Date of Award:

5-2000

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Nutrition, Dietetics, and Food Sciences

Department name when degree awarded

Nutrition and Food Sciences

Committee Chair(s)

Deloy G. Hendricks

Committee

Deloy G. Hendricks

Committee

Marie K. Walsh

Committee

Ilka Nemere

Abstract

To examine the effect of buttermilk fractions on growth, iron transport, and uptake, Caco-2 cells (human colon adenocarcinoma) were grown in a bicameral chamber. The Caco-2 cell culture system is a useful model to study micronutrient utilization in the human enterocyte, because Caco-2 cells continuously differentiate and form a monolayer, which has high polarity, a well-developed brush border, and a tight junction.

Iron bioavailabilty in various milks is very different depending upon milk composition. The fat fraction especially is known to be associated with iron absorption, because the fat fraction has milk fat globule membrane (MFGM), which contains bioactive molecules such as sphingolipids.

Composition of buttermilk that was concentrated by 10 K molecular sieving (MS) or by bacterial fermentation (Lactococcus latis PN-l) was reduced in lactose concentration and increased in protein concentration. Percent fat in MS buttermilk was concentrated to two times higher than in the original buttermilk (P < 0.05). Growth of Caco-2 cells with molecular sieved (MS) or fermented (FM) buttermilk in the growth medium was not significantly different. Transport and uptake of 59Fe was performed with/without cold iron (1 mmol/L) by iron-depleted or iron-repleted cells. Molecular sieved or fermented buttermilk and ganglioside or sphingomyelin standards with dimethyl sulfoxide (DMSO) were added to the Hank's balance salt solution (HBSS) in the apical chamber. With cold iron, addition of MS and FM buttermilk (1, 2, or 3 percent) increased 59Fe transport across iron-repleted cells (P < 0.01). Without cold iron, ganglioside depressed 59Fe transport (P < 0.01). Uptake of 59Fe was not significantly affected by buttermilk concentrates; however, more effective uptake was shown across iron-depleted cells. It is not clear from these studies that buttermilk fractions or their components influence iron uptake or transport by Caco-2 cell cultures.

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