Deep dive to the secrets of the PREDIMED trial

Mediterranean Diet and Cardiovascular Prevention: Why Analytical Observational Designs Do Support Causality and Not Only Associations

Causal reductions in cardiovascular disease (CVD) with the Mediterranean diet (MedDiet) are supported by randomized trials, but the ability of nonrandomized studies to provide causal inferences in nutritional epidemiology is questioned. The "Seguimiento Universidad de Navarra" (SUN) project, conducted during 1999-2019 with 18,419 participants, was used to try to refute non-causal explanations for the inverse association found between adherence to the MedDiet and reduced CVD risk. A framework of different analytical strategies is proposed: alternative definitions of the exposure, exploration of residual confounding, resampling methods, depiction of absolute risks across the follow-up period, trial emulation, and negative controls. Additionally, we calculated the rate advancement period (RAP). We found that one standard deviation increase in the most frequently used MedDiet score was associated with a 29% relative reduction in CVD risk (95% Confidence Interval [CI] 14-41%), which is almost identical to that found in 2 randomized trials. The RAP of CVD would be postponed by an average of 7.9 years (95% CI: 1.6 to 14.2 years) by switching from low (MDS = 0 to2) to high (MDS = 7 to 9) adherence to the MedDiet in the fully adjusted model. Sensitivity analyses, graphical representations of absolute risks, trial emulation, and negative controls also supported causality. In conclusion, a framework of analytical approaches supported the causal effect of the MedDiet on CVD prevention using observational data. Similar methodology could be applied for causal inferences regarding other hypotheses.

Association of ideal cardiovascular health with cardiovascular events and risk advancement periods in a Mediterranean population-based cohort

BACKGROUND

The American Heart Association recommends Life's Simple 7 as ideal cardiovascular health (ICVH) to reduce cardiovascular risk. Rate advancement period (RAP), a useful tool to quantify and communicate exposure impact on risks, may enhance communication about the benefits of achieving ICVH. We aimed to examine whether greater adherence to ICVH metrics was associated with reduced incidence of cardiovascular risk in a population-based cohort and estimate its impact on the timing of occurrence using RAP.

METHODS

Prospective analyses of 3826 participants, initially free from cardiovascular disease at baseline, enrolled in the Vascular Risk in Navarra Study (RIVANA), a Mediterranean population-based cohort of Spanish adults. ICVH metrics were defined using participants' baseline information as follows: never-smoker or quitting > 12 months ago, body mass index < 25 kg/m², ≥ 150 min/week of moderate physical activity or equivalent, healthy dietary pattern (≥ 9 points on a validated 14-item Mediterranean diet adherence screener), untreated cholesterol < 200 mg/dL, untreated blood pressure < 120/80 mmHg, and untreated fasting blood glucose < 100 mg/dL. Participants were assigned 1 point for each achieved metric and were grouped according to their number of accumulated metrics in ≤ 2, 3, 4, and ≥ 5. The primary endpoint was major cardiovascular events (composite of myocardial infarction, stroke, or death from cardiovascular causes). Cox proportional hazard ratios (HRs) and RAPs with their corresponding 95% confidence intervals (95% CI) adjusted for potential confounders were calculated.

RESULTS

During a median follow-up of 12.8 years (interquartile range 12.3-13.1), a total of 194 primary endpoints were identified. Compared to participants with ≤ 2 ideal metrics, HR (95% CI) for major cardiovascular events among participants meeting ≥ 5 metrics was 0.32 (0.17-0.60) with RAP (95% CI) of - 14.4 years (- 22.9, - 5.9).

CONCLUSIONS

Greater adherence to ICVH metrics was associated with lower cardiovascular risk among Spanish adults of the RIVANA cohort. Adherence to ideal metrics may substantially delay cardiovascular risk.

Women's health: optimal nutrition throughout the lifecycle

Sex differences are an important consideration when researching and establishing policies for nutrition and optimal health. For women's health, there are important physiologic, neurologic, and hormonal distinctions throughout the lifecycle that impact nutritional needs. Distinct from those for men, these nutritional needs must be translated into appropriate nutrition policy that aims to not only avoid overt nutritional deficiency, but also to promote health and minimize risk for chronic disease. Through a series of webinars, scientific experts discussed the advances in the understanding of the unique nutritional needs, challenges and opportunities of the various life stages for women across the life course and identified emerging nutritional interventions that may be beneficial for women. Nevertheless, there is concern that existing nutrition policy intended for women's health is falling short with examples of programs that are focused more on delivering calories than achieving optimal nutrition. To be locally effective, targeted nutrition needs to offer different proposals for different cultural, socio-economic, and geographic communities, and needs to be applicable at all stages of growth and development. There must be adequate access to nutritious foods, and the information to understand and implement proven nutritional opportunities. Experts provided recommendations for improvement of current entitlement programs that will address accessibility and other social and environmental issues to support women properly throughout the lifecycle.

Factors associated with successful dietary changes in an energy-reduced Mediterranean diet intervention: a longitudinal analysis in the PREDIMED-Plus trial

Purpose

Long-term nutrition trials may fail to respond to their original hypotheses if participants do not comply with the intended dietary intervention. We aimed to identify baseline factors associated with successful dietary changes towards an energy-reduced Mediterranean diet (MedDiet) in the PREDIMED-Plus randomized trial.

Methods

Longitudinal analysis of 2985 participants (Spanish overweight/obese older adults with metabolic syndrome) randomized to the active intervention arm of the PREDIMED-Plus trial. Dietary changes were assessed with a 17-item energy-reduced MedDiet questionnaire after 6 and 12 months of follow-up. Successful compliance was defined as dietary changes from baseline of ≥ 5 points for participants with baseline scores < 13 points or any increase if baseline score was ≥ 13 points. We conducted crude and adjusted multivariable logistic regression models to identify baseline factors related to compliance.

Results

Consistent factors independently associated with successful dietary change at both 6 and 12 months were high baseline perceived self-efficacy in modifying diet (OR_6-month: 1.51, 95% CI 1.25–1.83; OR_12-month: 1.66, 95% CI 1.37–2.01), higher baseline fiber intake (OR_6-month: 1.62, 95% CI 1.07–2.46; OR_12-month: 1.62, 95% CI 1.07–2.45), having > 3 chronic conditions (OR_6-month: 0.65, 95% CI 0.53–0.79; OR_12-month: 0.76, 95% CI 0.62–0.93), and suffering depression (OR_6-month: 0.80, 95% CI 0.64–0.99; OR_12-month: 0.71, 95% CI 0.57–0.88).

Conclusion

Our results suggested that recruitment of individuals with high perceived self-efficacy to dietary change, and those who initially follow diets relatively richer in fiber may lead to greater changes in nutritional recommendations. Participants with multiple chronic conditions, specifically depression, should receive specific tailored interventions.

Trial registration

ISRCTN registry 89898870, 24th July 2014 retrospectively registered http://www.isrctn.com/ISRCTN89898870.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00394-021-02697-8.

Persistent Moderate-to-Weak Mediterranean Diet Adherence and Low Scoring for Plant-Based Foods across Several Southern European Countries: Are We Overlooking the Mediterranean Diet Recommendations?

The Mediterranean diet (MD) has been sponsored worldwide as a healthy and sustainable diet. Our aim was to update and compare MD adherence and food choices across several Southern European countries: Spain (SP), Portugal (PT), Italy (IT), Greece (GR), and Cyprus (CY) (MED, Mediterranean), and Bulgaria (BG) and the Republic of North Macedonia (NMK) (non-MED, non-Mediterranean). Participants (N = 3145, ≥18 y) completed a survey (MeDiWeB) with sociodemographic, anthropometric, and food questions (14-item Mediterranean Diet Adherence Screener, 14-MEDAS). The MED and non-MED populations showed moderate (7.08 ± 1.96) and weak (5.58 ± 1.82) MD adherence, respectively, with significant yet small differences across countries (SP > PT > GR > IT > CY > BG > NMK, p-value < 0.001). The MED participants scored higher than the non-MED ones for most of the Mediterranean-typical foods, with the greatest differences found for olive oil (OO) and white meat preference. In most countries, ≥70% of the participants reported quantities of red meat, butter, sweet drinks, and desserts below the recommended cutoff points, whereas <50% achieved the targets for plant-based foods, OO, fish, and wine. Being a woman and increasing age were associated with superior adherence (p-value < 0.001), but differences were rather small. Our results suggest that the campaigns carried out to support and reinforce the MD and to promote plant-based foods have limited success across Southern Europe, and that more hard-hitting strategies are needed.