Eggs, dietary cholesterol, choline, betaine, and diabetes risk in the Women's Health Initiative: a prospective analysis

Association between egg consumption and risk of obesity: A comprehensive review: EGG CONSUMPTION AND OBESITY

Eggs serve as a vital source of high-quality protein and lipids in the human diet, contributing significantly to nutritional intake; however, the relation between egg intake and health risks has been controversial. This study aimed to assess the relationship between egg intake and obesity and the effects of the various nutrients in eggs on obesity were separately investigated. This review involved searching Scopus, PubMed, Google Scholar for relevant articles from 2002 to 2022. Studies suggested that moderate egg consumption exerts little effect on blood lipid levels, that due to the body regulates endogenous cholesterol production in response to the external cholesterol intake. Furthermore, certain studies also verified that the presence of other nutrients in eggs, such as lecithin, unsaturated fatty acids, and apolipoproteins, not only does not contribute to elevated blood lipids but also plays a role in regulating lipid metabolism to prevent obesity. Additionally, the study reveals that different cooking methods significantly impact the nutritional composition of eggs, with soft-boiled eggs generally being the most advantageous for human health. This article reveals that dietary cholesterol or moderate egg intake was not significantly associated with a higher risk of obesity in healthy adults. Nevertheless, cholesterol-sensitive individuals should ensure moderate cholesterol intake.

Dietary eggs, egg nutrients, polygenic score for body mass index, "Western pattern" diet, and weight change, a prospective analysis in the Women's health initiative

BACKGROUND & AIMS

Eggs contain nutrients which could help enrich the diets of postmenopausal women. Egg consumption and elevated body weight have been associated with elevated risk of serious chronic disease. It is possible that elevated body weight mediates between egg consumption and serious chronic disease. However, few studies exist on the link between egg consumption and body weight in post-menopausal women, and none of them accounted for genetic weight gain predispositions. Our objective was to examine associations between egg consumption, body weight, and genetic predisposition for an elevated Body Mass Index (BMI), in postmenopausal women.

METHODS

We analyzed data from 4439 healthy Women's Health Initiative participants of European descent during a 6-year follow up using multivariable generalized linear mixed models to prospectively evaluate egg and egg-nutrient intake (measured by a food frequency questionnaire) against body weight and a BMI polygenic score (PGS-BMI) derived from GWAS meta-analysis effect-allele frequencies.

RESULTS

We found a positive prospective association between change in egg intake and body weight during the 6-year follow up. For instance, at year 3, women whose intake had increased by 2.0 eggs/week had gained 0.70 kg (95%CI: 0.34, 1.07, p = 0.0002) more than women whose intake had decreased by 2.4 eggs/week, p-linear <0.0001. Cholesterol-intake and choline-intake, but not betaine-intake, showed similar significant associations. Exploratory analysis revealed that: 1) women only demonstrated these significant associations if they exhibited higher intakes of "Western-pattern" foods including processed and red meats, French fries, sweets and deserts, sugar-sweetened beverages, fried foods, and dietary fat, and dietary energy; and 2) there was a significant positive prospective association between PGS-BMI and body-weight change, but only in the top quintile of egg-intake change.

CONCLUSIONS

We found significant positive prospective associations between weight change and changes in egg intake, cholesterol intake, and choline intake among healthy postmenopausal women of European ancestry in the Women's Health Initiative. Exploratory analyses revealed that: 1) these significant associations only obtained among women who ate large amounts of "Western-pattern" foods; and 2) women with a higher genetic susceptibility for an elevated BMI gained more weight only if they increased their egg intake considerably. Our results require confirmation.

Decoding Betaine: A Critical Analysis of Therapeutic Potential Compared with Marketing Hype-A Narrative Review

Research interest in betaine supplementation has surged in recent years, for both enhancing sports performance and treating metabolic conditions. This surge aligns with an expanding market for betaine supplements, which are often marketed as promising aids for a range of metabolic conditions. Despite numerous in vitro and in vivo studies elucidating betaine's involvement in crucial metabolic pathways, consensus remains elusive on its clinical efficacy as a dietary supplement, based on results from randomized controlled trials. One analysis of dietary betaine intake in 28 observational studies showed a mean intake of 182 mg/d of betaine, with the main sources including grain-based foods, baked products, grains, cereals, and vegetables. Analysis of the results from human randomized clinical trials has shown that betaine supplementation improves body composition when combined with physical activity. Additionally, betaine supplementation decreases serum homocysteine levels, but does not affect liver enzymes, triglycerides, or high-density lipoprotein cholesterol levels, although it does increase total cholesterol and low-density lipoprotein cholesterol levels at doses ≥4 g/d. Market analysis has demonstrated that betaine is a popular supplement for supporting various physiological processes, such as digestibility, methylation, physical performance, and liver or cardiovascular health. Manufacturers suggest a diverse range of applications for betaine supplements, with 14 different uses identified. Additionally, high variability can be seen in the recommended usage directions for betaine. This narrative research sheds light on the evolving landscape of betaine supplementation and highlights the need for further investigation to clarify its clinical efficacy.

Choline and betaine intakes during pregnancy in relation to risk of gestational diabetes mellitus among Chinese women

Previous animal studies found beneficial effects of choline and betaine on maternal glucose metabolism during pregnancy, but few human studies explored the association between choline or betaine intake and incident gestational diabetes mellitus (GDM). We aimed to explore the correlation of dietary choline or betaine intake with GDM risk among Chinese pregnant women. A total of 168 pregnant women with GDM cases and 375 healthy controls were enrolled at the Seventh People's Hospital in Shanghai during their GDM screening at 24-28 gestational weeks. A validated semi-quantitative FFQ was used to estimate choline and betaine consumption through face-to-face interviews. An unconditional logistic regression model was adopted to examine OR and 95 % CI. Compared with the controls, those women with GDM incidence were likely to have higher pre-pregnancy BMI, be older, have more parities and have higher plasma TAG and lower plasma HDL-cholesterol. No significant correlation was observed between the consumption of choline or betaine and incident GDM (adjusted OR (95 % CI), 0·77 (0·41, 1·43) for choline; 0·80 (0·42, 1·52) for betaine). However, there was a significant interaction between betaine intake and parity on the risk of GDM (Pfor interaction = 0·01). Among those women with no parity history, there was a significantly inverse correlation between betaine intake and GDM risk (adjusted OR (95 % CI), 0·25 (0·06, 0·81)). These findings indicated that higher dietary betaine intake during pregnancy might be considered a protective factor for GDM among Chinese women with no parity history.

Plant foods, healthy plant-based diets, and type 2 diabetes: a review of the evidence

Type 2 diabetes (T2D) is a metabolic chronic disease in which insulin resistance and insufficient insulin production lead to elevated blood glucose levels. The prevalence of T2D is growing worldwide, mainly due to obesity and the adoption of Western diets. Replacing animal foods with healthy plant foods is associated with a lower risk of T2D in prospective studies. In randomized controlled trials, the consumption of healthy plant foods in place of animal foods led to cardiometabolic improvements in patients with T2D or who were at high risk of the disease. Dietary patterns that limit or exclude animal foods and focus on healthy plant foods (eg, fruits, vegetables, whole grains, nuts, legumes), known as healthy, plant-based diets, are consistently associated with a lower risk of T2D in cohort studies. The aim of this review is to examine the differential effects of plant foods and animal foods on T2D risk and to describe the existing literature about the role of healthy, plant-based diets, particularly healthy vegan diets, in T2D prevention and management. The evidence from cohort studies and randomized controlled trials will be reported, in addition to the potential biological mechanisms that seem to be involved.

One-Carbon Metabolism Nutrients, Genetic Variation, and Diabetes Mellitus

Diabetes mellitus (DM) affects about 9.3% of the population globally. Hyperhomocysteinemia (HHcy) has been implicated in the pathogenesis of DM, owing to its promotion of oxidative stress, β-cell dysfunction, and insulin resistance. HHcy can result from low status of one-carbon metabolism (OCM) nutrients (e.g., folate, choline, betaine, vitamin B6, B12), which work together to degrade homocysteine by methylation. The etiology of HHcy may also involve genetic variation encoding key enzymes in OCM. This review aimed to provide an overview of the existing literature assessing the link between OCM nutrients status, related genetic factors, and incident DM. We also discussed possible mechanisms underlying the role of OCM in DM development and provided recommendations for future research and practice. Even though the available evidence remains inconsistent, some studies support the potential beneficial effects of intakes or blood levels of OCM nutrients on DM development. Moreover, certain variants in OCM-related genes may influence metabolic handling of methyl-donors and presumably incidental DM. Future studies are warranted to establish the causal inference between OCM and DM and examine the interaction of OCM nutrients and genetic factors with DM development, which will inform the personalized recommendations for OCM nutrients intakes on DM prevention.

Dietary Intakes of Choline and Betaine and Incidence of Type 2 Diabetes: Tehran Lipid and Glucose Study

Background: Our knowledge for the possible link between choline and betaine and the risk of type 2 diabetes (T2D) is very limited and contradictory. This study aimed to investigate the prospective association of dietary choline and betaine intakes with the risk of T2D in a group of Tehranian adults. Methods: In this prospective study, 6022 eligible subjects aged ≥18 years were chosen from the participants of the Tehran Lipid and Glucose Study in a secondary analysis. Diet was assessed based on a valid and reliable semiquantitative food frequency questionnaire. At baseline and follow-up examinations, biochemical and anthropometric variables were assessed. Multivariable Cox proportional hazard regression models was used to estimate the new onset of T2D concerning choline and betaine intake. Results: The mean age ± SD of 2707 men and 3315 women were, respectively, 41.4 ± 14.2 and 39.1 ± 13.1. During a median follow-up of 6.63 years, 528 cases of T2D incidence were diagnosed. Participants with a higher intake of choline had a higher intake of protein, fiber, and B12 and a lower intake of energy and carbohydrates. After controlling of confounders a significant positive association was observed between choline intake and the hazard ratio (HR) of T2D across quartiles of choline intake [HR (CI) in the fourth quartile: 1.25 (1.14-1.38), P trend = 0.01], but this significant finding was not reported for betaine intake. For every 100 milligram increase in choline consumption, the HR of T2D increased significantly in all age, sex, and BMI subgroups. Conclusions: Choline consumption increased the risk of T2D in total population and subgroups. No statistically significant association was found between dietary betaine intake and the risk of T2D in total population and subgroups.

Dietary cholesterol consumption and incidence of type 2 diabetes mellitus: A dose-response meta-analysis of prospective cohort studies

BACKGROUND AND AIM

The purpose of this meta-analysis was to evaluate the dose-response relationship between dietary cholesterol (DC) consumption and the incidence of type 2 diabetes mellitus (T2DM).

METHODS AND RESULTS

Prospective studies with the endpoint of T2DM were included. The Random-effect model weighted by inverse variance was used. Meta-regression and subgroup analyses were conducted to explore the potential sources of heterogeneity by specified study characteristics. Restricted cubic splines regression models were used to estimate the dose-response relationship. 11 prospective studies comprising of 355 230 subjects were included. Compared to lowest DC consumption, highest DC consumption was associated with an increased risk of T2DM (RR 1.15, 95% CI 1.03 to 1.28, P = 0.012; chi-squared = 31.41, I-squared 58.6%, P _{heterogeneity} = 0.003). Subgroup analyses have shown that this positive association was more evident in western countries than in eastern countries (RR 1.19, 95% CI 1.06 to 1.36 VS 1.34, 95% CI 0.84 to 1.29; P _{subgroup difference} = 0.02). For 100 mg/d increment in DC intake, the pooled RR was 1.05, (95% CI 1.04 to 1.07, P_linearity = 0.000, P_nonlinearity = 0.02), 1.06 (95% CI 1.04 to 1.07, P_linearity=0.000), and 1.01 (95% CI 0.98 to 1.05, P_linearity = 0.525) for the incidence of T2DM, in western and eastern countries, respectively.

CONCLUSIONS

Our study suggests that there is a positive dose-response association between DC consumption and the incidence of T2DM, especially in western countries.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42020216318.

The association of egg consumption with blood pressure levels and glycated hemoglobin in Spanish adults according to body mass index

The objective of this study was to evaluate the association of egg consumption with blood pressure (BP) and glycated hemoglobin (HbA1c). In addition, it was assessed whether this association changes according to body weight status. This cross-sectional study is based on multicenter data from Spanish adult participants in the EVIDENT II trial. Egg consumption was assessed with a Food Frequency Questionnaire, and data on BP and HbA1c were collected using standardized procedures. Linear regression and ANCOVA models adjusted for the main confounders were performed. The analyses were stratified by body weight status. A total of 668 participants were analyzed (mean age 52.4 ± 11.8 years, 62.3% women). Compared with lower consumption, higher egg consumption was associated with lower systolic (ß =  - 6.15 ± 1.74; p-for-trend = 0.017), diastolic (ß =  - 4.41 ± 1.03; p-for-trend = 0.002), and mean arterial pressure (ß =  - 4.99 ± 1.17; p-for-trend = 0.003) and with lower HbA1c (ß =  - 0.19 ± 0.06; p-for-trend = 0.019) levels. These associations lost statistical significance in the adjusted analyses. The results did not vary by body weight status. In conclusion, consumption of up to 1 egg per day is not associated with BP or HbA1c, even in overweight or obese individuals. Our findings suggested that this frequency of egg consumption is safe as part of a healthy diet and lifestyle for cardiometabolic risk.