Abstracts

Breast Cancer

Breast Cancer

This study uses multinuclear NMR to examine the presence of phosphocholine in breast cancer cells. Choline was found to be transported into MCF7 human breast cancer cells and rapidly phosphorylated to phosphocholine which was then accumulated in the cells to high concentrations. The increased level of phosphocholine did not affect the rate of synthesis of phosphatidylcholine, indicating tight regulation of this pathway. It appears that the increased availability of choline in the blood circulation leads to accumulation of phosphocholine in the tumors by the same mechanism as in the cells.

Katz-Brull R; Margalit R; Bendel P; Degani H: Choline metabolism in breast cancer; 2H-, 13C- and 31P-NMR studies of cells and tumors, MAGMA, 1998 Aug; 6(1):44-52

Methylation capacity

Methylation capacity

Healthy adult men (#10) were fed a diet low in folate and exogenous methyl groups to study the effects on in vivo methylation capability.

Even with moderate folate depletion, none of these measures was decreased by low methionine and choline intakes. Plasma methionine concentrations were unchanged throughout. Limiting exogenous methyl group intake by restricting dietary methionine and choline did not impair in vivo methylation capabilities for the variables tested, even at low folate intake.

In vivo methylation capacity is not impaired in healthy men during short-term dietary folate and methyl group restriction. Jacob-RA; Pianalto-FS; Henning-SM; Zhang-JZ; Swendseid-ME. J-Nutr. 1995 Jun; 125(6): 1495-502.

Similarity to folate

Similarity to folate

This study analyzes the similarities between the pathways and metabolism of choline and folate in humans, by measuring the effects of folate depletion on plasma choline and phosphatidylcholine concentrations. Total folate intake was varied by supplementing low folate (25 and 56 microg/d for men and women, respectively) and low choline (238 and 147 mg/d for men and women, respectively) diets with pteroylglutamic acid for 2-6 wk following folate-depletion periods of 4-5 wk. The low folate/choline intakes resulted in subclinical folate deficiencies; mean plasma choline decreases of 28 and 25% in the men and women, respectively; and a plasma phosphatidylcholine decrease of 26% in the men. No functional choline deficiency occurred, as measured by serum transaminase and lipid concentrations. The decreases in choline status measures returned to baseline or higher upon moderate folate repletion and were more responsive to folate repletion than plasma folate and homocysteine. Feeding methionine supplements to the men did not prevent plasma choline depletion, indicating that folate is a more limiting nutrient for these methylation pathways. Three conclusions may be drawn from these results: 1) choline is utilized as a methyl donor when folate intake is low, 2) the de novo synthesis of phosphatidylcholine is insufficient to maintain choline status when intakes of folate and choline are low, and 3) dietary choline is required by adults in an amount > 250 mg/d to maintain plasma choline and phosphatidylcholine when folate intake is low.

Jacob RA; Jenden DJ; Allman-Farinelli MA; Swendseid ME: Folate nutriture alters choline status of women and men fed low choline diets, 1999 Mar: J Nutr, 129(3):712-7