The purpose of this study is to increase our understanding of how much choline humans need to get from their diet. Choline is an essential nutrient found in many foods, including eggs and milk. In addition to dietary sources, choline can be made in the liver. Choline is important in making membranes or wrappers for all the cells in the body and for making chemicals that allow nerve cells to work properly. In a previous study we found that the dietary requirement for choline varies greatly from person to person. This was caused, in part, by how much estrogen a person has and their genetic makeup. We are conducting this study to explore how estrogen levels and specific differences in genes influence choline requirements so that we can refine the dietary recommendations for this nutrient.
Primary Outcome Measures:
- Evidence of liver or muscle dysfunction (based on elevations in CPK, AST, ALT), or increased liver fat (measured by liver MRI) [ Time Frame: Labs measured every 3-4 days throughout 62-day trial. Liver MRI performed on study days 1, 10, 31, 52, 62. ] [ Designated as safety issue: No ]
| Estimated Enrollment: |
60 |
| Study Start Date: |
June 2007 |
| Estimated Study Completion Date: |
November 2011 |
| Estimated Primary Completion Date: |
November 2011 (Final data collection date for primary outcome measure) |
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1: Active Comparator
Post-menopausal women randomized to receive estrogen replacement therapy.
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Other: Estrogen plus choline depletion diet
Post-menopausal subjects receive estrogen and are then challenged with a low choline diet to determine if estrogen protects them from induction of choline deficiency.
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2: Placebo Comparator
Post-menopausal women randomized to receive a placebo.
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Other: Placebo plus choline depletion diet
Post-menopausal women are randomized to receive a placebo and are then subjected to a low choline diet to determine if clinical signs of choline deficiency can be induced.
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3: Experimental
Pre-menopausal women with specific genetic variants.
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Other: Pre-menopausal women with SNPs given a low choline diet
Pre-menopausal women with specific genetic polymorphisms in genes related to choline metabolism are placed on a choline depletion diet to determine if the SNPs increase or decrease the risk of diet-induced choline deficiency.
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Choline is an essential nutrient essential used for the structural integrity and signaling functions of cell membranes, cholinergic neurotransmission, and lipid transport/metabolism. Choline is obtained from the diet and from endogenous biosynthesis catalyzed by the enzyme phosphatidylethanolamine N-methyltransferase (PEMT). The major premise for this proposal is that humans require a dietary source of choline and that this requirement has significant individual variation and is modulated by estrogen and common genetic polymorphisms. The promoter of the PEMT gene is estrogen responsive, and we hypothesize that estrogen status influences the dietary requirement for choline. We identified other common single nucleotide polymorphisms (SNPs) that increase or decrease the likelihood that a human will develop organ dysfunction when fed a low choline diet. Experiments are proposed that will refine our understanding of estrogen-mediated induction of the PEMT promoter; determine whether postmenopausal women treated with estrogen have a decreased susceptibility to developing organ dysfunction associated with choline deficiency; determine the prevalence of SNPs that increase susceptibility to choline deficiency in the population and examine dietary choline requirements in humans with these SNPs.
Purpose
