Impact of Food Additives on Phosphorus Metabolism

Study Overview
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Brief Summary
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The purpose of the study is to learn more about how phosphorus-based food additives affect phosphorus metabolism in people with normal kidney function.

Detailed Description
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Phosphorus is a mineral that is found in foods such as dairy products, nuts, and meat, and is important for strengthening the bones. However, too much phosphorus in the blood may be bad for the health of your heart and blood vessels. The kidneys keep the blood levels of phosphorus normal by getting rid of extra phosphorus in the urine. New research has found that common forms of food additives that are high in phosphorus may increase blood phosphorus levels in individuals with kidney disease. In addition, these food additives may increase blood levels of hormones that control phosphorus such as parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23). Like high blood phosphorus levels, high levels of PTH and FGF23 in the blood may also be bad for the health of your heart and blood vessels. In this study, the investigators would like to examine the effects of food additives on blood levels of phosphorus, PTH and FGF23 in individuals with normal kidney function.

Official Title
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Impact of Food Additives on Phosphorus Metabolism

Conditions
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Healthy

Intervention / Treatment
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* Other: Research diet


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy volunteers, 19 - 45 years of age Exclusion Criteria: abnormal urinalysis-presence of hematuria, proteinuria, or leukocyturia. pregnancy or breast-feeding Medical conditions impacting phosphate metabolism-primary hyperparathyroidism; gastrointestinal malabsorption disorders such as Crohn's Disease, ulcerative colitis, celiac disease, or liver dysfunction; hyper- or hypothyroidism; irregular menses for female subjects. Body Mass Index (BMI) ≥ 30 g/m2 since obesity is independently associated with impaired phosphorus metabolism. Medications known to affect phosphorus metabolism- current use of phosphorus supplements, high-dose or activated vitamin D compounds, regular antacid or laxative use, anticonvulsants. Hyper- or hypophosphatemia (≥ 4.6 mg/dl or ≤ 2.5 mg/dl respectively), hyper- or hypocalcemia (≥ 10.6 or ≤ 8.5 mg/dl respectively), or severe anemia (hemoglobin < 8 g/dl for women and < 9 g/dl for men).

Ages Eligible for Study
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Minimum Age: 19 Years
Maximum Age: 45 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Subjects with healthy kidney function<br> | Other: Research diet<br>* Participants will be provided specially prepared meals to eat at home for two weeks. During the first week, participants will eat foods that do not have any phosphorus-based food additives in them (this is called the control diet). During the second week, participants will eat foods that all have phosphorus-based food additives in them (called the intervention diet).<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| FGF23 | Change in FGF23 levels | 2 weeks | 
| PTH | Change in PTH levels over 2 weeks | 2 weeks | 
| Serum phosphate | Change in serum phosphate over two weeks | 2 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Insulin sensitivity as measured by HOMA-IR | changes in HOMA-IR over two weeks | 2 weeks | 
| Brachial flow mediated dilatation measured by ultrasound | change in flow mediated dilatation over two weeks | 2 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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phosphorus-based food additives, phosphorus metabolism