Influence of amount and type of dietary fat on plasma cholesterol concentrations in goats

Adult, non-pregnant, dry goats were fed diets differing in the amount and type of fat. To modulate the type of dietary fat, rations containing either palm oil or olive oil were used, the amount of fat being 86 g/kg dry matter (DM). To modulate the amount of dietary fat, the oils were replaced by an isoenergetic amount of native corn starch so that the dietary fat concentration dropped to 26 g/kg DM. The high fat diets, when compared with the low fat diet, significantly raised plasma total cholesterol by 91%, high-density lipoprotein (HDL) cholesterol by 100%, triglycerides by 47% and phospholipids by 57%. On an average, dietary palm oil versus olive oil significantly increased plasma total cholesterol by 6%, HDL cholesterol by 9% and phospholipids by 4%, but left plasma triglycerides unchanged. This study shows that plasma lipid concentrations in goats respond to the amount and type of fat in the diet.     

Relation between fat distributions and several plasma adipocytokines after exercise training in premenopausal and postmenopausal women

Circulating concentrations of adipocytokines, such as leptin, tumor necrosis factor-alpha (TNF-alpha), and plasminogen activator inhibitor-1 (PAI-1), vary with exercise training, menopause, or regional variations in adipose tissues. In the present study, the relationships between body fat distributions and some adipocytokines were compared in premenopausal (N = 9) and postmenopausal women (N = 9), before and after exercise training. The training for 10 weeks (that is, 3 days/week) consisted of aqua exercise plus resistance exercise. The training reduced percent fat, body mass index, total fat mass (TFM), subcutaneous fat mass (SFM), and plasma levels of leptin and PAI-1 in both women. Mean value of plasma TNF-alpha tended to increase after training in both women. Plasma leptin levels were lower in postmenopausal than in premenopausal women, independently of training. In premenopausal women, plasma leptin levels correlated well with either TFM or SFM before and after training. Regression analysis of decreases in plasma leptin with a reduced amount of SFM revealed that decreases in plasma leptin depended to a greater extent on a loss of SFM. In postmenopausal women, no significant correlation was found between leptin levels and any of the fat depots. Plasma TNF-alpha levels correlated well with visceral fat mass (VFM) in premenopausal but not in postmenopausal women. Changes in TNF-alpha levels after training correlated well with reduced amount of VFM in premenopausal but not in postmenopausal women. Plasma PAI-1 levels were not different between groups. Moreover, no significant correlation was found between PAI-1 levels and any of the fat depots in both women. Thus, in premenopausal but not in postmenopausal women, changes in plasma concentrations of leptin and TNF-alpha correlate well with specific alterations in relative amount of SFM and VFM after training, respectively. However, no significant relationship between PAI-1 and any of the fat depots was found independently of either menopause or training.     

Choline status is not a reliable indicator of moderate changes in dietary choline consumption in premenopausal women

For the prevention of liver dysfunction in women, a choline adequate intake of 425 mg/day was established. To date, the relationship between dietary choline intake and plasma concentrations of choline moieties remains relatively unexplored. As an extension of our previous work, this 14-week controlled feeding study investigated the relationship between moderate changes in dietary choline intake and blood indicators of status. The influences of folate intake and the methylenetetrahydrofolate reductase (MTHFR) C677T genotype were also considered. Healthy premenopausal women (n=45, 18-46 years) with the MTHFR 677CC (n=28) or TT (n=17) genotype consumed a folate-restricted diet for 2 weeks followed by randomization to one of four dietary treatments (n=6-9/group) differing in total choline (344-486 mg/day), betaine (122-349 mg/day) and/or folate (400-800 microg dietary folate equivalents/day) content for 12 weeks. Responses to treatment were assessed as changes in the plasma levels of choline moieties (i.e., betaine, choline, phosphatidylcholine and sphingomyelin) and/or leukocyte global DNA methylation between pretreatment (Week 2) and posttreatment (Week 14) values. No significant changes were detected in the measured variables in response to dietary increases in choline (i.e., 41% increase) or betaine (i.e., 286% increase) intake. However, the MTHFR C677T genotype, alone or together with a diet, influenced betaine (P=.03) and phosphatidylcholine (P=.03). These data suggest that choline status is not a reliable indicator of moderate changes in dietary choline intake possibly due to the engagement of compensatory mechanisms. In addition, the MTHFR C677T genotype appears to influence the direction and use of choline moieties in this group of women.     

Enhanced dietary fat clearance in postobese women

The objective of this study was to examine the postprandial response to an exogenous fat source in eight weight-stable postobese subjects (2;-3 years after gastric bypass) and eight matched control women, using a stable isotope, [13C]oleate. After a high fat breakfast meal (1,062 cal, 67% fat), [13C]oleate in triglyceride (TG)-rich lipoproteins (Sf >400 and Sf 20;-400) and nonesterified fatty acids (NEFA), and 13C in breath CO2, were monitored over 8 h. There were no differences in resting energy expenditure, thermic effect of food, carbohydrate/fat oxidation ratio, breath 13CO2 enrichment, or fecal fat content between postobese and control subjects. Postprandially, there was no difference in S(f) 20;-400 TG or NEFA, but postobese subjects had lower Sf >400 incremental area under the curve (AUC) (- 33%, P < 0.0025) and glucose [P < 0.01 by repeated measures analysis of variance (RM ANOVA)]. Postprandial 13C in Sf >400 TG returned to fasting levels 4 h earlier in postobese subjects and was lower than in control subjects at 4 and 6 h (P < 0.05 by RM ANOVA). The greatest difference was in the [13C]NEFA profiles. In control subjects [13C]NEFA increased markedly over 8 h; postobese subject [13C]NEFA remained close to fasting nonenriched values, and was strikingly lower than in control subjects (72% lower by AUC, P < 0.0001 by RM ANOVA). Finally, postobese subjects tended to have lower postprandial insulin (P < 0.01, 4 h), lower postprandial acylation-stimulating protein, and lower fasting leptin (-46%, P < 0.02). This study demonstrates clear metabolic differences in exogenous dietary fat partitioning in postobese women. These findings are compatible with an increased efficiency of dietary fat storage and suggest one possible mechanism for promotion of weight regain in postobese individuals.     

Alkaline phosphatase and percentage body fat predict circulating C-reactive protein in premenopausal women

C-reactive protein (CRP) is considered a marker of inflammation, which is a risk factor for many chronic diseases. However, determinants of CRP remain unclear and were studied in a strictly defined cohort of healthy premenopausal women (n=233) using multiple regression models. Independent predictors of serum CRP (model R²=0.59) were percentage body fat, serum alkaline phosphatase (ALP), sex hormone-binding globulin and white blood cell count. The close association between CRP and ALP suggests that enzymatic activity of ALP may be important for the anti-inflammatory effects of CRP, which should be confirmed with additional studies.     

Anthropometric and leptin changes in women following different dietary approaches to weight loss

Leptin may favorably respond to fat mass (FM) losses induced by a low-carbohydrate (LC) diet, although this is unclear. We examined serum leptin concentrations in women in midlife undergoing different dietary approaches to body weight (BW) loss. Women followed either a LC, high-protein (LCHP; n = 13) or high-carbohydrate, low-fat (HCLF; n = 12) diet for 12 weeks. Changes in anthropometric and soft-tissue mass measurements and leptin concentrations were assessed. Women in both diet groups had reductions in BW, BMI, fat-free soft-tissue mass, FM, body fat percentage, and central abdominal fat (CAF) (P < 0.001 for all variables) over the 12-week intervention. These changes were not significantly different between diet groups. Serum leptin concentrations decreased by 41.8% (P < 0.001) in the LCHP group and by 44.3% (P < 0.001) in the HCLF group from baseline to week 12, with no significant difference between groups. The association of CAF (r = 0.73) and FM (r = 0.83) change with leptin change was strong in the HCLF group. Leptin change did not relate to change in any variable in the LCHP group. Both LCHP and HCLF diets favorably lower FM, CAF, and leptin in women, suggesting that beneficial changes in leptin can be similarly achieved through different dietary approaches to BW loss.     

Body fat content determination in premenopausal, overweight, and obese young women using DXA and FT-NIR

Even though BMI is the most commonly used method for assessing and monitoring obesity, it does not take into account the individual's body fat content assuming instead that body mass is closely associated with body fat, which is a tenuous assumption. The aim of this study was to make a direct comparison between measurements of body fat content using a convenient and rapid Fourier transform near-infrared (FT-NIR) spectroscopy and dual-energy X-ray absorptiometry (DXA). We recruited 52, premenopausal women (age range 19-45), all of whom had a BMI that classified them as either overweight or obese (range: 27-40 kg/m(2), mean: 31.1 ± 3.7 kg/m(2)) and indicated a statistically significant linear relationship between the fat content in kilograms measured by FT-NIR and DXA (r = 0.95, P < 0.001). Bland-Altman analysis showed that almost all the differences between two measurements fell within 2 s.d. We report here that the FT-NIR method provided comparable measurements of subcutaneous body fat content similar to those of total fat obtained using DXA. The FT-NIR method is a lower cost, easy to use and transport, and, based on comparison with DXA, an accurate method to measure body fat content. We propose that FT-NIR is an ideal method for safe repeat measurements in large trials or in screening and monitoring individuals during interventions in which changes in body fat will occur.     

Diet and urinary estrogen profile in premenopausal omnivorous and vegetarian women and in premenopausal women with breast cancer

The urinary estrogen profile was studied in the midfollicular phase twice, and diet four times during 1 yr in 10 premenopausal breast cancer (BC) patients consuming an omnivorous normal Finnish diet and in two control groups, one consuming an omnivorous (n = 12) and the other a lactovegetarian (n = 11) diet. Total fat intake in relation to caloric intake was almost identical in all three groups. Only with regard to grain fiber intake did the BC patients differ significantly from both other groups. No differences were found between the groups with regard to urinary excretion of 13 individual estrogens and total estrogens, with the exception of 4-hydroxyestrone (4-OH-E1), which was significantly lower (P less than 0.05) in the BC group than in the vegetarians. A high carbohydrate to protein ratio in the diet had a negative correlation with the excretion of 2-hydroxyestrogens and 2-hydroxyesterone (2-OH-E1) to 4-OH-E1 ratio. The BC group had significantly higher urinary 2-OH-E1 to E1 ratio (P less than 0.05) compared to the vegetarians. The 2-OH-E1 to 4-OH-E1 ratio was highest in the BC group (= 7.1) and differed significantly from that of the omnivores (= 4.3; P less than 0.02) and vegetarians (= 3.6; P less than 0.005). This ratio showed a negative correlation with intake of carbohydrates, starch, total and grain fiber. Urinary excretion of 4-OH-E1 correlated positively with total and grain fiber intake and plasma SHBG. Protein intake correlated positively with urinary 2-methoxy-E1 excretion, and retinol intake positively with catechol estrogen, E1 and E2 excretion. It is concluded that estrogen production and urinary estrogen profile in premenopausal breast cancer patients is normal with the exception of a low 4-OH-E1 excretion and high urinary 2-OH-E1 to 4-OH-E1 ratio. This ratio, which seems to depend on diet, is the only urinary estrogen parameter separating premenopausal BC patients from the control omnivorous and lactovegetarian women.     

Korean and Caucasian overweight premenopausal women have different relationship of body mass index to percent body fat with age.

The aim of the study was to investigate in premenopausal women whether the relationship between percentage body fat (PBF) and body mass index (BMI; in kg/m2) differs between Korean Asians (Ko-As) living in Seoul, South Korea, and Caucasians (Ca) living in New York City. Healthy premenopausal women (50 Ko-As; 38 Ca), ages 22-50 yr, were studied. Weight, height, and PBF by dual-energy X-ray absorptiometry were measured. Total body dual-energy X-ray absorptiometry data were collected using GE-Lunar systems (Prodigy-Korea and DPXL-New York), and all scan analyses were performed by one technician in New York. Similar soft tissue phantoms were used for daily instrument calibrations at both sites. The relationship between PBF and BMI was assessed by multiple regression analysis with race, age, reciprocal of BMI (1/BMI), and a race-by-age interaction as the final independent variables. Race (P = 0.003) and 1/BMI (P < 0.001) were significantly related to PBF in this model. A significant race-by-age interaction (P = 0.039) indicated that the slope of the lines for PBF vs. age differed between Ko-As and Ca. This study demonstrates in a Ko-As sample that the BMI-fat relationship differs significantly from that in a comparable group of Caucasian women. Investigators who use BMI as an index of fatness should be aware of the well documented differences in the relationship of BMI and fatness across race/ethnic groups.     

Metabolism of dietary genotoxins by the human colonic microflora; the fecapentaenes and heterocyclic amines

The microflora of the human colon is a complex ecosystem of anaerobic bacteria which have the capability of enzymatically transforming a variety of dietary (or biliary) compounds to genotoxic metabolites. In the past, most investigators studying the interplay between diet and colonic flora and its role in the etiology of cancers focused on the reductive and glycosidic potential of the bacterial enzymes--many of which reverse the oxidative and conjugative reactions performed by the liver. Recent work in our laboratory has focused on the metabolism of two relatively new classes of genotoxins, the fecapentaenes and the heterocyclic amines (pyrolysis carcinogens). The fecapentaenes (conjugated ether lipids) are produced in the colon by Bacteroides spp. from polyunsaturated ether phospholipids (plasmalogens) whose natural origin and function are unknown. The fecapentaenes are potent direct-acting genotoxins that are detected in the feces of most individuals on normal western diets. The heterocyclic amines, which originate from fried or broiled proteinaceous foods, normally require activation by the liver before being potent mutagens or carcinogens. However, the "IQ" subclass (e.g. IQ and MeIQ) can be activated in the colon by Eubacterium and Clostridium species to a 7-hydroxy form which is directly mutagenic in Salmonella. Although there is no direct evidence that the fecapentaenes or the 7-hydroxy "IQ" compounds influence risk for colon cancer, the potency and prevalence of these bacterial metabolites is cause for concern.     

Increasing dietary fat elicits similar changes in fat oxidation and markers of muscle oxidative capacity in lean and obese humans

In lean humans, increasing dietary fat intake causes an increase in whole-body fat oxidation and changes in genes that regulate fat oxidation in skeletal muscle, but whether this occurs in obese humans is not known. We compared changes in whole-body fat oxidation and markers of muscle oxidative capacity differ in lean (LN) and obese (OB) adults exposed to a 2-day high-fat (HF) diet. Ten LN (BMI = 22.5±2.5 kg/m², age = 30±8 yrs) and nine OB (BMI = 35.9±4.93 kg/m², 38±5 yrs, Mean±SD) were studied in a room calorimeter for 24hr while consuming isocaloric low-fat (LF, 20% of energy) and HF (50% of energy) diets. A muscle biopsy was obtained the next morning following an overnight fast. 24h respiratory quotient (RQ) did not significantly differ between groups (LN: 0.91±0.01; OB: 0.92±0.01) during LF, and similarly decreased during HF in LN (0.86±0.01) and OB (0.85±0.01). The expression of pyruvate dehydrogenase kinase 4 (PDK4) and the fatty acid transporter CD36 increased in both LN and OB during HF. No other changes in mRNA or protein were observed. However, in both LN and OB, the amounts of acetylated peroxisome proliferator-activated receptor γ coactivator-1-α (PGC1-α) significantly decreased and phosphorylated 5-AMP-activated protein kinase (AMPK) significantly increased. In response to an isoenergetic increase in dietary fat, whole-body fat oxidation similarly increases in LN and OB, in association with a shift towards oxidative metabolism in skeletal muscle, suggesting that the ability to adapt to an acute increase in dietary fat is not impaired in obesity.     

Laboratory and epidemiologic studies of fecapentaenes

Fecapentaenes are a class of conjugated ether lipids which have been identified as the major component of human fecal mutagenicity in the Ames Salmonella mutagenesis assay. Human epidemiologic data have indicated that most healthy North American populations eating a western diet do excrete detectable levels of fecapentaenes. Excreted fecapentaene levels seem to reflect levels throughout the colonic lumen, and levels vary characteristically between individuals. Those individuals found to excrete high levels of fecapentaene appear, based on limited data, to be at decreased risk of colorectal neoplasia. Carcinogenicity studies in rats and mice have been predominantly negative, however, increased tumor incidence in mice exposed to fecapentaenes as neonates has recently been reported. Fecapentaenes are direct-acting genotoxins, which may react with DNA through free radical mechanisms, and/or aldehyde formation. Mechanisms by which fecapentaene-induced DNA damage may mediate carcinogenesis are discussed.     

Manganese absorption and retention in rats is affected by the type of dietary fat

There is evidence that manganese (Mn) metabolism may be altered by the form and amount of dietary fat. Also, iron (Fe) absorption is greater with saturated fats, as compared to polyunsaturated fatty acids (PUFAs). The absorption of Fe and Mn are interrelated in many aspects; therefore, the form of dietary fat may indirectly alter Mn absorption. The reported studies were conducted to determine whether saturated fat, as compared to unsaturated fat, affected Mn absorption, retention, and metabolism. In experiment I, adult rats were fed diets containing either 0.7 or 100.4 μg/g Mn with the fat source as high-linoleic safflower oil or stearic acid. After 2 wk of equilibration, the animals were fed a test meal of ⁵⁴Mn followed by whole-body counting for 10 d. Manganese absorption was significantly (p<0.05) lower in the stearic acid group (0.9–4.8%) than in the safflower oil group (20–33.8%); however, the biological half-life was shorter in the safflower oil group. Retention of ⁵⁴Mn and total Mn was always significantly (p<0.05) greater in the safflower oil group when dietary Mn was low, but it was the same when dietary Mn was high. In experiment II, weanling rats were fed 1.3, 39.3, or 174.6 μg Mn/g and either stearate, high-oleic safflower oil or high-linoleic safflower oil for 8 wk. Long-term feeding of the stearate and low Mn-containing diet resulted in a significant (p<0.0001) reduction in heart superoxide dismutase activity and kidney and liver Mn concentrations compared to the other diets. These data show that stearic acid inhibitits Mn absorption, but it may not inhibit Mn retention when dietary Mn is high. The U.S. Department of Agriculture, Agricultural Research Service, Northern Plains Area, is an equal opportunity/affirmative action employer and all agency services are available without discrimination. Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable.