Capturing dietary diversity: are existing methods adequate?
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Black or African American↗
Biomedical subjects
T E Prewitt
Publications and source records attributed to T E Prewitt.
Maintenance of lower proportions of (n - 6) eicosanoid precursors in phospholipids of human plasma in response to added dietary (n - 3) fatty acids.
Competition between the (n - 3) and (n - 6) types of highly unsaturated fatty acids can diminish the abundance of (n - 6) eicosanoid precursors in a tissue, which in turn can diminish the intensity of tissue responses that are mediated by (n - 6) eicosanoids. The mixture of 20- and 22-carbon highly unsaturated fatty acids maintained in the phospholipids of human plasma is related to the dietary intake of 18:2 (n - 6) and 18:3 (n - 3) by empirical hyperbolic equations in a manner very similar to the relationship reported for laboratory rats (Lands, W.E.M., Morris, A. and Libelt, B. (1990) Lipids 25, 505-516). Analytical results from volunteers ingesting self-selected diets showed an inter-individual variance for the proportion of (n - 6) eicosanoid precursors in the fatty acids of plasma phospholipids of about 5%, but the variance among multiple samples taken from the same individual throughout the day was less (about 3%), closer to the experimental variance of the analytical procedure (about 1%). The reproducibility of the results makes it likely that analysis of fatty-acid composition of plasma lipids from individuals will prove useful in estimating the diet-related tendency for severe thrombotic, arthritic or other disorders that are mediated by (n - 6) eicosanoids. Additional constants and terms were included in the equations to account for the effects of 20- and 22-carbon highly unsaturated (n - 3) fatty acids in the diet. A lower constant for the 20- and 22-carbon (n - 3) fatty acids compared to that for the 18-carbon (n - 3) fatty acid in decreasing the ability of dietary 18:2 (n - 6) to maintain 20:4 (n - 6) in tissue lipids confirmed the greater competitive effectiveness of the more highly unsaturated n - 3 fatty acids in the elongation/desaturation process. Also, a lower constant for direct incorporation of 20-carbon fatty acids of the n - 6 vs. the n - 3 type indicated a greater competitive effectiveness of 20:4 (n - 6) relative to 20:5 (n - 3) in reesterification after release from tissue lipids. The equations may be used in reverse to estimate the dietary intakes of the (n - 3) and (n - 6) fatty acids by using the composition of the fatty acids that had been maintained in plasma lipids.
Aged↗
Insulin-like growth factor I and low-density-lipoprotein cholesterol in women during high- and low-fat feeding.
In vitro studies suggest that insulin-like growth factor I (IGF-I) may modulate hepatic production and peripheral utilization of lipoproteins. We measured blood concentrations of IGF-I; total, high-density-lipoprotein, and low-density-lipoprotein (LDL) cholesterol; and apolipoproteins in 18 women with above average cholesterol after high- and low-fat diet periods. Total cholesterol fell 6% (P less than 0.02) during the low-fat diet because of reduced concentrations of LDL cholesterol (P less than 0.01). Serum concentrations of IGF-I were inversely correlated with total and LDL cholesterol and apolipoprotein B during both high-fat (r = -0.676, P less than 0.005; r = -0.745, P less than 0.001; and r = -0.504, P less than 0.04, respectively) and low-fat (r = -0.656, P less than 0.005; r = -0.757, P less than 0.001; and r = -0.695, P less than 0.001, respectively) diets. IGF-I increased with reduced fat intake in obese subjects only. Thus, IGF-I may contribute to the regulation of LDL cholesterol in mildly hypercholesterolemic women but may not mediate the beneficial response to reduced fat intake.
Adult↗
Differential reduction of plasma cholesterol by the American Heart Association Phase 3 Diet in moderately hypercholesterolemic, premenopausal women with different body mass indexes.
The ability of a low-fat, low-cholesterol diet to improve the risk-factor profiles of moderately hypercholesterolemic, premenopausal women was evaluated. Nineteen women were fed a typical American diet for 1 mo, after which a low-fat diet consisting of 21% of total energy (en%) as fat, 59 en% carbohydrates, 19 en% protein, and 96 mg cholesterol/d (P:S 1.8) was given. After 5 months, total and low-density lipoprotein (LDL) cholesterol was decreased by 7% and 11%, respectively, and total triglycerides increased by approximately 30%. High-density-lipoprotein (HDL) cholesterol was decreased by 12% at month 2 and 5% at month 5 (P less than 0.05). Although HDL2 cholesterol decreased progressively throughout the diet period to -35% by month 5, HDL3 cholesterol, which decreased to -5% at month 1, increased to +7% by month 5. Of the plasma apolipoproteins only apo A-II was altered (+15%) by the diet. Body mass index correlated to baseline values and affected response to diet; only the leanest women had significant decreases in total, LDL, and HDL2 cholesterol in response to the low-fat diet.
Adult↗
Changes in body weight, body composition, and energy intake in women fed high- and low-fat diets.
The effects of a 20%-fat diet (LF) on total body weight, lean body weight, and adiposity were studied in 18 premenopausal women with body mass index (BMI) of 18-44. Subjects were fed a 37%-fat (HF) control diet for 4 wk followed by the LF diet for 20 wk. Total body weight, lean body weight, and fat weight were measured at the end of the HF and LF dietary periods by hydrostatic weighing. Despite adjustments in energy intake to maintain weight throughout the study, subjects exhibited a 2.8% decrease in total body weight (P less than 0.0006), an 11.3% decrease in fat weight (P less than 0.0001), and a 2.2% increase in lean body weight (P less than 0.0149) by the end of the LF period. Similar changes were observed in obese (BMI greater than 30) and non-obese women (BMI less than 30). By the end of the LF period, energy intake had increased significantly in comparison with the HF diet (119% of the HF intake, P less than 0.0001). Results could not be explained by changes in daily activity levels and suggest that macronutrient composition plays a role in energy requirements for weight maintenance.
Adipose Tissue↗
Modest dietary restriction and serum somatomedin-C/insulin like growth factor-I in young, mature and old rats.
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Aging↗
Nutrient intake, lipids, and lipoprotein cholesterols in black and white children: the Lipid Research Clinics Prevalence Study.
Our specific aim was to assess differences in nutrient intake and in lipids and lipoprotein cholesterols between blacks and whites in 259 black children (129 boys, 130 girls) and in 811 white children (424 boys, 387 girls) ages 5-19. The nutrient intake data were obtained by 24-hr recall from the Houston and Cincinnati Lipid Research Clinics. The fundamental nutrient differences between blacks and whites were in total calories and in calories per kilogram of body weight, both of which were uniformly and significantly lower among black than white boys and generally, but less consistently and significantly, lower among black than white girls. No racial differences in total cholesterol or cholesterol intake per kilogram body weight were observed. After statistically controlling for education of the head of household, there were no consistent significant racial differences in Quetelet index. There was no significant independent effect of education of head of household on the children's caloric intake and racial differences in socioeconomic status did not appear to systematically account for differences in total energy intake. In aggregate, black children had lower triglyceride and very-low-density lipoprotein cholesterol levels, and higher levels of high-density lipoprotein cholesterol than whites; there were no significant differences by race in low-density lipoprotein cholesterol levels. Race was a significant independent explanatory variable for high-density lipoprotein cholesterol levels (higher in blacks) and for very-low-density lipoprotein and triglyceride levels (higher in whites) (P less than 0.005), after covariance adjusting for education of head of household, sex, age, Quetelet index, calories, saturated fat (g/day/kg body wt), and clinic. Lower caloric intake among blacks compared with whites, the major nutrient difference in the current study, did not account for differences in lipoprotein cholesterol levels between the two groups.
Adolescent↗
Selected nutrient intakes of free-living white children ages 6-19 years. The Lipid Research Clinics Program Prevalence Study.
We report energy intake and selected nutrient intakes-protein, fat (total, saturated, and polyunsaturated), carbohydrate (total, starch, and sucrose), and cholesterol-for 1251 white children ages 6-19 years. The data were obtained, by means of a 24-h dietary recall, from children who were randomly selected from the North American populations studied by the Lipid Research Clinics Program. Females (N = 584) consumed about 2000 kcal daily, an intake that remained relatively constant throughout the age groups studied. Males (N = 667) had an energy intake of 2000 kcal/day during childhood that increased to over 3000 kcal/day in adolescence. Energy sources for both sexes were approximately 15% protein, 38% total fat, 15% saturated fat, 6% polyunsaturated fat, 48% total carbohydrate, 19% starch, and 11% sucrose; cholesterol intake averaged about 145 mg/1000 kcal. For both sexes, fat intake increased with age. Compared to females, males ingested greater amounts of cholesterol and total and saturated fat.
Adolescent↗
Relationship of serum immunoreactive somatomedin-C to dietary protein and energy in growing rats.
Protein-energy undernutrition has its most devastating consequences during growth. Postal somatic growth now appears to be regulated in large part by the somatomedins, a family of growth hormone-dependent peptide mitogens. This study, using growing rats as the model, was designed to determine the relationship between protein and energy intake and serum immunoreactive somatomedin-C. Four-week-old male Sprague-Dawley rats were fed ad libitum three levels of isoenergetic protein diets (5%, 10%, and 15% lactalbumin) at each of three levels of energy (ad libitum, 75% or 50% of ad libitum quantities). Dietary fat was held constant at 11.9% as cottonseed oil. At 5 weeks of age, serum somatomedin-C concentration was predominately influenced by the dietary protein and increased linearly as protein intake increased from 5% to 15%. at 6, 9, and 12 weeks of age, serum somatomedin-C concentration was influenced by both protein and energy intake, although protein intake appeared to be the more important variable. Serum somatomedin-C was highly correlated with both body weight (r = 0.84, P less than 0.001) and tail length (r = 0.74, P less than 0.01). These results indicate that measurement of immunoreactive somatomedin-C provides a valuable biochemical index of protein-energy nutriture.
Animals↗
Quantitative assessment of recruitment efforts for prevention trials in two diverse black populations.
BACKGROUND: Prevention efforts to reduce the morbidity and mortality disparity between blacks and whites in the United States present a national health priority. However, participation of blacks in prevention trials has been low. The present study reports successful recruitment processes from two economically diverse black populations. METHODS: The two studies were independent projects, but both were part of a nationally funded collaboration on cardiovascular health. "Hip Hop to Health" is a 4-year randomized controlled trial aimed at dietary fat reduction and increased exercise among inner-city black families. The Fat Reduction Intervention Trial in African-Americans project is a 5-year trial to reduce total fat, saturated fat, and cholesterol intake among black families from a working class community. RESULTS: The two populations differed on demographic characteristics. Direct presentation was the most effective recruitment strategy in the "Hip Hop to Health" program. In contrast, telephone recruitment and neighborhood canvassing were the more successful strategies for FRITAA. CONCLUSIONS: Although both populations were black and at comparable cardiovascular disease risk, the differing demographics between the groups made different recruitment strategies necessary. This study documented the labor-intensive quality of successful recruitment, and results suggest that successful recruitment requires strategies tailored to the needs, experiences, and environment of the target group.
Adult↗
The relation of central adiposity to components of the insulin resistance syndrome in a biracial US population sample.
The higher rates of type 2 diabetes mellitus, hypertension, and many others factors of the insulin resistant syndrome (IRS) often seen in African Americans compared to whites do not seem to be explained by differences in central obesity. Reasons for this may be due, in part, to the validity of the commonly used anthropometric surrogate of central adiposity. Recent findings have shown that waist circumference is a better surrogate of total body and visceral adipose tissue and is better correlated with CVD than the traditionally used anthropometric indexes of the body mass index or waist/hip ratios. In this study, waist circumference was employed to determine the association between central adiposity and components of the insulin resistance syndrome in blacks (N=1963) and whites (N=4894) from the US national population-based samples. Sex-specific correlation coefficients were used to estimate the association between waist circumference and factors of the IRS. Multiple linear regression analyses were used to determine racial differences in waist circumference and the independent association of waist circumference to some known factors of IRS adjusting for age, BMI, alcohol use, and smoking. Waist circumference was positively correlated with plasma glucose, DBP, SBP, LDL cholesterol, fasting insulin, serum triglyceride, total cholesterol and total cholesterol/HDL ratio in black and white men and women (P<0.01). In both biracial groups, waist circumference was significantly associated with increases in glucose, DBP, LDL cholesterol, total cholesterol, triglyceride and fasting insulin levels controlling for age, BMI, and behavioral risk factors, such as alcohol use and smoking (P<0.05). Our data shows that central adiposity assessed with waist girth did not wholly explain the higher prevalence of IRS components often seen among blacks. The results of this study reinforce the need to encourage the use of waist measure as a public health tool in screening for CVD risks.
Abdomen↗