Thank you for your interest in the MAC study.

About the MAC Study 

MAC stands for Macadamia Nut Effects on Adiposity and Cardiometabolic Risk. The MAC study is a research project aimed to answer the question whether eating macadamia nuts daily for two months has an impact on body weight, body composition, and newer risk factors for heart disease.  

This is a clinical trial conducted by the School of Public Health at Loma Linda University. This study is an intervention with usual diet with and without macadamia nuts for a total of five months


What is the Macadamia Nut Effects on Adiposity and Cardiometabolic Risk (MAC) Study?

The purpose of this study is to test the health benefits of macadamia nuts. Specifically, we will examine the effects of macadamia nuts on body weight and body composition and some selected newer risk factors for heart disease.

Who is eligible for the study?

We are looking for men and post-menopausal women, age 40 years and above, and overweight. To be eligible for the study, potential participants must also have one additional risk factor for heart disease, such as high blood pressure, high cholesterol or a high glucose. Volunteers must not be allergic to nuts.

What is expected of participants?

During the study, participants are expected to consume their usual diet for two months and then consume macadamia nuts daily along with their usual diet for another two months. One month break will be provided between these two diet periods. When you are on the macadamia nut diet, you will be provided with the supply of macadamia nuts. Approximately 1-2 ounces of macadamia nuts will need to be consumed per day during this diet period (15% of total energy intake). 

During each 2-month intervention, participants are expected to attend clinic every 2 weeks for a total of 10 visits.  Body measurements and urine samples will be obtained at the beginning and end of each intervention period.  Blood samples will be drawn at the beginning of the study and twice at the end of each 2-month intervention period (5 times).

How long will the study last?

The study will last for five months, from the time you are randomized

What are the benefits of participating in the study?

Upon successful completion of the study, participants will receive:

  • Free macadamia nuts
  • Body composition results from two state-of the art methods. 
  • Your health test results, including plasma cholesterol, insulin and glucose levels. 

Besides, the above benefits of participation, being part of this study would also contribute to advancing knowledge on the health effects of macadamia nuts.

How can I participate?

You can let us know if you are interested in the MAC Study in any of the following ways:

Fill out the participant form
Send us an email at: and one of the study investigators will give you a call.
Call us at 909-558-8382 and leave a message and one of our study investigators will give you a call.

What are the next steps

  • Complete your screening form
  • If approved you will be invited to come to an information session
  • That will be followed by 1-1 interview with 2 investigators after which you will be informed if you are selected for the study.