L.O. Luedecke

Inhibitory effect of conjugated dienoic derivatives of linoleic acid and β-carotene on the in vitro growth of human cancer cells

The effects of physiologic concentrations of conjugated linoleic acid (CLA) and beta-carotene were assessed on human (M21-HPB, malignant melanoma; HT-29, colorectal; MCF-7, breast) cancer cells. The incubation of cancer cells with CLA showed significant reductions in proliferation (18-100%) compared to control cultures. M21-HPB and MCF-7 cell mortality was dose- and time-dependent. beta-Carotene was inhibitory to breast cells only. MCF-7 cells supplemented with CLA incorporated significantly less [3H]leucine (45%), [3H]uridine (63%) and [3H]thymidine (46%) than control cultures. M21-HPB and HT-29 cells supplemented with CLA incorporated less [3H]leucine (25-30%). These in vitro results suggest that CLA and beta-carotene may be cytotoxic to human cancer cells in vivo.

Effect of cheddar cheese consumption on plasma conjugated linoleic acid concentrations in men

Abstract Conjugated linoleic acid (CLA) is a mixture of positional and geometric isomers of linoleic acid with conjugated double bonds. Conjugated linoleic acid has anticarcinogenic properties and has been identified in human biological fluids and adipose tissue. The origin of CLA in humans is not known, but diet may be contributory. A variety of cheeses, including Cheddar, are good sources of CLA. To investigate the effect of Cheddar cheese consumption (112 g/day) on plasma phospholipid-esterified CLA concentrations, nine healthy men were studied. Cheddar cheese was added to their daily diets for four weeks. Three-day diet records and fasting blood samples were obtained. Protein and total fat intakes increased significantly during dietary intervention. Plasma CLA was significantly higher following Cheddar cheese feeding, exceeding by 19–27% the concentrations observed initially and following intervention. The molar ratio of CLA to linoleic acid also increased significantly following dietary intervention. Plasma concentrations of linoleic and arachidonic acids, cholesterol and phospholipids were not affected by cheese feeding. Since CLA may represent a protective factor against cancer, further study identifying dietary sources and the health benefits of CLA are warranted.

Effect of high hydrostatic pressure and whey proteins on the disruption of casein micelle isolates.

High hydrostatic pressure disruption of casein micelle isolates was studied by analytical ultracentrifugation and transmission electron microscopy. Casein micelles were isolated from skim milk and subjected to combinations of thermal treatment (85 degrees C, 20 min) and high hydrostatic pressure (up to 676 MPa) with and without whey protein added. High hydrostatic pressure promoted extensive disruption of the casein micelles in the 250 to 310 MPa pressure range. At pressures greater than 310 MPa no further disruption was observed. The addition of whey protein to casein micelle isolates protected the micelles from high hydrostatic pressure induced disruption only when the mix was thermally processed before pressure treatment. The more whey protein was added (up to 5 g/l) the more the protection against high hydrostatic pressure induced micelle disruption was observed in thermally treated samples subjected to 310 MPa.