Fish & Fiber Study

Join us in a study of the benefits of fish oil & fiber!

A group of seniors at a park

Fish oil and fiber together reduce colon tumor formation in animals. In humans, there are only studies looking at each separately. We want to understand how the combination works in healthy humans. We will look at changes in health markers and in the gut microbiome.

Participants will take study supplements during two periods. For one month it will be fish oil and corn fiber and for the other, corn oil and a non-fiber corn product (placebo). We will compare the effects within each person.

The purpose of the study is to answer scientific questions. Participants must be able to visit Fred Hutchinson Cancer Center's campus at South Lake Union throughout the 4-month study. Participants will receive $250 for completing the study.

You may be eligible if you are healthy, between 50-75 years old, and:

  • live in the greater Seattle area
  • don't eat a lot of vegetables
  • don't smoke or use recreational drugs
  • don't  drink more than 2 alcoholic drinks most days
  • have not taken antibiotics in the past 3 months
  • don't take (more than once/week NSAIDs) aspirin, ibuprofen, naproxen) or Lovaza,
  • don't take blood clottng medications such as Coumadin, Eliquis, Plaviz, Xarelto
  • have a BMI (Body Mass Index) between 18 and 30. To see if you are eligible, see chart below.

Thank you for your interest in our study. We have completed our recruitment of participants and are no longer enrolling into the study.

Study Activities

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Participants will take oil and fiber supplements for two 30-day periods, with a 60-day period in between. The study oil comes in small glass bottles containing about 1 tablespoon of oil. Participants take two a day. It has a very mild taste and can be added to food, mixed with liquid or taken straight. The fiber supplement is in powder form and participants take one packet a day. It can be easily added to foods or liquids.

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Participants will collect stool samples at the beginning, middle (day 15) and end of each of the two 30-day intervention periods.

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Participants will visit Fred Hutch during each 30-day period (before, mid and after) to get the supplements, deliver stool samples and have blood drawn. 

Eligibility based on Body Mass Index

To see if you are eligible based on Body Mass Index, find your height in the left-hand column labeled ”Your Height”. Move across to “Your Weight”. If you weigh between the weights stated, you may be eligible for this study.

Your Height


Your Weight (lbs)

86 - 143 lbs 
89 - 148 lbs
92 - 153 lbs
95 - 158 lbs
98 - 164 lbs
101 - 169 lbs
104 - 169 lbs
108 - 180 lbs
112 - 186 lbs
115 - 191 lbs
118 - 197 lbs
122 - 203 lbs
126 - 209 lbs
129 - 215 lbs
133 - 221 lbs
137 - 227 lbs
140 - 223 lbs
144 - 240 lbs
148 - 246 lbs

Principal Investigators

Johanna Lampe, Ph.D., R.D.

Principal Investigator

Associate Director, Public Health Sciences Division, Fred Hutch

Meredith Hullar, Ph.D.

Co-Principal Investigator

Senior Staff Scientist, Fred Hutch

Robert Chapkin, Ph.D.

Co-Principal Investigator

Distinguished Professor and University Faculty Fellow, Texas A&M

Contact the Fish & Fiber Study Team