Inclusion Criteria:

- Adenoma cases from the TCPS study (IRB # 090235) or from Vanderbilt University
Hospital

- Consent to be contacted for future studies in TCPS (IRB # 090235)

- Participants with a calcium intake ≥ 700 mg/day measuring with 24 hour dietary
recalls

- Participants with a calcium intake < 2000 mg/day measuring with 24 hour dietary
recalls

- Participants with a calcium/magnesium intake ratio > 2.6

- Participants with known genotype for Thr1482Ile polymorphism in TRPM7

- Non African-American

- Will live in Nashville or surrounding area in the next 6 months

Exclusion Criteria:

- Intolerance to magnesium glycinate or microcrystalline cellulose (placebo)

- Chronic renal diseases and hepatic cirrhosis

- Chronic ischemic heart disease with unstable angina, chronic heart failure at class
III or IV and acute myocardial infarction in the last 6 months

- Chronic diarrhea

- Current breastfeeding

- Current or planned pregnancy

- Type I diabetes mellitus

- Pituitary dwarfism

- Use of digoxin and licorice

- Current use of blood anticoagulant drugs such as Dicumarol(Warfarin), Clopidogrel
(Plavix), Prasugrel HCl (Efficent), Ticlopidine (Ticlid), Lovenox (Enoxaparin),
Fragmin (Dalteparin), Innohep (Tinzaparin), Eptifibatide (Integrilin), Tyrofiban
(Aggrastat), and Abciximab (Reopro)

- Current use of lithium carbonate therapy (Eskalith, Lithobid, Lithonate, Lithotabs,
Apo-Lithium carbonate, Apo-Lithium carbonate SR, Carbolth, Duralith, PMS-Lithium
carbonate, PMS-Lithium citrate)

- Individuals with a history of colon resection or colectomy due to any reason

- Individuals with any history of cancer other than non-melanoma skin cancer

- Individual with history of any organ transplantation

- Individuals with Inflammatory bowel disease

- Individuals if creatinine clearance is < 50

- Currently institutionalized

- Homeless individual (address, telephone etc.)

- Unable to provide informed consent

- Any condition that in the opinion of the investigator raises concerns about protocol
compliance