Beverly A. Clevidence

Dietary cis and trans monounsaturated and saturated FA and plasma lipids and lipoproteins in men.

Trans monounsaturated fatty acids (TFA) are hypercholesterolemic compared to oleic acid to a degree approaching or equivalent to saturated FA. However, it is unknown to what extent these effects may be due to cholesterol lowering by oleic acid rather than elevation by saturated FA and TFA. In order to better understand the impact of replacing TFA in foods, it is first necessary to know the relative lipid-modifying effects of the major FA that change as TFA are lowered or removed. For 5 wk, 50 normocholesterolemic men were fed controlled diets providing approximately 15% of energy from protein, 39% from fat, and 46% from carbohydrate in a randomized, 6×6, crossover design. Eight percent of energy was replaced across diets with the following: carbohydrate (CHO) (1∶1 simple to complex); oleic acid (OL); TFA; stearic acid (STE); TFA/STE (4% of energy from each); carbon 12∶0 16∶0 saturated FA (LMP). LDL cholesterol concentrations (mmol/l) were as follows (different superscripts indicate significance at P≤0.01): OL 2.95a; CHO 3.05a,b; STE 3.10b,c; LMP 3.21c,d; TFA+STE 3.32d,e; and TFA 3.36e. HDL cholesterol concentrations (mmol/L) were as allows: STE 1.16a; IFA 1.16a,b; TFA/STE 1.17a,b; CHO 1.19b; OL 1.24c; and LMP 1.30d. Triacylglycerides were highest after STE (1.13) and lowest after OL (0.88) (P<0.001). Thus, compared to the carbohydrate control diet, TFA raised LDL cholesterol at least equivalent to LMP but had no effect on HDI cholesterol; STE had no effect on LDL cholesterol but lowered HDL cholesterol; LMP raised both LDL cholesterol and HDL cholesterol; and oleic acid raised HDL cholesterol but had no effect on LDL cholesterol.

Plant sterol esters lower plasma lipids and most carotenoids in mildly hypercholesterolemic adults.

The ability of plant sterol esters (PSE) in salad dressing to modify plasma lipids and carotenoids was determined in 26 men and 27 women fed controlled, weight-maintaining, isocaloric diets. Diets contained typical American foods that provided 32% of energy from fat. Dressings contained 8 g (ranch) or 4 g (Italian) of fat per serving. PSF (3.6 g/d) were provided in two servings/d of one of the dressings. Diets with ranch or Italian dressing without and with PSE were fed for 3 wk/diet and crossed over randomly within dressings. Diets were adjusted to similar fat and fatty acid concentrations. Type of salad dressing did not affect plasma lipids, lipoproteins, carotenoids, or fat-soluble vitamins (P>0.05). Switching from a self-selected baseline diet to the control diet resulted in reduction in low density lipoprotein (LDL) cholesterol of 7.9%, a decrease in high density lipoprotein (HDL) cholesterol of 3.1%, and a decrease in triglycerides (TG) of 9.3%. Consumption of 3.6 g of PSE resulted in further decreases in LDL cholesterol (9.7%) and TG (7.3%) but no additional change in HDL cholesterol. Total plasma carotenoids decreased 9.6% with PSE. An automated stepwise procedure was developed to produce candidate mixed models relating plasma carotenoid response to PSE. These models adjusted for preintervention plasma carotenoid levels and effects of diets on blood lipids. There were significant decreases in β-carotene, α-carotene, and β-cryptoxanthin (females only) not associated with changes in plasma lipids. Plasma carotenoids on all diets remained within normal ranges. We conclude that low-fat foods, such as salad dressings, are effective carriers for PSE.

Bioavailability of anthocyanins from purple carrot juice: effects of acylation and plant matrix.

Absorption of cyanidin-based anthocyanins is not fully understood with respect to dose or anthocyanin structure. In feeding studies using whole foods, nonacylated anthocyanins are more bioavailable than their acylated counterparts, but the extent to which plant matrix determines relative bioavailability of anthocyanins is unknown. Using juice of purple carrots to circumvent matrix effects, a feeding trial was conducted to determine relative bioavailability of acylated and nonacylated anthocyanins and to assess dose-response effects. Appearance of anthocyanins in plasma was measured in 10 healthy adults for 8 h following consumption of purple carrot juice. Each subject consumed 50, 150, and 250 mL of juice containing 76 micromol (65 mg), 228 micromol (194 mg), and 380 micromol (323 mg) of total anthocyanins, respectively. Acylated anthocyanins comprised 76% of total anthocyanins in the juice, yet their bioavailability was found to be significantly less than that of nonacylated anthocyanins. Peak plasma concentrations of nonacylated anthocyanins were 4-fold higher than that for acylated anthocyanins. Absorption efficiency declined across the doses administered. Because the treatments were consumed as juice, it could be discerned that the difference in bioavailability of acylated versus nonacylated anthocyanins was not primarily caused by interactions with the plant matrix.

Plasma Lipoprotein (a) Levels in Men and Women Consuming Diets Enriched in Saturated, Cis -, or Trans -Monounsaturated Fatty Acids

Studies that have shown adverse effects of trans-unsaturated fatty acids on plasma lipoprotein (a) [Lp(a)] levels have used levels of trans-fatty acid that are higher than those in the average U.S. diet. This study was conducted to clarify the effects on Lp(a) of trans-fatty acids levels commonly found in U.S. diets. Lp(a) levels were measured in a double-blind study of 29 men and 29 women who ate 4 controlled diets in random order for 6 weeks each. Fatty acids represented 39% to 40% of energy. The diets were: (1) Oleic (16.7% of energy as oleic acid); (2) Moderate trans (3.8% of energy as trans-monoenes, approximately the trans content of the U.S. diet); (3) High trans (6.6% of energy as trans-monoenes); (4) Saturated (16.2% of energy as lauric plus myristic plus palmitic acids). The Saturated diet lowered Lp(a) levels significantly (by 8% to 11%). Compared to the Oleic diet, the trans diets had no adverse effect on Lp(a) levels when all subjects were considered collectively. A subset with initially high levels of Lp(a) (> or = 30 mg/dL), however, responded to the High trans diet with a slight (5%) increase in Lp(a) levels relative to the Oleic and Moderate trans diets. Thus, in amounts commonly found in the typical U.S. diet, saturated fatty acids consistently decrease Lp(a) concentrations. The adverse effects of replacing cis- with trans-fatty acids are only suggestive and are restricted to high trans intakes in subjects with high Lp(a) levels.

Usefulness of body mass index as a sufficient adiposity measurement for sex hormone concentration associations in postmenopausal women.

Background: Both obesity and sex hormones are known risk factors for postmenopausal breast cancer. Although adiposity and sex hormones have been studied in the past, previous reports in postmenopausal women have not been conducted under carefully controlled dietary conditions. In this study, we investigated the usefulness of body mass index (BMI) as a sufficient adiposity measurement to assess associations with sex hormone levels. Methods: This study was conducted as a cross-sectional analysis within the control segment (0 g alcohol group) of a randomized, crossover design, in which 51 postmenopausal women consumed 0 (control), 15 (one drink), and 30 (two drinks) g alcohol (ethanol)/d for 8 weeks each as part of a controlled diet. Dual-energy X-ray absorptiometry scans were administered to the women during the control (0 g alcohol) segment, and a blood sample was drawn at the end of that diet period for hormone analysis. Results: In multivariate analysis (adjusted for age, race, family history of breast cancer, parity, and menarche <12 years), women who were overweight or obese had significantly higher serum concentrations of estradiol, bioavailable estradiol, estrone, and estrone sulfate and lower sex hormone-binding globulin than normal weight women (all P < 0.05). In models adjusted for BMI and the covariates above, none of the dual-energy X-ray absorptiometry adiposity measures added further information (all P > 0.10) for these five analytes beyond that of BMI alone. Conclusions: In this population of postmenopausal women, under carefully controlled dietary conditions, we confirmed previous findings that higher levels of adiposity were associated with higher concentrations of estrogens and lower sex hormone-binding globulin, and we found that the use of the epidemiology-friendly BMI seems sufficient to assess associations with these hormone levels. (Cancer Epidemiol Biomarkers Prev 2006;15(12):2502–7)

Effect of cocoa and green tea on biomarkers of glucose regulation, oxidative stress, inflammation and hemostasis in obese adults at risk for insulin resistance

Background/Objectives:Flavanols may provide protection against insulin resistance, but little is known about the amounts and types of flavanols that may be efficacious.Subjects/Methods:This study was designed to determine whether cocoa flavanols, over a range of intakes, improve biomarkers of glucose regulation, inflammation and hemostasis in obese adults at risk for insulin resistance. As an adjunct, green tea and cocoa flavanols were compared for their ability to modulate these biomarkers. In a randomized crossover design, 20 adults consumed a controlled diet for 5 days along with four cocoa beverages containing 30–900 mg flavanol per day, or tea matched to a cocoa beverage for monomeric flavanol content.Results:Cocoa beverages produced no significant changes in glucose, insulin, total area under the concentration–time curve (AUC) for glucose or total insulin AUC. As the dose of cocoa flavanols increased, total 8-isoprostane concentrations were lowered (linear contrast, P=0.02), as were C-reactive protein (CRP) concentrations (linear contrast, P=0.01). The relationship between cocoa flavanol levels and interleukin-6 (IL-6) concentrations was quadratic, suggesting that a maximum effective dose was achieved (quadratic contrast, P=0.01). There were no significant effects on measured indices of glucose regulation, nor on those of total 8-isoprostane, CRP and IL-6 concentrations, when cocoa and green tea were compared. However, relative to cocoa, green tea lowered fibrinogen concentrations (P=0.0003).Conclusions:Short-term intake of cocoa and green tea flavanols does not appear to improve glucose metabolism; they do affect selected markers of one or more measures of oxidative stress, inflammation or hemostasis in obese adults at risk for insulin resistance.

Calorie intake misreporting by diet record and food frequency questionnaire compared to doubly labeled water among postmenopausal women

Objective:We assessed the extent of energy misreporting from the use of a self-administered 7-day diet record (7-DDR) and a widely used food frequency questionnaire (FFQ) compared to total energy expenditure from doubly labeled water (DLW) in a group of postmenopausal women.Design:At baseline, 65 healthy postmenopausal women were instructed to fill out the National Cancer Institutes (NCI) FFQ and a 7-DDR. Average total energy expenditure using the DLW method was also performed at baseline.Results:On average, the women underestimated total energy intake compared to total energy expenditure assessed from DLW by 37% on the 7-DDR and 42% on the FFQ.Conclusions:These findings suggest that the interpretation of findings from the 7-DDR- and FFQ-based energy-disease association studies in postmenopausal women needs further evaluation.Sponsorship:This research was supported (in part) by the Intramural Program of the NIH (National Cancer Institute).

Measures of adiposity and body fat distribution in relation to serum folate levels in postmenopausal women in a feeding study

Objective:To assess the associations between serum folate concentration and measures of adiposity in postmenopausal women.Design:This study was conducted as a cross-sectional analysis within the control segment of a randomized, crossover trial in which postmenopausal women (n=51) consumed 0 g (control), 15 g (one drink) and 30 g (two drinks) alcohol (ethanol)/day for 8 weeks as part of a controlled diet. Subjects in one treatment arm were crossed-over to another arm after a 2- to 5-week washout period. Body mass index (BMI) was measured, and dual energy X-ray absorptiometry (DEXA) scan administered to the women during the control (0 g alcohol) treatment, and a blood sample from this group was collected at baseline and week 8 of each diet period and analyzed for folate, B12, homocysteine and methylmalonic acid.Setting:This study was conducted at the Beltsville Human Nutrition Research Center, MD, USA.Results:In multivariate analysis, women who were overweight had a 12% lower, and obese women had a 22% lower serum folate concentrations compared to normal weight women (P-trend=0.02). Vitamin B12 also decreased with increasing BMI (P-trend=0.08). Increased BMI, percent body fat, and absolute amounts of central and peripheral fat were all significantly associated with decreased serum folate, but were unrelated to serum B12, homocysteine or methylmalonic acid.Conclusions:Our data show that adiposity is associated with lower serum folate levels in postmenopausal women. With obesity at epidemic proportions, these data, if confirmed by prospective or randomized controlled studies, have important public health implications.

Plasma appearance of labeled β-carotene, lutein, and retinol in humans after consumption of isotopically labeled kale

The bioavailability of carotenoids from kale was investigated by labeling nutrients in kale with 13C, feeding the kale to seven adult volunteers, and analyzing serial plasma samples for labeled lutein, β-carotene, and retinol. Ingested doses of labeled carotenoids were 34 μmol for β-carotene and 33 μmol for lutein. Peak plasma concentrations, areas under the plasma concentration-time curves (AUCs), and percentages of dose recovered at peak plasma concentrations were calculated. Average peak plasma concentrations were 0.38, 0.068, and 0.079 μM for [13C]lutein, [13C]β-carotene, and [13C]retinol, respectively. Average AUC values (over 28 days) were 42.8, 13.6, 13.2 μM h for [13C]lutein, [13C]β-carotene, and [13C]retinol, respectively. Percentages of dose recovered at peak plasma concentrations were 3.6, 0.7, and 0.7% for [13C]lutein, [13C]β-carotene, and [13C]retinol, respectively. A positive relationship was observed between baseline plasma retinol levels and [13C]retinol plasma response. It is possible that this relationship was mediated either through some aspect of β-carotene absorption or via the common pathways of metabolism for postdose and endogenous retinoid.

Effects of Anthocyanin and Carotenoid Combinations on Foliage and Immature Fruit Color of Capsicum annuum L.

Shades ranging from violet to black pigmentation in pepper (Capsicum annuum L.) are attributed to anthocyanin accumulation. High-performance liquid chromatography and mass spectrometry analysis of violet and black fruit tissue identified a single anthocyanin that was determined to be delphinidin-3-p-coumaroyl-rutinoside-5-glucoside. Leaf tissue of a black-pigmented foliage genotype contained the same anthocyanin found in fruit but at a considerably higher concentration in comparison to violet and black fruit tissue. Fruit chlorophyll concentration was approximately 14-fold higher in black fruit in comparison to violet fruit that contained relatively little chlorophyll. Beta-carotene, lutein, violaxanthin, and neoxanthin carotenoid concentrations in black fruit were also significantly greater in comparison to violet fruit. High concentrations of delphinidin in combination with chlorophyll and accessory carotenoid pigments produced the characteristic black pigmentation observed in fruits and leaves of selected genotypes. Anthocyanins were accumulated in the outer mesocarp of violet and black fruit and in the palisade and mesophyll cells of black leaves. Consistent with chlorophyll content of respective genotypes, chloroplast density was greater in cells of black fruits. Utilizing Capsicum pigment variants, we determine the biochemical factors responsible for violet versus black-pigmented pepper tissue in the context of described pepper color genes.