Systemic inflammation and oxidative stress are increasingly being associated with obesity and cardiovascular disease. Antioxidants may be protective of cardiovascular disease because they decrease free radical damage to the endothelial lining of the arteries or the susceptibility for low density lipoproteins (LDL) to become oxidised. Alternatively, antioxidant nutrients may cause increases in vitamin C levels via recycling processes, and this in turn may provide improved vitamin C status in endothelial cells which strengthens collagen and decreases arterial lining permeability thus preventing scurvy like micro-bleeding. A number of antioxidants have been shown to possess benefits against the development of cardiovascular disease including vitamin C, vitamin E, flavonoids and carotenoids. Red wine is a complex chemical mixture of various chain-breaking antioxidants that shown possible benefits against a number of diseases if drunk regularly. Red wine may prevent lipid peroxidation in LDL particles because of its phenolic and alcohol content.
Researchers1 have investigated the effects of consuming red and white wine on the ability to protect LDL particles and plasma from lipid peroxidation. Seventeen healthy subjects were administered 400mL/d red or white wine containing 11% alcohol for 2 weeks. The results showed that red wine reduced the propensity for the plasma to undergo lipid peroxidation by around 20% after plasma was exposed to artificial free radical generating mechanisms [thiobarbituric acid reactive substance (TBARS) assay] in vitro. In addition the red wine reduced the propensity for LDL to undergo lipid peroxidation as measured by a 46, 72 and 54% decrease in the content of TBARS, lipid peroxides and conjugate diones in LDL particles, respectively. Red wine also prolonged the duration before lipid peroxidation occurred in the LDL particles. In contrast white wine consumption increased the propensity for plasma peroxidation by 34% and LDL peroxidation by 41%.
These results suggest that the beneficial effects of red wine with regard to the prevention of lipid peroxidation may result from components present in red wine but absent from white wine. The red colour in red wine is caused by high concentrations of phenolic substances present in the skins of the grapes and these have been shown to have powerful in vitro and in vivo antioxidant effects. For example, red wine contains 1.4g/L of quercetin equivalents compared to 0.25g/L in white wine. In this study the total phenolic concentration of LDL was elevated 4-fold after the 2 weeks of red wine supplementation, which was associated with a 2.3-fold decrease in the susceptibility for copper induced lipid peroxidation. This suggests that phenolic antioxidants may be the reason for the beneficial effects, and this is in agreement with other studies.
Alcohol is known to increase high density lipoprotein (HDL) concentrations in plasma, but after 2 weeks in this study only the subjects consuming red wine showed elevated HDL levels. Previous studies have shown that HDL concentrations rise after 3 weeks of alcohol consumption, and the shorter-duration of this study may therefore have prevented this. The pro-oxidant effects of white wine in this study may relate to the oxidative stress caused by alcohol consumption, in combination with the low phenolic content that allowed oxidation to proceed. However, other studies have shown beneficial effects of white wine against lipid peroxidation, and this may relate to the type of wine chosen in the studies, or perhaps the antioxidant status of the subjects. Alcohol has also been shown to decrease linoleic acid (LA, C18:2 (n-6)) in plasma membranes and to increase palmitic acid which could decrease the susceptibility of membranes to lipid peroxidation.
RdB
