Applied nutritional investigationSwitching to a 10-day Mediterranean-style diet improves mood and cardiovascular function in a controlled crossover study
Introduction
A high-level consumption of fresh fruit, vegetables, whole grains, and legumes, as well as moderate consumption of oily fish, olive oil, and dairy products, such as milk and yogurt, have been described as a Mediterranean-style diet (MedDi). The MedDi is considered particularly healthy because it contains higher levels of nutrients, such as ω-3 essential fatty acids, magnesium, and vitamins that are associated with better cardiovascular and neurocognitive health [1], [2], [3].
Epidemiologic studies report that greater adherence to the MedDi is associated with reduced risk for developing cardiovascular disease (CVD) [4], type 2 diabetes [5], metabolic syndrome [6], stroke [4], mild cognitive impairment [7], and Alzheimer's disease [8]. In individuals with compromised cardiovascular health, the MedDi has been shown to improve lipid profiles, inflammation, and insulin resistance [5] and to increase levels of cognitive function [9]. These beneficial effects may have the potential to contribute to better management of hypertension, CVD, vascular dementia, Alzheimer's disease, and cognitive decline in clinical samples [10].
Reports of beneficial effects of the MedDi are not restricted to clinical samples, or those with cardiovascular pathology or cognitive deficits. A 24-y longitudinal study found that greater lifetime adherence to the MedDi was associated with lower levels of arterial stiffness at age 36; as well as lower levels of other cardiovascular risk factors, including blood pressure (BP), total cholesterol, and body mass index [11]. These results suggest that following a MedDi during childhood through to adulthood may be associated with decreased risk for CVD. This raises the questions of whether switching to a MedDi also may have health benefits in young, healthy cohorts, including prevention of adverse cardiovascular events associated with a substantial increase in arterial stiffness during adulthood [11].
In addition to cardiovascular health, there is some evidence that following MedDi may benefit cognition. In older, dementia-free individuals, adherence to a MedDi has been associated with a slower rate of global cognitive decline over 7 y [12]. Similarly, antioxidant- and flavanol-rich foods, which are integral components of the MedDi, have been correlated with better performance on individual measures of memory in people aged 55 to 80 y [9]. With regard to younger cohorts, a recent pilot (N = 25) study investigated the effects of a 10-d MedDi intervention on mood and cognitive performance in healthy, young women. In comparison to participants who did not change their diet, those on the MedDi had significantly improved self-reported vigor, contentment, and alertness with decreased levels of depression, anxiety, and confusion. The cognitive effects were mixed with the MedDi condition being associated with faster spatial working memory, but with slower numeric working memory and word recognition [13].
The present study was a partial replication of the previous trial [13]. We adopted a crossover design to limit intrasubject variability and also to allow examination of the effects of a transient diet change. Additionally, we investigated cardiovascular functioning over the same period. Based on previous findings [13], it was hypothesized that switching to a 10-d MedDi would cause improvements in mood, particularly alertness, contentment, and vigor. We were also interested in the extent to which the cognitive effects were consistent from study to study. On the basis of recent observational studies [11], [14], it was also predicted that the MedDi would reduce systolic BP and measures of aortic stiffness, including central aortic pressure.
Section snippets
Design
In partial replication of the earlier study [13], the present study examined the effects of a 10-d diet change intervention on mood, cognition, and cardiovascular functioning utilizing a randomized, balanced, crossover design. The study was approved by the Swinburne University Human Research Ethics Committee, and carried out in accordance with the Declaration of Helsinki.
Participants
Twenty-four healthy women aged 20 to 38 y (mean = 25.6, SD = 5.1) were recruited via social media using the snowball
Participant demographic characteristics
Demographic and morphometric characteristics of the sample are displayed in Table 1. Participants were aged in their mid-20s with BMI within the normal range; brachial systolic pressure was normal across the sample.
Adherence to diet
There were no dropouts during the study. Assessment of the food diaries revealed that all participants met the set MedDi adherence criterion of 80% compliance in the MedDi condition (mean = 94%, range, 80%–100%). However, one participant was excluded due to 91% MedDi compliance in
Discussion
The results of the present study are broadly consistent with those reported in a pilot study [13], with improved alertness and contentment associated with a 10-d MedDi. Cognitive effects were again mixed and not wholly consistent with previous findings, with better secondary memory performance and impaired working memory associated with the 10-d MedDi. Additionally, the MedDi was associated with a significant reduction in augmentation pressure and a trend for reduced systolic BP.
These data
Conclusion
The present study indicates that short-term switching to a MedDi can improve aspects of mood and cardiovascular health in young, healthy women. In light of these findings, future research is needed to further evaluate the psychological benefits of following a MedDi, including comprehensive cognitive assessment, in both healthy and clinical populations.
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Cited by (0)
All authors were responsible for study conception, data-analysis and interpretation. JL, JR, MT, and LV were responsible for data collection. JL, MP, AP, and AS were responsible for drafting the manuscript. All authors approved the final version of the manuscript. No external funding was obtained for the present study. During this project, MPP was funded by a Menzies Foundation Scholarship in Allied Health Sciences. The authors have no conflicts of interest to report.