Association of healthy dietary patterns and cardiorespiratory fitness in the community

AIMS

To evaluate the associations of dietary indices and quantitative cardiorespiratory fitness (CRF) measures in a large, community-based sample harnessing metabolomic profiling to interrogate shared biology.

METHODS AND RESULTS

Framingham Heart Study (FHS) participants underwent maximum effort cardiopulmonary exercise tests for CRF quantification (via peak VO2) and completed semi-quantitative food frequency questionnaires. Dietary quality was assessed by the Alternative Healthy Eating Index (AHEI) and Mediterranean-style Diet Score (MDS), and fasting blood concentrations of 201 metabolites were quantified. In 2380 FHS participants (54 ± 9 years, 54% female, body mass index 28 ± 5 kg/m2), 1 SD higher AHEI and MDS were associated with 5.2% (1.2 mL/kg/min, 95% CI 4.3-6.0%, P < 0.0001) and 4.5% (1.0 mL/kg/min, 95% CI 3.6-5.3%, P < 0.0001) greater peak VO2 in linear models adjusted for age, sex, total daily energy intake, cardiovascular risk factors, and physical activity. In participants with metabolite profiling (N = 1154), 24 metabolites were concordantly associated with both dietary indices and peak VO2 in multivariable-adjusted linear models (FDR < 5%). Metabolites that were associated with lower CRF and poorer dietary quality included C6 and C7 carnitines, C16:0 ceramide, and dimethylguanidino valeric acid, and metabolites that were positively associated with higher CRF and favourable dietary quality included C38:7 phosphatidylcholine plasmalogen and C38:7 and C40:7 phosphatidylethanolamine plasmalogens.

CONCLUSION

Higher diet quality is associated with greater CRF cross-sectionally in a middle-aged community-dwelling sample, and metabolites highlight potential shared favourable effects on cardiometabolic health.

An Opportunity for Improvement: Evaluation of Diabetes Technology Education Among Adult Endocrinology Training Programs

BACKGROUND

Despite increases in continuous glucose monitor (CGM) and insulin pump use in adults with diabetes, there is room for expansion. Technology adoption may be influenced by the training environment and fellowship education. However, little is known about adult endocrinology trainee comfort with, understanding of, or methods by which trainees receive education about diabetes technology.

METHODS

Mixed methods, sequential explanatory evaluation using survey and semi-structured interviews of endocrinology trainees and fellowship leadership in Accreditation Council for Graduate Medical Education (ACGME)-accredited adult endocrinology fellowship programs to assess trainee and leadership comfort with, perceived knowledge of, and current methods for diabetes technology education.

RESULTS

Seventy-seven respondents completed the survey. The majority of training programs have curricula for training on insulin pumps (74%) and CGM (75.3%); 52% of fellows felt curricula are adequate. First- and second-year fellows were more comfortable with CGM than insulin pump use. Only half of third-year fellows felt comfortable with starting insulin pump therapy or recommending insulin dose adjustments based on CGM rate of change arrows. Qualitative interviews identified the importance of both direct instruction and experiential learning in diabetes technology education.

CONCLUSIONS

Almost half of trainees feel that curricula for learning to use and manage insulin pumps and CGM are inadequate and feel uncomfortable with critical aspects of technology use, demonstrating the need for increased attention to trainee education in the use of diabetes technology. Based on a better understanding of current and preferred methods for instruction, this study provides direction for future development of initiatives to improve fellow education in this field.

Lung function impairment and risk of incident heart failure: the NHLBI Pooled Cohorts Study

AIMS

The aim is to evaluate associations of lung function impairment with risk of incident heart failure (HF).

METHODS AND RESULTS

Data were pooled across eight US population-based cohorts that enrolled participants from 1987 to 2004. Participants with self-reported baseline cardiovascular disease were excluded. Spirometry was used to define obstructive [forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC) <0.70] or restrictive (FEV1/FVC ≥0.70, FVC <80%) lung physiology. The incident HF was defined as hospitalization or death caused by HF. In a sub-set, HF events were sub-classified as HF with reduced ejection fraction (HFrEF; EF <50%) or preserved EF (HFpEF; EF ≥50%). The Fine-Gray proportional sub-distribution hazards models were adjusted for sociodemographic factors, smoking, and cardiovascular risk factors. In models of incident HF sub-types, HFrEF, HFpEF, and non-HF mortality were treated as competing risks. Among 31 677 adults, there were 3344 incident HF events over a median follow-up of 21.0 years. Of 2066 classifiable HF events, 1030 were classified as HFrEF and 1036 as HFpEF. Obstructive [adjusted hazard ratio (HR) 1.17, 95% confidence interval (CI) 1.07-1.27] and restrictive physiology (adjusted HR 1.43, 95% CI 1.27-1.62) were associated with incident HF. Obstructive and restrictive ventilatory defects were associated with HFpEF but not HFrEF. The magnitude of the association between restrictive physiology and HFpEF was similar to associations with hypertension, diabetes, and smoking.

CONCLUSION

Lung function impairment was associated with increased risk of incident HF, and particularly incident HFpEF, independent of and to a similar extent as major known cardiovascular risk factors.

Acute carbohydrate overfeeding: a redox model of insulin action and its impact on metabolic dysfunction in humans

A role for fat overfeeding in metabolic dysfunction in humans is commonly implied in the literature. Comparatively less is known about acute carbohydrate overfeeding (COF). We tested the hypothesis that COF predisposes to oxidative stress by channeling electrons away from antioxidants to support energy storage. In a study of 24 healthy human subjects with and without obesity, COF was simulated by oral administration of excess carbohydrates; a two-step hyperinsulinemic clamp was used to evaluate insulin action. The distribution of electrons between oxidative and reductive pathways was evaluated by the changes in the reduction potentials (Eh) of cytoplasmic (lactate, pyruvate) and mitochondrial (β-hydroxybutyrate, acetoacetate) redox couples. Antioxidant redox was measured by the ratio of reduced to oxidized glutathione. We used cross-correlation analysis to evaluate the relationships between the trajectories of Eh, insulin, glucose, and respiratory exchange during COF. DDIT3 and XBP1s/u mRNA were measured as markers of endoplasmic reticulum stress (ER stress) in adipose tissue before and after COF. Here, we show that acute COF is characterized by net transfer of electrons from mitochondria to cytoplasm. Circulating glutathione is oxidized in a manner that significantly cross-correlates with increasing insulin levels and precedes the decrease in cytoplasmic Eh. This effect is more pronounced in overweight individuals (OW). Markers of ER stress in subcutaneous fat are detectable in OW within 4 h. We conclude that acute COF contributes to metabolic dysfunction through insulin-dependent pathways that promote electron transfer to the cytoplasm and decrease antioxidant capacity. Characterization of redox during overfeeding is important for understanding the pathophysiology of obesity and type 2 diabetes.NEW & NOTEWORTHY Current principles assume that conversion of thermic energy to metabolically useful energy follows fixed rules. These principles ignore the possibility of variable proton uncoupling in mitochondria. Our study shows that the net balance of electron distribution between mitochondria and cytoplasm is influenced by insulin in a manner that reduces proton leakage during overfeeding. Characterization of the effects of insulin on redox balance is important for understanding obesity and insulin resistance.

Biomarkers representing key aging-related biological pathways are associated with subclinical atherosclerosis and all-cause mortality: The Framingham Study

BACKGROUND

Increased oxidative stress, leukocyte telomere length (LTL) shortening, endothelial dysfunction, and lower insulin-like growth factor (IGF)-1 concentrations reflect key molecular mechanisms of aging. We hypothesized that biomarkers representing these pathways are associated with measures of subclinical atherosclerosis and all-cause mortality.

METHODS AND RESULTS

We evaluated up to 2,314 Framingham Offspring Study participants (mean age 61 years, 55% women) with available biomarkers of aging: LTL, circulating concentrations of IGF-1, asymmetrical dimethylarginine (ADMA), and urinary F2-Isoprostanes indexed to urinary creatinine. We evaluated the association of each biomarker with coronary artery calcium [ln (CAC+1)] and carotid intima-media thickness (IMT). In multivariable-adjusted linear regression models, higher ADMA levels were associated with higher CAC values (βADMA per 1-SD increase 0.25; 95% confidence interval [CI] [0.11, 0.39]). Additionally, shorter LTL and lower IGF-1 values were associated with higher IMT values (βLTL -0.08, 95%CI -0.14, -0.02, and βIGF-1 -0.04, 95%CI -0.08, -0.01, respectively). During a median follow-up of 15.5 years, 593 subjects died. In multivariable-adjusted Cox regression models, LTL and IGF-1 values were inversely associated with all-cause mortality (hazard ratios [HR] per SD increase in biomarker, 0.85, 95% CI 0.74-0.99, and 0.90, 95% CI 0.82-0.98 for LTL and IGF-1, respectively). F2-Isoprostanes and ADMA values were positively associated with all-cause mortality (HR per SD increase in biomarker, 1.15, 95% CI, 1.10-1.22, and 1.10, 95% CI, 1.02-1.20, respectively).

CONCLUSION

In our prospective community-based study, aging-related biomarkers were associated with measures of subclinical atherosclerosis cross-sectionally and with all-cause mortality prospectively, supporting the concept that these biomarkers may reflect the aging process in community-dwelling adults.

Protein Intake and Human Health: Implications of Units of Protein Intake

Understanding the health effects of protein intake is bedeviled by a number of factors, including protein quality and source. In addition, different units, including grams, grams per kilogram body weight (g/kg BW), and percent energy, may contribute to confusion about protein's effects on health, especially BW-based units in increasingly obese populations. We aimed to review the literature and to conduct a modeling demonstration of various units of protein intake in relation to markers of cardiometabolic health. Data from the Framingham Heart Study Offspring (n = 1847; 60.3 y; 62.5% women) and Third Generation (n = 2548; 46.2 y; 55.3% women) cohorts and the NHANES 2003-04 (n = 1625; 46.2 y; 49.7% women) and 2005-06 (n = 1347; 43.7 y; 49.5% women) cycles were used to model cross-sectional associations between 7 protein units (grams, percent energy, g/kg ideal BW, g/kg actual BW, BW-adjusted g/kg actual BW, g/kg lean BW, and g/kg fat-free BW) and 9 cardiometabolic outcomes (fasting glucose, systolic and diastolic blood pressure, total and HDL cholesterol, triglycerides, BMI, waist circumference, and estimated glomerular filtration rate). The literature review indicated the use of myriad units of protein intake, with differential results on cardiometabolic outcomes. The modeling demonstration showed units expressed in BW were confounded by BW, irrespective of outcome. Units expressed in grams, percent energy, and ideal BW showed similar results, with or without adjustment for body size. After adjusting for BW, results of units expressed in BW aligned with results of grams, percent energy, and ideal BW. In conclusion, protein intake in cardiometabolic health appears to depend on protein's unit of expression. Authors should be specific about the use of WHO (g/kg ideal BW) compared with US (g/kg actual BW) units, and ideally use gram or percent energy in observational studies. In populations where overweight/obesity are prevalent, intake based on actual BW should be reevaluated.

Dietary Patterns, Ceramide Ratios, and Risk of All-Cause and Cause-Specific Mortality: The Framingham Offspring Study

BACKGROUND

Prior evidence suggests that diet modifies the association of blood ceramides with the risk of incident cardiovascular disease (CVD). It remains unknown if diet quality modifies the association of very long-chain-to-long-chain ceramide ratios with mortality in the community.

OBJECTIVES

Our objectives were to determine how healthy dietary patterns associate with blood ceramide concentrations and to examine if healthy dietary patterns modify associations of ceramide ratios (C22:0/C16:0 and C24:0/C16:0) with all-cause and cause-specific mortality.

METHODS

We examined 2157 participants of the Framingham Offspring Study (mean age = 66 y, 55% women). Blood ceramides were quantified using a validated assay. We evaluated prospective associations of the Dietary Guidelines Adherence Index (DGAI) and Mediterranean-style Diet Score (MDS) with incidence of all-cause and cause-specific mortality using Cox proportional hazards models. Cross-sectional associations of the DGAI and MDS with ceramides were evaluated using multivariable linear regression models.

RESULTS

The C22:0/C16:0 and C24:0/C16:0 ceramide ratios were inversely associated with all-cause, CVD, and cancer mortality; multivariable-adjusted HRs (95% CIs) were 0.73 (0.67, 0.80) and 0.70 (0.63, 0.77) for all-cause mortality, 0.74 (0.60, 0.90) and 0.69 (0.55, 0.86) for CVD mortality, and 0.75 (0.65, 0.87) and 0.75 (0.64, 0.88) for cancer mortality, respectively. Inverse associations of the C22:0/C16:0 and C24:0/C16:0 ceramide ratios with cancer mortality were attenuated among individuals with a higher diet quality (DGAI or MDS above the median, all P-interaction ≤0.1). The DGAI and MDS had distinct associations with ceramide ratios (DGAI: lower C22:0/C16:0 across quartiles; MDS: higher C24:0/C16:0 across quartiles; all P-trend ≤0.01).

CONCLUSION

In our community-based sample, ceramide ratios (C22:0/C16:0 and C24:0/C16:0) were associated with a lower risk of all-cause and cause-specific mortality. Further, we observed that a higher overall diet quality attenuates the association between blood ceramide ratios and cancer mortality and that dietary patterns have distinct relations with ceramide ratios.

Tau accumulations in the brains of woodpeckers

Woodpeckers experience forces up to 1200-1400 g while pecking. It is assumed due to evolutionary adaptations, the woodpecker is immune to brain injury. This assumption has led to the use of the woodpecker as a model in the development of sports safety equipment such as football helmets. However, it is unknown at this time if the woodpecker brain develops neuro-trauma in relation to the high g-forces experienced during pecking. The brains of 10 ethanol preserved woodpeckers and 5 ethanol preserved red-winged black bird experimental controls were examined using Gallyas silver stain and anti-phospho-tau. The results demonstrated perivascular and white matter tract silver-positive deposits in eight out of the 10 woodpecker brains. The tau positive accumulations were seen in white matter tracts in 2 of the 3 woodpeckers examined. No staining was identified in control birds. The negative staining of controls birds contrasted with the diffuse positive staining woodpecker sections suggest the possibility that pecking may induce the accumulation of tau in the woodpecker brain. Further research is needed to better understand the relationship.