While the cholesterol lowering abilities of phytosterols are well established, lead to a range of products thickly spread on supermarket shelves, some questions had remained unanswered regarding the ingredient’s affects on antioxidant levels in the body – it is know that phytosterols may decrease levels of fat-soluble vitamins.
According to results of a new randomised parallel trial from Valencia, Spain, while a reduction in the levels of some antioxidants were observed, no overall detrimental effect on antioxidant defences was observed.
Phytosterols, cholesterol-like molecules derived from plants, are increasingly well known to consumers due to their scientifically proven ability to reduce cholesterol levels. As consumer awareness has increased, the number of products containing plant sterols or plant stanols and their esters has increased.
Numerous clinical trials in controlled settings have reported that daily consumption of 1.5 to 3 grams of phytosterols/-stanols from foods can reduce total cholesterol levels by eight to 17 per cent, representing a significant reduction in the risk of cardiovascular disease.
“Our results confirm and extend the positive effect of including a PS supplement in dietary measures by demonstrating that it reduces the lipoprotein-mediated risk of cardiovascular disease,” wrote the authors, led by Celia Banuls from University Hospital Dr. Peset and CIBER Actions in Epidemiology and Public Health.
“The phytosterol-mediated decrease in fat-soluble antioxidants does not lead to a global impairment of antioxidative defences or an enhancement of oxidative stress, although it does impede improvement in the resistance of LDL cholesterol particles to oxidation associated with dietary therapy,” they added.
Using a phytosterol-enriched milk provided by Unilever, the effects of three-months of supplementation was investigated in 40 people with high cholesterol levels. Banuls and her co-workers randomly assigned the participants to receive 2 grams of phytosterol-enriched low-fat milk, or a plain low-fat milk, for three months.
People consuming the phytosterols experienced a 6.4 per cent reduction in their total cholesterol levels, a 10 per cent reduction in LDL cholesterol levels, and a 5 per cent reduction in the ratio of apolipoprotein B to apolipoprotein A-I (apo B/apo A-I), said by some to be a better marker of coronary heart disease risk than lipid concentrations or lipid ratios.
Apo B is the main apolipoprotein of LDL cholesterol and is responsible for the transport of cholesterol to tissues. On the other hand, apo AI is the main apolipoprotein for HDL cholesterol.
When the researchers looked at antioxidant levels, they only observed a 29 per cent decrease in levels of cryptoxanthin level. No changes were observed in the antioxidant capacity of LDL cholesterol particles, total antioxidant status or lipid oxidation, they said.
Furthermore, no adverse effects were reported after three months of consuming the phytosterols in the low-fat milk.
“Despite a decrease in the concentration of cryptoxanthin, no evidence of a global impairment of antioxidative defences or an enhancement of oxidative stress parameters was found,” wrote the researchers.
“Thus, this approach would seem to represent a useful additional therapeutic measure to the classic low cholesterolemic diet when aiming to reduce cardiovascular risk,” they concluded.
According to recent research from Frost & Sullivan, phytosterols are one the ‘big four’ ingredients that dominate the heart health market – the others being omega-3s, beta-glucans, and soy protein.
Source: The Journal of Nutritional Biochemistry
Published online ahead of print,
“Evaluation of cardiovascular risk and oxidative stress parameters in hypercholesterolemic subjects on a standard healthy diet including low-fat milk enriched with plant sterols”
Authors: C. Banuls, M.L. Martinez-Triguero, A. Lopez-Ruiz, C. Morillas, R. Lacomba, V.M. Victor, M. Rocha, A. Hernandez-Mijares