary Outcome Measures

Outcome Measure	Time Frame
change from baseline in body weight pounds at 12 weeks	change from baseline at 12 weeks
change from baseline in nutrient intake at 12 weeks	change from baseline at 12 weeks

Collaborators and Investigators

• Sponsor: University of California, Los Angeles
• Collaborators: California Walnut Commission

Publications and helpful links

General Publications

• Robbins WA, Xun L, FitzGerald LZ, Esguerra S, Henning SM, Carpenter CL. Walnuts improve semen quality in men consuming a Western-style diet: randomized control dietary intervention trial. Biol Reprod. 2012 Oct 25;87(4):101. doi: 10.1095/biolreprod.112.101634. Print 2012 Oct.

Study record dates

Study Major Dates

• Study Start: November 1, 2009
• Primary Completion (Actual): December 1, 2010
• Study Completion (Actual): December 1, 2010

Study Registration Dates

• First Submitted: December 31, 2011
• First Submitted That Met QC Criteria: January 3, 2012
• First Posted (Estimate): January 6, 2012

Study Record Updates

• Last Update Posted (Estimate): November 28, 2016
• Last Update Submitted That Met QC Criteria: November 23, 2016
• Last Verified: November 1, 2016

More Information

Terms related to this study

• Keywords: Antioxidants; Diet; Nutritional Sciences; Fertility; Reproduction; Fatty Acids; Andrology; Body weight changes
• Additional Relevant MeSH Terms: Infertility; Nutrition Disorders
• Other Study ID Numbers: 445246WR77518