What You Eat Matters—How Everyday Foods Affect Bone and Kidney Health

Recruiting
30 years - 75 years
All
1 Location

Brief description of study

Researchers at the IU School of Medicine are studying how diet affects bone, heart, and kidney health in people with chronic kidney disease (CKD). 

Certain minerals found in food, such as calcium and phosphorous, can be harder for the body to manage with CKD.  By comparing diets with different amounts of these minerals, we hope to better understand how food choices affect health in people with with this condition.

You may qualify for this study if you are 30–75 years of age, have moderate to severe chronic kidney disease (CKD), and are willing to attend multiple study visits (including overnights) to the clinical research center at University Hospital in Indianapolis, IN.

Detailed description of study

You will attend a screening visit (about 1 hour) to confirm your eligibility and complete basic health checks.

If you qualify and join the study, you will take part in two study diets, each lasting about 3 weeks:

  • One diet has an average amount of phosphorus
  • One diet has a lower amount of phosphorus

Everyone will try both diets, with a break in between. This helps researchers compare how each diet affects the body.

You will also:

  • Spend one week at home, one week staying at the research center, and one week back at home during each diet period
  • Have a few short clinic visits for routine health checks and sample collection
  • Take a daily vitamin D supplement during parts of the study
  • Eat only the meals and snacks provided during each study diet period
  • Provide blood, urine, and stool samples at certain times
  • Study activities will take place in the Clinical Research Center at IUH University Hospital in Indianapolis, IN.
  • You will be able to review example menus before deciding to join, and the meals are designed to help you feel comfortable—not too hungry or too full.

The entire study lasts about 9–11 weeks, including breaks. The study team will guide you through each step and answer questions along the way.

You may receive up to $4,000 on a prepaid debit card for your time and effort for completing all of the study activities.  The card works like a regular debit card, and funds will be added to it after each completed visit.  We will also reimburse parking and ride-share or taxi costs related to study visits, if needed.

Eligibility of study

You may be eligible for this study if you meet the following criteria:

  • Conditions: Moderate to Severe Chronic Kidney Disease, CKD
  • Age: 30 years - 75 years
  • Gender: All

Additional Inclusion Criteria:
  • Have moderate to severe chronic kidney disease (CKD) (not on dialysis)
  • Have stable kidney-related lab results, including parathyroid hormone levels
  • English-speaking
  • Women must be postmenopausal or unable to become pregnant
  • Have been on stable medications for at least one month
  • If you have diabetes, it is well controlled
  • Are willing to stop taking certain supplements (such as vitamin D, calcium, or multivitamins) during the study
  • Have regular bowel habits (about 1–3 bowel movements per day)

Additional Exclusion Criteria:

  • Expect to start dialysis within the next 6 months
  • Have high calcium, potassium, or phosphorus levels
  • Have serious digestive conditions that affect nutrient absorption (such as celiac disease or prior bariatric surgery)
  • Have uncontrolled medical conditions (such as poorly controlled diabetes, high blood pressure, or autoimmune disease)
  • Are pregnant or breastfeeding
  • Take certain medications that affect calcium or phosphorus levels

Updated on 20 Apr 2026. Study ID: NEPH-UM-PHOSPHORUS, 29638

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