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Association of dietary adherence and dietary quality with weight loss success among those following low-carbohydrate and low-fat diets: a secondary analysis of the DIETFITS randomized clinical trial.
Hauser, ME, Hartle, JC, Landry, MJ, Fielding-Singh, P, Shih, CW, Qin, F, Rigdon, J, Gardner, CD
The American journal of clinical nutrition. 2024;(1):174-184
Abstract
BACKGROUND Eating a high-quality diet or adhering to a given dietary strategy may influence weight loss. However, these 2 factors have not been examined concurrently for those following macronutrient-limiting diets. OBJECTIVE To determine whether improvement in dietary quality, change in dietary macronutrient composition, or the combination of these factors is associated with differential weight loss when following a healthy low-carbohydrate (HLC) or healthy low-fat (HLF) diet. DESIGN Generally healthy adults were randomly assigned to HLC or HLF diets for 12 mo (n = 609) as part of a randomized controlled weight loss study. Participants with complete 24-h dietary recall data at baseline and 12-mo were included in this secondary analysis (total N = 448; N = 224 HLC, N = 224 HLF). Participants were divided into 4 subgroups according to 12-mo change in HEI-2010 score [above median = high quality (HQ) and below median = low quality (LQ)] and 12-mo change in macronutrient intake [below median = high adherence (HA) and above median = low adherence (LA) for net carbohydrate (g) or fat (g) for HLC and HLF, respectively]. Baseline to 12-mo changes in mean BMI were compared for those in HQ/HA, HQ/LA, LQ/HA subgroups with the LQ/LA subgroup within HLC and HLF. RESULTS For HLC, changes (95 % confidence level [CI]) in mean BMI were -1.15 kg/m2 (-2.04, -0.26) for HQ/HA, -0.30 (-1.22, 0.61) for HQ/LA, and -0.80 (-1.74, 0.14) for LQ/HA compared with the LQ/LA subgroup. For HLF, changes (95% CI) in mean BMI were -1.11kg/m2 (-2.10, -0.11) for HQ/HA, -0.26 (-1.26, 0.75) for HQ/LA, and -0.66 (-1.74, 0.41) for LQ/HA compared with the LQ/LA subgroup. CONCLUSION Within both HLC and HLF diet arms, 12-mo decrease in BMI was significantly greater in HQ/HA subgroups relative to LQ/LA subgroups. Neither HQ nor HA alone were significantly different than LQ/LA subgroups. Results of this analysis support the combination of dietary adherence and high-quality diets for weight loss. CLINICAL TRIAL REGISTRY clinicaltrials.gov (Identifier: NCT01826591).
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Randomized controlled trial demonstrates response to a probiotic intervention for metabolic syndrome that may correspond to diet.
Wastyk, HC, Perelman, D, Topf, M, Fragiadakis, GK, Robinson, JL, Sonnenburg, JL, Gardner, CD, Sonnenburg, ED
Gut microbes. 2023;15(1):2178794
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Rates of metabolic syndrome are high throughout developed countries. Metabolic syndrome is a cluster of conditions that occur together and increase your risk for heart disease, stroke, and type 2 diabetes. Studies in animals and humans have shown that the composition of the gut microbiome may be linked to metabolic syndrome and that it is affected by diet. This randomised control trial of 39 individuals showed that the supplementation of a probiotic containing three different probiotic strains did not have a population wide effect but did influence a subset of individuals. These individuals had a different microbiome by the end of the trial and a decrease in blood pressure and blood lipids. Interestingly these individuals also had a higher dietary intake of sugar, yet a lower blood sugar level. It was concluded that the response to probiotic supplements may be dependent upon an individual’s diet. This study could be used by healthcare professionals to understand that diet may influence the success of probiotics, however more research is warranted before firm conclusions are made on the optimal diet during supplementation.
Abstract
An individual's immune and metabolic status is coupled to their microbiome. Probiotics offer a promising, safe route to influence host health, possibly via the microbiome. Here, we report an 18-week, randomized prospective study that explores the effects of a probiotic vs. placebo supplement on 39 adults with elevated parameters of metabolic syndrome. We performed longitudinal sampling of stool and blood to profile the human microbiome and immune system. While we did not see changes in metabolic syndrome markers in response to the probiotic across the entire cohort, there were significant improvements in triglycerides and diastolic blood pressure in a subset of probiotic arm participants. Conversely, the non-responders had increased blood glucose and insulin levels over time. The responders had a distinct microbiome profile at the end of the intervention relative to the non-responders and placebo arm. Importantly, diet was a key differentiating factor between responders and non-responders. Our results show participant-specific effects of a probiotic supplement on improving parameters of metabolic syndrome and suggest that dietary factors may enhance stability and efficacy of the supplement.
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Cardiometabolic Effects of Omnivorous vs Vegan Diets in Identical Twins: A Randomized Clinical Trial.
Landry, MJ, Ward, CP, Cunanan, KM, Durand, LR, Perelman, D, Robinson, JL, Hennings, T, Koh, L, Dant, C, Zeitlin, A, et al
JAMA network open. 2023;6(11):e2344457
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A vegan dietary pattern is typically lower in energy density but higher in fibre, vitamins, minerals, and phytonutrients compared with other dietary patterns. However, sometimes a vegan dietary pattern can limit specific nutrients, such as vitamin B12, iron, and calcium. In addition, a poorly formulated vegan diet can include low-quality plant foods, such as refined carbohydrates and added sugars. The aim of this study was to compare the cardiometabolic effects of a healthy vegan diet with a healthy omnivorous diet, exposing both groups to vegetables, legumes, fruits, whole grains, nuts, and seeds. This study was a single-site, parallel-group, dietary intervention randomised clinical trial which randomised healthy, adult identical twins to a healthy vegan or omnivorous diet for 8 weeks. Results showed that: - low-density lipoprotein was significantly lower for twins receiving the vegan diet compared with twins receiving the omnivorous diet. - insulin levels and weight were also significantly lower among the twins on the vegan diet from baseline to 8 weeks. - vegan-diet participants had total lower protein intake as a percentage of calories, lower dietary satisfaction, lower intake of dietary cholesterol, but higher intake of vegetable servings and intake of dietary iron. - vegans had lower intake of vitamin B12, yet serum vitamin B12 levels were not statistically different than omnivores at 8 weeks. Authors concluded that their findings show cardiometabolic advantages for the healthy vegan vs the healthy omnivorous diet among healthy, adult identical twins. Thus, clinicians may consider recommending plant-based diets to reduce cardiometabolic risk factors, as well as aligning with environmental benefits.
Abstract
IMPORTANCE Increasing evidence suggests that, compared with an omnivorous diet, a vegan diet confers potential cardiovascular benefits from improved diet quality (ie, higher consumption of vegetables, legumes, fruits, whole grains, nuts, and seeds). OBJECTIVE To compare the effects of a healthy vegan vs healthy omnivorous diet on cardiometabolic measures during an 8-week intervention. DESIGN, SETTING, AND PARTICIPANTS This single-center, population-based randomized clinical trial of 22 pairs of twins (N = 44) randomized participants to a vegan or omnivorous diet (1 twin per diet). Participant enrollment began March 28, 2022, and continued through May 5, 2022. The date of final follow-up data collection was July 20, 2022. This 8-week, open-label, parallel, dietary randomized clinical trial compared the health impact of a vegan diet vs an omnivorous diet in identical twins. Primary analysis included all available data. INTERVENTION Twin pairs were randomized to follow a healthy vegan diet or a healthy omnivorous diet for 8 weeks. Diet-specific meals were provided via a meal delivery service from baseline through week 4, and from weeks 5 to 8 participants prepared their own diet-appropriate meals and snacks. MAIN OUTCOMES AND MEASURES The primary outcome was difference in low-density lipoprotein cholesterol concentration from baseline to end point (week 8). Secondary outcome measures were changes in cardiometabolic factors (plasma lipids, glucose, and insulin levels and serum trimethylamine N-oxide level), plasma vitamin B12 level, and body weight. Exploratory measures were adherence to study diets, ease or difficulty in following the diets, participant energy levels, and sense of well-being. RESULTS A total of 22 pairs (N = 44) of twins (34 [77.3%] female; mean [SD] age, 39.6 [12.7] years; mean [SD] body mass index, 25.9 [4.7]) were enrolled in the study. After 8 weeks, compared with twins randomized to an omnivorous diet, the twins randomized to the vegan diet experienced significant mean (SD) decreases in low-density lipoprotein cholesterol concentration (-13.9 [5.8] mg/dL; 95% CI, -25.3 to -2.4 mg/dL), fasting insulin level (-2.9 [1.3] μIU/mL; 95% CI, -5.3 to -0.4 μIU/mL), and body weight (-1.9 [0.7] kg; 95% CI, -3.3 to -0.6 kg). CONCLUSIONS AND RELEVANCE In this randomized clinical trial of the cardiometabolic effects of omnivorous vs vegan diets in identical twins, the healthy vegan diet led to improved cardiometabolic outcomes compared with a healthy omnivorous diet. Clinicians can consider this dietary approach as a healthy alternative for their patients. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT05297825.
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Popular Dietary Patterns: Alignment With American Heart Association 2021 Dietary Guidance: A Scientific Statement From the American Heart Association.
Gardner, CD, Vadiveloo, MK, Petersen, KS, Anderson, CAM, Springfield, S, Van Horn, L, Khera, A, Lamendola, C, Mayo, SM, Joseph, JJ, et al
Circulation. 2023;(22):1715-1730
Abstract
The evolution of dietary guidelines from isolated nutrients to broader dietary pattern recommendations results from growing knowledge of the synergy between nutrients and their food sources as they influence health. Macronutrient and micronutrient needs can be met by consuming various dietary patterns, but guidance is often required to facilitate population-wide adherence to wise food choices to achieve a healthy dietary pattern. This is particularly true in this era with the proliferation of nutrition misinformation and misplaced emphasis. In 2021, the American Heart Association issued a scientific statement outlining key principles of a heart-healthy dietary pattern that could be operationalized in various ways. The objective of this scientific statement is to assess alignment of commonly practiced US dietary patterns with the recently published American Heart Association criteria, to determine clinical and cultural factors that affect long-term adherence, and to propose approaches for adoption of healthy dietary patterns. This scientific statement is intended to serve as a tool for clinicians and consumers to evaluate whether these popular dietary pattern(s) promote cardiometabolic health and suggests factors to consider when adopting any pattern to improve alignment with the 2021 American Heart Association Dietary Guidance. Numerous patterns strongly aligned with 2021 American Heart Association Dietary Guidance (ie, Mediterranean, DASH [Dietary Approaches to Stop Hypertension], pescetarian, vegetarian) can be adapted to reflect personal and cultural preferences and budgetary constraints. Thus, optimal cardiovascular health would be best supported by developing a food environment that supports adherence to these patterns wherever food is prepared or consumed.
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Ultra-processed Foods, Weight Gain, and Co-morbidity Risk.
Crimarco, A, Landry, MJ, Gardner, CD
Current obesity reports. 2022;(3):80-92
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PURPOSE OF REVIEW The purpose of this review is to provide an update on the available data regarding the associations of Ultra-processed food (UPF) consumption with food intake and possible underlying mechanisms relating UPF consumption to weight gain and co-morbidities. RECENT FINDINGS In primarily observational studies, UPF consumption is consistently associated with an increased risk for weight gain among adults and children and increased risk for adiposity-related co-morbidities in adults. In a single mechanistic study, consumption of UPFs led to increased energy intake and weight gain relative to whole foods. UPFs tend to be more energy-dense than nutrient-dense, and UPF consumption is associated with increased adiposity and co-morbidity risk. These data suggest that recommendations to limit UPF consumption may be beneficial to health - though further mechanistic studies are needed.
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Strengthening US Food Policies and Programs to Promote Equity in Nutrition Security: A Policy Statement From the American Heart Association.
Thorndike, AN, Gardner, CD, Kendrick, KB, Seligman, HK, Yaroch, AL, Gomes, AV, Ivy, KN, Scarmo, S, Cotwright, CJ, Schwartz, MB, et al
Circulation. 2022;(24):e1077-e1093
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Abstract
Nutritionally inadequate dietary intake is a leading contributor to chronic cardiometabolic diseases. Differences in dietary quality contribute to socioeconomic and racial and ethnic health disparities. Food insecurity, a household-level social or economic condition of limited access to sufficient food, is a common cause of inadequate dietary intake. Although US food assistance policies and programs are designed to improve food security, there is growing consensus that they should have a broader focus on nutrition security. In this policy statement, we define nutrition security as an individual or household condition of having equitable and stable availability, access, affordability, and utilization of foods and beverages that promote well-being and prevent and treat disease. Despite existing policies and programs, significant gaps remain for achieving equity in nutrition security across the life span. We provide recommendations for expanding and improving current food assistance policies and programs to achieve nutrition security. These recommendations are guided by several overarching principles: emphasizing nutritional quality, improving reach, ensuring optimal utilization, improving coordination across programs, ensuring stability of access to programs across the life course, and ensuring equity and dignity for access and utilization. We suggest a critical next step will be to develop and implement national measures of nutrition security that can be added to the current US food security measures. Achieving equity in nutrition security will require coordinated and sustained efforts at the federal, state, and local levels. Future advocacy, innovation, and research will be needed to expand existing food assistance policies and programs and to develop and implement new policies and programs that will improve cardiovascular health and reduce disparities in chronic disease.
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Effect of a ketogenic diet versus Mediterranean diet on glycated hemoglobin in individuals with prediabetes and type 2 diabetes mellitus: The interventional Keto-Med randomized crossover trial.
Gardner, CD, Landry, MJ, Perelman, D, Petlura, C, Durand, LR, Aronica, L, Crimarco, A, Cunanan, KM, Chang, A, Dant, CC, et al
The American journal of clinical nutrition. 2022;(3):640-652
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BACKGROUND Consensus has not been reached on what constitutes an optimal diet in individuals with prediabetes and type 2 diabetes mellitus (T2DM), especially between low-carbohydrate options. OBJECTIVES We compared 2 low-carbohydrate diets with 3 key similarities (incorporating nonstarchy vegetables and avoiding added sugars and refined grains) and 3 key differences (incorporating compared with avoiding legumes, fruits, and whole, intact grains) for their effects on glucose control and cardiometabolic risk factors in individuals with prediabetes and T2DM. METHODS Keto-Med was a randomized, crossover, interventional trial. Forty participants aged ≥18 years with prediabetes or T2DM followed the well-formulated ketogenic diet (WFKD) and the Mediterranean-plus diet (Med-Plus) for 12 weeks each, in random order. The diets shared the 3 key similarities noted above. The Med-Plus incorporated legumes, fruits, and whole, intact grains, while the WFKD avoided them. The primary outcome was the percentage change in glycated hemoglobin (HbA1c) after 12 weeks on each diet. Secondary and exploratory outcomes included percentage changes in body weight, fasting insulin, glucose, and blood lipids; average glucose from continuous glucose monitor (CGM), and nutrient intake. RESULTS The primary analysis was of 33 participants with complete data. The HbA1c values did not differ between diets at 12 weeks. Triglycerides decreased more for the WFKD [percentage changes, -16% (SEM, 4%) compared with -5% (SEM, 6%) for the Med-Plus; P = 0.02] and LDL cholesterol was higher for the WFKD [percentage changes, +10% (SEM, 4%) compared with -5% (SEM, 5%) for the Med-Plus; P = 0.01]. Weight decreased 8% (SEM, 1%) compared with 7% (SEM, 1%) and HDL cholesterol increased 11% (SEM, 2%) compared with 7% (SEM, 3%) for the WFKD compared with the Med-Plus, respectively; however, there was a significant interaction of diet × order for both. Participants had lower intakes of fiber and 3 nutrients on the WFKD compared with the Med-Plus. Twelve-week follow-up data suggest the Med-Plus is more sustainable. CONCLUSIONS HbA1c values were not different between diet phases after 12 weeks, but improved from baseline on both diets, likely due to several shared dietary aspects. The WFKD led to a greater decrease in triglycerides, but also had potential untoward risks from elevated LDL cholesterol and lower nutrient intakes from avoiding legumes, fruits, and whole, intact grains, as well as being less sustainable. This trial was registered at clinicaltrials.gov as NCT03810378.
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Examining differences between overweight women and men in 12-month weight loss study comparing healthy low-carbohydrate vs. low-fat diets.
Aronica, L, Rigdon, J, Offringa, LC, Stefanick, ML, Gardner, CD
International journal of obesity (2005). 2021;(1):225-234
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BACKGROUND/OBJECTIVES Biological sex factors and sociocultural gender norms affect the physiology and behavior of weight loss. However, most diet intervention studies do not report outcomes by sex, thereby impeding reproducibility. The objectives of this study were to compare 12-month changes in body weight and composition in groups defined by diet and sex, and adherence to a healthy low carbohydrate (HLC) vs. healthy low fat (HLF) diet. PARTICIPANTS/METHODS This was a secondary analysis of the DIETFITS trial, in which 609 overweight/obese nondiabetic participants (age, 18-50 years) were randomized to a 12-month HLC (n = 304) or HLF (n = 305) diet. Our first aim concerned comparisons in 12-month changes in weight, fat mass, and lean mass by group with appropriate adjustment for potential confounders. The second aim was to assess whether or not adherence differed by diet-sex group (HLC women n = 179, HLC men n = 125, HLF women n = 167, HLF men n = 138). RESULTS 12-month changes in weight (p < 0.001) were different by group. HLC produced significantly greater weight loss, as well as greater loss of both fat mass and lean mass, than HLF among men [-2.98 kg (-4.47, -1.50); P < 0.001], but not among women. Men were more adherent to HLC than women (p = 0.02). Weight loss estimates within group remained similar after adjusting for adherence, suggesting adherence was not a mediator. CONCLUSIONS By reporting outcomes by sex significant weight loss differences were identified between HLC and HLF, which were not recognized in the original primary analysis. These findings highlight the need to consider sex in the design, analysis, and reporting of diet trials.
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A Critical Review of the Study of Neuroprotective Diets to Reduce Cognitive Decline.
Duplantier, SC, Gardner, CD
Nutrients. 2021;(7)
Abstract
Alzheimer's disease (AD) and other dementias are now the seventh leading cause of death in the world and are projected to affect 115.4 million people by 2050. Delaying the onset of AD by just five years is estimated to reduce the cost and prevalence of the disease by half. There is no cure for AD nor any drug therapies to halt its progression once the disease begins. Lifestyle choices including diet are being seen as a viable complementary therapy to reduce cognitive decline, the hallmark of AD. Mediterranean, DASH (Dietary Approaches to Stop Hypertension), and MIND (Mediterranean-DASH Intervention for Neurodegenerative Delay) diets have biological mechanisms supporting their potential neuroprotective benefits, but the findings of study outcomes about these benefits have been inconsistent. This paper analyzed five Randomized Clinical Trials (RCTs) (from 2000 to 2021) and 27 observational studies (from 2010 to 2021) focused on the link between cognitive health and the Mediterranean/DASH/MIND diets to identify gaps and challenges that could lead to inconsistent results. These include a lack of accuracy in assessing food intake, multiple dietary pattern scoring systems, a shifting metric among studies focused on the Mediterranean diet, a lack of standards in the tools used to assess cognitive decline, and studies that were underpowered or had follow-up periods too short to detect cognitive change. Insights from these gaps and challenges are summarized in recommendations for future RCTs, including both pragmatic and explanatory RCTs.
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Therapeutic Implications of Diet in Inflammatory Bowel Disease and Related Immune-Mediated Inflammatory Diseases.
Jiang, Y, Jarr, K, Layton, C, Gardner, CD, Ashouri, JF, Abreu, MT, Sinha, SR
Nutrients. 2021;(3)
Abstract
Despite being a focal issue to patients, the effect of diet on adult inflammatory bowel disease (IBD) remains underexplored with limited guidance. While promising clinical trials are currently underway, there is a need for further evidence-based recommendations. As such, we summarize the current evidence on various diets used in the treatment of IBD and also explore the potential applications of dietary data from related immune-mediated inflammatory diseases (IMIDs), such as rheumatoid arthritis and psoriasis, to provide additional information to inform IBD providers. To date, there have been multiple diets investigated as adjunctive therapy in IBD, but many associated studies are small, non-randomized, and not controlled. Mediterranean, vegetarian/vegan, and reduced-calorie/fasting diets have been studied and have shown some positive results in other IMIDs, which may suggest potential applicability to those with IBD, but larger, well-designed clinical trials are needed for further guidance. Gluten-free and low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP)diets do not appear to have an impact on IBD disease activity, but low FODMAP may potentially be helpful for those with concurrent functional gastrointestinal symptoms. Specific carbohydrate diets have been mainly assessed in children but show some potential in small adult studies.