Phytosterol

Phytosterols, also called phytosterols, are a group of chemical compounds found in plants from the class of sterols. They differ from the animal zoosterols and Mycosterinen fungi by a double bond at C- 22 and C1 or C2 - substituent at C -24. The hydrated forms ( 5α - hydrogenation ) of the respective phytosterols are referred to as stanols. The phytosterols are free in the plants, in ester or glycoside form and on the unsaponifiable component of vegetable fats and oils. The most common plant sterols are stigmasterol, β - sitosterol and campesterol. Phytosterols function as structural components in the cell membrane of plants, similar to the cholesterol in cell membranes of animals, but which is not a phytosterol itself since it does not occur in plants.

Occurrence

Phytosterols are mainly found in fatty parts of plants. Particularly rich they are contained in sunflower seeds, wheat germ, sesame and soybeans and pumpkin seeds. By processing, such as Refining of oils, they lose a large part of their salary. Valuable are therefore particularly untreated virgin oils, fats and seeds.

Phytosterols can be commercially obtained from soybean or from softwoods as a byproduct of the paper making (Finland). A particularly rich source of phytosterols are the unsaponifiable matter of vegetable fats and oils, as well as obtained in the refining of vegetable fats / oils -products.

β -sitosterol is in the normal dietary phytosterol most represented with about 65%. Other sterols are stigmasterol and campesterol. An important representative of stanols is the stigmastanol.

The absorption and metabolism

In normal, Western European diet 160-360 mg of phytosterols are added daily. Vegetarians come to approximately double the amount. This is also reflected in the higher sitosterol concentration reflected in the serum of vegetarians. 5-10% of the amount consumed is absorbed (taken in the intestine ), the rest is excreted with the feces. The absorbed fraction is excreted via the bile.

The plant sterol concentrations in serum are sufficiently far below those of cholesterol and fluctuate with normal diet from 0.3 to 1.7 mg / dl.

Phytosterols as active ingredients

Mechanism of action

As a mechanism of action of a competitive inhibition of cholesterol absorption in the intestine is assumed, ie by the presence of phytosterols, the absorption of cholesterol is reduced. Since cholesterol is however produced food regardless of body about 90% of itself, occurs as a result of a Phytosterinaufnahme an increased endogenous ( body's own ) synthesis. However, it comes to an overall slight reduction in total and LDL cholesterol ( partial compensation ).

In addition to the reduced absorption appear still other mechanisms - an accelerated excretion of absorbed sterols and others - to play a role. Phytosterols reduce total and LDL - cholesterol irrespective of whether the individual has normal or elevated blood lipids. Phytosterols cause the same effect in men and women and act independent of age.

Triglycerides and HDL cholesterol remain unchanged. Unless checked, all clinical parameters except for serum cholesterol ( ALT, AST, hemoglobin, glucose, serum proteins, serum bilirubin ) remain unimpaired.

Phytosterols have due to their strong similarity to cholesterol itself atherogenic (atherosclerosis triggering ) potential. At what concentration of this atherogenic potential comes in place, is currently controversial.

Dosage

As an effective minimum applies the intake of 2 g per day. This amount can be caused by the consumption of 100 ml yogurt drink (enriched with 1.6 g plant sterols ) or 20-30 g fat spread / margarine with phytosterols (usually about 10%) in addition to those taken with a normal mixed diet from 0.2 to 0, 4 g per day can be achieved.

Side effects, interactions, toxicity

In virtually all studies, no influence on other metabolic parameters was observed except for the reduction of total cholesterol and LDL - cholesterol. Phytosterols show an additive effect with statins and other cholesterol -lowering agents with respect to the reduction of blood lipids. Experience has shown can be obtained by doubling the statin dose, an additional LDL - cholesterol reduction by 6-8 %. Through a combination therapy ( statin phytosterinangereicherter eg yogurt) in LDL cholesterol can be lowered by 10%.

So far there is no study such as Becel clearly demonstrated an adverse effect on health of food products enriched with phytosterols in individuals without Phytosterinämie. However, according to the latest findings plant sterols can also have negative effects on vascular health and therefore do not have the heart protective effect, with which they are advertised. Play an important role in genetic polymorphisms that have an impact on the plant sterol absorption. Your sponsorship is on the one hand with increased Phytosterinspiegeln in the blood and at the same time connected with an increased cardiovascular risk.

Influence on other fat-soluble nutrients

There is evidence that phytosterols interfere with the absorption of fat- soluble vitamins. Thus, decreased carotene, vitamin E ( α -tocopherol) and Lycopenspiegel were found.

The intake of vitamin D is not affected.

Effect of purchasable Phytosterinprodukte

The cholesterol-lowering effect of plant sterols was first described in 1951 and subsequently confirmed by numerous clinical studies. Thus can be explained by the addition of 1-4 g of phytosterols per day, a dose-dependent LDL - cholesterol reduction by 5-15 % of the initial values ​​reach. The market enriched with phytosterols foods ( yogurt drink, margarine ) are available now.

Several randomized, placebo-controlled studies demonstrate the improvement of the lipid profile after the 6-week consumption of phytosterols with (1.6 g per serving) -enriched yogurt drinks. Within 3 weeks, the LDL - cholesterol decreased in the phytosterol group compared with placebo by up to 12.2%, within 6 weeks by up to 10.6%. HDL - cholesterol and triglyceride levels showed no significant changes.

20 g fat spread with 2-3 g of sterols can reduce cholesterol levels by an average of 6-10 %.

The efficacy on relevant clinical endpoints ( such as the reduction in mortality from heart attacks and strokes ) is missing.

Indication

An indication that the intake of phytosterols only hypercholesterolemia is called in adults so far.

Contraindication

To identify potential hypovitaminoses (A and E) to prevent children under 5 years, pregnant women and nursing mothers should not consume enriched with phytosterols products.

Phytosterinämie

Is a very rare recessive genetic disorder of Phytosterinaufnahme. In the presence of Phytosterinämie significantly more sterols are absorbed ( 50-60% of Nahrungssterine ). Sufferers should limit the intake of phytosterols as far as possible.

Criticisms

Abbreviated summary of criticisms and concerns of the EFSA (European Food Safety Authority):

• The maximum amount of sterols should not exceed 3 g per day.
• Possible risk of carotene deficiency
• Special hazards People with Phytosterinämie
• Patients on cholesterol-lowering medication
• Nursing mothers
• Pregnancy