Introducing their study, published in the August issue of Food Research International, Alemany-Costa et al. noted that foods enriched with plant sterols (PS) (including phytosterols and phytostanols) may help reduce LDL cholesterol levels.
Citing other studies, they said that PS consumption of 2g/day resulted in a cholesterol reduction of around 9%, exerts beneficial effects upon other lipid variables, and had been described as anti-inflammatory and anti-cancer compounds.
Yet like all unsaturated lipids, phytosterols were liable to oxidation, Alemany-Costa and colleagues noted, giving rise to phytosterol oxidation products (POPs), “compounds known to be implicated in the initiation and progression of major chronic diseases”.
Biological effects unclear
These included atherosclerosis, neurodegenerative processes, diabetes and others, the scientists wrote, although they said “the biological effects of POPs are still unclear”.
For the present study, the team used two different plant sterol (PS) ingredients in the manufacture of two types of functional beverage, one a milk-based fruit drink, the other a fruit beverage.
One PS ingredient was drawn from tall oil (a wood pulp byproduct), the other was esterified from soybean, rapeseed, sunflower and corn oils, and both were formulated into a powder form.
PS profile and contents in analyzed samples conformed to current legislation, the scientists found, and reflected differences previously reported among diverse commercially available ingredients used for PS enrichment.
Only POPs corresponding to β-sitosterol were detected (7α-hydroxysitosterol, 7β-hydroxysitosterol, α- and β-epoxysitosterol and 7-ketositosterol), showing its status as the main sterol in the two drinks.
The team found that total POP amounts found ranged between 42.9 mg/100 g of PS in the milk-based fruit beverage sample and 57.4 mg/100 g of PS in the fruit-based beverage.
Mean β-sitosterol oxifation percentage was around 0.07%, Alemany-Costa and colleagues said, reflecting limited PS oxidation in the drinks, although they noted their production in lab conditions.
“In summary, the present paper for the first time offers information on the PS and POP contents in PS-enriched milk-based fruit beverages and fruit beverages, regarded as functional foods,” the scientists wrote.
“Further studies are needed to evaluate PS stability and POP contents in enriched foods, and their relation to the enrichment source used, as well as the physiological effects that may result from their consumption.”
Title: ‘Sterol stability in functional fruit beverages enriched with different plant sterol sources’
Authors: L.Alemany-Costa, M. Gozalez-Larena, G.Garcia-Llatas, A.Alegria, R.Barbera, L.M Sanchez-Siles, M.J Lagarda.
Source: Food Research International (Volume 48, Issue 1) August 2012, http://dx.doi.org/10.1016/j.foodres.2012.05.005