Colorectal (CRC) cancer is the third most common cancer in the United States and its incidence is rising in younger populations. Diet seems to affect risk for CRC.

Many parts of our diet are processed and modified by the microbes or bacteria in our gut. There are many different types of bacteria in our gut, each one of us has a "community" of different types and amounts of each type.

When we eat flaxseeds, certain types of bacteria will process them - producing compounds that can then affect our body. How much of these compounds are produced by each person depends on the "community" of bacteria in the gut.

Flaxseed and in certain nuts contain lignans, compounds that may have health benefits. Gut bacteria can convert the lignans into biologically active compounds that in animal models prevent the development of colon cancer. The investigators will study how these biologically active compounds affect colon cell-signaling pathways important to colorectal cancer risk.

Results from our study will bridge the current knowledge from animal studies and epidemiologic studies and may help to inform approaches for future CRC prevention.

Part 1 (Screening):

Potential participants submit a screening questionnaire for eligibility. Eligible participants will come for an orientation for Part 1. If they consent the study coordinator will measure their height and weight and give them all the materials to do the activities for Part 1.

1. Stool sample
2. Days 1-3: take a lignan pill for three days
3. Day 3: 24-hour urine collection.

No all participants will be eligible for Part 2.

Part 2 (Trial):

Eligible participants will come for an orientation and consent.

Activities:

1. 3-day food record
2. Stool sample
3. Fasting blood draw.
4. Colon cleanse (at home). 2 months- no study activities Period 1,

1. Day 0: Stool sample 2. Day 0: 24-h urine collection 3. Take study capsule daily for 2 months. 4. Day 54: Stool sample 5. Day 54: 24-hour urine 6. Day 55: Fasting blood draw 7. Day 60 Sigmoidoscopy with biopsies 2 months- no study activities Period 2

1. Day 0: Stool sample
2. Day 0: 24-h urine collection
3. Take the other study capsule daily for 2 months.
4. Day 54: Stool sample
5. Day 54: 24-hour urine
6. Day 55: Fasting blood draw
7. Day 60 Sigmoidoscopy with biopsies

Inclusion Criteria:

• healthy
• non-smoking men and women
• ages 20-45 y
• don't eat a lot of vegetables

Exclusion Criteria:

• chronic medical illness, history of gastrointestinal disorders (e.g., ulcerative colitis, Crohn disease, celiac sprue, HNPCC, familial adenomatous polyposis, pancreatic disease, previous gastrointestinal resection, radiation or chemotherapy) and cancer (other than non-melanoma skin cancer);
• pregnancy or lactation;
• weight change greater than 4.5 kg within past year;
• oral or IV antibiotic use within the past 3 months;
• alcohol intake of >2 drinks/day (2 drinks being equivalent to 720 ml beer, 240 ml wine, or 90 ml spirits);
• dietary fiber intake >15 g/day;
• abnormal renal, liver or metabolic test results at baseline;
• inability to swallow pills;
• contraindications to sigmoidoscopy;
• regular use of prescription or over-the-counter medications, including oral contraceptives;
• known allergy to nuts, seeds and flaxseed;
• intention to relocate out of study area within next 12 months.