In a world where there are more and more dietary alternatives, it is important to study the best options to reduce the health risk and prevent cardiovascular problems. To this end, a group of researchers have conducted a systematic review and meta-analysis of randomised controlled clinical trials, analysing up to seven types of dietary patterns and their relationship with both mortality and cardiovascular risk.
The researchers identified 40 clinical trials that met the criteria, with a total of 35,548 patients and seven types of diet to be analysed: low-fat diet (18 studies), Mediterranean diet (12 studies), very low-fat diet (6 studies), modified fat diet (4 studies), combination of low-fat and low-sodium diet (3 studies), Ornish diet (3 studies) and Pritikin diet (1 study).
The results of the review indicate that the Mediterranean diet is the best option for reducing the risk of overall mortality, cardiovascular and cerebrovascular risk, with moderate evidence of certainty, compared to the other dietary patterns analysed. Low-fat diets were also shown to be superior to the minimal intervention, with low-moderate certainty, with respect to the risk of all-cause mortality, heart attack or stroke.
Importantly, these results were mainly observed in patients who already had a previous elevated cardiovascular risk. In this sense, the effects of these diets could be particularly relevant in the prevention of cardiovascular disease in high-risk populations.
However, it is important to keep in mind the limitations of the study. One of the main limitations is the lack of information on adherence to the diets during the study. In addition, some dietary programmes coexisted with pharmacological treatment and smoking cessation attempts, which could suggest that there are side effects to these interventions and not only due to diet.
Another limitation of the study is that the classifications of dietary programmes specified in its protocol were modified to distinguish standard low-fat programmes, which aim to reduce fat to <30% of caloric intake, from programmes with <20% fat-based caloric intake, which is consistent with other reviews.
In conclusion, the Mediterranean diet and low-fat diets probably reduce the risk of mortality and the risk of non-fatal heart attack in people at increased cardiovascular risk. In addition, the Mediterranean diet in particular also appears to reduce the risk of stroke. These findings need to be taken into account when choosing a healthy diet to reduce the risk of complications associated with cardiovascular disease. However, further research is needed to learn more about the effects of different dietary patterns on cardiovascular health.