PHYTOSTEROLS INHUMANNUTRITION

Abstract

Phytosterols are cholesterol-like molecules found in all plant foods, with the highest concentrations occurring in vegetable oils. They are absorbed only in trace amounts but inhibit the absorption of intestinal cholesterol including recirculating endogenous biliary cholesterol, a key step in cholesterol elimination. Natural dietary intake varies from about 167-437 mg/day. Attempts to measure biological effects in feeding studies have been impeded by limited solubility in both water and fat. Esterification of phytosterols with long-chain fatty acids increases fat solubility by 10-fold and allows delivery of several grams daily in fatty foods such as margarine. A dose of 2 g/day as the ester reduces low density lipoprotein cholesterol by 10%, and little difference is observed between Delta(5)-sterols and 5alpha-reduced sterols (stanols). Phytosterols can also be dispersed in water after emulsification with lecithin and reduce cholesterol absorption when added to nonfat foods. In contrast to these supplementation studies, much less is known about the effect of low phytosterol levels in the natural diet. However, reduction of cholesterol absorption can be measured at a dose of only 150 mg during otherwise sterol-free test meals, suggesting that natural food phytosterols may be clinically important. Current literature suggests that phytosterols are safe when added to the diet, and measured absorption and plasma levels are very small. Increasing the aggregate amount of phytosterols consumed in a variety of foods may be an important way of reducing population cholesterol levels and preventing coronary heart disease.

Influence of production system, age an sex on carcass parameters and some biochemical meat quality characteristics of reindeer (Rangifer tarandus tarandus L.)

“…To our knowledge there is no available data on squalene in lichens. Squalene is a natural triterpene and the precursor for phytosterols (Bosku, 2000;Ostlund, 2002), and therefore is suggested to be present in trace amounts in most green plants containing phytosterols. Significant amounts of plant-derived squalene are detected in olive oil, wheat germ oil, bran oil and yeast (Bosku, 2000), as well as in Amaranthus grain and Echium plants (He et al, 2002).…”

“…However, when the amount of squalene is calculated as the total amount of squalene per g meat, the levels are very similar for animals from all treatments (~ 0.02 g/100 g meat). This suggests that the feed is partly responsible for the presence of squalene in the meat, since squalene is present in plant and animal tissue as a key intermediate in the biosynthesis of steroids (He et al, 2002;Ostlund, 2002). There may be a predetermined level for squalene in the muscle, due to its role in the biosynthesis of cholesterol.…”

Impact of Protein Gel Porosity on the Digestion of Lipid Emulsions

“…The overconsumption of highly appealing energy dense foods is seen by some as a key contributor to this issue, and the consumption of diets rich in lipids is often cited as a leading cause of obesity (2). However, lipids are a good source of energy, essential fatty acids and play an important role in the absorption of micronutrients (vitamins, minerals), anti-nutrients (cholesterol) and class II pharmaceuticals (3)(4)(5)(6)(7)(8). What is unknown is how much the balance of the role of fat in our diet is evolutionary or environmental.…”

Similar serum plant sterol responses of human subjects heterozygous for a mutation causing sitosterolemia and controls to diets enriched in plant sterols or stanols

“…Phytosterols such as b-sitosterol and campesterol are plantderived sterols that are structurally similar to cholesterol (Law, 2000;Ostlund, 2002). Although phytosterols and cholesterol are absorbed by the same principle mechanism, it is remarkable that the absorption rates for plant sterols and their hydrogenated derivatives, stanols, are much lower than those for cholesterol (Salen et al, 1992b;Heinemann et al, 1993;Ostlund et al, 2002).…”