Suzanne Summer

One-year comparison of a high-monounsaturated fat diet with a high-carbohydrate diet in type 2 diabetes

OBJECTIVE—The purpose of this study was to compare the effects of high–monounsaturated fatty acid (MUFA) and high-carbohydrate (CHO) diets on body weight and glycemic control in men and women with type 2 diabetes. RESEARCH DESIGN AND METHODS—Overweight/obese participants with type 2 diabetes (n = 124, age = 56.5 ± 0.8 years, BMI = 35.9 ± 0.3 kg/m2, and A1C = 7.3 ± 0.1%) were randomly assigned to 1 year of a high-MUFA or high-CHO diet. Anthropometric and metabolic parameters were assessed at baseline and after 4, 8, and 12 months of dieting. RESULTS—Baseline characteristics were similar between the treatment groups. The overall retention rate for 1 year was 77% (69% for the high-MUFA group and 84% for the high-CHO group; P = 0.06). Based on food records, both groups had similar energy intake but a significant difference in MUFA intake. Both groups had similar weight loss over 1 year (−4.0 ± 0.8 vs. −3.8 ± 0.6 kg) and comparable improvement in body fat, waist circumference, diastolic blood pressure, HDL cholesterol, A1C, and fasting glucose and insulin. There were no differences in these parameters between the groups. A follow-up assessment of a subset of participants (n = 36) was conducted 18 months after completion of the 52-week diet. These participants maintained their weight loss and A1C during the follow-up period. CONCLUSIONS—In individuals with type 2 diabetes, high-MUFA diets are an alternative to conventional lower-fat, high-CHO diets with comparable beneficial effects on body weight, body composition, cardiovascular risk factors, and glycemic control.

Dietary Factors Influence Production of the Soy Isoflavone Metabolite S-(-)Equol in Healthy Adults

S-(-)equol, an intestinally derived metabolite of the soy isoflavone daidzein, is proposed to enhance the efficacy of soy diets. Adults differ in their ability to produce equol when consuming soy foods for reasons that remain unclear. Therefore, we performed a comprehensive dietary analysis of 143 macro- and micronutrients in 159 healthy adults in the United States (n = 89) and Australia (n = 70) to determine whether the intake of specific nutrients favors equol production. Three-d diet records were collected and analyzed using Nutrition Data System for Research software and S-(-)equol was measured in urine by mass spectrometry. Additionally, in a subset of equol producers and nonproducers (n = 10/group), we examined the long-term stability of equol producer status by retesting 12, 18, and 24 mo later. Finally, the effect of oral administration of the antibiotic metronidazole (500 mg/d for 7 d) on equol production was examined in 5 adults monitored during a 4-mo follow-up period. Equol producers accounted for 30.3% and 28.6% of the United States and Australian participants, respectively (overall frequency, 29.6%). No significant differences were observed for total protein, carbohydrate, fat, saturated fat, or fiber intakes between equol producers and nonproducers. However, principal component analysis revealed differences in several nutrients, including higher intakes of polyunsaturated fatty acids (P = 0.039), maltose (P = 0.02), and vitamins A (P = 0.01) and E (P = 0.035) and a lower intake of total cholesterol (P = 0.010) in equol producers. During a 2-y period, equol producer status remained unchanged in all nonproducers and in 80% of equol producers, whereas metronidazole abolished equol production in only 20% of participants. In conclusion, these findings suggest that major differences in the macronutrient content of the diet appear not to influence equol production, but subtle differences in some nutrients may influence the ability to produce equol, which was a relatively stable phenomenon.

Adiponectin changes in relation to the macronutrient composition of a weight-loss diet.

Adiponectin is an adipose‐derived protein with beneficial metabolic effects. Low adiponectin is associated with obesity and related diseases. Significant weight loss increases adiponectin, reducing disease risk. This study compared the effects of two weight‐loss diets with different macronutrient compositions on adiponectin. Eighty‐one obese women in two cohorts were randomized to a low‐fat (LF) or a low‐carbohydrate (LC) diet. All subjects underwent equivalent weight‐loss intervention, with weight and other measures assessed at baseline and after 6 (cohort I) or 4 (cohort II) months. Body fat was measured by dual energy X‐ray absorptiometry. Adiponectin was measured by radioimmunoassay. Diet intake was assessed using 24‐h recalls and 3‐day diet records. Data were analyzed via t‐tests and repeated‐measures factorial ANOVA using time, diet, and replicate (cohort I vs. cohort II) as factors. Age, weight, body fat, BMI, adiponectin, and diet were similar at baseline. Following intervention, macronutrient composition of the diet was vastly different between the groups, reflecting the assigned diet. Both groups lost weight and body fat (P < 0.001), with effect in LC dieters greater than LF dieters (−9.1 kg vs. −4.97 kg weight, P < 0.05 and −5.45 kg vs. −2.62 kg fat, P < 0.001). Adiponectin increased in the LC (+1.92 mcg/ml, P < 0.01), but not the LF (+0.86 mcg/ml, P = 0.81), group. There was no correlation between weight loss and increase in adiponectin. These results confirm that diet‐induced loss of weight and body fat is associated with increased adiponectin concentrations. This effect is evident with weight loss of 10% or more, and may be greater with LC diets.

Acute Administration of Unacylated Ghrelin Has No Effect on Basal or Stimulated Insulin Secretion in Healthy Humans

Unacylated ghrelin (UAG) is the predominant ghrelin isoform in the circulation. Despite its inability to activate the classical ghrelin receptor, preclinical studies suggest that UAG may promote β-cell function. We hypothesized that UAG would oppose the effects of acylated ghrelin (AG) on insulin secretion and glucose tolerance. AG (1 µg/kg/h), UAG (4 µg/kg/h), combined AG+UAG, or saline were infused to 17 healthy subjects (9 men and 8 women) on four occasions in randomized order. Ghrelin was infused for 30 min to achieve steady-state levels and continued through a 3-h intravenous glucose tolerance test. The acute insulin response to glucose (AIRg), insulin sensitivity index (SI), disposition index (DI), and intravenous glucose tolerance (kg) were compared for each subject during the four infusions. AG infusion raised fasting glucose levels but had no effect on fasting plasma insulin. Compared with the saline control, AG and AG+UAG both decreased AIRg, but UAG alone had no effect. SI did not differ among the treatments. AG, but not UAG, reduced DI and kg and increased plasma growth hormone. UAG did not alter growth hormone, cortisol, glucagon, or free fatty acid levels. UAG selectively decreased glucose and fructose consumption compared with the other treatments. In contrast to previous reports, acute administration of UAG does not have independent effects on glucose tolerance or β-cell function and neither augments nor antagonizes the effects of AG.

Fat malabsorption in cystic fibrosis: comparison of quantitative fat assay and a novel assay using fecal lauric/behenic acid.

Objectives: The gold standard for the diagnosis of fat malabsorption, the 72-hour fat balance study, requires a 3-day collection to generate a coefficient of fat absorption (CFA). We hypothesized that a new test using behenic acid (behenate test) as a nonabsorbable lipid marker may provide a facile means to assess fat absorption. The study proposed to answer 2 questions: first, whether the behenate test correlated with the gold standard and, second, whether the CFA improved when taking pancreatic enzymes during meals instead of taking them before meals. Patients and Methods: The study compared the behenate test with the gold standard in 15 patients with cystic fibrosis during 3 arms that require 3- to 4-day hospitalization: first, taking pancreatic enzymes before meals; second, taking it during meals; and third, without taking it. Results: The mean CFA was 78.3% when pancreatic enzymes were taken during meals and 80.4% when these enzymes were taken before meals. Correlation between the CFA and the behenate test for collections during all 3 arms was r2 = 0.219 (P = 0.001). Conclusions: Timing of ingestion of pancreatic enzymes does not significantly alter the CFA. Although the CFA correlates with the behenate test, the correlation is not robust enough to justify replacement of the gold standard by this test. It is unclear whether the poor correlation between tests relates to intermeal variability in fat excretion or other factors; however, the behenate test may be suitable as a screening test for the detection of fat malabsorption.

Branched-chain fatty acid composition of human milk and the impact of maternal diet: the Global Exploration of Human Milk (GEHM) Study

BACKGROUND An understudied component of the diet, branched-chain fatty acids (BCFAs) are distinctive saturated fatty acids that may have an important influence on health. Human-milk fatty acid composition is known to differ worldwide, but comparative data are lacking on BCFAs. OBJECTIVE We tested the hypotheses that concentrations of BCFAs in human milk differ between populations and are associated with maternal diet. DESIGN We surveyed the BCFA composition of samples collected as part of a standardized, prospective study of human-milk composition. Mothers were enrolled from 3 urban populations with differing diets: Cincinnati, Ohio; Shanghai, China; and Mexico City, Mexico. Enrollment was limited to healthy mothers of term singleton infants. We undertook a cross-sectional analysis of milk from all women with samples at postpartum week 4 (n = 359; ∼120 women/site). Fatty acids were extracted from milk by using a modified Bligh-Dyer technique and analyzed by gas chromatography. Statistical analysis was performed by ANOVA and Tobit regression. For Cincinnati mothers, 24-h diet recalls were analyzed in relation to the individual BCFA concentrations measured in milk samples. RESULTS Total BCFAs in milk differed by site, with the highest concentration in Cincinnati followed by Mexico City and Shanghai (mean ± SE: 7.90 ± 0.41, 6.10 ± 0.36, and 4.27 ± 0.25 mg/100 mL, respectively; P < 0.001). Site differences persisted after delivery mode, maternal age, and body mass index were controlled for. The individual concentrations of iso-14:0, iso-16:0, iso-18:0, anteiso-15:0, and anteiso-17:0 also differed between sites. Milk concentrations of iso-14:0 and anteiso-15:0 were associated with maternal intake of dairy; iso-16:0 was associated with maternal intakes of dairy and beef. CONCLUSIONS BCFA concentrations in milk at 4 wk postpartum differed between mothers from Cincinnati, Shanghai, and Mexico City. Variations in human-milk BCFAs are influenced by diet. The impact of BCFAs on infant health warrants investigation.

Cross-Border Use of Food Databases: Equivalence of US and Australian Databases for Macronutrients

When estimating dietary intake across multiple countries, the lack of a single comprehensive dietary database may lead researchers to modify one database to analyze intakes for all participants. This approach may yield results different from those using the country-specific database and introduce measurement error. We examined whether nutrient intakes of Australians calculated with a modified US database would be similar to those calculated with an Australian database. We analyzed 3-day food records of 68 Australian adults using the US-based Nutrition Data System for Research, modified to reflect food items consumed in Australia. Modification entailed identifying a substitute food whose energy and macronutrient content were within 10% of the Australian food or by adding a new food to the database. Paired Wilcoxon signed rank tests were used to compare differences in nutrient intakes estimated by both databases, and Pearson and intraclass correlation coefficients measured degree of association and agreement between intake estimates for individuals. Median intakes of energy, carbohydrate, protein, and fiber differed by <5% at the group level. Larger discrepancies were seen for fat (11%; P<0.0001) and most micronutrients. Despite strong correlations, nutrient intakes differed by >10% for an appreciable percentage of participants (35% for energy to 69% for total fat). Adding country-specific food items to an existing database resulted in similar overall macronutrient intake estimates but was insufficient for estimating individual intakes. When analyzing nutrient intakes in multinational studies, greater standardization and modification of databases may be required to more accurately estimate intake of individuals.

Comparison of an interviewer-administered with an automated self-administered 24 h (ASA24) dietary recall in adolescents

OBJECTIVE The current pilot study aimed to assess whether reporting quality would decline materially in adolescents completing weekly web-based Automated Self-Administered 24-Hour dietary recalls (ASA24-Kids-2014) and interviewer-administered 24 h dietary recalls for six weeks. We also aimed to assess method preference. DESIGN We conducted two studies. Study 1 (n 20) randomized participants to complete either one ASA24-Kids-2014 or one interviewer-administered recall weekly, for six weeks. Energy intake and number of foods reported were described for each method over time. Differences between recall methods for each measure were tested using mixed-effects regression. Study 2 (n 10) employed a randomized crossover design to describe method preference. SETTING Dietary intake was collected either by telephone (interviewer-administered dietary recalls) or via the Internet (ASA24-Kids-2014 dietary recalls). SUBJECTS Adolescents aged 12-17 years with no prior diet recording experience were enrolled. RESULTS In Study 1, mean (sd) total energy and number of foods reported decreased by 50 (222) kJ (12 (53) kcal) and 0·05 (0·31) items v. 38 (138) kJ (9 (33) kcal) and 0·17 (0·14) items per recall for participants randomized to the ASA24-Kids-2014 v. interviewer-administered recalls, respectively. There was no difference between groups for either measure (P > 0·57). In Study 2, eight of ten participants preferred the interviewer-administered recall over the ASA24-Kids-2014. Overall, seven of twenty participants experienced technical difficulties with the ASA24-Kids-2014. CONCLUSIONS No appreciable decay in reporting quality was seen for either method. However, participants reported a preference for the interviewer-administered recall. Our findings can help inform and support larger studies to further characterize the performance of the ASA24 in adolescents.

RESTING ENERGY EXPENDITURE IN INFANTS WITH SINGLE VENTRICLE CONGENITAL HEART DISEASE

Infants with single ventricle congenital heart disease (SV) are at risk for early failure to thrive. The etiology of this failure is poorly understood and higher than normal energy expenditure has been theorized as a predictor of growth failure. We sought to measure resting energy expenditure (REE)

Enhanced cerebral bioenergetics with dietary ketosis in Mild Cognitive Impairment

BACKGROUND: Metabolic disturbance is associated with risk for neurodegeneration, and cerebral glucose hypometabolism is prominent in Alzheimer’s disease (AD). Ketone metabolism can compensate for glucose hypometabolism and confers other benefits pertinent to neurodegeneration, among them reduction of oxidative stress and AD pathological factors, suggesting its potential as a therapeutic intervention. In a prior controlled trial, we showed that six weeks’ carbohydrate restriction induced ketogenesis and produced improvements in metabolic parameters and memory performance in older adults with Mild Cognitive Impairment (MCI). Those benefits were attributed to the correction of hyperinsulinemia and to the presumed enhancement of cerebral bioenergetic function associated with ketone metabolism. OBJECTIVE: To assess the effect of dietary ketosis on cerebral metabolites in older adults with MCI. METHODS: We enrolled a sample of five MCI participants in a ketogenic dietary regimen and performed pre- and postintervention proton magnetic resonance spectroscopy to investigate changes in neurochemical metabolites. We also assessed cognitive function and metabolic and anthropometric factors. RESULTS: We observed a significant increase in myo-inositol (p = 0.02) and trends for increases in N-acetyl-aspartate (p = 0.09) and creatine + phosphocreatine (p = 0.11) after six weeks on the ketogenic regimen. Working memory (p = 0.01) and long-term memory (p = 0.07) performances also improved. CONCLUSIONS: This study offers novel, preliminary evidence of cerebral bioenergetic enhancement with mild dietary ketosis in aging humans. Further investigation in controlled trials is warranted to assess the preventive and treatment implications of this intervention for age-related memory decline and dementia.