Dried fruit intake and lower risk of type 2 diabetes: a two-sample mendelian randomization study
Background: Previous studies have shown controversy about whether dried fruit intake is associated with type 2 diabetes. This study aimed to examine the potential causal effect of dried fruit intake on type 2 diabetes by conducting a two-sample Mendelian randomization study. Methods: We used genome-wide association study (GWAS) summary statistics for MR analysis to explore the causal association of dried fruit intake with T2D. The inverse-variance weighted (IVW) method was used as the main analytical method for MR analysis. In addition, the MR-Egger method and the weighted median method were applied to supplement the IVW method. Furthermore, Cochrane's Q test, MR-Egger intercept test, and leave-one-out analysis were used to perform sensitivity analysis. The funnel plot was used to assess publication bias. Results: The results from the IVW analysis indicated that dried fruit intake could reduce the risk of T2D [odds ratio (OR) = 0.392, 95% confidence interval (CI): 0.241-0.636, p-value = 0.0001]. In addition, the result of additional method Weighted median is parallel to the effects estimated by IVW. Furthermore, the sensitivity analysis illustrates that our MR analysis was unaffected by heterogeneity and horizontal pleiotropy. Finally, the results of the leave-one-out method showed the robustness of our MR results. And the funnel plot shows a symmetrical distribution. Conclusion: Our study provides evidence for the benefits of dried fruit intake on T2D. Therefore, a reasonable consumption of dried fruit may provide primary prevention. https://doi.org/10.1186/s12986-024-00813-z
Effectiveness of date seed on glycemia and advanced glycation end-products in type 2 diabetes: a randomized placebo-controlled trial
Background: Type 2 diabetes mellitus (T2DM) is a chronic medical condition affecting more than 95% of people with diabetes. Traditionally, some medicinal plants have been considered as an effective approach in management of T2DM. This trial evaluated the effects of date seed powder (DSP) on glycemia indices and oxidative stress in T2DM patients. Methods: In this trail, 43 patients with T2DM were randomized to two groups: either 5 g/d of the DSP or placebo for 8 weeks. Levels of glycemic indices, lipolpolysaccharide (LPS), and soluble receptor for advanced glycation end products (s-RAGE), as well as other parameters associated with oxidative stress were assessed at baseline and after 8 weeks. Independent t-test and analysis of covariance (ANCOVA) were used for between-groups comparisons at baseline and the post-intervention phase, respectively. Results: The results showed that supplementation with DSP significantly decreased HbA1c (-0.30 ± 0.48%), insulin (-1.70 ± 2.21 μU/ml), HOMA-IR (-1.05 ± 0.21), HOMA-B (-0.76 ± 21.21), lipopolysaccharide (LPS) (-3.68 ± 6.05 EU/mL), and pentosidine (118.99 ± 21.67 pg/mL) (P < 0.05, ANCOVA adjusted for baseline and confounding factors). On the other hand, DSP supplementation significantly increased total antioxidant capacity (TAC) (0.50 ± 0.26 mmol/L), superoxide dismutase (SOD) (0.69 ± 0.32 U/ml), and s-RAGE (240.13 ± 54.25 pg/mL) compared to the placebo group. FPG, hs-CRP, GPx, CML, and uric acid had no significant within- or between-group changes. Conclusion: Supplementation of DSP could be considered an effective strategy to improve glycemic control and oxidative stress in T2DM patients (Registration ID at www.irct.ir: IRCT20150205020965N10). https://doi.org/10.1038/s41387-024-00287-1
Brazil nut consumption reduces DNA damage in overweight type 2 diabetes mellitus patients
Type 2 diabetes mellitus (T2D) is a metabolic disease, which occurs largely due to unhealthy lifestyle. As oxidative stress is believed to promote T2D, by inducing damage to lipids, proteins, and DNA, appropriate dietary interventions seem critical to prevent, manage, and even reverse this condition. Brazil nuts (Bertholletia excelsa, H.B.K.) are nature's richest source of selenium, a mineral that has shown several health benefits. Therefore, this study aims to assess the effects of selenium consumption, through Brazil nuts, on biochemical and oxidative stress parameters, and genomic instability in T2D patients. We recruited 133 patients with T2D, registered in the Integrated Clinics of the University of Southern Santa Catarina (Brazil). Participants consumed one Brazil nut a day for six months. Blood samples and exfoliated buccal cells were collected at the beginning and the end of the intervention. The glycemic profile, lipid profile, renal profile and hepatic profile, DNA damage and selenium content were evaluated. A total of 74 participants completed the intervention. Brazil nut consumption increased selenium and GSH levels, GPx, and CAT activity while DCF and nitrites levels decreased. Total thiols increased, and protein carbonyl and MDA levels decreased. Levels of baseline and oxidative DNA damage in T2D patients were significantly decreased, as well as the frequency of micronuclei and nuclear buds. The fasting glucose levels, HDL and LDL cholesterol, and GGT levels that increased significantly in patients with type 2 diabetes were significantly reduced with nut consumption. Our results show an increase in antioxidant activity, along with reductions of protein and lipid oxidation as well as DNA damage, suggesting that Brazil nut consumption could be an ally in reducing oxidative stress and modulating the genomic instability in T2D patients.
https://doi.org/10.1016/j.mrgentox.2024.503739
https://doi.org/10.1016/j.tjnut.2024.03.012
Red meat intake and risk of type 2 diabetes in a prospective cohort study of United States females and males
Background: Studies with methodological advancements are warranted to confirm the relation of red meat consumption to the incidence of type 2 diabetes (T2D). Objective: We aimed to assess the relationships of intakes of total, processed, and unprocessed red meat to risk of T2D and to estimate the effects of substituting different protein sources for red meats on T2D risk. Methods: Our study included 216,695 participants (81% females) from the Nurses' Health Study (NHS), NHS II, and Health Professionals Follow-up Study (HPFS). Red meat intakes were assessed with semiquantitative food frequency questionnaires (FFQs) every 2 to 4 y since the study baselines. We used multivariable-adjusted proportional hazards models to estimate the associations between red meats and T2D. Results: Over 5,483,981 person-years of follow-up, we documented 22,761 T2D cases. Intakes of total, processed, and unprocessed red meat were positively and approximately linearly associated with higher risks of T2D. Comparing the highest to the lowest quintiles, hazard ratios (HR) were 1.62 (95% confidence interval [CI]: 1.53, 1.71) for total red meat, 1.51 (95% CI: 1.44, 1.58) for processed red meat, and 1.40 (95% CI: 1.33, 1.47) for unprocessed red meat. The percentage lower risk of T2D associated with substituting 1 serving/d of nuts and legumes for total red meat was 30% (HR = 0.70, 95% CI: 0.66, 0.74), for processed red meat was 41% (HR = 0.59, 95% CI: 0.55, 0.64), and for unprocessed red meat was 29% (HR = 0.71, 95% CI: 0.67, 0.75); Substituting 1 serving/d of dairy for total, processed, or unprocessed red meat was also associated with significantly lower risk of T2D. The observed associations became stronger after we calibrated dietary intakes to intakes assessed by weighed diet records. Conclusions: Our study supports current dietary recommendations for limiting consumption of red meat intake and emphasizes the importance of different alternative sources of protein for T2D prevention. https://doi.org/10.1016/j.ajcnut.2023.08.021
The Portfolio Diet and Incident Type 2 Diabetes: Findings From the Women's Health Initiative Prospective Cohort Study
Objective: A plant-based dietary pattern, the Portfolio Diet, has been shown to lower LDL cholesterol and other cardiovascular disease risk factors. However, no study has evaluated the association of this diet with incident type 2 diabetes. Research design and methods: This analysis included 145,299 postmenopausal women free of diabetes at baseline in the Women's Health Initiative (WHI) Clinical Trials and Observational Study from 1993 to 2021. Adherence to the diet was assessed with a score based on six components (high in plant protein [soy and pulses], nuts, viscous fiber, plant sterols, and monounsaturated fat and low in saturated fat and cholesterol) determined from a validated food-frequency questionnaire. We used Cox proportional hazards models to estimate hazard ratios (HRs) and 95% CIs of the association of the Portfolio Diet, alongside the Dietary Approaches to Stop Hypertension (DASH) and Mediterranean diets, with incident type 2 diabetes, with adjustment for potential confounders. Results: Over a mean follow-up of 16.0 years, 13,943 cases of incident type 2 diabetes were identified. In comparisons of the highest with the lowest quintiles of adherence, the HRs for risk of incident type 2 diabetes were 0.77 (95% CI 0.72, 0.82) for the Portfolio Diet, 0.69 (0.64, 0.73) for the DASH diet, and 0.78 (0.74, 0.83) for the Mediterranean diet. These findings were attenuated by 10% after additional adjustment for BMI. Conclusions: Greater adherence to the plant-predominant Portfolio, DASH, and Mediterranean diets was prospectively associated with lower risk of type 2 diabetes in postmenopausal women. https://doi.org/10.2337/dc22-1029
Red meat intake and risk of type 2 diabetes in a prospective cohort study of United States females and males
Background: Studies with methodological advancements are warranted to confirm the relation of red meat consumption to the incidence of type 2 diabetes (T2D). Objective: We aimed to assess the relationships of intakes of total, processed, and unprocessed red meat to risk of T2D and to estimate the effects of substituting different protein sources for red meats on T2D risk. Methods: Our study included 216,695 participants (81% females) from the Nurses’ Health Study (NHS), NHS II, and Health Professionals Follow-up Study (HPFS). Red meat intakes were assessed with semiquantitative food frequency questionnaires (FFQs) every 2 to 4 y since the study baselines. We used multivariable-adjusted proportional hazards models to estimate the associations between red meats and T2D. Results: Over 5,483,981 person-years of follow-up, we documented 22,761 T2D cases. Intakes of total, processed, and unprocessed red meat were positively and approximately linearly associated with higher risks of T2D. Comparing the highest to the lowest quintiles, hazard ratios (HR) were 1.62 (95% confidence interval [CI]: 1.53, 1.71) for total red meat, 1.51 (95% CI: 1.44, 1.58) for processed red meat, and 1.40 (95% CI: 1.33, 1.47) for unprocessed red meat. The percentage lower risk of T2D associated with substituting 1 serving/d of nuts and legumes for total red meat was 30% (HR = 0.70, 95% CI: 0.66, 0.74), for processed red meat was 41% (HR = 0.59, 95% CI: 0.55, 0.64), and for unprocessed red meat was 29% (HR = 0.71, 95% CI: 0.67, 0.75); Substituting 1 serving/d of dairy for total, processed, or unprocessed red meat was also associated with significantly lower risk of T2D. The observed associations became stronger after we calibrated dietary intakes to intakes assessed by weighed diet records. Conclusions: Our study supports current dietary recommendations for limiting consumption of red meat intake and emphasizes the importance of different alternative sources of protein for T2D prevention. https://doi.org/10.1016/j.ajcnut.2023.08.021
Yearly attained adherence to Mediterranean diet and incidence of diabetes in a large randomized trial
Background: Several large observational prospective studies have reported a protection by the traditional Mediterranean diet against type 2 diabetes, but none of them used yearly repeated measures of dietary intake. Repeated measurements of dietary intake are able to improve subject classification and to increase the quality of the assessed relationships in nutritional epidemiology. Beyond observational studies, randomized trials provide stronger causal evidence. In the context of a randomized trial of primary cardiovascular prevention, we assessed type 2 diabetes incidence according to yearly repeated measures of compliance with a nutritional intervention based on the traditional Mediterranean diet. Methods: PREDIMED (''PREvención con DIeta MEDiterránea'') was a Spanish trial including 7447 men and women at high cardiovascular risk. We assessed 3541 participants initially free of diabetes and originally randomized to 1 of 3 diets: low-fat diet (n = 1147, control group), Mediterranean diet supplemented with extra virgin olive (n = 1154) or Mediterranean diet supplemented with mixed nuts (n = 1240). As exposure we used actual adherence to Mediterranean diet (cumulative average), yearly assessed with the Mediterranean Diet Adherence Screener (scoring 0 to 14 points), and repeated up to 8 times (baseline and 7 consecutive follow-up years). This score was categorized into four groups: < 8, 8-< 10, 10- < 12, and 12-14 points. The outcome was new-onset type 2 diabetes. Results: Multivariable-adjusted hazard ratios from time-varying Cox models were 0.80 (95% confidence interval, 0.70-0.92) per + 2 points in Mediterranean Diet Adherence Screener (linear trend p = .001), and 0.46 (0.25-0.83) for the highest (12-14 points) versus the lowest (< 8) adherence. This inverse association was maintained after additionally adjusting for the randomized arm. Age- and sex-adjusted analysis of a validated plasma metabolomic signature of the Mediterranean Diet Adherence Screener (constituted of 67 metabolites) in a subset of 889 participants also supported these results. Conclusions: Dietary intervention trials should quantify actual dietary adherence throughout the trial period to enhance the benefits and to assist results interpretation. A rapid dietary assessment tool, yearly repeated as a screener, was able to capture a strong inverse linear relationship between Mediterranean diet and type 2 diabetes. Trial registration ISRCTN35739639. https://doi.org/10.1186/s12933-023-01994-2
Associations of Nut Consumption with All-Cause Mortality among Individuals with Type 2 Diabetes
Background: Nuts are energy-dense, high-fat foods, and whether nut consumption influences mortality risk among individuals with type 2 diabetes (T2D) remains unclear. Objectives: This study aimed to investigate the associations of nut consumption with all-cause mortality among adults with T2D and to further explore the potential mediation effects of cardiometabolic biomarkers. Methods: The current analysis included 5090 US participants with T2D from the National Health and Nutrition Examination Survey (1999–2014). Cox proportional hazards models were conducted to estimate hazard ratio (HR) and 95% confidence interval (CI). Results: After 35,632 person-y of follow-up, 1174 deaths were documented. Higher nut consumption was significantly associated with a lower risk of all-cause mortality among individuals with T2D. After multivariable adjustment including lifestyles and dietary factors, diabetes duration, and glycated hemoglobin, compared with participants who did not consume nuts, the HR (95% CI) for those who consumed nuts over 3.5 ounce equivalent (oz.eq)/wk was 0.64 (0.50, 0.82; P-trend < 0.001) for all-cause mortality. A linear dose–response relationship was observed between nut consumption and all-cause mortality among individuals with T2D (Poverall=0.004, Pnonlinearity=0.35). In substitution analyses, replacing one serving of red and processed meat, refined grains, eggs, and dairy foods with one serving of nuts was associated with a 18% to 22% lower risk of all-cause mortality. In addition, mediation analysis suggested that C-reactive protein and γ-glutamine transaminase explained 6.7% and 9.1% of the relationship between nut consumption with all-cause mortality, respectively. Conclusions: Higher nut consumption was significantly associated with lower all-cause mortality among individuals with T2D. These findings indicate a potential benefit of nut consumption in the prevention of premature death among individuals with T2D.
https://doi.org/10.1016/j.tjnut.2023.08.004
The effects of long-term almond consumption on whole-body insulin sensitivity, postprandial glucose responses, and 48 h continuous glucose concentrations in males and females with prediabetes: a randomized controlled trial
Purpose: Findings concerning the effects of almond consumption on glucose metabolism are inconsistent which might relate to body weight gain. The effects of long-term almond consumption on glucose metabolism are investigated in a free-living setting without detailed dietary instructions in males and females with overweight/obesity and prediabetes. Methods: Forty-three participants volunteered in this randomized, cross-over trial with a 5-months control and intervention period and a 2-months wash-out. In the intervention period participants daily consumed 50 g whole almonds. At the end of both periods’ insulin sensitivity was assessed by a hyperinsulinemic euglycemic clamp, and postprandial glucose responses, and 48 h continuous glucose concentrations were measured. Results: Almond consumption significantly decreased insulin sensitivity (P = 0.002), and increased postprandial glucose concentrations (P = 0.019), as well as fasting insulin concentrations (P = 0.003) as compared to the control period. The AUCs for 24 h glucose concentrations were not significantly different between control and intervention (P = 0.066). Almond consumption also significantly increased BMI (P = 0.002), and waist circumference (P = 0.013), supported by the concurrent increased energy intake (P = 0.031). The effects on glucose metabolism could only partly be explained by the observed weight gain as the almond effect remained after correcting for BMI changes. Conclusions: In participants with prediabetes, long-term almond consumption showed adverse effects on insulin sensitivity and glucose metabolism. As almonds seemed not to have fully replaced other food items, it might be necessary to provide more supporting guidelines on how to incorporate energy-dense nuts into healthy diets to prevent type 2 diabetes development. https://doi.org/10.1007/s00394-023-03178-w