Sucrose polyesters (SPE) are a synthetic non-absorbable mixture of hexa-, hepta- and octa-fatty acids that were developed as a weight loss product. Sucrose polyesters have an appearance much like other dietary lipids, but are not absorbed in the small intestine. Sucrose polyesters are thought to inhibit fat and other lipid absorption and thus it was initially suggested that this may have weight loss effects. However, as well as limiting the absorption of dietary triglycerides, the SPEs also limit the absorption of fat soluble vitamins and so concerns surrounding their long term use have been expressed. Further, as they inhibit fat absorption in the small intestine, this fat passess to the colon and is excreted in the faeces producing unpredictable loose stools that make their use intolerable by many. Studies have also shown that as well as triglycerides, SPE can also limit the absorption of cholesterol and may inhibit the metabolism of dietary cholesterol and plant sterols by the colonic microflora.
The effects of SPE were investigated extensively in the 1980s when they were developed. For example, one study1 examined the effects of SPE on faecal bile acid excretion in healthy non-obese subjects with normal cholesterol levels. The study was conducted over 40 days and the subjects were fed isocaloric diets containing either 800, 300 or less than 50 mg of cholesterol per day (theses diets provided a polyunsaturated to saturated fatty acid ratio of 0.4, 1.0 and 1.5, respectively). Subjects followed their diets for 10 days before being administered SPE at 8 grams per day for 10 days, and this was followed by two subsequent SPE supplementation periods of 10 days containing 16 and 35 mg of SPE respectively. The results showed that the consumption of the SPE had no effects on the excretion of bile acids in the subjects at any of the dosages administered or any of the cholesterol levels. The authors concluded that there were no significant consistent effects in any of the subjects from the SPE supplements.
Therefore the effects of SPE on cholesterol metabolism that have been shown elsewhere seem not to be mediated through an increase in the excretion of bile acids. This suggests that SPE have an inhibitory effect on the absorption of cholesterol and that this cholesterol is then excreted from the body in the faeces. This is in contrast to the effects of dietary fibres, which have similar cholesterol lowering effects, but which accomplish this probably through an increase in bile acid excretion. Some of the subjects in the study experienced a change in the composition of the bile acids characterised by a decrease in lithocholic acid, which is a bacterial degradation product of the bile salt chenodeoxycholic acid. This indicated a decrease in the conversion of chenodeoxycholic acid to lithocholic acid in the colon through bacterial action. Therefore SPE may decrease the metabolism of primary bile acids to secondary bile acids through interference with bacterial degradation.
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