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.

Short-Term Tea Consumption Is Not Associated with a Reduction in Blood Lipids or Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

A recent systematic review of epidemiological evidence suggests that higher amounts of tea intake are associated with lower risks of cardiovascular disease (CVD) incidence and mortality.

OBJECTIVES

Our study objective was to assess mechanisms by which tea consumption may influence CVD risks.

METHODS

A systematic review and meta-analysis was conducted to investigate the effects of green and/or black tea consumption (≥4 wk) on systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol, LDL cholesterol, HDL cholesterol, and triglyceride (TG) in healthy populations and among at-risk adults (analyzed separately) with metabolic syndrome, prediabetes, and hypercholesterolemia. The Grading of Recommendations Assessment, Development and Evaluation approach was used to rate the strength of evidence (SoE).

RESULTS

A total of 14 unique RCTs which randomly assigned 798 participants to either green tea, black tea, or placebo controls were included in our analyses. Intervention durations ranged from 4 to 24 wk (mean: 7.4 wk). Individual studies were judged as moderate to high quality based on risk of bias assessments. SoE was low to moderate owing to low sample sizes and insufficient power for most included studies to observe changes in the measured CVD biomarkers. Meta-analyses showed no significant effects of tea consumption on SBP, DBP, total cholesterol, LDL cholesterol, HDL cholesterol, and TG in healthy and at-risk adults (i.e., adults with obesity, prediabetes, borderline hypercholesterolemia, and metabolic syndrome).

CONCLUSIONS

Short-term (4-24 wk) tea consumption does not appear to significantly affect blood pressure or lipids in healthy or at-risk adults, although the evidence is limited by insufficient power to detect changes in these CVD biomarkers. High-quality RCTs with longer durations and sufficient sample sizes are needed to fully elucidate the effects of tea. This systematic review was registered at www.crd.york.ac.uk/prospero/ as CRD42020134513.

Total carotenoid intake is associated with reduced loss of grip strength and gait speed over time in adults: The Framingham Offspring Study

BACKGROUND

Lower antioxidant serum concentrations have been linked to declines in lean mass and physical function in older adults. Yet population data on the effect of dietary antioxidants on loss of muscle strength and physical function are lacking.

OBJECTIVE

We sought to determine the association of antioxidant intake [vitamin C, vitamin E, and total and individual carotenoids (α-carotene, β-carotene, β-cryptoxanthin, lycopene, and lutein + zeaxanthin)] with annualized change in grip strength and gait speed in adults from the Framingham Offspring study.

METHODS

This prospective cohort study included participants with a valid FFQ at the index examination and up to 2 prior examinations and at ≥2 measures of primary outcomes: grip strength (n = 2452) and/or gait speed (n = 2422) measured over 3 subsequent examinations. Annualized change in grip strength (kg/y) and change in gait speed (m/s/y) over the follow-up period were used. Linear regression was used to calculate β coefficients and P values, adjusting for covariates.

RESULTS

Mean ± SD age of participants was 61 ± 9 y (range: 33-88 y). Median intakes (IQR, mg/d) of vitamin C, vitamin E, and total carotenoid across available examinations were 209.2 (133.1-394.2), 27.1 (7.4-199.0), and 15.3 (10.4-21.3), respectively. The mean follow-up time was ∼12 ± 2 y (range: 4.5-15.4 y). In the sex-combined sample, higher intakes of total carotenoids, lycopene, and lutein + zeaxanthin were associated with increased annualized change in grip strength [β (SE) per 10-mg higher intake/d, range: 0.0316 (0.0146) to 0.1223 (0.0603) kg/y)]. All antioxidants except for vitamin C were associated with faster gait speed [β (SE) per 10-mg higher intake/d, range: 0.00008 (0.00004) to 0.0187 (0.0081) m/s/y].

CONCLUSIONS

Higher antioxidant intake was associated with increase in grip strength and faster gait speed in this cohort of adults. This finding highlights the need for a randomized controlled trial of dietary antioxidants and their effect on muscle strength and physical function.

Knowledge gaps in understanding the metabolic and clinical effects of excess folates/folic acid: a summary, and perspectives, from an NIH workshop

Folate, an essential nutrient found naturally in foods in a reduced form, is present in dietary supplements and fortified foods in an oxidized synthetic form (folic acid). There is widespread agreement that maintaining adequate folate status is critical to prevent diseases due to folate inadequacy (e.g., anemia, birth defects, and cancer). However, there are concerns of potential adverse effects of excess folic acid intake and/or elevated folate status, with the original concern focused on exacerbation of clinical effects of vitamin B-12 deficiency and its role in neurocognitive health. More recently, animal and observational studies have suggested potential adverse effects on cancer risk, birth outcomes, and other diseases. Observations indicating adverse effects from excess folic acid intake, elevated folate status, and unmetabolized folic acid (UMFA) remain inconclusive; the data do not provide the evidence needed to affect public health recommendations. Moreover, strong biological and mechanistic premises connecting elevated folic acid intake, UMFA, and/or high folate status to adverse health outcomes are lacking. However, the body of evidence on potential adverse health outcomes indicates the need for comprehensive research to clarify these issues and bridge knowledge gaps. Three key research questions encompass the additional research needed to establish whether high folic acid or total folate intake contributes to disease risk. 1) Does UMFA affect biological pathways leading to adverse health effects? 2) Does elevated folate status resulting from any form of folate intake affect vitamin B-12 function and its roles in sustaining health? 3) Does elevated folate intake, regardless of form, affect biological pathways leading to adverse health effects other than those linked to vitamin B-12 function? This article summarizes the proceedings of an August 2019 NIH expert workshop focused on addressing these research areas.

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.

Protein Intake and Functional Integrity in Aging: The Framingham Heart Study Offspring

BACKGROUND

Higher protein intake is linked to maintenance of muscle mass and strength, but few studies have related protein to physical function and disability in aging.

METHODS

In participants of the Framingham Heart Study Offspring, we examined associations between protein intake (g/d), estimated from food frequency questionnaires, and maintenance of functional integrity, as a functional integrity score based on responses to 17 questions from Katz Activities of Daily Living, Nagi, and Rosow-Breslau questionnaires, repeated up to five times (1991/1995-2011/2014) over 23 years of follow-up. Cox proportional hazard models were used to estimate risk of incident loss of functional integrity (functional integrity score ≤ 15th percentile).

RESULTS

In 2,917 participants (age 54.5 [9.8] years), baseline protein intake was 77.2 (15.6) g/d. The functional integrity score (baseline, mean 98.9, range 82.4-100.0) was associated with objective performance (gait speed, grip strength) and lower odds of falls, fractures, and frailty. Across follow-up, there were 731 incident cases of loss of functional integrity. In fully adjusted models, participants in the highest category of protein intake (median 92.2 g/d) had 30% lower risk of loss of functional integrity (hazard ratio [95% confidence interval] 0.70 [0.52, 0.95], p trend = .03), versus those with the lowest intake (median 64.4 g/d). However, sex-stratified analyses indicated the association was driven by the association in women alone (hazard ratio [95% confidence interval] 0.49 [0.32, 0.74], p trend = .002) and was nonsignificant in men (hazard ratio [95% confidence interval] 1.14 [0.70, 1.86], p trend = .59).

CONCLUSIONS

Higher protein intake was beneficially associated with maintenance of physical function in middle-aged, high-functioning U.S. adults over the span of two decades. This association was particularly evident in women.

Long-term dietary flavonoid intake and risk of Alzheimer disease and related dementias in the Framingham Offspring Cohort

BACKGROUND

Findings from existing prospective observational studies on the protective associations of flavonoid intake and the risk of Alzheimer disease and related dementias (ADRD) are inconsistent largely due to limitations of these studies.

OBJECTIVES

To examine the prospective relation between total and 6 classes of dietary flavonoid intake and risk of ADRD and Alzheimer disease (AD) while addressing limitations of earlier observational studies.

METHODS

We used data from the Framingham Heart Study Offspring Cohort exams 5 through 9. Participants were ADRD-free with a valid FFQ at baseline. Flavonoid intakes were updated at each exam to represent the cumulative average intake across the 5 exams, and were expressed as percentile categories of intake (≤15th, >15th to 30th, >30th to 60th, >60th) to handle their nonlinear relation with ADRD and AD. Cox proportional hazards regression was used to estimate the HRs for the association between the flavonoid intakes and incidence of ADRD and AD.

RESULTS

Over an average follow-up of 19.7 y in 2801 participants (mean baseline age = 59.1 y; 52% females), there were 193 ADRD events of which 158 were AD. After multivariate and dietary adjustments, individuals with the highest (>60th percentile) intakes of flavonols, anthocyanins, and flavonoid polymers had a lower risk of ADRD relative to individuals with the lowest intakes (≤15th percentile), with HRs (95% CI; P-trend) of 0.54 (0.32, 0.90; P = 0.003) for flavonols, 0.24 (0.15, 0.39; P < 0.001) for anthocyanins, and 0.58 (0.35, 0.94; P = 0.03) for flavonoid polymers. The same pattern of associations was seen with AD for flavonols and anthocyanins but not for flavonoid polymers.

CONCLUSIONS

Our findings imply that higher long-term dietary intakes of flavonoids are associated with lower risks of ADRD and AD in US adults.

Dose-Response Relation between Tea Consumption and Risk of Cardiovascular Disease and All-Cause Mortality: A Systematic Review and Meta-Analysis of Population-Based Studies

Tea flavonoids have been suggested to offer potential benefits to cardiovascular health. This review synthesized the evidence on the relation between tea consumption and risks of cardiovascular disease (CVD) and all-cause mortality among generally healthy adults. PubMed, EMBASE, Web of Science, Cochrane Central Register of Controlled Trials, Food Science and Technology Abstracts, and Ovid CAB Abstract databases were searched to identify English-language publications through 1 November 2019, including randomized trials, prospective cohort studies, and nested case-control (or case-cohort) studies with data on tea consumption and risk of incident cardiovascular events (cardiac or peripheral vascular events), stroke events (including mortality), CVD-specific mortality, or all-cause mortality. Data from 39 prospective cohort publications were synthesized. Linear meta-regression showed that each cup (236.6 mL)  increase in daily tea consumption (estimated 280 mg  and 338 mg  total flavonoids/d for black and green tea, respectively) was associated with an average 4% lower risk of CVD mortality, a 2% lower risk of CVD events, a 4% lower risk of stroke, and a 1.5% lower risk of all-cause mortality. Subgroup meta-analysis results showed that the magnitude of association was larger in elderly individuals for both CVD mortality (n = 4; pooled adjusted RR: 0.89; 95% CI: 0.83, 0.96; P = 0.001), with large heterogeneity (I2 = 72.4%), and all-cause mortality (n = 3; pooled adjusted RR: 0.92; 95% CI: 0.90, 0.94; P < 0.0001; I2 = 0.3%). Generally, studies with higher risk of bias appeared to show larger magnitudes of associations than studies with lower risk of bias. Strength of evidence was rated as low and moderate (depending on study population age group) for CVD-specific mortality outcome and was rated as low for CVD events, stroke, and all-cause mortality outcomes. Daily tea intake as part of a healthy habitual dietary pattern may be associated with lower risks of CVD and all-cause mortality among adults.

Long-term dietary flavonoid intake and change in cognitive function in the Framingham Offspring cohort

OBJECTIVE

To examine the association between long-term intake of total and the six classes of dietary flavonoids and decline in cognitive function over a follow-up period of up to 15 years.

DESIGN

In this longitudinal study, we evaluated change in eight cognitive domain scores (verbal and visual memory, verbal learning, attention and concentration, abstract reasoning, language, visuoperceptual organisation and the global function) based on three neuropsychological exams and characterised the annualised change between consecutive exams. Long-term intakes of total and six flavonoid classes were assessed up to four times by a validated FFQ. Repeated-measures regression models were used to examine the longitudinal association between total and six flavonoid classes and annualised change in the eight cognitive domains.

SETTING

The Framingham Heart Study (FHS), a prospective cohort study.

PARTICIPANTS

One thousand seven hundred and seventy-nine subjects who were free of dementia, aged ≥45 years and had attended at least two of the last three FHS Offspring cohort study exams.

RESULTS

Over a median follow-up of 11·8 years with 1779 participants, nominally significant trends towards a slower decline in cognitive function were observed among those with higher flavanol and flavon-3-ol intakes for global function, verbal and visual memory; higher total flavonoids and flavonoid polymers for visual memory; and higher flavanols for verbal learning.

CONCLUSIONS

In spite of modest nominal trends, overall, our findings do not support a clear association between higher long-term flavonoid intake and slowing age-related cognitive decline.

Flavonoid Intake and MRI Markers of Brain Health in the Framingham Offspring Cohort

BACKGROUND

Although greater flavonoid intake is associated with a reduced risk of Alzheimer's disease (AD) and related dementias (ADRD), evidence relating dietary flavonoid intake to brain health based on MRI is lacking.

OBJECTIVE

The objective of this study was to explore the association between dietary flavonoid intake and MRI measures of brain health, including total brain tissue volume (TBV), white matter hyperintensities volume (WMHV), and hippocampal volume (HV).

METHODS

Eligible subjects included members of the Framingham Heart Study Offspring Cohort who were free of stroke at exam 7 and had at least 1 valid food frequency questionnaire from exams 5, 6, or 7 (n = 2086; mean age at exam 7, 60.6 y). Flavonoid intakes represented the cumulative mean of intakes across the 3 exams and were categorized based on quartiles categories of intake. TBV, WMHV, and HV were assessed at exam 7. Multiple linear regression models were used to examine the cross-sectional association between total and the 6 classes of flavonoids and the 3 aforementioned MRI measures.

RESULTS

The mean (95% CI) of the WMHV of subjects in the highest quartile category of flavan-3-ols [0.56 (0.52, 0.61)] and flavonoid polymers [0.57 (0.52, 0.61)] intake was significantly smaller relative to that of subjects in the lowest quartile category of flavan-3-ols [0.65 (0.60, 0.71)] and flavonoid polymers [0.66 (0.60, 0.71)] after accounting for important demographic, lifestyle, and clinical factors. Inverse trend associations with WMHV were also seen for flavan-3-ols (P = 0.01) and flavonoid polymers (P = 0.01) as well as for total flavonoids (P = 0.01). TBV and HV were not associated with dietary flavonoid intake following the adjustment for potential confounders.

CONCLUSIONS

Our results contribute to the literature on flavonoids and ADRD as they suggest that higher flavonoid intakes may affect ADRD risk in middle-aged and older adults by reducing WMHV, a marker strongly associated with ADRD.

Proteomic and Metabolomic Correlates of Healthy Dietary Patterns: The Framingham Heart Study

Data on proteomic and metabolomic signatures of healthy dietary patterns are limited. We evaluated the cross-sectional association of serum proteomic and metabolomic markers with three dietary patterns: the Alternative Healthy Eating Index (AHEI), the Dietary Approaches to Stop Hypertension (DASH) diet; and a Mediterranean-style (MDS) diet. We examined participants from the Framingham Offspring Study (mean age; 55 years; 52% women) who had complete proteomic (n = 1713) and metabolomic (n = 2284) data; using food frequency questionnaires to derive dietary pattern indices. Proteins and metabolites were quantified using the SomaScan platform and liquid chromatography/tandem mass spectrometry; respectively. We used multivariable-adjusted linear regression models to relate each dietary pattern index (independent variables) to each proteomic and metabolomic marker (dependent variables). Of the 1373 proteins; 103 were associated with at least one dietary pattern (48 with AHEI; 83 with DASH; and 8 with MDS; all false discovery rate [FDR] ≤ 0.05). We identified unique associations between dietary patterns and proteins (17 with AHEI; 52 with DASH; and 3 with MDS; all FDR ≤ 0.05). Significant proteins enriched biological pathways involved in cellular metabolism/proliferation and immune response/inflammation. Of the 216 metabolites; 65 were associated with at least one dietary pattern (38 with AHEI; 43 with DASH; and 50 with MDS; all FDR ≤ 0.05). All three dietary patterns were associated with a common signature of 24 metabolites (63% lipids). Proteins and metabolites associated with dietary patterns may help characterize intermediate phenotypes that provide insights into the molecular mechanisms mediating diet-related disease. Our findings warrant replication in independent populations.

Dairy Intake in 2 American Adult Cohorts Associates with Novel and Known Targeted and Nontargeted Circulating Metabolites

BACKGROUND

The role of dairy in health can be elucidated by investigating circulating metabolites associated with intake.

OBJECTIVES

We sought to identify metabolites associated with quantity and type of dairy intake in the Framingham Heart Study Offspring and Third Generation (Gen3) cohorts.

METHODS

Dairy intake (total dairy, milk, cheese, yogurt, and cream/butter) was analyzed in relation to targeted (Offspring, n = 2205, 55.1 ± 9.8 y, 52% female, 217 signals; Gen3, n = 866, 40.5 ± 8.8 y, 54.9% female, 79 signals) and nontargeted metabolites (Gen3, ∼7031 signals) in a 2-step analysis including orthogonal projections to latent structures with discriminant analysis (OPLS-DA) in discovery subsets to identify metabolites distinguishing between high and low intake; and linear regression in confirmation subsets to assess putative associations, subsequently tested in the total samples. Previously reported associations were also investigated.

RESULTS

OPLS-DA in the Offspring targeted discovery subset resulted in a variable importance in projection (VIP) >1 of 65, 60, 58, 66, and 60 metabolites for total dairy, milk, cream/butter, cheese, and yogurt, respectively, of which 5, 3, 1, 6, and 4 metabolites, respectively, remained after confirmation. In the Gen3 targeted discovery subset, OPLS-DA resulted in a VIP >1 of 17, 15, 13, 7, and 6 metabolites for total dairy, milk, cream/butter, cheese, and yogurt, respectively. In the Gen3 nontargeted discovery subset, OPLS-DA resulted in a VIP >2 of 203, 503, 78, 186, and 206 metabolites, respectively. Combining targeted and nontargeted results in Gen3, significant associations of 7 (6 unannotated), 2, 12 (11 unannotated), 0, and 61 (all unannotated) metabolites, respectively, remained. Candidate identities of unannotated signals included fatty acids and food flavorings. Results supported relations previously reported for C14:0 sphingomyelin, and marginal associations for deoxycholates.

CONCLUSIONS

Dairy in 2 American adult cohorts associated with numerous circulating metabolites. Reports about diet-metabolite relations and confirmation of previous findings might be limited by specificity of dietary intake and breadth of measured metabolites.

Dairy versus other saturated fats source and cardiometabolic risk markers: Systematic review of randomized controlled trials

To analyze the effects of dairy intake on cardiometabolic risk markers compared to other dietary fat sources in adults. Literature database and gray literature were searched for studies published up to October 2018. Two independent authors selected and extracted data from articles. Summary tables were constructed to present data for all outcomes. The intake of dairy appears to have a protective effect on some cardiovascular risk factors, or it is not worse than other SFA sources. The higher intake of dairy can decrease total cholesterol and reduce waist circumference and increase HDL cholesterol. However, it can also increase LDL and triglycerides, although those were small changes. It was observed that the effect of dairy on several serum lipids varied according to the type dairy product used on intervention. Dairy products seem to present a different effect on cardiometabolic risk factors than other fat sources, with evidence of improvement on metabolic parameters compared to another animal source of SFA.

Cumulative sugar-sweetened beverage consumption is associated with higher concentrations of circulating ceramides in the Framingham Offspring Cohort

BACKGROUND

Ceramides have been implicated in the pathogenesis of type 2 diabetes and cardiovascular disease. Limited data exist on how habitual dietary intake of foods that can alter hepatic lipid metabolism may influence circulating ceramide concentrations.

OBJECTIVES

We investigated the cross-sectional association of cumulative sugar-sweetened beverage (SSB) consumption with concentrations of 3 circulating ceramides and ceramide ratios.

METHODS

We examined participants from the Framingham Heart Study's Offspring Cohort who had 3 ceramides measured (n  = 1561, mean age 66 y, 59% women). SSB consumption was measured 4 times over ∼14 y. Participants were categorized by cumulative SSB intake as nonconsumers (0 to <1 SSB serving/mo) and occasional (1 SSB serving/mo to <1 serving/wk), frequent (1 SSB serving/wk to <1 serving/d), and daily (≥1 SSB serving/d) consumers. Multivariable linear regression models were used to relate cumulative SSB consumption (independent variable) to blood concentrations of ceramides (C16:0, C22:0, and C24:0) and ceramide ratios (C22:0/C16:0 and C24:0/C16:0).

RESULTS

In adjusted models, more frequent cumulative SSB consumption was positively associated with concentrations of the C16:0 and C22:0 ceramides (Ptrend < 0.05). Compared with nonconsumers, daily consumers had 0.01 μg/mL (95% CI: 0.002, 0.017 µg/mL) and 0.06 µg/mL (95% CI: 0.018, 0.092 µg/mL) higher mean concentrations of the C16:0 and C22:0 ceramides, respectively. Results were consistent when modeling continuous cumulative SSB consumption per 1 serving/d. We observed effect modification by diabetes status in the relation between cumulative SSB consumption and concentrations of the C24:0 ceramide (Pinteraction = 0.014). In a stratified analysis, more frequent cumulative SSB consumption was positively associated with concentrations of the C24:0 ceramide only in individuals with prediabetes or diabetes (Ptrend = 0.001).

CONCLUSIONS

Our study raises the possibility that higher concentrations of distinct ceramide species, previously associated with adverse metabolic health, may be one mechanism by which SSB consumption contributes to higher risk of cardiometabolic diseases.

Diet Indices Reflecting Changes to Dietary Guidelines for Americans from 1990 to 2015 Are More Strongly Associated with Risk of Coronary Artery Disease Than the 1990 Diet Index

BACKGROUND

The Dietary Guidelines for Americans (DGAs) provide dietary recommendations for the general population with the intent of preventing chronic disease such as cardiovascular disease. An evaluation of whether updated versions of the DGAs accomplish this goal is lacking.

OBJECTIVE

The objective of this project was to determine whether updates to DGAs over time, reflected in subsequent versions of diet quality indices, strengthened the associations between diet quality and risk of cardiovascular disease outcomes.

METHODS

Dietary data collected using an FFQ in the Framingham Heart Study Offspring cohort were used to assess adherence to sequential versions of the Healthy Eating Index (HEI) (1990, 2005, 2010, and 2015) and Alternative HEI (2000 and 2010) (n = 3267). We conducted prospective analyses using Cox regression to estimate the associations between diet indices and incident cardiovascular disease outcomes.

RESULTS

Among the 3267 study participants, 54% were female, mean age was 55 y, and BMI was 27 kg/m2. There were a total of 544 events for the composite outcome of cardiovascular diseases (324 coronary artery disease events, 153 stroke events, and 187 heart failure events). Adherence to any dietary index was inversely associated with risk of cardiovascular disease, coronary artery disease, and heart failure, but not stroke. Compared with HEI-1990, scores for the more recent diet indices were more strongly associated with coronary artery disease risk, but not cardiovascular disease, heart failure, or stroke.

CONCLUSIONS

More recent iterations of diet indices, reflecting updates to the DGAs over time, are more strongly associated with risk of incident coronary artery disease than the original diet index (HEI-1990).

Change in Cardiometabolic Risk Factors Associated With Magnitude of Weight Regain 3 Years After a 1-Year Intensive Lifestyle Intervention in Type 2 Diabetes Mellitus: The Look AHEAD Trial

Background

Weight regain after weight loss is common. The impact on cardiometabolic risk factors is not well established.

Methods and Results

Publicly available data were analyzed from participants of the Look AHEAD (Action for Health in Diabetes) trial with ≥3% initial weight loss (n=1561) during a 1‐year intensive lifestyle intervention and with year 4 follow‐up data. Participants who regained (regainers) or maintained (maintainers) weight loss were defined with 5 dichotomized cut points (0%, 25%, 50%, 75%, and 100%) of percentage weight loss regained (weight change from years 1–4 as percentage of first year weight loss). Change in cardiometabolic risk factors after initial weight loss was compared in maintainers and regainers, after controlling for demographics, medications, and baseline and year 1 change in body mass index. The effect was assessed separately in participants with <10% and ≥10% initial weight loss, and women and men. Maintainers exhibited significant improvements to the cardiometabolic risk factors assessed compared with regainers. No weight regain cut point maximized risk difference between maintainers and regainers across risk factors or sex/initial weight loss subgroups. For many risk factors, allowing more regain as part of maintenance (increasing cut point) diminished the cardiometabolic benefit among maintainers.

Conclusions

Maintaining weight loss was better than regain for all risk factors. No single cut point maximized the risk difference between maintainers and regainers. Maintainers who kept off ≥75% of weight lost had the greatest benefit. These findings emphasize the importance of intervention programs focusing not only on weight loss but weight loss maintenance, given the adverse consequences of the latter.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00017953.

Healthy diet is associated with gene expression in blood: the Framingham Heart Study

BACKGROUND

Genes in metabolic and nutrient signaling pathways play important roles in lifespan in model organisms and human longevity.

OBJECTIVE

The aim of this study was to examine the relation of a quantitative measure of healthy diet to gene expression in a community-based cohort.

METHODS

We used the 2015 Dietary Guidelines for Americans Adherence Index (DGAI) score to quantify key dietary recommendations of an overall healthy diet. Our current analyses included 2220 Offspring participants (mean age 66 ± 9 y, 55.4% women) and 2941 Third-Generation participants (mean age 46 ± 9 y, 54.5% women) from the Framingham Heart Study. Gene expression was profiled in blood through the use of the Affymetrix Human Exon 1.0 ST Array. We conducted a transcriptome-wide association study of DGAI adjusting for age, sex, smoking, cell counts, and technical covariates. We also constructed a combined gene score from genes significantly associated with DGAI.

RESULTS

The DGAI was significantly associated with the expression of 19 genes (false discovery rate <0.05). The most significant gene, ARRDC3, is a member of the arrestin family of proteins, and evidence in animal models and human data suggests that this gene is a regulator of obesity and energy expenditure. The DGAI gene score was associated with body mass index (P = 1.4 × 10-50), fasting glucose concentration (P = 2.5 × 10-11), type 2 diabetes (P = 1.1 × 10-5), and metabolic syndrome (P = 1.8 × 10-32).

CONCLUSIONS

Healthier diet was associated with genes involved in metabolic function. Further work is needed to replicate our findings and investigate the relation of a healthy diet to altered gene regulation.

Association of dietary folate and vitamin B-12 intake with genome-wide DNA methylation in blood: a large-scale epigenome-wide association analysis in 5841 individuals

BACKGROUND

Folate and vitamin B-12 are essential micronutrients involved in the donation of methyl groups in cellular metabolism. However, associations between intake of these nutrients and genome-wide DNA methylation levels have not been studied comprehensively in humans.

OBJECTIVE

The aim of this study was to assess whether folate and/or vitamin B-12 intake are asssociated with genome-wide changes in DNA methylation in leukocytes.

METHODS

A large-scale epigenome-wide association study of folate and vitamin B-12 intake was performed on DNA from 5841 participants from 10 cohorts using Illumina 450k arrays. Folate and vitamin B-12 intakes were calculated from food-frequency questionnaires (FFQs). Continuous and categorical (low compared with high intake) linear regression mixed models were applied per cohort, controlling for confounders. A meta-analysis was performed to identify significant differentially methylated positions (DMPs) and regions (DMRs), and a pathway analysis was performed on the DMR annotated genes.

RESULTS

The categorical model resulted in 6 DMPs, which are all negatively associated with folate intake, annotated to FAM64A, WRAP73, FRMD8, CUX1, and LCN8 genes, which have a role in cellular processes including centrosome localization, cell proliferation, and tumorigenesis. Regional analysis showed 74 folate-associated DMRs, of which 73 were negatively associated with folate intake. The most significant folate-associated DMR was a 400-base pair (bp) spanning region annotated to the LGALS3BP gene. In the categorical model, vitamin B-12 intake was associated with 29 DMRs annotated to 48 genes, of which the most significant was a 1100-bp spanning region annotated to the calcium-binding tyrosine phosphorylation-regulated gene (CABYR). Vitamin B-12 intake was not associated with DMPs.

CONCLUSIONS

We identified novel epigenetic loci that are associated with folate and vitamin B-12 intake. Interestingly, we found a negative association between folate and DNA methylation. Replication of these methylation loci is necessary in future studies.

Biomarkers of Dietary Omega-6 Fatty Acids and Incident Cardiovascular Disease and Mortality

BACKGROUND

Global dietary recommendations for and cardiovascular effects of linoleic acid, the major dietary omega-6 fatty acid, and its major metabolite, arachidonic acid, remain controversial. To address this uncertainty and inform international recommendations, we evaluated how in vivo circulating and tissue levels of linoleic acid (LA) and arachidonic acid (AA) relate to incident cardiovascular disease (CVD) across multiple international studies.

METHODS

We performed harmonized, de novo, individual-level analyses in a global consortium of 30 prospective observational studies from 13 countries. Multivariable-adjusted associations of circulating and adipose tissue LA and AA biomarkers with incident total CVD and subtypes (coronary heart disease, ischemic stroke, cardiovascular mortality) were investigated according to a prespecified analytic plan. Levels of LA and AA, measured as the percentage of total fatty acids, were evaluated linearly according to their interquintile range (ie, the range between the midpoint of the first and fifth quintiles), and categorically by quintiles. Study-specific results were pooled using inverse-variance-weighted meta-analysis. Heterogeneity was explored by age, sex, race, diabetes mellitus, statin use, aspirin use, omega-3 levels, and fatty acid desaturase 1 genotype (when available).

RESULTS

In 30 prospective studies with medians of follow-up ranging 2.5 to 31.9 years, 15 198 incident cardiovascular events occurred among 68 659 participants. Higher levels of LA were significantly associated with lower risks of total CVD, cardiovascular mortality, and ischemic stroke, with hazard ratios per interquintile range of 0.93 (95% CI, 0.88-0.99), 0.78 (0.70-0.85), and 0.88 (0.79-0.98), respectively, and nonsignificantly with lower coronary heart disease risk (0.94; 0.88-1.00). Relationships were similar for LA evaluated across quintiles. AA levels were not associated with higher risk of cardiovascular outcomes; in a comparison of extreme quintiles, higher levels were associated with lower risk of total CVD (0.92; 0.86-0.99). No consistent heterogeneity by population subgroups was identified in the observed relationships.

CONCLUSIONS

In pooled global analyses, higher in vivo circulating and tissue levels of LA and possibly AA were associated with lower risk of major cardiovascular events. These results support a favorable role for LA in CVD prevention.

Dietary Protein and Changes in Biomarkers of Inflammation and Oxidative Stress in the Framingham Heart Study Offspring Cohort

BACKGROUND

Chronic inflammation is thought to be a major characteristic of aging, which may increase need for substrates, specifically protein, to support anti-inflammatory processes.

OBJECTIVES

The aim of this study was to assess associations between dietary protein and changes in biomarkers of inflammation and oxidative stress over the long term in a community-dwelling population.

METHODS

In 2061 participants of the Framingham Heart Study Offspring cohort who attended exams 7 (1998-2001; mean ± SD age 60.0 ± 8.8 y, 56% female) and 8 (2005-2008), total, animal, and plant protein intakes were assessed by food-frequency questionnaire at each exam, energy adjusted, and averaged. We defined an inflammation and oxidative stress score as the sum of rank-normalized values of 9 circulating biomarkers (C-reactive protein, osteoprotegerin, P-selectin, tumor necrosis factor receptor II, soluble intercellular adhesion molecule-1, interleukin 6, monocyte chemoattractant protein 1, and lipoprotein phospholipase A2 mass and activity), and urinary isoprostanes, along with 2 subscores. Adjusted least-square means of changes in the scores and log individual biomarkers in quartile categories of intake were estimated with the use of linear regression models, across mean ± SD 6.6 ± 0.7 y of follow-up.

RESULTS

Protein intake was inversely associated with changes in the inflammation and oxidative stress score (mean ± SE in Q1 compared with Q4: 0.77 ± 0.17 compared with 0.31 ± 0.19; P-trend = 0.02), indicating overall inflammation/oxidative stress increased less in those with the highest intake than in those with the lowest. Favorable associations were observed for plant protein (Q1 compared with Q4: 0.89 ± 0.25 compared with 0.14 ± 0.25; P-trend = 0.001), but only trended toward significance for animal protein (Q1 compared with Q4: 0.70 ± 0.26 compared with 0.31 ± 0.26; P-trend = 0.05). Total protein and plant protein intakes were also inversely associated with changes in monocyte chemoattractant protein 1 (total: Q1 compared with Q4: 0.19 ± 0.01 compared with 0.15 ± 0.01 log-pg/mL; P-trend = 0.03; plant: Q1 compared with Q4: 0.21 ± 0.01 compared with 0.16 ± 0.01 log-pg/mL; P-trend = 0.003).

CONCLUSIONS

Dietary protein, particularly from plant sources, may be associated with beneficial changes in the inflammatory burden in aging populations.

Associations of protein intake in early childhood with body composition, height, and insulin-like growth factor I in mid-childhood and early adolescence

BACKGROUND

Early protein intake may program later body composition and height growth, perhaps mediated by insulin-like growth factor I (IGF-I). In infancy, higher protein intake is consistently associated with higher IGF-I concentrations and more rapid growth, but associations of protein intake after infancy with later growth and IGF-I are less clear.

OBJECTIVES

Our objective was to examine associations of protein intake in early childhood (median 3.2 y) with height, IGF-I, and measures of adiposity and lean mass in mid-childhood (median 7.7 y) and early adolescence (median 13.0 y), and with changes in these outcomes over time. We hypothesized that early childhood protein intake programs later growth.

METHODS

We studied 1165 children in the Boston-area Project Viva cohort. Mothers reported children's diet using food-frequency questionnaires. We stratified by child sex and examined associations of early childhood protein intake with mid-childhood and early adolescent BMI z score, skinfold thicknesses, dual-energy X-ray absorptiometry (DXA) fat mass, DXA lean mass, height z score, and IGF-I concentration. We adjusted linear regression models for race/ethnicity, family sociodemographics, parental and birth anthropometrics, breastfeeding status, physical activity, and fast food intake.

RESULTS

Mean protein intake in early childhood was 58.3 g/d. There were no associations of protein intake in early childhood with any of the mid-childhood outcomes. Among boys, however, each 10-g increase in early childhood total protein intake was associated with several markers of early adolescent size, namely BMI z score (0.12 higher; 95% CI: 0.01, 0.23), DXA lean mass index (1.34% higher; 95% CI: -0.07%, 2.78%), and circulating IGF-I (5.67% higher; 95% CI: 0.30%, 11.3%). There were no associations with fat mass and no associations with any adolescent outcomes among girls.

CONCLUSIONS

Early childhood protein intake may contribute to programming lean mass and IGF-I around the time of puberty in boys, but not to adiposity development. This study was registered at clinicaltrials.gov as NCT02820402.

Theoretical Food and Nutrient Composition of Whole-Food Plant-Based and Vegan Diets Compared to Current Dietary Recommendations

Public interest in popular diets is increasing, in particular whole-food plant-based (WFPB) and vegan diets. Whether these diets, as theoretically implemented, meet current food-based and nutrient-based recommendations has not been evaluated in detail. Self-identified WFPB and vegan diet followers in the Adhering to Dietary Approaches for Personal Taste (ADAPT) Feasibility Survey reported their most frequently used sources of information on nutrition and cooking. Thirty representative days of meal plans were created for each diet. Weighted mean food group and nutrient levels were calculated using the Nutrition Data System for Research (NDSR) and data were compared to DRIs and/or USDA Dietary Guidelines/MyPlate meal plan recommendations. The calculated HEI-2015 scores were 88 out of 100 for both WFPB and vegan meal plans. Because of similar nutrient composition, only WFPB results are presented. In comparison to MyPlate, WFPB meal plans provide more total vegetables (180%), green leafy vegetables (238%), legumes (460%), whole fruit (100%), whole grains (132%), and less refined grains (−74%). Fiber level exceeds the adequate intakes (AI) across all age groups. WFPB meal plans failed to meet the Recommended Dietary Allowances (RDA)s for vitamin B12 and D without supplementation, as well as the RDA for calcium for women aged 51–70. Individuals who adhere to WFBP meal plans would have higher overall dietary quality as defined by the HEI-2015 score as compared to typical US intakes with the exceptions of calcium for older women and vitamins B12 and D without supplementation. Future research should compare actual self-reported dietary intakes to theoretical targets.

Body Mass Index Mediates the Association between Dietary Fiber and Symptomatic Knee Osteoarthritis in the Osteoarthritis Initiative and the Framingham Osteoarthritis Study

Background

Dietary fiber reduces body weight and inflammation in clinical trials. It is unclear whether body mass index (BMI) and inflammation might explain the observed association between higher fiber intake and the lower risk of symptomatic knee osteoarthritis (SXKOA).

Objectives

We quantified the extent to which BMI and inflammation influenced the relation between dietary fiber and SXKOA.

Methods

We used longitudinal data from the Osteoarthritis Initiative (OAI) and the Framingham Offspring Osteoarthritis Study. At baseline of each study, men and women (mean age: 61 y) with or at risk of knee osteoarthritis were followed for 48 mo in the OAI. Adults (mean age: 53 y) were followed for 9.5 y in the Framingham study. Dietary fiber intake was estimated using a validated food-frequency questionnaire. Measured weight and height were used to calculate BMI. Serum high-sensitivity C-reactive protein (CRP) was measured in the Framingham study only. Incident SXKOA was defined as new onset of a combination of knee pain and radiographic osteoarthritis. We applied marginal structural models to quantify the mediation through BMI in the OAI and the sequential mediation through BMI and CRP in the Framingham study.

Results

Incident SXKOA occurred in 861 knees among 2876 persons in the OAI and in 143 knees among 971 persons in the Framingham study. In persons whose fiber intake was ≥21 g/d compared with those with intakes <21 g/d, the OR (95% CI) was 0.70 (0.53, 0.91) for the overall association with SXKOA and was 0.93 (0.92, 0.95) for the mediation via BMI (per kg/m2) in the OAI. In the Framingham study, the overall association was 0.57 (0.30, 1.09), the mediation through BMI (via BMI and the influence of BMI on CRP) was 0.94 (0.85, 1.02), and the mediation through CRP (per milligram per liter) was 0.99 (0.84, 1.19).

Conclusion

Our findings suggest that the inverse association of fiber intake and the risk of incident symptomatic knee osteoarthritis is partially mediated by BMI.