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Changes in Gut Microbiota-Related Metabolites and Long-term Successful Weight Loss in Response to Weight-Loss Diets: The POUNDS Lost Trial.
Heianza, Y, Sun, D, Smith, SR, Bray, GA, Sacks, FM, Qi, L
Diabetes care. 2018;41(3):413-419
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Evidence has demonstrated that weight loss contributes to lowering the risk of developing type 2 diabetes among obese patients. The aim of this study was to examine whether diet-induced metabolites were associated with improvements in adiposity and metabolism during a weight-loss diet intervention in 510 overweight and obese individuals. Participants were randomly assigned to one of four diets with varying macronutrient composition to adhere to for six months. Blood samples and anthropometric data were taken at baseline and 6 months to monitor changes. This study found that overweight and obese individuals with reduced choline or L-carnitine levels achieved greater improvements of adiposity and energy metabolism. Based on these results, the authors conclude that metabolites are predictive of patient responsiveness to dietary interventions, and suggest further studies evaluate these effects in the pre-diabetic obese population.
Abstract
OBJECTIVE Adiposity and the gut microbiota are both related to the risk of type 2 diabetes. We aimed to comprehensively examine how changes induced by a weight-loss diet intervention in gut microbiota-related metabolites, such as trimethylamine N-oxide (TMAO) and its precursors (choline and l-carnitine), were associated with improvements in adiposity and regional fat deposition. RESEARCH DESIGN AND METHODS This study included 510 overweight and obese individuals who were randomly assigned one of four diets varying in macronutrient intake. We examined associations of 6-month changes in blood metabolites (TMAO, choline, and l-carnitine) with improvements in body weight (BW), waist circumference (WC), body fat composition, fat distribution, and resting energy expenditure (REE). RESULTS Individuals with a greater reduction of choline (P < 0.0001) and l-carnitine (P < 0.01) rather than TMAO showed significant losses of BW and WC at 6 months. The reduction of choline was significantly predictive of decreases in body fat composition, fat distribution, and REE. Results of sensitivity analysis showed that the baseline diabetes risk status, such as the presence of hyperglycemia (31% of the total participants) and fasting glucose levels, did not modify the associations. Early changes in choline and l-carnitine were significantly predictive of weight loss over 2 years (P < 0.05 for all). Individuals with increases in choline or l-carnitine were 2.35-times (95% CI 1.38, 4.00) or 1.77-times (1.06, 2.95) more likely to fail to lose weight (-5% or more loss) at 2 years. CONCLUSIONS Overweight and obese individuals who showed decreases in circulating choline or l-carnitine levels achieved greater improvements of adiposity and energy metabolism by eating a low-calorie weight-loss diet, suggesting that such metabolites are predictive of individuals' response to the treatment. Further investigations are necessary to confirm our findings, particularly in a population with prediabetes that is more representative of the U.S. population with obesity.
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Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion: The DIETFITS Randomized Clinical Trial.
Gardner, CD, Trepanowski, JF, Del Gobbo, LC, Hauser, ME, Rigdon, J, Ioannidis, JPA, Desai, M, King, AC
JAMA. 2018;319(7):667-679
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Obesity is a major public health challenge and different dietary strategies are employed to lose weight. This randomised clinical trial of 609 obese adults between the age of 18 and 50 aimed to determine the effects of a healthy low-fat diet in comparison to a healthy low-carbohydrate diet on weight change over a 12 month period. The study also assessed whether 3 genetic markers and blood sugar management affected weight loss in the 2 groups. Participants in the study were offered 22 group sessions of health coaching to support adherence to the programme. 481 participants completed the study. The low-carbohydrate group lost on average 6kg and the low-fat group lost on average 5.4kg. The difference between the 2 groups did not achieve significance for weight loss. There was also no significant genetic or blood sugar management effect in relation to dietary pattern and weight loss. The authors of this study conclude that the results of this study do not help in identifying which dietary type is better for whom in relation to 3 genetic markers and blood sugar management.
Abstract
Importance: Dietary modification remains key to successful weight loss. Yet, no one dietary strategy is consistently superior to others for the general population. Previous research suggests genotype or insulin-glucose dynamics may modify the effects of diets. Objective: To determine the effect of a healthy low-fat (HLF) diet vs a healthy low-carbohydrate (HLC) diet on weight change and if genotype pattern or insulin secretion are related to the dietary effects on weight loss. Design, Setting, and Participants: The Diet Intervention Examining The Factors Interacting with Treatment Success (DIETFITS) randomized clinical trial included 609 adults aged 18 to 50 years without diabetes with a body mass index between 28 and 40. The trial enrollment was from January 29, 2013, through April 14, 2015; the date of final follow-up was May 16, 2016. Participants were randomized to the 12-month HLF or HLC diet. The study also tested whether 3 single-nucleotide polymorphism multilocus genotype responsiveness patterns or insulin secretion (INS-30; blood concentration of insulin 30 minutes after a glucose challenge) were associated with weight loss. Interventions: Health educators delivered the behavior modification intervention to HLF (n = 305) and HLC (n = 304) participants via 22 diet-specific small group sessions administered over 12 months. The sessions focused on ways to achieve the lowest fat or carbohydrate intake that could be maintained long-term and emphasized diet quality. Main Outcomes and Measures: Primary outcome was 12-month weight change and determination of whether there were significant interactions among diet type and genotype pattern, diet and insulin secretion, and diet and weight loss. Results: Among 609 participants randomized (mean age, 40 [SD, 7] years; 57% women; mean body mass index, 33 [SD, 3]; 244 [40%] had a low-fat genotype; 180 [30%] had a low-carbohydrate genotype; mean baseline INS-30, 93 μIU/mL), 481 (79%) completed the trial. In the HLF vs HLC diets, respectively, the mean 12-month macronutrient distributions were 48% vs 30% for carbohydrates, 29% vs 45% for fat, and 21% vs 23% for protein. Weight change at 12 months was -5.3 kg for the HLF diet vs -6.0 kg for the HLC diet (mean between-group difference, 0.7 kg [95% CI, -0.2 to 1.6 kg]). There was no significant diet-genotype pattern interaction (P = .20) or diet-insulin secretion (INS-30) interaction (P = .47) with 12-month weight loss. There were 18 adverse events or serious adverse events that were evenly distributed across the 2 diet groups. Conclusions and Relevance: In this 12-month weight loss diet study, there was no significant difference in weight change between a healthy low-fat diet vs a healthy low-carbohydrate diet, and neither genotype pattern nor baseline insulin secretion was associated with the dietary effects on weight loss. In the context of these 2 common weight loss diet approaches, neither of the 2 hypothesized predisposing factors was helpful in identifying which diet was better for whom. Trial Registration: clinicaltrials.gov Identifier: NCT01826591.
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Effective nationwide school-based participatory extramural program on adolescent body mass index, health knowledge and behaviors.
Heo, M, Jimenez, CC, Lim, J, Isasi, CR, Blank, AE, Lounsbury, DW, Fredericks, L, Bouchard, M, Faith, MS, Wylie-Rosett, J
BMC pediatrics. 2018;18(1):7
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Adolescent obesity is a major public health concern that affects health status not only during adolescence but also during adulthood. The aim of this study was to test whether the HealthCorps program would improve weight status represented by body mass index (BMI; kg/m2) z-score and obesity class. A secondary aim was to identify knowledge and health behaviour domains that would be increased with the program. The study design was a two parallel arm quasi-experimental pre-post comparison design. A total of 2279 students from 62 schools participated in the HealthCorps program. Results indicate that HealthCorps program participation resulted in BMI z-score improvement among overweight/obese female students. Participation also resulted in increased knowledge in most domains regardless of sex and improved a few behaviour domains. However, it did not improve weight status among male students. Authors conclude that the HealthCorps was effective for BMI z-score improvements among female students in addition to significant positive effects on knowledge and a few behaviors in both sexes.
Abstract
BACKGROUND Adolescent obesity is a major public health concern. Open to all high school students regardless of weight status, HealthCorps is a nationwide program offering a comprehensive high school-based participatory educational program to indirectly address obesity. We tested a hypothesis that the HealthCorps program would decrease BMI z-scores among overweight or obese students, and reduce obesity rates, and evaluated its effects on health knowledge and behaviors. METHODS HealthCorps aimed to improve student knowledge and behaviors regarding nutrition quality, physical activity, sleep, breakfast intake, and mental resilience. Participating students received through HealthCorps coordinators weekly or bi-weekly classroom lessons either for a semester or a year in addition to various during- and after-school health-promoting activities and mentorship. Self-reported height and weight were collected along with questionnaires assessing knowledge and behaviors during 2013-2014 academic year among 14 HealthCorps-participating New York City high schools. This quasi experimental two-arm pre-post trial included 611 HealthCorps and 221 comparison arm students for the analytic sample. Sex-specific analyses stratified by weight status were adjusted for age and Hispanic ethnicity with clustering effects of schools and students taken into account. RESULTS HealthCorps female overweight/obese and obese student had a significant decrease in BMI z-scores (post-pre delta BMI z-score = -0.16 (95%CI = (-0.26, -0.05), p = 0.004 for the former; and = -0.23 (-0.44, -0.03), p = 0.028, for the latter) whereas comparison female counterparts did not. The HealthCorps students, but not the comparison students, had a significant increase for all knowledge domains except for the breakfast realm, and reported a greater number of significant behavior changes including fruit and vegetable intake and physical activities. CONCLUSIONS The HealthCorps program was associated with reduced BMI z-score in overweight/obese and obese female adolescents, with enhanced health knowledge and behavior for both sexes. With its wide reach, this may be a promising program to help combat adolescent obesity in schools. TRIAL REGISTRATION This study is registered as a clinical trial at the ClinicalTrials.gov registry with trial number NCT02277496 on September 10, 2014 (Retrospectively registered).
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Cruciferous Vegetables, Isothiocyanates, and Bladder Cancer Prevention.
Abbaoui, B, Lucas, CR, Riedl, KM, Clinton, SK, Mortazavi, A
Molecular nutrition & food research. 2018;62(18):e1800079
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Worldwide, almost 400,000 cases of bladder cancer are diagnosed each year, with 150,000 deaths, a high rate of recurrence and a high treatment cost. This review article evaluates the literature regarding the potential role of cruciferous vegetables (broccoli, cauliflower, cabbages, pak choi, watercress, wasabi are all examples of cruciferous vegetables) in bladder cancer prevention and as an adjunct to current treatment protocols. In vitro studies have shown inhibition of bladder cancer cell reproduction, stalled cancer cell cycles, and cancer cell death by compounds in cruciferous vegetables, in particular sulphoraphane (known to be high in broccoli and broccoli sprouts) and erucin (available in rocket for example). Studies show an inverse relationship between cruciferous vegetable intake and risk of bladder cancer, with those consuming 2 or more portions per week having a 39% lower risk of bladder cancer than those who consume less than 1 portion per week. The review also looks at cooking method, with steaming, stir-frying and sauteeing protecting the important nutrients when compared to boiling. The authors call for pre-clinical studies to be performed, examining multiple formulations of cruciferous vegetables in a variety of bladder cancer models, looking at prevention in high risk groups and adjuvant to standard treatment protocols. Nutrition Practitioners may want to consider including regular intake of cruciferous vegetables in their client protocols.
Abstract
Bladder cancer is a significant health burden due to its high prevalence, risk of mortality, morbidity, and high cost of medical care. Epidemiologic evidence suggests that diets rich in cruciferous vegetables, particularly broccoli, are associated with lower bladder cancer risk. Phytochemicals in cruciferous vegetables, such as glucosinolates, which are enzymatically hydrolyzed to bioactive isothiocyanates, are possible mediators of an anticancer effect. In vitro studies have shown inhibition of bladder cancer cell lines, cell cycle arrest, and induction of apoptosis by these isothiocyanates, in particular sulforaphane and erucin. Although not yet completely understood, many mechanisms of anticancer activity at the steps of cancer initiation, promotion, and progression have been attributed to these isothiocyanates. They target multiple pathways including the adaptive stress response, phase I/II enzyme modulation, pro-growth, pro-survival, pro-inflammatory signaling, angiogenesis, and even epigenetic modulation. Multiple in vivo studies have shown the bioavailability of isothiocyanates and their antitumoral effects. Although human studies are limited, they support oral bioavailability with reasonable plasma and urine concentrations achieved. Overall, both cell and animal studies support a potential role for isothiocyanates in bladder cancer prevention and treatment. Future studies are necessary to examine clinically relevant outcomes and define guidelines on ameliorating the bladder cancer burden.
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The effect of a short-term low-carbohydrate, high-fat diet with or without postmeal walks on glycemic control and inflammation in type 2 diabetes: a randomized trial.
Myette-Côté, É, Durrer, C, Neudorf, H, Bammert, TD, Botezelli, JD, Johnson, JD, DeSouza, CA, Little, JP
American journal of physiology. Regulatory, integrative and comparative physiology. 2018;315(6):R1210-R1219
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Inflammation is associated with the pathogenesis of insulin resistance, type 2 diabetes (T2D), and related complications. Lifestyle therapy is a frontline treatment for improving glucose control in people with T2D. The main aim of this study was to determine whether reducing hyperglycaemia with a low-carbohydrate high-fat (LC) diet could lower markers of innate immune cell activation and systemic inflammation in people with T2D. A secondary aim was to examine if the combination of an LCHF diet with strategically timed postmeal walking was superior to an LCHF diet alone. The study is a randomised cross over study which enrolled Individuals with physician-diagnosed T2D to complete three short-term controlled-intervention periods. Sixteen participants were enrolled (men = 8 and women = 8) who were aged between 48 and 72 years. Results indicate that while LC and LC together with exercise (LC+Ex) led to superior improvements in glucose control and fasting proinsulin (the pro-hormone precursor to insulin) levels as compared with low-fat low glycaemic index diet (GL), all three diets (GL, LC and LC+Ex), appeared to lower a particular marker of cellular inflammation over the short-term. Authors conclude that an LCHF diet with or without daily postmeal walks improved four-day glycaemic control and fasting proinsulin levels compared with a GL diet.
Abstract
Lowering carbohydrate consumption effectively lowers glucose, but impacts on inflammation are unclear. The objectives of this study were to: 1) determine whether reducing hyperglycemia by following a low-carbohydrate, high-fat (LC) diet could lower markers of innate immune cell activation in type 2 diabetes (T2D) and 2) examine if the combination of an LC diet with strategically timed postmeal walking was superior to an LC diet alone. Participants with T2D ( n = 11) completed a randomized crossover study involving three 4-day diet interventions: 1) low-fat low-glycemic index (GL), 2) and 3) LC with 15-min postmeal walks (LC+Ex). Four-day mean glucose was significantly lower in the LC+Ex group as compared with LC (-5%, P < 0.05), whereas both LC+Ex (-16%, P < 0.001) and LC (-12%, P < 0.001) conditions were lower than GL. A significant main effect of time was observed for peripheral blood mononuclear cells phosphorylated c-Jun N-terminal kinase ( P < 0.001), with decreases in all three conditions (GL: -32%, LC: -45%, and LC+Ex: -44%). A significant condition by time interaction was observed for monocyte microparticles ( P = 0.040) with a significant decrease in GL (-76%, P = 0.035) and a tendency for a reduction in LC (-70%, P = 0.064), whereas there was no significant change in LC+Ex (0.5%, P = 0.990). Both LC (-27%, P = 0.001) and LC+Ex (-35%, P = 0.005) also led to significant reductions in circulating proinsulin. An LC diet improved 4-day glycemic control and fasting proinsulin levels when compared with GL, with added glucose-lowering benefits when LC was combined with postmeal walking.
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Fructose metabolism and metabolic disease.
Hannou, SA, Haslam, DE, McKeown, NM, Herman, MA
The Journal of clinical investigation. 2018;128(2):545-555
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Sugar consumption is thought to be a contributing factor in the increase in diabetes and obesity and the associated risk of cardiovascular disease worldwide. Sucrose (table sugar) and high fructose corn syrup contain almost equal amounts of fructose and glucose and are commonly added to processed foods. Whilst long-term studies are lacking, some short-term intervention studies show that fructose can impair lipid metabolism and insulin sensitivity in humans. This article reviews the biochemistry and molecular genetics of fructose metabolism as well as potential mechanisms by which excessive fructose consumption contributes to cardiometabolic disease. Fructose absorption in the human intestine is saturable, and there is a large range in capacity to absorb fructose between individuals, and unabsorbed fructose may contribute to gastrointestinal symptoms including pain and bloating. Fructose concentrations in the blood can increase 10-fold after consumption, but are rapidly cleared, mostly by the liver, where it provides substrate for metabolic processes, but may also be involved in signalling functions. Fructose may enhance glucose uptake by the liver and storage as glycogen and lipids. It may also increase production of uric acid which is implicated with gout. Excessive fructose consumption affects lipid metabolism and may contribute to fat accumulation in the liver and increase circulating triglycerides, a risk factor for heart disease. In animal models it also induces increased insulin levels. Fructose is one of the sweetest sugars which may affect appetite and overeating. It may also induce addiction-like behaviours such as binging and dependence in part by stimulating dopaminergic pathways. It also appears to induce leptin resistance which further increases food intake and obesity.
Abstract
Increased sugar consumption is increasingly considered to be a contributor to the worldwide epidemics of obesity and diabetes and their associated cardiometabolic risks. As a result of its unique metabolic properties, the fructose component of sugar may be particularly harmful. Diets high in fructose can rapidly produce all of the key features of the metabolic syndrome. Here we review the biology of fructose metabolism as well as potential mechanisms by which excessive fructose consumption may contribute to cardiometabolic disease.
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Anti-Inflammatory Effects of a Vegan Diet Versus the American Heart Association-Recommended Diet in Coronary Artery Disease Trial.
Shah, B, Newman, JD, Woolf, K, Ganguzza, L, Guo, Y, Allen, N, Zhong, J, Fisher, EA, Slater, J
Journal of the American Heart Association. 2018;7(23):e011367
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Inflammation plays a central role in the progression of atherosclerosis and is associated with adverse cardiovascular events. The aim of this study was to determine the effects of a vegan versus American Heart Association (AHA)-recommended diet on high-sensitivity C-reactive protein (hsCRP) [a type of protein found in blood plasma], as well as other markers of inflammation, glucometabolic markers, and lipid profiles in patients with established coronary artery disease (CAD) on guideline-directed medical therapy. This study is a prospective, randomized, open-label, blinded end point study design. The active study duration was 8 weeks, with an interim visit at 4 weeks and a final visit at 8 weeks. Results show: - a significantly greater reduction in hsCRP with a vegan versus AHA-recommended diet in patients with established CAD on guideline-directed medical therapy. - that the degree of weight loss, as measured by both body mass index and waist circumference, did not significantly differ between the 2 diet groups. - that markers of glycaemic control and lipid profiles, overall, also did not significantly differ in the vegan diet group when compared with the AHA-recommended diet group. Authors conclude that in patients with CAD and an elevated hsCRP, despite guideline-directed medical therapy, a vegan diet may be considered to further lower the parameters of inflammation.
Abstract
Background Dietary interventions may play a role in secondary cardiovascular prevention. hsCRP (High-sensitivity C-reactive protein) is a marker of risk for major adverse cardiovascular outcomes in coronary artery disease. Methods and Results The open-label, blinded end-point, EVADE CAD (Effects of a Vegan Versus the American Heart Association-Recommended Diet in Coronary Artery Disease) trial randomized participants (n=100) with coronary artery disease to 8 weeks of a vegan or American Heart Association-recommended diet with provision of groceries, tools to measure dietary intake, and dietary counseling. The primary end point was high-sensitivity C-reactive protein. A linear regression model compared end points after 8 weeks of a vegan versus American Heart Association diet and adjusted for baseline concentration of the end point. Significance levels for the primary and secondary end points were set at 0.05 and 0.0015, respectively. A vegan diet resulted in a significant 32% lower high-sensitivity C-reactive protein (β, 0.68, 95% confidence interval [0.49-0.94]; P=0.02) when compared with the American Heart Association diet. Results were consistent after adjustment for age, race, baseline waist circumference, diabetes mellitus, and prior myocardial infarction (adjusted β, 0.67 [0.47-0.94], P=0.02). The degree of reduction in body mass index and waist circumference did not significantly differ between the 2 diet groups (adjusted β, 0.99 [0.97-1.00], P=0.10; and adjusted β, 1.00 [0.98-1.01], P=0.66, respectively). There were also no significant differences in markers of glycemic control between the 2 diet groups. There was a nonsignificant 13% reduction in low-density lipoprotein cholesterol with the vegan diet when compared with the American Heart Association diet (adjusted β, 0.87 [0.78-0.97], P=0.01). There were no significant differences in other lipid parameters. Conclusions In patients with coronary artery disease on guideline-directed medical therapy, a vegan diet may be considered to lower high-sensitivity C-reactive protein as a risk marker of adverse outcomes. Clinical Trial Registration URL http://www.clinicaltrials.gov . Unique identifier: NCT 02135939.
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High-Dose Vitamin D3 Administration Is Associated With Increases in Hemoglobin Concentrations in Mechanically Ventilated Critically Ill Adults: A Pilot Double-Blind, Randomized, Placebo-Controlled Trial.
Smith, EM, Jones, JL, Han, JE, Alvarez, JA, Sloan, JH, Konrad, RJ, Zughaier, SM, Martin, GS, Ziegler, TR, Tangpricha, V
JPEN. Journal of parenteral and enteral nutrition. 2018;42(1):87-94
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Anaemia is common in critically ill patients and is associated with increased mortality and potentially an extended need for a ventilator. Treatment for anaemia can be invasive and carries a level of risk; therefore further studies on complementary therapies are warranted. Vitamin D has the potential to decrease anaemia through decreasing the production of the iron-regulatory hormone hepcidin. The study aimed to test whether high dose vitamin D would affect haemoglobin concentrations in critically ill patients. In this pilot double-blind randomised control trial, 30 critically ill patients were assigned 250,000 IU vitamin D, 500,000 IU vitamin D or placebo split over 5 doses in 5 days. Blood was taken weekly for up to four weeks and analysed for vitamin D and hepcidin concentrations. Vitamin D concentrations increased significantly in both groups that received vitamin D, compared to no change in the placebo group. Compared to placebo, haemaglobin concentrations significantly increased by 8% in the group receiving 500,000 IU vitamin D but not in the lower dose group. After one week, hepcidin concentrations were significantly decreased in the 500,000 IU vitamin D group, however this was not sustained and no differences between either group and placebo were observed at the end of the study. This did not translate into a reduction in anaemia in either group at any point throughout the study. Extremely high dose vitamin D supplementation was shown to significantly increase circulating vitamin D concentrations and acutely reduce hepcidin. Although anaemia was not affected, clinicians could use this study as an example of safe usage of high dose vitamin D in critically ill patients to improve haemaglobin concentrations, which could reduce the need for invasive treatments, reduce hospital stay duration and treatment costs.
Abstract
BACKGROUND Anemia and vitamin D deficiency are highly prevalent in critical illness, and vitamin D status has been associated with hemoglobin concentrations in epidemiologic studies. We examined the effect of high-dose vitamin D therapy on hemoglobin and hepcidin concentrations in critically ill adults. MATERIALS AND METHODS Mechanically ventilated critically ill adults (N = 30) enrolled in a pilot double-blind, randomized, placebo-controlled trial of high-dose vitamin D3 (D3 ) were included in this analysis. Participants were randomized to receive placebo, 50,000 IU D3 , or 100,000 IU D3 daily for 5 days (totaling 250,000 IU D3 and 500,000 IU D3 , respectively). Blood was drawn weekly throughout hospitalization for up to 4 weeks. Linear mixed-effects models were used to assess change in hemoglobin and hepcidin concentrations by treatment group over time. RESULTS At enrollment, >75% of participants in all groups had plasma 25-hydroxyvitamin D (25(OH)D) concentrations <30 ng/mL, and >85% of participants across groups were anemic. In the 500,000-IU D3 group, hemoglobin concentrations increased significantly over time (Pgroup × time = .01) compared with placebo but did not change in the 250,000-IU D3 group (Pgroup × time = 0.59). Hepcidin concentrations decreased acutely in the 500,000-IU D3 group relative to placebo after 1 week (P = .007). Hepcidin did not change significantly in the 250,000-IU D3 group. CONCLUSION In these critically ill adults, treatment with 500,000 IU D3 was associated with increased hemoglobin concentrations over time and acutely reduced serum hepcidin concentrations. These findings suggest that high-dose vitamin D may improve iron metabolism in critical illness and should be confirmed in larger studies.
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Lifestyle and vascular risk effects on MRI-based biomarkers of Alzheimer's disease: a cross-sectional study of middle-aged adults from the broader New York City area.
Mosconi, L, Walters, M, Sterling, J, Quinn, C, McHugh, P, Andrews, RE, Matthews, DC, Ganzer, C, Osorio, RS, Isaacson, RS, et al
BMJ open. 2018;8(3):e019362
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Alzheimer’s disease (AD) is the most common form of dementia, affecting nearly 34 million people worldwide. It has been estimated that one in every three cases of AD may be attributable to diet and lifestyle factors. The aim of this study was to investigate the effects of lifestyle and vascular-related risk factors for AD. Researchers studied the brain scans of 116 healthy adults aged 30-60 years. They collected information on factors related to lifestyle, such as diet, physical activity and intellectual enrichment. They also looked at markers for vascular risk such as body mass index (BMI), cholesterol and homocysteine, as well as cognitive function. The researchers found that a Mediterranean-style diet and good insulin sensitivity were both associated with a healthier brain structure. A better score for intellectual enrichment and lower BMI were both associated with better cognition. They concluded that adopting a Mediterranean-style diet and maintaining a healthy weight might reduce the risk of developing AD.
Abstract
OBJECTIVE To investigate the effects of lifestyle and vascular-related risk factors for Alzheimer's disease (AD) on in vivo MRI-based brain atrophy in asymptomatic young to middle-aged adults. DESIGN Cross-sectional, observational. SETTING Broader New York City area. Two research centres affiliated with the Alzheimer's disease Core Center at New York University School of Medicine. PARTICIPANTS We studied 116 cognitively normal healthy research participants aged 30-60 years, who completed a three-dimensional T1-weighted volumetric MRI and had lifestyle (diet, physical activity and intellectual enrichment), vascular risk (overweight, hypertension, insulin resistance, elevated cholesterol and homocysteine) and cognition (memory, executive function, language) data. Estimates of cortical thickness for entorhinal (EC), posterior cingulate, orbitofrontal, inferior and middle temporal cortex were obtained by use of automated segmentation tools. We applied confirmatory factor analysis and structural equation modelling to evaluate the associations between lifestyle, vascular risk, brain and cognition. RESULTS Adherence to a Mediterranean-style diet (MeDi) and insulin sensitivity were both positively associated with MRI-based cortical thickness (diet: βs≥0.26, insulin sensitivity βs≥0.58, P≤0.008). After accounting for vascular risk, EC in turn explained variance in memory (P≤0.001). None of the other lifestyle and vascular risk variables were associated with brain thickness. In addition, the path associations between intellectual enrichment and better cognition were significant (βs≥0.25 P≤0.001), as were those between overweight and lower cognition (βs≥-0.22, P≤0.01). CONCLUSIONS In cognitively normal middle-aged adults, MeDi and insulin sensitivity explained cortical thickness in key brain regions for AD, and EC thickness predicted memory performance in turn. Intellectual activity and overweight were associated with cognitive performance through different pathways. Our findings support further investigation of lifestyle and vascular risk factor modification against brain ageing and AD. More studies with larger samples are needed to replicate these research findings in more diverse, community-based settings.
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A spatial gradient of bacterial diversity in the human oral cavity shaped by salivary flow.
Proctor, DM, Fukuyama, JA, Loomer, PM, Armitage, GC, Lee, SA, Davis, NM, Ryder, MI, Holmes, SP, Relman, DA
Nature communications. 2018;9(1):681
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Identifying spatial patterns in the human microbiota is necessary to provide insight into mechanisms that either maintain or disrupt its healthy state. The aim of this study was to identify the type and extent of oral spatial patterns formed by bacterial communities, as well as observe the impact of low salivary flow on the spatial patterns. Dental exams were performed on 31 participants to evaluate the oral health status and follow-up was dependent on group allocation. This study found bacterial communities were distinguishable depending on types of teeth and tissue. Further, bacteria on soft and hard tissues varied across the front and back of the oral cavity in a gradient-manner, implying that salivary flow plays a role in establishing the bacterial community gradient in the oral cavity. Based on these results, the authors recommend spatial patterns and processes be explored in other body parts to better understand health and disease.
Abstract
Spatial and temporal patterns in microbial communities provide insights into the forces that shape them, their functions and roles in health and disease. Here, we used spatial and ecological statistics to analyze the role that saliva plays in structuring bacterial communities of the human mouth using >9000 dental and mucosal samples. We show that regardless of tissue type (teeth, alveolar mucosa, keratinized gingiva, or buccal mucosa), surface-associated bacterial communities vary along an ecological gradient from the front to the back of the mouth, and that on exposed tooth surfaces, the gradient is pronounced on lingual compared to buccal surfaces. Furthermore, our data suggest that this gradient is attenuated in individuals with low salivary flow due to Sjögren's syndrome. Taken together, our findings imply that salivary flow influences the spatial organization of microbial communities and that biogeographical patterns may be useful for understanding host physiological processes and for predicting disease.