Flaxseed (FS) is a safe and well tolerated supplement with an ability to fight inflammation and oxidative stress - a byproduct of daily stress the human body faces everyday and especially with chronic diseases. Cystic fibrosis (CF) is a genetic disease resulting from a mutation in sodium and chloride transport channels that results in pancreatic insufficiency, chronic sinusitis and chronic lung infections. The investigators hypothesize that chronic inflammation and oxidative stress are a part of the chronic exacerbations that are a part of cystic fibrosis. The investigators believe that flaxseed with its anti-inflammatory and antioxidative properties can help dampen these stressors on the CF lung and potentially result in fewer exacerbations of CF, fewer antibiotics, fewer hospitalizations, and improved well-being.

Ten patients with steady-state cystic fibrosis (CF) - not hospitalized, not on intravenous antibiotics, with stable FEV1 40-100% predicted were enrolled in a four week long pilot study where-in each patient consumed 40 grams of flaxseed each day, in the form of finely ground flaxseed, however they wished. Prior to starting flaxseed, each week, and then four weeks after each patient had finished taking flaxseed, markers of inflammation and oxidative stress, as well as measurements of flaxseed metabolism were collected. F2-isoprostanes, 8-oxo-dGuo, as well as cytokines including IL-6, TNF-a, IFN-g among others were measured to trend flaxseed effects. Enterolignans - enterodiol and enterolactone (products of flaxseed metabolism) were measured each week as well.

Inclusion Criteria:

1. Genetic and clinical diagnosis of cystic fibrosis (CF)
2. FEV1 predicted between 40-100%
3. Age 18-64
4. Pancreatic enzyme adherence (or pancreatic sufficiency)
5. Demonstration of continued long-term dedication and follow-up with CF primary care provider

Exclusion Criteria:

1. Prior or planned hospitalization or surgical procedure within one month of enrollment (other than simple dental procedure)
2. An acute pulmonary exacerbation
3. History of bowel resection, inflammatory bowel disease or distal intestinal obstruction syndrome
4. Receiving broad spectrum intravenous antibiotics (other than maintenance azithromycin, inhaled tobramycin, or inhaled aztreonam within one month of enrollment)
5. Current supplementation with FS or soy derivatives or allergies to them
6. Active or prior ingestion of Vitamin E exceeding 30 IU within 21 days
7. Significant liver disease (cirrhosis)
8. Significant renal dysfunction (GFR below 50 ml/hr/m2)
9. Poorly controlled diabetes (evidenced by HgbA1c>7.5% or consistently with blood glucose >250 mg/dl)