Mediterranean diet significantly lowers heart failure risk, especially in women

A new meta-analysis reveals that sticking to the Mediterranean diet can reduce heart failure risk, with stronger benefits for women. Could the power of anti-inflammatory foods be the key to heart health?

Study: Effect of the Mediterranean diet on incidence of heart failure in European countries: a systematic review and meta-analysis of cohort studies. Image Credit: leonori / Shutterstock

In a recent study published in the European Journal of Clinical Nutrition, researchers investigated the relationship between the Mediterranean diet (Med Diet) and heart failure (HF) risk in European countries. They found that increased adherence to the Med Diet was associated with a significantly reduced risk of HF, especially in women.

Background

Cardiovascular disease (CVD) is a major cause of mortality worldwide, contributing to rising hospitalizations and economic burden. HF, a common CVD, is associated with poor survival rates, with about 50% of patients surviving five years post-diagnosis. Its prevalence increases with age, affecting up to 20% of people over 80. Given these outcomes, effective prevention strategies are crucial to reducing HF incidence and improving patient outcomes.

The Med Diet has been linked to reduced all-cause mortality and cardiovascular risk, including in patients with HF. However, evidence from observational studies on its role in HF prevention remains limited. Previous research, including a major clinical trial, showed mixed results regarding its effectiveness in lowering HF risk. A prior meta-analysis also had limitations, such as including few studies and combining observational and randomized controlled trials, leading to questions about its conclusions. Therefore, researchers performed a systematic review and meta-analysis of observational studies conducted across European countries to update the current evidence on the impact of the Med Diet on HF risk.

About the study

In the present study, two independent reviewers searched PubMed, Web of Science, Scopus, and the Cochrane Library for relevant studies up to May 2023. Inclusion criteria focused on prospective or retrospective cohort studies of adults without HF at baseline. The preliminary literature search identified 682 publications. Letters, reviews, experimental studies, commentaries, or studies with participants under 18 were excluded. The final analysis included six prospective studies involving nine independent cohorts across Europe, totaling 216,385 adults without HF at baseline. The study population was 54.7% female, and the mean follow-up was 11 years.

Data extraction and bias assessment were independently conducted, with disagreements resolved by a third reviewer. Study quality was evaluated using the Newcastle-Ottawa scale. The primary analysis used risk ratios (RR) to compare HF incidence based on adherence to the Med Diet, with a random effects model used to assess statistical significance. Heterogeneity and publication bias were assessed. An increase of one point in the Med Diet score was used to harmonize the data.

Results and discussion

A total of 6,978 participants developed HF (cumulative incidence 3%). The analysis revealed that a one-point increase in Med Diet adherence was significantly associated with a lower HF risk (RR = 0.940, p < 0.0001), with no evidence of publication bias. The positive association was more pronounced in women (RR = 0.942, p = 0.001), while no significant association was found in men. This sex-specific difference may be due to several factors, including hormonal differences that could influence how dietary components affect cardiovascular health. Prior studies have shown that women tend to benefit more from anti-inflammatory and antioxidant effects, both of which are key properties of the Med Diet. The results of the sensitivity analysis corroborated the main findings. The overall study quality was found to be good, though the most common bias was inadequate follow-up reporting. One study was found to be of lower quality as it was presented only as an abstract.

According to the study, the protective effects of the Med Diet may be attributed to its anti-inflammatory and antioxidant properties, which help lower inflammation and oxidative stress, both key factors in CVD and HF. For example, research has shown that the Med Diet can lower levels of specific biomarkers like NT-proBNP, a marker linked to heart failure. The diet also reduces inflammatory cytokines such as TNF-α, which are elevated in HF patients. Furthermore, its beneficial effects on glucose metabolism, insulin resistance, and lipid levels contribute to reducing heart failure risk. While the findings align with previous literature, the present study’s limitations include limited European-only studies, potential declines in Med Diet adherence, outdated dietary assessments, lack of follow-up on dietary changes, and observational design biases. Further research is needed to confirm these findings and explore the potential clinical applicability of the Med Diet.

Conclusion

In conclusion, the study found that higher adherence to the Med Diet is linked to a significantly lower risk of HF, especially in women. This sex-specific finding may indicate that women experience stronger cardiovascular benefits from the Med Diet due to differences in metabolic responses and hormone levels. These findings emphasize the importance of lifestyle and diet in heart health, offering a potential strategy for prevention that could guide future dietary recommendations and public health initiatives. Further interventional studies are needed to explore the long-term effects of the Med Diet on HF and related outcomes.