Walnut Immune Study Participants Needed

Thanks for your interest in the Walnut Immune Study. This study will test the health benefits of walnuts. The primary goal of this study is to determine whether eating walnuts daily for 12 weeks can improve immunity in older men and post-menopausal women. The following tabs below answer a lot of questions regarding the study, if interested please fill out the walnut immune study screening form. 

Who is eligible for the study?

Investigators are looking for older men and post-menopausal women aged 55-75 years 2. Have a BMI of 25-32 3. Being able to commute to Loma Linda University 4. Not taking medication or supplements that affect immunity 
Exclusion Criteria:1.  Intolerance or allergy to walnuts  2. Regular intake of walnuts and/or other nuts (>3 ounces/week) 3. Immune system insufficiency or disease 4. Using immune boosting supplements 5. Exposure to antibiotics and corticoids immediately prior to the study 6. Participants with uncontrolled chronic diseases and relevant psychiatric illnesses, including major depression, will not be included in the study. 7. Flu vaccination or COVID-19 booster within the past three months

What is expected of participants?

Participants must be willing to commit for a total duration of 12 weeks and to attend four office visits. During this time, participants are expected to attend all scheduled meetings and visits. Participants must be equally willing to consume walnuts or abstain from walnuts and other nuts, while continuing their usual diet and other routines or lifestyle habits.  Participants are expected to visit the clinic 4 times during the study (about once a month). At these visits, you may be given walnuts depending on the group you have been randomly assigned to. You will be randomly assigned to either Group 1: Walnuts (where you will be asked to eat 1 or 2 ounces of walnuts daily depending on your habitual calorie intake) or Group 2 (where you will be asked to continue your habitual diet and abstain from walnuts and other nuts). You will be randomly assigned based on your age and gender using a random number table. Body composition measurements which mean measuring your weight, body fat mass and muscle mass using an InBody machine will be done, at the baseline clinic visit, and week 12 visit by a trained clinician. During two of these visits participants will be fasting (this means that you must have nothing to eat and drink except water after 8 p.m. the evening before) to provide blood samples. About 3 tablespoons of blood will be collected during the blood draw visits. During two of the visits, you will be asked to provide stool and urine samples.

How can I participate?

You can let us know if you are interested in participating in the study by either of the two ways:

  1. Send us an email to walnutstudy@llu.edu
  2. Call us at (909) 558-8382 from 9:00 a.m. to 5:00 p.m.

Please let us know the days and the time you will be available to take calls.

How long will the study last?

The study will last for 12 weeks (3 months) from start to finish. 

Will it cost me anything?

There is NO cost to the participants for any of the study-associated intervention or tests.


The committee at Loma Linda University that reviews human studies (Institutional Review Board) has determined that participating in this study could expose you to minimal risk. Possible discomfort may result from the blood drawings. This includes slight pain and minor bleeding or bruising at the point of needle insertion. Breach of confidentiality is also a potential risk during the study. Risks also include allergic reactions to walnuts.


You may or may not benefit personally from the intervention.  However, it is expected that this study will increase knowledge about the effect of walnuts on immunity and reduce the number and severity of upper respiratory tract infections. Therefore, by participating you will be helping us gain a deeper understanding of the biological functions of walnuts and contributing towards a lasting benefit for humanity.


Your results from a variety of tests will be provided to you upon completion of the study.


Participants will receive $200-$300 as compensation at the end of the study upon successful completion of all study procedures.

Voluntary Participation

Participation in this study is voluntary. Your decision on whether to participate in or withdraw at any time from the study will not affect your ongoing medical care or relationship to your doctors and will not involve any penalty or loss of benefits to which you are otherwise entitled.

Required Dates

Dates will be provided soon.

Research Team

Joan Sabate, DrPH, MD

Joan Sabate, DrPH, MD

Principal Investigator

Dr. Joan Sabate has a doctoral degree in public health nutrition, and has worked in the area of Environmental Nutrition for over 10 years. He has a broad, multidisciplinary background including nutrition, epidemiology, and statistics. He was Chair of the nutrition department at Loma Linda University for 17 years and led many research projects to completion. Currently, Joan is the co-Director of the Environmental Nutrition research program at Loma Linda University.

Ifeanyi Nwachukwu, PhD

Ifeanyi Nwachukwu, PhD

Assistant Professor of Nutritional Biochemistry

Dr. Ifeanyi Nwachukwu is an Assistant Professor of Nutritional Biochemistry in the School of Public Health, Loma Linda University. He is one of the co-investigators for this study. Dr. Nwachukwu earned a PhD in Human Nutritional Sciences from the University of Manitoba and worked briefly as a postdoctoral scientist at the University of Ottawa before joining LLU. He has authored/co-authored over 40 peer-reviewed publications. His most recent works were focused on the health-promoting properties of plant food protein-derived bioactive peptides.

Amandeep Wright, MPH

Amandeep Wright, MPH


Amandeep Wright is a Research Manager at the Loma Linda University School of Public Health. She did her Master’s in Public Health at SPH. She has been working with the PI of the walnut study, Dr. Sabate, and the nutrition research team for the past five years. She has expertise in coordinating and managing the conduct of clinical trials. She has been involved with larger clinical trials like the Habitual Diet and Avocado Trail, which was a multi-center trial (UCLA, Tufts University, Penn State and Loma Linda University) with over a 1000 participants. She was the main coordinator for the Loma Linda site during the trial. Her role in Walnut Study will include among other things, the coordination of recruitment and selection of participants, clinic visits, and data collection and management.

Rawiwan Sirirat, DrPH

Rawiwan Sirirat, DrPH

Research Associate

Dr. Rawiwan Sirirat is a research associate at Nutrition Research Center. She is a Registered Dietitian with doctoral degree of public health in Nutrition. Her main interest is in nutrition epidemiology. Dr. Sirirat has accumulated research experience over the years via multiple clinical trials as well as a large cohort study. Her experiences include nutrition data collections, quality control of the data as well as nutrition data management. She is also well acquainted with laboratory analyses of nutrition biomarkers, bio specimen processing and handling. She will be primarily involved in data and bio specimen collection and handling in this study.

Jayme Brisco

Jayme Brisco

Graduate Assistant

Jayme Brisco is a doctoral student in nutrition in the School of Public Health. She has a master’s degree in nutritional science from San Diego State University where she completed research on dried plum's impact on bone disease biomarkers. Jayme is a registered dietitian with 10+ years of experience in clinical nutrition and has been teaching a medical nutrition therapy course at Pepperdine University since 2019.