Racial differences in insulin secretion and sensitivity in prepubertal children: role of physical fitness and physical activity

OBJECTIVE: To investigate in prepubertal children whether physical fitness and/or physical activity are: 1) associated with insulin secretion and sensitivity and 2) account for racial differences in insulin secretion and sensitivity. RESEARCH METHODS AND PROCEDURES: Subjects included 34 African American and 34 white nondiabetic children aged 5 to 11 years. Data were divided into two sets according to the availability of VO2max and physical activity data. Body composition was measured by dual-energy X-ray absorptiometry. Subcutaneous abdominal adipose tissue and intra-abdominal adipose tissue were examined by computed tomography. Insulin sensitivity (S1) and acute insulin response (AIR) were determined by a frequently sampled intravenous glucose tolerance test. An all-out, progressive treadmill exercise test was used for measuring VO2max. Physical activity data were collected by questionnaire. RESULTS: African American children had lower SI and higher AIR than white children, after adjusting for total body fat mass. African Americans reported higher levels of physical activity (hours/wk) than whites, but had a lower VO2max. In multiple linear regression analysis, hours/wk of activity and hours/wk of vigorous activity, but not moderate activity, were independently related to SI and AIR after adjusting for race, total body fat mass or fat distribution, and total lean tissue mass. VO2max was not related to AIR, and was inversely related to SI, after adjusting for body composition. Race remained significantly associated with both SI and AIR, even after adjusting for body composition, fat distribution, and hours/wk of activity or hours/wk of vigorous activity. DISCUSSION: In summary, overall physical activity and, especially, vigorous activity were associated with insulin secretion and sensitivity. However, neither physical activity nor VO2max explained the racial difference in insulin secretion (higher in African Americans) and sensitivity (lower in African Americans). Thus, racial (African American to white) differences in aspects of insulin action seem to be due to factors other than body composition, fat distribution, cardiovascular fitness, and amount of physical activity.     

The relation of sugar intake to beta cell function in overweight Latino children

BACKGROUND: Few studies have investigated the association between sugar intake and insulin dynamics in children, and none have examined this association in overweight Latino youth. OBJECTIVE: We aimed to examine the relation between dietary components, especially sugar intake, and insulin dynamics in overweight Latino youth. DESIGN: We examined 63 overweight Latino children aged 9-13 y. Dietary intake was determined by 3-d records, and body composition was measured with dual-energy X-ray absorptiometry. Insulin sensitivity (S(I)), acute insulin response (AIR), and disposition index (an index of beta cell function) were measured by using a frequently sampled intravenous-glucose-tolerance test and minimal modeling. Hierarchical regression analysis ascertained the potential independent relation between insulin dynamics and dietary components. RESULTS: The relation between macronutrient intake and any variable related to insulin dynamics was not significant. However, higher total sugar intake, although not related to S(I), was significantly associated with lower AIR (beta = -0.296, P = 0.045) and lower beta cell function (beta = -0.421, P = 0.043), independent of the covariates age, sex, body composition, Tanner stage, and energy intake. Sugar-sweetened beverage intakes trended toward inverse association with lower AIR (beta = -0.219, P = 0.072) and beta cell function (beta = -0.298, P = 0.077). CONCLUSIONS: In overweight Latino children, higher intakes of sugar and sugar-sweetened beverages were associated with lower AIR and disposition index, which suggested that these children already have early signs of poor beta cell function. These results emphasize the need for early nutritional interventions to reduce daily sugar intake in overweight Latino children and potentially reduce their risk for type 2 diabetes.     

Effects of weight loss on changes in insulin sensitivity and lipid concentrations in premenopausal African American and white women

BACKGROUND: Few studies have tested the hypothesis that changes in disease risk factors are more closely associated with changes in visceral fat than with changes in other adipose tissue depots, particularly in subjects with different ethnic or racial backgrounds. OBJECTIVE: We describe changes in triacylglycerol, total cholesterol, HDL cholesterol, LDL cholesterol, insulin sensitivity (S(i)), visceral fat, and subcutaneous abdominal adipose tissue (SAAT) with weight loss in premenopausal, overweight [body mass index (in kg/m(2)): 27-30], African American (n = 19) and white (n = 18) women. DESIGN: Assessments were performed before and after diet-induced weight loss to a BMI < 25. Body composition and body fat distribution were assessed with dual-energy X-ray absorptiometry and computed tomography, respectively; S(i) was assessed with an intravenous-glucose-tolerance test and minimal modeling. RESULTS: White women lost significantly more visceral fat and less SAAT than did African American women despite similar weight losses (approximately 13 kg). Mixed-model analysis indicated significant effects of time (ie, weight loss) on S(i), triacylglycerol, HDL cholesterol, and LDL cholesterol and of race on triacylglycerol. Time x race interaction terms were not significant. After adjustment for either total body or visceral fat, time was not related to any outcome variable; however, race remained significantly related to triacylglycerol. CONCLUSIONS: With weight loss, moderately overweight African American and white women experienced significant improvements in S(i) and lipids. The beneficial effects of weight loss did not differ with race and could not be attributed to a specific body fat depot. Lower triacylglycerol concentrations among African American women are independent of both obesity status and body fat distribution.     

Diet quality varies by race/ethnicity of Head Start mothers

BACKGROUND: Despite the key role that women from limited income families play as family food providers and their high risk for diet-related chronic diseases, there is a paucity of data about their diet quality and how it might vary by race/ethnicity. OBJECTIVE: To compare nutrient and food intakes of multiethnic mothers with children in Head Start from Texas and Alabama. DESIGN: Cross-sectional, secondary data analysis. METHODS: The sample was 603 mothers, 33% Hispanic American from Texas; 19% African American from Texas; 24% African American from Alabama; and 24% white from Alabama who were interviewed from fall 2004 to spring 2005. Diet quality was evaluated by averaging 24-hour dietary recalls from 3 nonconsecutive days and calculating the percent meeting the Estimated Average Requirement, the Dietary Guidelines for fat and added sugar, and the mean adequacy ratio for eight nutrients. For multiple comparisons, the least square means statement was used for general linear model procedures, adjusted for age, body mass index, and energy intake. RESULTS: The average mean adequacy ratio scores for diet quality were low overall, but 44% of Hispanic Americans had mean adequacy ratio scores <85, whereas 96% to 97% of other groups did. Most mothers exceeded 35% of energy from fat, with Hispanic Americans having the lowest percentage. Overall, 15% of mothers exceeded 25% of energy from added sugars, with Hispanic Americans having 5% with excess intakes. Energy intakes were highest for Hispanic Americans (2,017 kcal) and lowest for African Americans (1,340 kcal). The Hispanic Americans surveyed averaged 4.6 c fruit and vegetables per day compared to 3.2, 2.3, and 2.9 c/day among African Americans from Texas, African Americans from Alabama, and whites from Alabama, respectively. CONCLUSIONS: Despite limited food resources, Hispanic-American mothers consumed adequate amounts of fruit and vegetables. There was considerable variation in diet quality among race/ethnic groups on a low income budget.     

Influence of total vs. visceral fat on insulin action and secretion in African American and white children

OBJECTIVE: To examine whether total body fat (FAT) in general or visceral fat (VFAT) in particular is associated with greater metabolic risk in white and African American children. RESEARCH METHODS AND PROCEDURES: A total of 68 white and 51 African American children had measures of insulin sensitivity (Si) and acute insulin response (AIR) by a frequently sampled intravenous glucose tolerance test, total body fat by DXA and abdominal fat distribution (visceral vs. subcutaneous) by computed tomography. The influence of FAT and VFAT on insulin parameters were examined by comparing subgroups of children with high or low FAT vs. high or low VFAT and by multiple regression analysis. RESULTS: In whites, fasting insulin, Si, and AIR were significantly influenced by FAT, but not VFAT (e.g., for Si, 9.8 +/- 0.8 in low FAT vs. 4.6 +/- 0.7 x 10(-4)/min/[microIU/mL[ in high FAT, p < 0.05; 6.8 +/- 0.7 in low VFAT vs. 7.5 +/- 0.8 x 10(-4)/min/[microIU/mL] in high VFAT, p > 0.1). In African Americans, fasting insulin and Si were also primarily influenced by FAT (e.g., for Si, 4.9 +/- 0.4 in low FAT vs. 2.8 +/- 0.5 x 10(-4)/min/[microIU/mL] in high FAT, p < 0.05) but not by VFAT, and there were no significant effects of either fat compartment on AIR. In multiple regression analysis, Si was significantly influenced by FAT (negative effect), ethnicity (lower in African Americans), and gender (lower in females), whereas fasting insulin was significantly influenced by VFAT (positive effect), ethnicity (higher in African Americans), and fat free mass (positive effect). DISCUSSION: Body fat in general is the predominant factor influencing Si, but VFAT may have additional effects on fasting insulin. The lack of major effects of VFAT on Si in children may be explained by lower levels of VFAT or because VFAT affects aspects of whole body insulin action that are not measured by the minimal model.     

Ethnic differences in dietary intakes, physical activity, and energy expenditure in middle-aged, premenopausal women: the Healthy Transitions Study.

BACKGROUND: Menopause is a time of increased risk of obesity in women. The effect of menopause in African American women, in whom obesity is already highly prevalent, is unknown. OBJECTIVE: We compared dietary intakes and energy expenditure (EE) between middle-aged, premenopausal African American and white women participating in a longitudinal study of the menopausal transition. DESIGN: Dietary intakes by food record, EE by triaxial accelerometer, physical activity by self-report, and body composition by dual-energy X-ray absorptiometry were compared in 97 white and 52 African American women. Twenty-four-hour and sleeping EE were measured by whole-room indirect calorimetry in 56 women. RESULTS: Sleeping EE (adjusted for lean and fat mass) was lower in African American than in white women (5749 +/- 155 compared with 6176 +/- 75 kJ/d; P = 0.02); however, there was no significant difference in 24-h EE between groups. Reported leisure activity over the course of a week was less in African American than in white women (556 +/- 155 compared with 1079 +/- 100 kJ/d; P = 0.02), as were the daily hours spent standing and climbing stairs. Dietary intakes of protein, fiber, calcium, magnesium, and several fatty acids were significantly less in African Americans, whereas there were no observed ethnic differences in intakes of fat or carbohydrate. Body fat within the whole group was positively correlated with total, saturated, and monounsaturated fat intakes and inversely associated with fiber and calcium intakes. Fiber was the strongest single predictor of fatness. CONCLUSION: Ethnic differences in EE and the intake of certain nutrients may influence the effect of menopausal transition on obesity in African American women.     

Dairy, fruit, and vegetable intakes and functional limitations and disability in a biracial cohort: the Atherosclerosis Risk in Communities Study

BACKGROUND: Dairy, fruit, and vegetable intakes may be associated with functional limitations and disability through their role in muscle function, osteoporosis, and prevention of the oxidative damage associated with aging and chronic disease. OBJECTIVE: The associations between dairy, fruit, and vegetable intakes and functional limitations and disability were examined in African Americans and whites (baseline age: 45-64 y; n=9404) in the Atherosclerosis Risk in Communities (ARIC) Study. DESIGN: Logistic regression analyses were used to ascertain the associations between usual dairy, fruit, and vegetable intakes obtained at baseline by using a food-frequency questionnaire and lower-extremity function, activities of daily living (ADLs), and instrumental ADLs (IADLs) self-reported approximately 9 y later in models stratified by race and sex. RESULTS: Baseline dairy, fruit, and vegetable intakes tended to be inversely associated with impaired lower-extremity function, ADLs, and IADLs approximately 9 y later, particularly in African American women. For example, in African American women, baseline dairy intakes were inversely associated with impaired ADLs and IADLs [odds ratio (95% CI): 0.60 (0.40, 0.90) and 0.69 (0.48, 0.98), respectively [corrected] in the 3rd versus the [corrected] 1st tertile of intake (P [corrected] for trend<0.05]. Combined baseline intakes of fruit and vegetables were also inversely associated with impaired lower-extremity function, ADLs, and IADLs [odds ratio (95% CI): 0.67 (0.47, 0.95), 0.52 (0.36, 0.76), and 0.64 (0.45, 0.90), respectively; P for trend<0.05]. CONCLUSIONS: Dairy, fruit, and vegetable intakes may be inversely associated with functional limitations and disability. Further research is needed to ascertain the effect of diet on subsequent functional limitations and disability.     

Comparison of dietary intakes associated with metabolic syndrome risk factors in young adults: the Bogalusa Heart Study

BACKGROUND: Previous studies suggested that dietary intakes affect individual risk factors associated with metabolic syndrome. OBJECTIVE: The objective of this study was to examine dietary intakes in 1181 young adults aged 19-38 y (38.1% men; 25% African Americans and 75% whites) in relation to metabolic syndrome risk factors in the Bogalusa Heart Study. DESIGN: Participants were stratified into 3 groups according to the number of risk factors (0, 1-2, >/=3) associated with the metabolic syndrome according to the diagnostic criteria of the National Cholesterol Education Program, and dietary intakes were compared between the groups with a cross-sectional analysis. RESULTS: After adjustment for age, total energy intake, body mass index, and physical activity, mean (+/-SE) intakes of fruit, fruit juice, and vegetables were significantly higher in subjects who had no risk factors than in subjects who had 1-2 risk factors (3.30 +/- 0.09 compared with 2.99 +/- 0.07 servings/d; P < 0.05). The mean intake of sweetened beverages was lower in subjects who had no risk factors than in subjects who had 1-2 risk factors or >/=3 risk factors among whites (1.45 +/- 0.08 compared with 1.77 +/- 0.07 and 2.22 +/- 0.15 serving/d, respectively, in men; 1.26 +/- 0.06 compared with 1.62 +/- 0.05 and 1.78 +/- 0.13 servings/d, respectively, in women; P < 0.001) but not among African Americans. CONCLUSION: Our results suggest that low fruit and vegetable consumption and high sweetened beverage consumption are independently associated with the prevalence of metabolic syndrome in specific sex-ethnicity populations.     

Hispanic and non-Hispanic white elders from Massachusetts have different patterns of carotenoid intake and plasma concentrations

Carotenoids have been linked with protective roles against diseases associated with aging, including cancer, cardiovascular disease, cataracts, and age-related macular degeneration. With data from a semiquantitative, validated FFQ, we examined carotenoid intake of 340 Puerto Ricans, 98 Dominicans, and 146 non-Hispanic whites (>60 y old) in Massachusetts. Compared with non-Hispanic white men, Hispanic men reported a higher intake of lycopene and lower intakes of alpha-carotene, lutein + zeaxanthin, beta-carotene (from diet only), and total beta-carotene (diet and supplements) (P < 0.001). Hispanic women reported higher intakes of beta-cryptoxanthin and lycopene but lower intakes of lutein + zeaxanthin (P < 0.001) than non-Hispanic white women. The frequency of consumption of fruit and vegetables was higher among Hispanic women, relative to non-Hispanic white women (P < 0.05). Plasma concentrations of alpha-carotene and lycopene were higher in Hispanic than in non-Hispanic white men and women. For both ethnic groups, higher intakes of carotenoids were associated with higher plasma concentrations of the respective carotenoids, except for lycopene (Hispanics) and lutein + zeaxanthin (non-Hispanic whites). Food sources contributing most to total intakes differed among the groups. The major sources of alpha- and beta-carotene were carrots for non-Hispanic whites and winter squash for Hispanics. The major source of lycopene was cooked tomato products for Hispanics, and pasta dishes for non-Hispanic whites. Traditional foods such as beans and plantains were also important contributors of carotenoids for Hispanics. Because of the potential importance of carotenoids as protective factors against chronic diseases, more attention to food-related practices associated with carotenoid intake in differing population groups is warranted.     

Associations of whole-grain,refined-grain,and fruit and vegetable consumption with risks of all-cause mortality and incident coronary artery disease and ischemic stroke: the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND: Recent epidemiologic study results showed that subjects who had high intakes of whole-grain foods had lower risks of death and heart disease than did subjects who had low intakes. However, the findings were inconsistent for fruit and vegetable intake. OBJECTIVE: The relations of whole-grain, refined-grain, and fruit and vegetable intakes with the risk of total mortality and the incidence of coronary artery disease (CAD) and ischemic stroke were studied in the Atherosclerosis Risk in Communities (ARIC) cohort (baseline: age 45-64 y, n = 15,792). DESIGN: Proportional hazards regression analyses were used to assess the relations of whole-grain, refined-grain, and fruit and vegetable intakes with the risk of death and the incidence of CAD and ischemic stroke, with adjustment for age, sex, ethnicity, energy intake, and cardiovascular disease risk factors. Dietary intakes were assessed by using a food-frequency questionnaire. RESULTS: Over an 11-y follow-up period, whole-grain intake was inversely associated with total mortality and incident CAD. The relative hazards of death for quintiles 2-5 of fruit and vegetable intake were 1.08 (95% CI: 0.88, 1.33), 0.94 (0.75, 1.17), 0.87 (0.68, 1.10), and 0.78 (0.61, 1.01), respectively; P for trend = 0.02. An inverse association between fruit and vegetable intake and CAD was observed among African Americans but not among whites (P for interaction = 0.01). The risk of ischemic stroke was not significantly related to whole-grain, refined-grain, or fruit and vegetable consumption. CONCLUSION: These observational findings suggest a beneficial effect of whole-grain and fruit and vegetable consumption on the risks of total mortality and incident CAD but not on the risk of ischemic stroke.     

Dietary fat intake and insulin resistance in black and white children

OBJECTIVE: The purpose of this study was to determine whether dietary fat intake above current Acceptable Macronutrient Distribution Range (AMDR) guidelines was associated with greater insulin resistance in black and white children. RESEARCH METHODS AND PROCEDURES: We studied 142 healthy children (n = 81 whites, n = 61 blacks), 6.5 to 14 years old. Dietary composition was determined by repeated 24-hour dietary recall, body composition by DXA, visceral fat by computed tomography, and insulin sensitivity (SI) and acute insulin response to glucose (AIRg) by frequently sampled intravenous glucose tolerance test. Subjects were categorized by ethnicity (white/black) and dietary fat intake (above-AMDR/within-AMDR guidelines), and differences were analyzed by 2 x 2 analysis of covariance, adjusting for covariates. RESULTS: After adjusting for total body fat, gender, and Tanner stage, subjects consuming dietary fat above AMDR intake guidelines had lower SI and higher AIRg. This effect was specific to black children (32% lower SI and 62% higher AIRg in above-AMDR compared with within-AMDR blacks) and was not seen in whites. DISCUSSION: In black, but not white, children, those with dietary fat intake above current AMDR guidelines had lower SI and higher AIRg than those who met AMDR guidelines. These findings support current AMDR guidelines for dietary fat in black children and adolescents. The mechanism(s) underlying the ethnic differences in the relationship between dietary fat intake and SI in children require further investigation.     

Dietary magnesium intake in a national sample of US adults

Despite the role of magnesium in maintaining health, much of the U.S. population has historically not consumed adequate amounts of magnesium. Furthermore, significant racial or ethnic disparities in magnesium intake exist. Our objective was to provide more recent data about magnesium intake in the U.S. population. We analyzed the 24-h dietary recall data from 4257 participants aged >or=20 y from the National Health and Nutrition Examination Survey 1999-2000. The median intake of magnesium was 326 mg/d (mean 352 mg/d) among Caucasian men, 237 mg/d (mean 278 mg/d) among African American men, 297 mg/d (330 mg/d) among Mexican American men, 237 mg/d (mean 256 mg/d) among Caucasian women, 177 mg/d (mean 202 mg/d) among African American women, and 221 mg/d (mean 242 mg/d) among Mexican American women. Among men and women, Caucasians had significantly higher mean intakes of dietary magnesium than African Americans but not Mexican Americans. Magnesium intake decreased with increasing age (P for linear trend = 0.035 for Caucasians; P for linear trend <0.001 for African Americans and Mexican Americans). Men had higher intakes of magnesium than women for each of the three race or ethnic groups (P < 0.001 in each group). Caucasian men, African American men and Caucasian women who used vitamin, mineral or dietary supplements consumed significantly more magnesium in their diets than did those who did not. Substantial numbers of U.S. adults fail to consume adequate magnesium in their diets. Furthermore, racial or ethnic differences in magnesium persist and may contribute to some health disparities.     

Portion size effects on daily energy intake in low-income Hispanic and African American children and their mothers

BACKGROUND: Portion size influences children's energy intakes at meals, but effects on daily intake are unknown. OBJECTIVE: Effects of large portions on daily energy intake were tested in 5-y-old Hispanic and African American children from low-income families. Maternal food intake data were collected to evaluate familial susceptibility to portion size. DESIGN: A within-subjects experimental design with reference and large portion sizes was used in a study of 59 low-income Hispanic and African American preschool-aged children and their mothers. The portion size of 3 entrées (lunch, dinner, and breakfast) and an afternoon snack served during a 24-h period were of a reference size in one condition and doubled in the other condition. Portion sizes of other foods and beverages did not vary across conditions. Weighed food intake, anthropometric measures, and self-reported data were obtained. RESULTS: Doubling the portion size of several entrées and a snack served during a 24-h period increased energy intake from those foods by 23% (180 kcal) among children (P < 0.0001) and by 21% (270 kcal) among mothers (P < 0.0001). Child and maternal energy intakes from other foods for which portion size was not altered did not differ across conditions. Consequently, total energy intakes in the large-portion condition were 12% (P < 0.001) and 6% (P < 0.01) higher in children and mothers, respectively, than in the reference condition. Child and maternal intakes of the portion-manipulated foods were not correlated. CONCLUSIONS: Large portions may contribute to obesigenic dietary environments by promoting excess daily intakes among Hispanic and African American children.     

Age, sex, ethnicity, body composition, and resting energy expenditure of obese African American and white children and adolescents

BACKGROUND: African Americans may have a lower resting energy expenditure (REE) than do whites, although the data are limited for obese children and adolescents and for boys. Differences in bone density and trunk lean body mass may account for some of these measured differences in REE. OBJECTIVE: We assessed the REE and body composition of obese African American and white children and adolescents. DESIGN: Obese, 5-17-y-old children and adolescents were evaluated (n = 203). Body composition was assessed by dual-energy X-ray absorptiometry. REE was measured by open-circuit calorimetry. African American and white children were compared. The relation between REE and the independent variables (age, sex, ethnic group, fat mass, and fat-free mass or lean tissue mass) was assessed. RESULTS: Of those evaluated, 66% were girls and 34% were African American. Age, sex, pubertal status, and body composition did not differ significantly by ethnic group. All the independent variables were significantly associated with REE. Using lean tissue mass to account for differences in bone density did not significantly alter the results. REE decreased with age and was lower in the girls than in the boys and in the African Americans than in the whites. When trunk fat-free mass was included in the model in place of whole-body fat-free mass, the ethnic difference in REE decreased. CONCLUSIONS: Adjustment for trunk lean tissue mass partially explains the lower REE of obese African American children and adolescents. The lower relative REE of older obese children suggests the importance of early intervention in the prevention of childhood obesity. The lower REE of girls and of African Americans may contribute to the difficulty in weight management in these groups.     

Relation between mothers' child-feeding practices and children's adiposity

BACKGROUND: The prevalence of obesity in American children is currently estimated to be 25%. Poor nutritional habits during childhood have been directly related to pediatric obesity. OBJECTIVE: Our objective was to evaluate the relation between mothers' child-feeding practices and children's adiposity in a sample of boys and girls from 2 ethnic groups. DESIGN: A total of 74 white (25 boys and 49 girls) and 46 African American (22 boys and 24 girls) children ( plus minus SD age: 11 plus minus 1.7 y) and their mothers participated in this study. The children's body composition was assessed by dual-energy X-ray absorptiometry. The mothers' child-feeding practices were assessed with the Child Feeding Questionnaire. Dietary intake data were based on three 24-h dietary recalls conducted by use of the multiple-pass technique. RESULTS: Two subscales of the Child Feeding Questionnaire, pressure to eat and concern for child's weight, explained 15% of the variance in total fat mass in both African American and white boys and girls (P < 0.001) after correction for total lean mass and energy intake (which explained 5% of the variance in total fat mass). Ethnicity, sex, and socioeconomic status did not contribute significantly to variance in total fat mass. CONCLUSIONS: Child-feeding practices are key behavioral variables that explain more of the variance in total fat mass than does energy intake in a biethnic population of boys and girls. These findings have important implications for the prevention of obesity in children because they suggest that prevention programs need to focus on the feeding behaviors of parents in addition to the macronutrient and energy intakes of children.     

Dietary linolenic acid is inversely associated with plasma triacylglycerol: the National Heart, Lung, and Blood Institute Family Heart Study

BACKGROUND: Dietary intake of linolenic acid is associated with a decreased risk of cardiovascular disease mortality. However, the mechanisms by which dietary linolenic acid affects cardiovascular disease risk are not clearly understood. OBJECTIVE: We examined the association between dietary linolenic acid and plasma triacylglycerol concentrations. DESIGN: In a cross-sectional design, we studied 4440 white subjects (2036 men and 2404 women) aged 25-93 y who participated in the National Heart, Lung, and Blood Institute Family Heart Study. We used generalized linear models to estimate adjusted mean triacylglycerol concentrations according to categories of total dietary linolenic acid (alpha- and gamma-linolenic acid) intake. RESULTS: The mean dietary linolenic acid intakes were 0.81 and 0.69 g/d for the men and the women, respectively. High consumption of dietary linolenic acid was associated with young age; high intakes of energy, fat, carbohydrates, fruit, vegetables, and fish; low HDL cholesterol; current smoking; and frequent consumption of creamy salad dressing. High consumption of dietary linolenic acid was also associated with low plasma triacylglycerol concentrations. From the lowest to the highest quintile of linolenic acid intake, the multivariate-adjusted mean triacylglycerol concentrations were 1.75 (95% CI: 1.65, 1.85), 1.74 (1.66, 1.82), 1.69 (1.61, 1.77), 1.66 (1.58, 1.74), and 1.54 (1.44, 1.64) mmol/L, respectively (P for linear trend = 0.007). When linolenic acid was used as a continuous variable, the corresponding regression coefficient was -0.2811 (-0.4922, -0.07001). CONCLUSIONS: Consumption of total linolenic acid is inversely related to plasma triacylglycerol concentrations in both white men and white women. This suggests a pathway by which dietary linolenic acid might reduce cardiovascular disease risk.     

Circulating phylloquinone concentrations of adults in the United States differ according to race and ethnicity

Differences in micronutrient status are reported to contribute to racial and ethnic differences in chronic diseases. Diseases related to vitamin K are reported to differ by race and ethnicity, but it is unclear if circulating vitamin K concentrations similarly differ. We examined racial and ethnic differences in serum phylloquionone (K1) in the Multiethnic Study of Atherosclerosis (MESA) (mean ± SD age = 62 ± 10 y; 52% female; 262 white, 180 African American, 169 Hispanic, 93 Chinese American). Overall, 25% had serum K1 <0.1 nmol/L (the lower limit of detection). The prevalence of low serum K1 was 4% in Chinese Americans compared with 24% of whites, 29% of African Americans, and 33% of Hispanics. Compared with whites, Chinese Americans were significantly less likely to have serum K1 <0.1 nmol/L [OR (95% CI): 0.23 (0.09-0.23), adjusted for serum TG, K1 intake, age, sex, BMI, smoking, total cholesterol, site, season, and lipid-lowering medication use]. African Americans and Hispanics had similar odds to whites for having serum K1 <0.1 nmol/L [OR(95% CI): 1.30 (0.79-2.15) and 1.19 (0.66-2.15), respectively; fully adjusted]. In participants with detectable concentrations (n = 523), (natural log) serum K1 was higher in the Chinese Americans compared with whites, African Americans, and Hispanics (geometric mean ± SEM = 2.2 ± 0.1 nmol/L vs. 1.2 ± 0.1 nmol/L, 1.5 ± 0.1 nmol/L, and 1.1 ± 0.1 nmol/L, respectively, adjusted for serum TG, K1 intake, and additional covariates; all P < 0.001). These findings suggest circulating K1 differs by race and ethnicity in U.S. adults, especially among those of Chinese American descent, which merits consideration in the design and interpretation of future population-based and clinical studies of vitamin K and related diseases.     

Comparison of regional fat distribution and health risk factors in middle-aged white and African American women: The Healthy Transitions Study

OBJECTIVE: Both ethnicity and menopause appear to influence intra-abdominal fat distribution. This study evaluated intra-abdominal fat distribution and obesity-related health risks in perimenopausal white and African American women. RESEARCH METHODS AND PROCEDURES: Baseline data from a longitudinal study of changes in body composition and energy balance during menopause are reported. Healthy women (55 African Americans and 103 whites) who were on no medication and had at least five menstrual cycles in the previous 6 months were recruited. Body composition was assessed by DXA, and visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were assessed by computed tomography scan. SAT was divided into deep and superficial layers demarcated by the fascia superficialis. RESULTS: African American women were slightly younger (46.7 +/- 0.2 vs. 47.7 +/- 0.2 years, p = 0.002) and fatter (42.4% +/- 1.0% vs. 39.4% +/- 0.8% body fat, p = 0.02) than white women. In unadjusted data, African Americans had significantly more total abdominal fat and total, deep, and superficial SAT than whites. After adjustment for percent body fat and age, only total and superficial SAT remained significantly higher in African Americans. VAT, although slightly less in African American women, did not differ significantly by race. In multiple regression analysis, VAT was the strongest predictor of serum lipids, glucose, and insulin in women of both races, although superficial SAT was significantly associated with fasting glucose in whites. CONCLUSIONS: Middle-aged African American women have larger SAT depots, adjusted for total body fatness, but do not differ from white women with regard to VAT. The complexity of the relationship between abdominal fat and metabolic risk is increased by ethnic differences in such associations.     

Nutrient intake from multivitamin/mineral supplements is similar among users from five ethnic groups: the Multiethnic Cohort Study

A multivitamin/mineral supplement is the most widely used type of dietary supplement among American adults. Therefore, accurate assessment of intake from this supplement is crucial when studying diet and chronic diseases. From 1999 to 2001, the Multiethnic Cohort Study collected detailed information on multivitamin/mineral use among five ethnic groups: African Americans, Native Hawaiians, Japanese Americans, Latinos, and whites. Daily nutrient intakes from multivitamin/minerals were calculated using the nutrient composition specified on the product label. For reported supplements with insufficient detail to match to a specific product, default nutrient profiles were assigned. Multivitamin/mineral use was reported by 50% of the participants (38% for Native Hawaiians to 57% for whites). Default profiles were assigned for 38% of users. The median daily nutrient intakes from multivitamin/minerals among users (n=75,865) were well above the Recommended Daily Allowance or Adequate Intake for vitamins A, B-6, B-12, and E, thiamin, riboflavin, niacin, pantothenic acid, folate, and zinc. Although nutrient intakes from multivitamin/minerals varied widely among individuals, there was no substantial difference in the median intake across ethnic groups. To accurately estimate nutrient intakes from multivitamin/minerals, detailed information on the product consumed should be collected. When detailed information is not available, the same default nutrient profiles can be used when estimating intakes for these five ethnic groups.     

Diet and blood pressure in South Africa: Intake of foods containing sodium, potassium, calcium, and magnesium in three ethnic groups

OBJECTIVES: We investigated whether habitual intakes of sodium (Na), potassium, magnesium, and calcium differ across South African ethnic groups, assessed the proportion of Na intake, which is discretionary, and identified which food sources were the major contributors to Na intake. METHODS: This was a cross-sectional study of 325 black, white, and mixed ancestry hypertensive and normotensive subjects. Three repeated 24-h urine samples were collected for assessment of urinary Na, and three corresponding 24-h dietary recalls were administered by trained fieldworkers. Blood pressure and weight were measured at each visit. Secondary analyses were performed on existing dietary databases obtained from four regional surveys undertaken in South African adults. RESULTS: Mean urinary Na excretion values equated to daily salt (NaCl) intakes of 7.8, 8.5, and 9.5 g in black, mixed ancestry, and white subjects, respectively (P < 0.05). Between 33% and 46% of total Na intake was discretionary, and, of the non-discretionary sources, bread was the single greatest contributor to Na intake in all groups. Ethnic differences in calcium intake were evident, with black subjects having particularly low intakes. Urban versus rural differences existed with respect to sources of dietary Na, with greater than 70% of total non-discretionary Na being provided by bread and cereals in rural black South Africans compared with 49% to 54% in urban dwellers. CONCLUSION: White South Africans have higher habitual intakes of Na, but also higher calcium intakes, than their black and mixed ancestry counterparts. All ethnic groups had Na intakes in excess of 6 g/d of salt, whereas potassium intakes in all groups were below the recommended level of 90 mM/d. Dietary differences may contribute to ethnically related differences in blood pressure.