The impact of a vegetarian diet and fasting on cardiovascular parameters
Date
2018-06-21
Authors
Phukubje, Edgar Matome
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Abstract
It is widely known that a fruit and vegetable based diet is associated with a reduction in blood pressure (BP) in European/ Western countries. However, information about the effects of a short-term fruit and vegetable fasting diet on BP and arterial stiffness in sub-Saharan countries such as South Africa remains uncertain. Hence the focus of this study was to investigate the impact of a fruit and vegetable fasting diet on BP and pulse wave velocity (PWV); a measure of arterial stiffness. Our study was divided into two parts. For the first part of the study, 39 participants of African ancestry who were on a religious fruit and vegetable fasting diet for three weeks were recruited. The impact of a fruit and vegetable fasting diet on serum and urinary electrolytes on BP and PWV were assessed. For the second part of the study, 625 participants from the same population group were recruited to look at the crosssectional relationship between urinary electrolytes on BP and arterial stiffness. The 21-day fruit and vegetable based fast did not produce any significant changes in serum sodium (Na+), potassium (K+) and magnesium (Mg2+) concentrations (all P>0.05). However, serum calcium (Ca2+) concentrations were significantly increased after the fruit and vegetable fasting diet (p=0.0299). Furthermore, total cholesterol (TCHOL) and low-density lipoproteins (LDL) were also significantly decreased after the fruit and vegetable fasting diet (p=0.0148 and p=0.0423 respectively). The 21day fruit and vegetable based fast did not produce any significant changes in bodyweight, BMI, waist circumference and WHR; all P>0.05). Urinary Na+ excretion concentrations of twenty-four hours (p<0.0001), daytime (p=0.0277) and night-time (p=0.0212) were significantly reduced after the fruit and vegetable fasting diet. Twenty-four hour urinary Ca2+ (p=0.0168) and Ca2+/Mg2+ (p=0.0096) were also significantly reduced after the fruit and vegetable fasting diet. The fruit and vegetable fasting diet had a significant effect on systolic blood pressure (SBP) and PWV as both were reduced (p=0.0150 and p=0.0419 respectively). In the large crosssectional study, both systolic BP (C_SBP) and diastolic BP (C_DBP) were significantly associated with arterial stiffness (both P<0.0001). A multivariate regression analysis showed that C_SBP was significantly associated with dietary K+, Mg2+ and Na+ (r2= -0.13, p=0.0464; r2= -0.14, p=0.0336 and r2= 0.16, p=0.0125 respectively). C_DBP was only associated with K+ (r2= -0.10, p=0.0222). Both Na+ and Mg2+ were independently associated with arterial stiffness (r2= 0.24, p=0.0005
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and r2= -0.18, p=0.0080 respectively). Since both BP and arterial stiffness are determined by nutrients found mainly in fruits and vegetables, the findings of this study indicate the significant role of a fruit and vegetable fasting diet in the management and control of HT and in preventing large artery pathology.
Description
A dissertation submitted to the Faculty of Health Sciences, University of the Witwatersrand, in fulfilment of the requirements for the Degree of Master of Science in Medicine, Johannesburg 2018