The Mediterranean diet (MedDiet) is based on ample consumption of healthy foods such as vegetables, fruits, legumes, whole grains, fruit, fish, moderate alcohol and olive oil. The MedDiet pattern has been associated with reduced cardiovascular disease (CVD) outcomes in both epidemiological studies and clinical trials. Therefore, many health authorities recommend the consumption of more vegetables, fruit, whole grains and fish. It’s also a common assumption that ingredients associated with a Western dietary pattern may cause more adverse effects. Therefore, the decreased consumption of processed foods that contain refined carbohydrates, sugar, sodium, and saturated fats are also recommended.
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Though it’s assumed that a healthy diet is beneficial for patients who already have coronary heart disease (CHD), very little research has established any associated outcomes. Because diet is rarely assessed in a clinical situation, it is important to understand if dietary pattern assessment during routine clinical care could also be considered a potent secondary prevention strategy that deserves more attention.
A study published in the European Heart Journal aimed to establish whether the MedDiet or Western dietary patterns predict adverse outcomes in high-risk patients or in those with stable CHD.
Taken from the Stability trial, a total of 15,482 participants from 39 countries were included in this secondary observational analysis. Participants were either at high risk of CVD or currently had stable CHD. Though the Stability trial was initially designed to assess the risk of adverse CVD events from Darapladib, a lipoprotein inhibitor, the trial also collected dietary information from food frequency questionnaires.
This secondary analysis logged food consumption data into selective food groups and scored them along both the Mediterranean diet score (MDS) and the Western diet score (WDS). The researchers reported that the primary outcome of the study “was the first occurrence of major adverse cardiac events (MACE) defined as non-fatal myocardial infarction, non-fatal stroke, or death from a CV cause during a median follow-up of 3.7 years.”
The results of the study showed that a higher MDS score is significantly associated with lower risk of CVD death, myocardial infarction, stroke and all-cause death. Every one-unit increase in MDS score was associated with a seven-percent reduction in adverse outcomes. The authors suggest that the MedDiet pattern evaluated in this study is similar to the DASH diet and consumption of the healthy foods commonly recommended in dietary guidelines.
According to the analysis, fruits, vegetables, fish, alcohol, dairy foods and tofu/soybean were associated with decreased risk of MACE. Surprisingly, legumes, whole grains, sweetened drinks, refined grains desserts, sweet snacks, and meat showed no association. Therefore, while the MedDiet clearly shows a decreased risk, the Western dietary pattern was not shown to increase risk of adverse outcomes in this study, which was an unexpected result.
The research indicates that dietary advice to increase the consumption of fruits, vegetables and fish may be more important than recommending a reduction of Western dietary foods. While this study could not establish an association between adverse effects on CVD outcomes and typical Western foods, it certainly doesn’t give individuals permission to consume junk food in copious amounts.
As an author of the study, Ralph Stewart, was quoted as saying in the Sydney Morning Herald, “because the assessments were relatively crude, some harm cannot be excluded.” It must also be noted that this is an observational study, which does not show cause and effect.
One thing is clear, the results of this large observational study do show that the dietary advice to include more healthy foods still stands strong. And, on a public health level, placing dietary pattern assessment into routine clinical care for CVD and CHD patients may in fact act as a potent secondary prevention measure.