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Modulation of oxidative stress biomarkers by rooibos in adults at risk of developing coronary heart disease
Author(s)
Muiruri, Macharia
Date Issued
2008
Type
Thesis
Publisher
Cape Peninsula University of Technology
Abstract
Observational studies link higher intake of polyphenols from plant based foods and
beverages with a lower risk of cardiovascular disease (CVD) which remains the leading
cause of death in the world. Although the mechanisms explaining this observation remains
unclear, research suggest that polyphenols, with their potent antioxidant properties, may
decrease oxidative stress by impairing the oxidation of lipids. Increased oxidation of lipids,
particularly low density lipoproteins, is recognised as an important risk factor in coronary
heart disease. Attention has focussed on dietary sources with antioxidant potential that
are capable of modulating the body’s oxidative stress via various modes for example
increasing the antioxidant capacity or shifting the antioxidant redox status.Rooibos (Aspalathus linearis) has been shown to possess potent antioxidant, immunemodulating
and chemopreventive actions in various in vitro, ex vivo and animal models
and consequently has been suggested to be potentially beneficial to human health. The
aim of this study was to investigate the effect of rooibos consumption on parameters of
oxidative stress and redox status in blood of humans at risk for coronary heart disease. A
fourteen-week dietary intervention study was conducted in which forty volunteers
consumed six cups of rooibos tea daily for six weeks which was preceded by a 2-week
baseline and 2-week washout period and followed by a 4-week control period when water
was consumed. Before and after the intervention, several parameters were measured
including indices of antioxidant activity, lipid peroxidation (LPO) antioxidant redox status
(ratio of reduced to oxidised glutathione i.e. GSH: GSSG) and antioxidant content. Plasma
antioxidant capacity was not affected by the 6-week rooibos intake but total polyphenols
were significantly (P<0.05) raised by 11 %. Significant (P<0.05) decreases were reported
in markers of LPO (conjugated dienes and malondialdehyde), total cholesterol, low
density lipoprotein-cholesterol as well as oxidized glutathione. Reduced glutathione as
well as the ratio GSH:GSSG were both significantly (P<0.05) increased by the rooibos
intervention compared to the control phase. Rooibos consumption did not cause any
adverse effects in the study participants and neither were the serum iron levels alteredThese results suggest that rooibos consumption may impair lipid peroxidation in the body
and therefore play a beneficial role in cardiovascular health in humans. In addition, the
results confirm the safety of short term consumption of rooibos with regards to liver and
kidney function as no toxicity was associated with its intake.
beverages with a lower risk of cardiovascular disease (CVD) which remains the leading
cause of death in the world. Although the mechanisms explaining this observation remains
unclear, research suggest that polyphenols, with their potent antioxidant properties, may
decrease oxidative stress by impairing the oxidation of lipids. Increased oxidation of lipids,
particularly low density lipoproteins, is recognised as an important risk factor in coronary
heart disease. Attention has focussed on dietary sources with antioxidant potential that
are capable of modulating the body’s oxidative stress via various modes for example
increasing the antioxidant capacity or shifting the antioxidant redox status.Rooibos (Aspalathus linearis) has been shown to possess potent antioxidant, immunemodulating
and chemopreventive actions in various in vitro, ex vivo and animal models
and consequently has been suggested to be potentially beneficial to human health. The
aim of this study was to investigate the effect of rooibos consumption on parameters of
oxidative stress and redox status in blood of humans at risk for coronary heart disease. A
fourteen-week dietary intervention study was conducted in which forty volunteers
consumed six cups of rooibos tea daily for six weeks which was preceded by a 2-week
baseline and 2-week washout period and followed by a 4-week control period when water
was consumed. Before and after the intervention, several parameters were measured
including indices of antioxidant activity, lipid peroxidation (LPO) antioxidant redox status
(ratio of reduced to oxidised glutathione i.e. GSH: GSSG) and antioxidant content. Plasma
antioxidant capacity was not affected by the 6-week rooibos intake but total polyphenols
were significantly (P<0.05) raised by 11 %. Significant (P<0.05) decreases were reported
in markers of LPO (conjugated dienes and malondialdehyde), total cholesterol, low
density lipoprotein-cholesterol as well as oxidized glutathione. Reduced glutathione as
well as the ratio GSH:GSSG were both significantly (P<0.05) increased by the rooibos
intervention compared to the control phase. Rooibos consumption did not cause any
adverse effects in the study participants and neither were the serum iron levels alteredThese results suggest that rooibos consumption may impair lipid peroxidation in the body
and therefore play a beneficial role in cardiovascular health in humans. In addition, the
results confirm the safety of short term consumption of rooibos with regards to liver and
kidney function as no toxicity was associated with its intake.
Additional information
Thesis (MTech (Biomedical Technology))--Cape Peninsula University of Technology, 2008
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