The effect of a low carotenoid diet on malondialdehyde-thiobarbituric acid (MDA-TBA) concentrations in women: a placebo-controlled double-blind study.

OBJECTIVE: The purpose of the study was to evaluate the effect of a low carotenoid diet (83 micrograms Beta-carotene) on malondialdehyde-thiobarbituric acid (MDA-TBA) concentrations of nine pre-menopausal women. METHODS: Subjects lived on the metabolic research unit of the Western Human Nutrition Research Center (WHNRC), where diet, exercise and other activities were controlled. Five subjects (Group C, control group) consumed a low carotenoid diet and received an additional 0.5 mg/day of Beta-carotene while four subjects (Group P, placebo group) received only the low carotenoid diet during days 1 to 60 (period 1). All subjects received 0.5 mg/day of Beta-carotene during days 60 to 100 (period 2), plus three capsules/day mixed carotenoid supplement (Neo-Life Company) during study days 100 to 120. Changes in MDA-TBA concentrations were analyzed during the study periods and between the groups. RESULTS: At the start of the study (day 1), no significant difference in the MDA-TBA concentration was observed between the control (Group C) and the placebo (Group P) subjects. During period 1 (days 2 to 60), when Group P subjects consumed the low carotenoid diet without supplementation, the MDA-TBA values for Group P rose markedly and were significantly (p < 0.05) higher than the MDA-TBA values for Group C subjects who were receiving carotenoid supplementation. During period 2 (days 60 to 100) when both groups received carotenoid supplementation, the MDA-TBA values of Group P subjects were significantly (p < 0.05) reduced to the point where they were similar to the MDA-TBA values for Group C subjects. CONCLUSIONS: These findings provide evidence to support the beneficial effects of carotenoids in preventing lipid peroxidation in the cells. Further studies are needed to identify the exact mechanism by which carotenoids prevent lipid peroxidation and the amount needed for normal activity.

Nutrient density estimates from an average of food frequency and food records correlate well with serum concentration of vitamins E and the carotenoids in free-living adults.

Dietary intakes are usually estimated by either a food frequency test, or by food records. We hypothesized that dietary intake estimates for fat soluble vitamins might be more accurate if information from both food frequency tests and food records were used. We estimated dietary intakes in 10 healthy adults by 4 food frequency questionnaires and ten 3-day food records collected over a year. Serum antioxidant nutrient concentrations (vitamins A, E, and the carotenoids) were measured by HPLC throughout the year. Few changes in intake occurred over the year. Estimates of nutrient densities correlated more often than estimates of nutrient intakes to serum nutrient concentrations. Nutrient density estimates derived from the average of food frequency and food record estimates were significantly correlated with serum nutrient concentrations more often than dietary estimates derived from either food frequency or food records alone. We suggest that nutrient density estimates derived from a combination of food frequency and food records may be useful for studies of free-living individuals.

Effects of a carotene-deficient diet on measures of oxidative susceptibility and superoxide dismutase activity in adult women.

The effect of consuming a low carotene diet (approximately 60 micrograms carotene/day) on oxidative susceptibility and superoxide dismutase (SOD) activity in women living in a metabolic research unit was evaluated. The diet had sufficient vitamins A, E, and C. The women ate the diet supplemented with 1500 micrograms/day beta-carotene for 4 days (baseline), then the unsupplemented diet for 68 days (depletion), followed by the diet supplemented with > 15,000 micrograms/day carotene for 28 days (repletion). Production of hexanal, pentanal, and pentane by copper-oxidized plasma low density lipoproteins from carotene-depleted women was greater than their production of these compounds when repleted with carotene. Erythrocyte SOD activity was depressed in carotene-depleted women; it recovered with repletion. Thiobarbituric acid reactive substances in plasma of carotene-depleted women were elevated and diminished with repletion. Dietary carotene seems to be needed, not only as a precursor of vitamin A, but also to inhibit oxidative damage and decrease oxidation susceptibility.

Effect of Degree of Sanitation From Slaughter Through Fabrication on the Microbiological and Sensory Characteristics of Beef.

Steers were slaughtered, dressed, and fabricated using conventional procedures or strict sanitary procedures. Strict sanitary procedures involved antemortem washing of steers, use of disposable gloves, careful handling of carcasses to prevent cross-contamination, and spraying of carcasses with hot (55°C) 1% L-lactic acid before evisceration and before entering the chill cooler. Mean aerobic plate counts (APC, log10/cm2) of carcasses slaughtered under strict sanitary conditions and of subprimals (boneless strip loins and ribs) from animals handled under strict sanitary conditions and stored at 1°C in high-oxygen barrier (HOB) film (0 to 80 d) were lower than those of carcasses and subprimals from animals slaughtered and fabricated using conventional procedures. In most cases, APCs of steaks displayed in polyvinyl chloride (PVC) film for 0 to 6 d from animals and subprimals handled under strict conditions were lower than those of steaks from animals and subprimals handled under conventional procedures. Bacillus spp., Micrococcus spp., and yeasts were the dominant (50% or more of microflora) microbial types on carcasses that were slaughtered and dressed using strict sanitary conditions. For carcasses slaughtered using conventional procedures, Micrococcus spp. and to a lesser extent Streptococcus , coagulase-negative Staphylococcus and/or coryneform bacteria were the dominant microbial types. After 20 d of storage, there were no consistent differences in the percentage distribution of microbial types on the two groups of subprimals. Lactobacilli dominated the microflora of subprimals at that time. When scores for lean color, surface discoloration, fat color, overall appearance, and odor of steaks from subprimals handled under strict sanitary conditions were significantly different (P<0.05) from controls, treated steaks were more desirable than those of comparable steaks from control subprimals.