Effect of High Stanol Ester Dose on Serum Lipids, Carotenoids and Fat-soluble Vitamins

Several studies have shown that 2-3 g of plant stanols as stanol esters reduce serum total and LDL cholesterol concentrations by 10-15%. There are only a few studies in which cholesterol-lowering effects of plant stanols have been studied with higher doses than that. In these studies with the stanol dose of 4 g/d no additional cholesterol-lowering effect has been reached. However, it would be interesting to know, how effective plant stanols are, if a dose is very high, or whether there is really a threshold effect in inhibition of cholesterol absorption. Plant sterols and stanols have been found to reduce serum β-carotene concentrations. Although they have not been shown to affect serum vitamin A concentrations, a concern has been aroused about safety of high doses of plant sterol and stanols. This is not unjustified, because the number of plant sterol and stanol containing products on the market continues to expand, and therefore, it is possible that the daily intake of plant sterols and stanols can rise very high.

In humans, the metabolism of plant sterols and stanols is not completely known. Recently, we showed that plant sterols are esterified in enterocytes as well as cholesterol facilitating their transport in lipoproteins. However, it is not known, how consumption of high doses of stanol esters affect the metabolism of plant sterols in enterocytes and their transport. This is important to know, when new foodstuffs enriched with plant sterols or stanols for cholesterol-lowering are developed.

In this study, the aim was to investigate the effects of the consumption of high doses of plant stanol esters on concentrations of serum lipids, carotenoids and fat soluble vitamins. In addition, we investigated the metabolism of absorbed plant sterols from intestine without and with the consumption of plant stanol esters.

Altogether 50 subjects with normo- or hypercholesterolemia (total cholesterol 4.5-7.5 mmol/l) were recruited to the study from an announcement in the local newspaper. The study is carried out with a randomized, double-blind and parallel design. The intervention group (n=25) consumes spread and oat drink enriched with plant stanol esters (9 g/d stanols) and the control group (n=25) the same product containing no added stanols for 10 weeks. The fasting blood samples are taken at weeks 0, 9, 10 and 14 (4 weeks after the end of the test product consumption). At week 10, an oral postprandial test is performed in 40 subjects in order to study the postprandial metabolism of plant sterols. From blood samples blood count and levels of serum liver enzymes (0 and 10 wk), concentrations of serum lipids, squalene and non-cholesterol sterols, α and β carotenoids, fat soluble vitamins A, E and D (0, 9 and 10 wk) and serum squalene and non-cholesterol sterols (14 wk) will be analyzed.