Applied nutritional investigationEncouraging effects of a short-term, adapted Nordic diet intervention on skin microvascular function and skin oxygen tension in younger and older adults
Introduction
Cardiovascular disease (CVD) is the number one cause of death worldwide with 17.5 million deaths reported in 2012 [1]. Risk factors for developing CVD include inflammatory diseases such as type II diabetes and hypertension, aging, sex, and lifestyle factors such as smoking and poor nutrition [1]. Endothelial dysfunction, a pathologic condition characterized by impaired vasodilation and systemic inflammation [2], is a precursor of acute coronary syndromes, atherosclerosis, and CVD [3]. However, endothelial dysfunction appears to be reversible, and endothelial health can be improved by modifying cardiovascular risk factors [2]. Therefore, emerging literature has sought to investigate the effects of lifestyle modifications as possible treatment strategies [4], and dietary intervention is one lifestyle modification that appears promising [5].
However, dietary interventions are difficult to sustain, and factors such as taste preferences, culinary habits, and social acceptability might contribute to poor long-term adherence [6]. Bere and Brug [7] recommend that strategies that are tailored to regional eating preferences might lead to better long-term success and, interestingly, data are beginning to suggest that regional diets might offer health benefits. Indeed, evidence now suggests that the Mediterranean diet can reduce the risk of CVD [5], alleviate metabolic syndrome [8], reduce blood pressure, and enhance weight loss [9].
The Nordic diet is a regional diet that encourages the consumption of Nordic vegetables and fruits as well as whole grains, fish, rapeseed oil, and low-fat dairy products. Early data suggest that this diet might lead to reduced inflammation [10], improved insulin metabolism [11], and weight loss [6]. The cardiovascular health benefits of the diet are also beginning to appear in the literature: Adamsson et al. [12] demonstrated that a 10-wk intervention led to lower cholesterol, reduced blood pressure, and decreased serum insulin in patients with hypercholesterolemia.
However, to date, the microvascular health effects of Nordic diets have yet to be explored. The integrity of the microcirculation to sustain blood flood, tissue oxygenation, and nutrient delivery affects susceptibility to disease and appears to decline with age [13]. Therefore, the identification of strategies that maintain or improve microvascular function are important for sustaining long-term health.
The aim of this study was to investigate the effects of a short-term, adapted Nordic diet (AND), modified for British taste preferences, on the microvasculature by assessing tissue oxygenation and endothelial function. The circulatory system functions differently at rest and during activity [14], and age-related endothelial dysfunction, characterized by diminished arterial vasodilation and reduced nitric oxide supply, has been observed in older adults [15]. Therefore, we compared the effects of the diet in younger (18–35 y old) and older, sedentary participants (55–75 y old) at rest and during submaximal exercise. We hypothesized that the intervention would improve microvascular health and endothelial function in both groups, with older participants experiencing greater improvements.
Section snippets
Ethical approval
Ethical approval for this research was granted by Sheffield Hallam University's Health and Wellbeing Research Ethics Committee. This research was conducted in accordance with the Declaration of Helsinki.
Participants
A total of 16 young participants ages 18 to 35 y (mean 28 y [standard deviation (SD), 5 y]) and 16 older participants ages 55 to 75 y (mean 64 y [6 y]) provided informed consent. Recruitment took place via posters, word of mouth, and through the emailing systems of Sheffield Hallam University
Participants
Of the 16 young and 16 older participants originally recruited, 13 young (aged 18–35 y) and 15 older (aged 55–75 y) participants completed the study, equating to an 82% and 94% completion rate, respectively. Participants' characteristics are presented in Table 4.
Dietary analysis
Baseline Kcals (young: 1615.2 [645.6]; old: 2595.2 [567.3]; P = 0.14), total fat (young: 61.2 g [22.6]; old: 122.0 g [56.4]; P = 0.03), saturated fat (young: 22.0 g [7.3]; old: 38.5 g [13.8]; P = 0.027), and fiber (young: 15.4 g [4.9];
Discussion
Our study is, to our knowledge, the first to investigate the effects of a short-term AND intervention on endothelial function and tissue oxygenation in adults at rest and during mild-to-moderate exercise. These results highlight the short-term effects of the diet with respect to a number of parameters that define CVD risk and day-to-day function in older and younger individuals. Furthermore, our findings support previous work that elucidated the effects of sedentary aging on cutaneous
Conclusions
This study supports current evidence highlighting the health benefits of regional diets. Our participants were sedentary but observed improvements in body composition and microvascular function by integrating Nordic foods into their diet for a 4-wk period. There is a need to investigate the effects of Nordic-type diets over longer intervention periods, particularly among older individuals (ages 55 + y) who appeared to be less responsive to the intervention in the current study. Age-related
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Sources of support: This study was funded by the University of Sheffield and Sheffield Hallam University. The consumables supplied to the participants were provided by the Iceland Foods Charitable Foundation. No funding body or organization contributed to or influenced the design of the study or the collection, analysis, and interpretation of data or the writing of the manuscript.